CN115528739B

CN115528739B - Parallel operation synchronization method and system for single-phase inverter, single-phase inverter and storage medium

Info

Publication number: CN115528739B
Application number: CN202211265967.3A
Authority: CN
Inventors: 焦凌云; 田永立; 曹会平; 赵子龙; 贾振杰
Original assignee: Shijiazhuang Tonghe Electronics Co Ltd
Current assignee: Shijiazhuang Tonghe Electronics Co Ltd
Priority date: 2022-10-17
Filing date: 2022-10-17
Publication date: 2025-07-29
Anticipated expiration: 2042-10-17
Also published as: CN115528739A

Abstract

The present invention provides a single-phase inverter parallel synchronization method and system, a single-phase inverter, and a storage medium. The method includes: determining whether the mains power is normal; if the mains power is normal, correcting a first quasi-tracking phase angle based on high and low level signals corresponding to the mains power, and performing phase synchronization on the current phase angle of the single-phase inverter according to the corrected first quasi-tracking phase angle; if the mains power is abnormal, and the single-phase inverter is the master or has seized the master position, generating a synchronization signal according to the phase of the single-phase inverter, and sending the synchronization signal to each slave; if the mains power is abnormal and the single-phase inverter is the slave, correcting a second quasi-tracking phase angle according to the synchronization signal, and performing phase synchronization on the current phase angle of the single-phase inverter according to the corrected second quasi-tracking phase angle. Based on the present invention, parallel synchronization of all single-phase inverters connected in parallel can be achieved, and the reliability and stability of the operation of the single-phase inverter parallel synchronization system can also be effectively improved.

Description

Parallel operation synchronization method and system for single-phase inverter, single-phase inverter and storage medium

Technical Field

The invention relates to the technical field of parallel application of inverters, in particular to a parallel operation synchronization method and system of a single-phase inverter, the single-phase inverter and a storage medium.

Background

With the rapid development of inverter technology, the requirements on the capacity, performance and reliability of a power supply system are higher and higher, and as the power supply system requires higher and higher power, more and more products start to increase the parallel operation function so as to meet the requirements of high power and redundancy of modular design.

In the prior art, in order to realize parallel operation between inverters, the consistency of the amplitude, the frequency and the phase of the output voltage of each inverter must be ensured, and the current implementation of the phase following of the output voltage of the inverter is generally based on a second-order generalized integrator (Second Order Generalized Integrator, SOGI) and coordinate transformation operation, however, since the SOGI operation cannot completely filter harmonic content caused by interference of a sampling circuit contained in the commercial power, the phase-locked angle obtained by phase following calculation has deviation.

However, the phase-locked angle has deviation, which can cause the phase of each inverter to be asynchronous, further can cause the circulation of the inverter to be increased and even damage the machine, so that the phase following link in the parallel operation system of the inverter is very critical for the reliable and stable operation of the parallel operation system of the inverter.

Disclosure of Invention

The embodiment of the invention provides a parallel operation synchronization method and system of a single-phase inverter, the single-phase inverter and a storage medium, and aims to solve the problem that in the prior art, the calculation accuracy of a phase-locked angle is affected by harmonic content caused by interference of a sampling circuit contained in commercial power, so that the parallel operation phase of each inverter is asynchronous.

In a first aspect, an embodiment of the present invention provides a single-phase inverter parallel synchronization method, where the single-phase inverter parallel synchronization method is applied to each single-phase inverter in a single-phase inverter parallel synchronization system including at least two single-phase inverters connected in parallel;

The parallel operation synchronization method of the single-phase inverter comprises the following steps:

Judging whether the commercial power is normal or not;

If the mains supply is normal, correcting a first to-be-tracked phase angle according to a high-low level signal output by a zero-crossing detection unit in the single-phase inverter to obtain a first to-be-tracked phase angle correction value, and carrying out phase synchronization on the current phase angle of the single-phase inverter according to the first to-be-tracked phase angle correction value;

If the commercial power is abnormal and the single-phase inverter is a master machine, or if the commercial power is abnormal and the single-phase inverter is a slave machine and the single-phase inverter is preempted to a master machine position in the single-phase inverter parallel synchronization system, generating a synchronization signal according to the phase of the single-phase inverter, and sending the synchronization signal to each slave machine in the single-phase inverter parallel synchronization system;

And if the commercial power is abnormal and the single-phase inverter is a slave machine, correcting a second to-be-tracked phase angle according to the synchronous signal after receiving the synchronous signal sent by the master machine in the single-phase inverter parallel operation synchronous system, obtaining a second to-be-tracked phase angle correction value, and carrying out phase synchronization on the current phase angle of the single-phase inverter according to the second to-be-tracked phase angle correction value.

In a second aspect, an embodiment of the present invention provides a single-phase inverter, including a control unit, a zero-crossing detection unit, and an output isolation unit;

the control unit comprises a memory for storing a computer program, a processor for calling and running the computer program, performing the steps of the method as described above in the first aspect or any possible implementation of the first aspect;

The input end of the zero-crossing detection unit is used for being connected with the mains supply, the output end of the zero-crossing detection unit is connected with the input end of the control unit, the output end of the control unit is connected with the input end of the output isolation unit, and the output end of the output isolation unit is connected with the CAP port of the control unit.

In a third aspect, an embodiment of the present invention provides a parallel operation synchronization system for a single-phase inverter, including at least two single-phase inverters as described in the second aspect above;

the output end of the output isolation unit in each single-phase inverter is connected with the CAP port of the control unit in other single-phase inverters.

In a fourth aspect, embodiments of the present invention provide a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the method as described above in the first aspect or any one of the possible implementations of the first aspect.

The embodiment of the invention provides a single-phase inverter parallel synchronization method and system, a single-phase inverter and a storage medium, wherein the single-phase inverter parallel synchronization method is applied to each single-phase inverter in a single-phase inverter parallel synchronization system comprising at least two single-phase inverters connected in parallel; the method comprises the steps of judging whether mains supply is normal, correcting a first to-be-tracked phase angle according to a high-low level signal output by a zero-crossing detection unit in a single-phase inverter to obtain a first to-be-tracked phase angle correction value, carrying out phase synchronization on a current phase angle of the single-phase inverter according to the first to-be-tracked phase angle correction value, obtaining a second to-be-tracked phase angle correction value according to the synchronization signal after the mains supply is abnormal and the single-phase inverter is a master or after the mains supply is abnormal and the single-phase inverter is a slave and the single-phase inverter is preempted to a master position in a single-phase inverter parallel synchronization system, generating a synchronization signal according to the phase of the single-phase inverter and sending the synchronization signal to each slave in the single-phase inverter parallel synchronization system, and carrying out phase synchronization on the current phase angle of the single-phase inverter according to the second to-be-tracked phase angle correction value after the mains supply is abnormal and the single-phase inverter is a slave and the synchronization signal sent by the master in the single-phase inverter parallel synchronization system is received. In the embodiment of the invention, the phase of the standard phase angle corresponding to the mains voltage or the single-phase inverter serving as a host is used as the target phase followed by the phase of each single-phase inverter, each single-phase inverter adjusts the own phase based on the standard phase angle until the own phase of each single-phase inverter and the phase corresponding to the standard phase angle meet the preset condition, and the parallel synchronization of all the single-phase inverters connected in parallel is realized, and the parallel synchronization of each single-phase inverter is not realized through the mains self/sampling circuit, so that the problem that the phase-locked angle deviation is possibly caused by the harmonic content caused by the interference of the mains self/sampling circuit is also effectively avoided, and the reliable operation of the parallel synchronization system of the single-phase inverter is further improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a flowchart of an implementation of a parallel operation synchronization method of a single-phase inverter provided by an embodiment of the present invention;

fig. 2 is a parallel operation synchronization flow chart of a parallel operation synchronization method of a single-phase inverter provided by an embodiment of the present invention;

Fig. 3 is a phase following flow chart of a parallel operation synchronization method of a single-phase inverter provided by an embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a single-phase inverter according to an embodiment of the present invention;

Fig. 5 is a schematic structural diagram of a parallel operation synchronization system of a single-phase inverter according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a parallel operation synchronization device of a single-phase inverter according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a control unit according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the following description will be made by way of specific embodiments with reference to the accompanying drawings.

In the prior art, single-phase ac phase locking techniques are generally as follows:

(1) The alternating current signal is subjected to SOGI operation to obtain an in-phase signal alpha and a quadrature signal beta.

(2) The in-phase signal transfer function formula in the SOGI operation is: Wherein H _d(s) represents a transfer function of an in-phase signal, k represents a closed loop coefficient, k is generally 1.414 in engineering, ω _n represents a resonance frequency of the SOGI, ω _n =2pi f, s represents a characteristic parameter in a transfer function obtained from laplace transform, and a formula of a quadrature signal transfer function is: Where H _q(s) represents the transfer function of the quadrature signal.

(3) The above-obtained in-phase signal α and quadrature signal β are defined as: wherein a represents the effective value of the mains voltage, and θ represents the mains phase angle.

(4) The phase angle obtained after single-phase locking is defined as theta', and dq coordinate transformation is carried out on the phase angle as follows: wherein, theta' represents the phase angle of the commercial power after single-phase locking, and u _d、u_q represents the commercial power voltage in the two projection directions of the d axis and the q axis obtained by dq coordinate transformation.

The operation can be obtained: From this, it can be seen that θ - θ' =0, u _q =0 when the phase lock is successful, using And performing closed-loop control on the q-axis, and cumulatively calculating a phase angle value in a mains supply period to obtain a lock phase angle theta, wherein T represents an interrupt period of a control unit in the single-line inverter.

However, the single-phase alternating current phase locking technology in the prior art has the defects that 1) phase following is required to be subjected to SOGI and coordinate transformation operation, calculated amount is large, main frequency and sampling precision of a control unit MCU are required to be high, and 2) harmonic content caused by interference of self contained/sampled commercial power cannot be completely filtered through SOGI operation, so that deviation exists in a phase locking angle obtained through phase following calculation. Based on this, the embodiment of the invention provides a parallel operation synchronization method of single-phase inverters, and fig. 1 is a flowchart of an implementation of the parallel operation synchronization method of single-phase inverters, as shown in fig. 1, where the parallel operation synchronization method of single-phase inverters is applied to each single-phase inverter in a parallel operation synchronization system of single-phase inverters including at least two single-phase inverters connected in parallel.

and 101, judging whether the commercial power is normal or not.

In step 101, the step of judging whether the mains supply is normal may be that the control unit in the single-phase inverter calculates the mains supply voltage effective value and the frequency value by using the zero-crossing detection unit in the single-phase inverter, and then compares the obtained mains supply voltage effective value and the obtained mains supply voltage frequency value with a preset range, and judges whether the mains supply voltage effective value and the mains supply voltage frequency value are normal according to a comparison result, so as to determine whether the mains supply is normal. In this embodiment, by determining whether the utility power is normal, the single-phase inverter is further facilitated to perform corresponding operation based on the normal utility power or the abnormal utility power, so as to achieve parallel synchronization of all the single-phase inverters connected in parallel.

Step 102, if the commercial power is normal, correcting the first to-be-tracked phase angle according to the high-low level signal output by the zero-crossing detection unit in the single-phase inverter to obtain a first to-be-tracked phase angle correction value, and carrying out phase synchronization on the current phase angle of the single-phase inverter according to the first to-be-tracked phase angle correction value.

In step 102, fig. 2 is a parallel operation synchronization flowchart of a parallel operation synchronization method of a single-phase inverter provided by an embodiment of the present invention, and fig. 3 is a phase following flowchart of a parallel operation synchronization method of a single-phase inverter provided by an embodiment of the present invention (in fig. 3, θ (t) may represent a first to-be-tracked phase angle of a mains voltage or a second to-be-tracked phase angle of a host; referring to fig. 1 to 4, in fig. 4, the input end of the zero crossing detection unit in the single-phase inverter is connected with the mains supply, and the output end of the zero crossing detection unit is connected with the input end of the control unit, so that when the mains supply is normal, the zero crossing detection unit of the single-phase inverter generates a high-low level signal corresponding to the mains supply based on the normal mains supply and outputs the high-low level signal to the control unit, the control unit corrects a first pseudo tracking phase angle according to the high-low level signal to obtain a first pseudo tracking phase angle correction value, and then performs phase synchronization on the current phase angle of the single-phase inverter based on the first pseudo tracking phase angle correction value, so that all single-phase inverters in a single-phase inverter parallel synchronization system can be synchronized with the phase of the normal mains supply under the normal condition of the mains supply, and further the single-phase inverter parallel synchronization system can be reliably synchronized.

In one possible implementation manner, correcting the first to-be-tracked phase angle according to the high-low level signal output by the zero-crossing detection unit in the single-phase inverter to obtain a first to-be-tracked phase angle correction value includes:

Based on the interrupt period of the control unit in the single-phase inverter, a first quasi-tracking phase angle of the mains voltage at a moment i is obtained, wherein i is a positive integer.

It is determined whether the high-low level signal received by the single-phase inverter at time i is on a rising/falling edge.

And if the high-low level signal received by the single-phase inverter at the moment i is at the rising edge/the falling edge, correcting the first pseudo tracking phase angle of the moment i based on a first preset value, and obtaining a first pseudo tracking phase angle correction value of the moment i.

In this embodiment, please refer to fig. 1 to 4 together, based on the interrupt period of the control unit in the single-phase inverter, the interrupt period-by-interrupt period integration establish the city integrates the first pseudo-tracking phase angle of the electric voltage at the time i, where i is a positive integer. The control unit can be a single chip microcomputer control chip or a DSP control chip, etc., and the application is not limited to this. For example, the first to-be-tracked phase angle of the mains voltage at the time i may be calculated by: Wherein θ (T _i) is the first to-be-tracked phase angle of the mains voltage at the time i, θ (T _i-1) is the first to-be-tracked phase angle of the mains voltage at the time i-1, T is the interrupt period of the control unit in the single-phase inverter, and ω is the power frequency angular speed of the single-phase inverter. Then, whether the high-low level signal received by the single-phase inverter at the time i is at the rising edge/falling edge is determined, for example, the rising edge/falling edge may be determined as the rising edge when the low level of the high-low level signal changes to the high level, and the falling edge when the high level of the high-low level signal changes to the low level. If the high-low level signal received by the single-phase inverter at the time i is at the rising edge, the first preset value may be I.e. correct the first pseudo tracking phase angle at instant i toObtaining a first phase angle correction value to be tracked at time i, and if the single-phase inverter receives a high-low level signal at time i at a falling edge, the first preset value may beI.e. correct the first pseudo tracking phase angle at instant i toA first pseudo tracking phase angle correction value for time i is obtained. In this embodiment, after the first to-be-tracked phase angle of the mains voltage at the time i is obtained, whether the frequency corresponding to the high-low level signal of the mains voltage at the current time is normal or not is determined, and when the frequency of the mains voltage is normal, whether the high-low level signal is at the rising edge/falling edge is further determined, so that the normal mains voltage at the current time is determined in real time, and further the accuracy of the to-be-tracked phase angle correction value is effectively ensured. In this embodiment, due to possible deviation of clock cycles of the control units in each single-phase inverter, each single-phase inverter may have phase deviation when acquiring a mains phase, so that the acquired mains phase has deviation, and the phases of each single-phase inverter are not synchronized when being synchronized in parallel, based on this, in this embodiment, the phase of the mains supply obtained by the single-phase inverter is circularly corrected, so that the accuracy of the first phase angle to be tracked (i.e., the accuracy of the obtained phase of the mains supply) is effectively ensured, and further, each single-phase inverter can perform phase correction based on the corrected first phase angle to be tracked, so as to ensure that each single-phase inverter reliably and stably performs parallel operation synchronously.

In one possible implementation manner, after determining whether the high-low level signal received by the single-phase inverter at the time i is at a rising edge/falling edge, the method further includes:

If the high-low level signal received by the single-phase inverter at the time i is not at the rising edge/falling edge, let i=i+1, and return to execute the step of acquiring the first to-be-tracked phase angle of the mains voltage at the time i based on the interrupt period of the control unit in the single-phase inverter and the subsequent steps.

In this embodiment, please refer to fig. 1 to 4 together, when the high-low level signal received by the single-phase inverter at the time i is not at the rising edge/falling edge, the first phase angle to be tracked at the next time of the time i is calculated, i.e. i=i+1, and the step of "obtaining the first phase angle to be tracked at the time i based on the interrupt period of the control unit in the single-phase inverter" is skipped, according to the following stepsA first to-be-tracked phase angle of the mains voltage at the present instant i is calculated. In this embodiment, when the single-phase inverter detects that the high-low level signal is not at the rising edge or the falling edge, the first to-be-tracked phase angle at the current time i is continuously and circularly updated until the high-low level signal is at the rising edge or the falling edge, and the first to-be-tracked phase angle is not corrected, so as to ensure that the phase of the mains supply acquired by the single-phase inverter is identical to the phase of the actual mains supply, and further ensure that each single-phase inverter can perform phase synchronization based on the acquired mains supply phase with high precision, thereby realizing parallel synchronization of all single-phase inverters in a parallel synchronization system of the single-phase inverter.

In one possible implementation, before correcting the first to-be-tracked phase angle of the time i based on the first preset value to obtain the first to-be-tracked phase angle correction value of the time i, the method further includes:

And judging whether the frequency corresponding to the high-low level signal meets a first preset frequency range or not.

And if the frequency corresponding to the high-low level signal meets the first preset frequency range, correcting the first pseudo tracking phase angle of the time i based on the first preset value to obtain a first pseudo tracking phase angle correction value of the time i.

If the frequency corresponding to the high-low level signal does not meet the first preset frequency range, i=i+1 is returned to execute the step of acquiring the first phase angle to be tracked of the mains voltage at the moment i based on the interrupt period of the control unit in the single-phase inverter and the subsequent steps.

In this embodiment, referring to fig. 1 to 4, before the first pseudo tracking phase angle of the time i is corrected, it can also be determined whether the operating frequency of the mains supply is normal at this time, and after the first pseudo tracking phase angle is circularly acquired several times, the mains supply frequency may be abnormal, so that at this time, the frequencies corresponding to the high-low level signals can be determined based on the first preset frequency range, so as to ensure that the phase synchronization of the subsequent single-phase inverters is the phase of the mains supply with the normal frequency. The first preset frequency range may be, for example, 49.8hz to 50.2hz or 49.2hz to 50.8hz or a frequency fluctuation range that may exist when the mains voltage is normal, which is not limited in the present application. When the frequency corresponding to the high-low level signal meets a first preset frequency range, the mains supply is proved to be normal at the moment, so that the first pseudo tracking phase angle at the current moment (namely the moment i) is corrected based on the first preset value, and a first pseudo tracking phase angle correction value at the current moment is obtained. The first preset value may be, for exampleOr alternativelyThe application is not limited in this regard. When the frequency corresponding to the high-low level signal does not meet the first preset frequency range, it is proved that the mains supply is abnormal (possible abnormal conditions can be that the mains supply frequency fluctuates or the mains supply is powered down, and the like), at this time, i=i+1 is enabled to be based on the interrupt period of the control unit in the single-phase inverter again, a first to-be-tracked phase angle of the mains supply voltage at the moment i is obtained, and then whether the high-low level signal is on the rising edge/the falling edge or not and whether the first to-be-tracked phase angle is corrected or not is judged again. Therefore, the accuracy of the phase of the commercial power synchronized by each single-phase inverter when the commercial power is normal is effectively ensured, and further the parallel operation synchronous operation of each single-phase inverter is also effectively ensured.

In one possible implementation manner, while acquiring the first to-be-tracked phase angle of the mains voltage at the time i based on the interrupt period of the control unit in the single-phase inverter, the method further includes:

based on the interruption period, the current phase angle of the single-phase inverter at time i is obtained.

Phase synchronizing the current phase angle of the single-phase inverter according to the first to-be-tracked phase angle correction value includes:

based on the first to-be-tracked phase angle correction value and the interruption period of the moment i, the first to-be-tracked phase angle of the mains voltage at the moment i+1 is obtained, and based on the current phase angle and the interruption period of the moment i, the current phase angle of the single-phase inverter at the moment i+1 is obtained.

A first absolute difference value of the current phase angle at time i+1 and the first to-be-tracked phase angle at time i+1 is calculated.

When the absolute value of the first difference is larger than a preset threshold, the current phase angle of the moment i+1 is adjusted according to a preset step length, and a current phase angle adjusting value of the moment i+1 is obtained, so that phase synchronization is carried out according to the current phase angle adjusting value of the moment i+1.

In this embodiment, please refer to fig. 1 to fig. 4 together, when the first pseudo tracking phase angle of the mains voltage at the time i is obtained, the single-phase inverter also obtains the current phase angle of the single-phase inverter at the time i based on the interrupt period of the control unit in the single-phase inverter, after the first pseudo tracking phase angle of the mains voltage at the time i is corrected, the obtained first pseudo tracking phase angle correction value can effectively ensure the accuracy of the phase angle to be followed by each single-phase inverter, at this time, based on the first pseudo tracking phase angle corrected at the time i (i.e., the first pseudo tracking phase angle correction value at the time i) and the interrupt period of the single-phase inverter control unit, the first pseudo tracking phase angle of the mains voltage at the next time (i.e., the time i+1) is obtained, and based on the updated current phase angle after the time i and the interrupt period, at this time, the absolute difference value of the first pseudo tracking phase angle of the time i+1 can be effectively ensured, and when the absolute difference value of the current phase angle at the time i+1 and the first pseudo tracking phase angle at the next time (i+1) is calculated, the current phase angle of the single-phase inverter is not updated at the time i+1, and the phase angle of the single-phase inverter is adjusted according to the preset value, and the phase difference value of the phase angle is not adjusted to the current phase value of the current phase 1 at the time i+1. In this embodiment, whether the single-phase inverter is synchronous with the phase of the normal mains voltage at this time is determined by determining whether the absolute value of the first difference between the phase of the single-phase inverter and the phase of the mains voltage at the current time is greater than a preset threshold, and if not, the phase of the single-phase inverter is adjusted step by step based on a preset step length, so that real-time synchronization of the single-phase inverter with the phase of the normal mains voltage can be effectively ensured.

In one possible implementation manner, the adjusting the current phase angle of the time i+1 according to the preset step length to obtain the current phase angle adjustment value of the time i+1 includes:

And adjusting the current phase angle of the time i+1 according to theta' (t _i+1)＝θ'(t_i+1) +flag multiplied by delta theta to obtain a current phase angle adjustment value of the time i+1.

Where θ "(t _i+1) represents the current phase angle adjustment value at time i+1, θ' (t _i+1) represents the current phase angle at time i+1, flag=1 or flag= -1, represents the adjustment direction, and Δθ represents the preset step size.

In this embodiment, the current phase angle at time i+1 may be adjusted in a stepwise manner according to θ "(t _i+1)＝θ'(t_i+1) +flag×Δθ, to obtain the current phase angle adjustment value at time i+1. Where θ "(t _i+1) represents the current phase angle adjustment value at time i+1, θ' (t _i+1) represents the current phase angle at time i+1, flag=1 or flag= -1, represents the adjustment direction, and Δθ represents the preset step size. Illustratively, the preset step size may be: And the appropriate phase step size, as the present application is not limited thereto. In this embodiment, by adjusting the phase of the single-phase inverter in a stepwise manner, real-time synchronization of the single-phase inverter with the normal mains voltage phase can be effectively ensured.

In one possible implementation manner, when the absolute value of the first difference is greater than the preset threshold, the current phase angle at the time i+1 is adjusted according to the preset step length, and the value of the adjustment direction is determined in the case that the current phase angle adjustment value at the time i+1 is obtained:

It is determined whether the current phase angle at time i+1 is less than the first to-be-tracked phase angle at time i+1.

When the current phase angle at the time i+1 is smaller than the first to-be-tracked phase angle at the time i+1, whether the first difference absolute value is larger than a first judgment condition is judged.

If the first difference absolute value is greater than the first judgment condition, flag= -1.

If the absolute value of the first difference is not greater than the first judgment condition, flag=1.

And judging whether the absolute value of the first difference is larger than a second judgment condition when the current phase angle at the moment i+1 is not smaller than the first to-be-tracked phase angle at the moment i+1.

If the absolute value of the first difference is greater than the second judgment condition, flag=1.

If the absolute value of the first difference is not greater than the second judgment condition, flag= -1.

In this embodiment, when the phase of the single-phase inverter is adjusted to be synchronous with the phase of the normal mains voltage in a step-by-step manner, the phase shift left or the phase shift right may affect the synchronization period of the phase of the normal mains voltage on which the single-phase inverter is successfully synchronized, so that it may be determined that the phase shift left or the phase shift right may enable the single-phase inverter to synchronize the phase of the normal mains voltage in the minimum step-by-step adjustment number or the shortest synchronization period, so that the efficiency of the single-phase inverter for synchronizing the phase of the mains voltage is effectively ensured, and further parallel operation of all the single-phase inverters is also facilitated. Therefore, when the absolute value of the first difference is greater than the preset threshold, and the current phase angle of the moment i+1 is adjusted according to the preset step length to obtain the current phase angle adjustment value of the moment i+1, the adjustment direction may be determined in such a manner that, first, it is determined whether the current phase angle of the moment i+1 is smaller than the first to-be-tracked phase angle of the moment i+1, and when the current phase angle of the moment i+1 is smaller than the first to-be-tracked phase angle of the moment i+1, it is determined whether the absolute value of the first difference is greater than the first determination condition. For example, the current phase angle at time i+1 is represented by θ ' (t _i+1), the first to-be-tracked phase angle at time i+1 is represented by θ (t _i+1), the first difference absolute value is a ' = |a|= |θ ' (t _i+1)-θ(t_i+1) |, the first judgment condition may be b= |2pi+a|= |2pi+θ ' (t _i+1)-θ(t_i+1) |, and if the first difference absolute value a ' is greater than the first judgment condition B, flag= -1. If the first difference absolute value a' is not greater than the first judgment condition B, flag=1. And judging whether the absolute value of the first difference is larger than a second judgment condition when the current phase angle at the moment i+1 is not smaller than the first to-be-tracked phase angle at the moment i+1. For example, the second judgment condition may be C= |2 pi-A|= |2 pi- θ ' (t _i+1)+θ(t_i+1) |, if the first difference absolute value A ' is greater than the second judgment condition C, flag=1, and if the first difference absolute value A ' is not greater than the second judgment condition C, flag= -1.

Step 103, if the commercial power is abnormal and the single-phase inverter is a master machine, or if the commercial power is abnormal and the single-phase inverter is a slave machine and the single-phase inverter is preempted to the master machine position in the single-phase inverter parallel synchronization system, generating a synchronization signal according to the phase of the single-phase inverter, and sending the synchronization signal to each slave machine in the single-phase inverter parallel synchronization system.

In step 103, please refer to fig. 1 to 4 together, when the utility power is abnormal, if the parallel operation synchronization system of the single-phase inverters has a host, the host phase is used as the standard phase for synchronization, and if the parallel operation synchronization system of the single-phase inverters has a host, one single-phase inverter of each single-phase inverter takes the host as the host. After determining the master, the single-phase inverter as the master generates a synchronization signal based on its own phase information (for example, the synchronization signal may be a high-low level signal corresponding to the master), and transmits the synchronization signal to each slave in the single-phase inverter parallel synchronization system, so that each slave can achieve synchronization with the phase of the master after receiving the synchronization signal.

Step 104, if the commercial power is abnormal and the single-phase inverter is a slave machine, and after receiving a synchronous signal sent by a master machine in a parallel operation synchronous system of the single-phase inverter, correcting a second to-be-tracked phase angle according to the synchronous signal to obtain a second to-be-tracked phase angle correction value, and carrying out phase synchronization on the current phase angle of the single-phase inverter according to the second to-be-tracked phase angle correction value.

In step 104, please refer to fig. 1 to 4 together, when the utility power is abnormal, after the single-phase inverter in the single-phase inverter parallel operation synchronization system receives the synchronization signal sent by the host, the control unit disposed therein corrects the second to-be-tracked phase angle at a proper time according to the synchronization signal to obtain a second to-be-tracked phase angle correction value, and then synchronizes the current phase angle of the single-phase inverter based on the second to-be-tracked phase angle correction value, so as to ensure that each slave can be synchronized with the phase of the host, and further ensure reliable operation of the single-phase inverter parallel operation synchronization system.

In one possible implementation, correcting the second pseudo tracking phase angle according to the synchronization signal to obtain a second pseudo tracking phase angle correction value includes:

based on the interrupt period of the control unit in the single-phase inverter, a second to-be-tracked phase angle of the host at a moment i is obtained, wherein i is a positive integer.

It is determined whether the synchronization signal received by the single-phase inverter at time i is on a rising/falling edge.

And if the synchronous signal received by the single-phase inverter at the moment i is at the rising edge/the falling edge, correcting the second pseudo tracking phase angle at the moment i based on the first preset value, and obtaining a second pseudo tracking phase angle correction value at the moment i.

In this embodiment, please refer to fig. 1 to 4 together, the second pseudo tracking phase angle of the host at the time i is built by integrating the interrupt periods one by one based on the interrupt period of the control unit in the single-phase inverter, wherein i is a positive integer. In addition, the control unit of the single-phase inverter can be a single-chip microcomputer control chip or a DSP control chip, etc., and the application is not limited to this. For example, the second to-be-tracked phase angle of the host at the time i may be calculated by: wherein, θ ¹(t_i) is the second to-be-tracked phase angle of the host at the time i, θ ¹(t_i-1) is the second to-be-tracked phase angle of the host at the time i-1, T is the interrupt period of the control unit in the single-phase inverter, and ω is the power frequency angular velocity of the single-phase inverter. Then, whether the synchronous signal received by the single-phase inverter at the time i is at the rising edge/falling edge is judged, and an exemplary way of judging the rising edge/falling edge is to determine that the synchronous signal is at the rising edge when the low level of the synchronous signal changes to the high level and determine that the synchronous signal is at the falling edge when the high level of the synchronous signal changes to the low level. If the synchronization signal received by the single-phase inverter at time i is at a rising edge, the first preset value may be I.e. correct the second pseudo tracking phase angle at instant i toObtaining a second phase angle correction value to be tracked at time i, and if the single-phase inverter is at a falling edge of the synchronization signal received at time i, the first preset value may beI.e. correct the second pseudo tracking phase angle at instant i toA second pseudo tracking phase angle correction value for time i is obtained. In this embodiment, after the first to-be-tracked phase angle of the mains voltage at the time i is obtained, whether the frequency corresponding to the high-low level signal of the mains voltage at the current time is normal or not is determined, and when the frequency of the mains voltage is normal, whether the high-low level signal is at the rising edge/falling edge is further determined, so that the normal mains voltage at the current time is determined in real time, and further the accuracy of the to-be-tracked phase angle correction value is effectively ensured. In this embodiment, due to possible deviation of clock cycles of the control units in each single-phase inverter, each single-phase inverter may have phase deviation when acquiring the phase of the host, so that the acquired phase of the host has deviation, and the accuracy of phase synchronization of parallel operation of each single-phase inverter is reduced, based on this, in this embodiment, the phase of the host acquired by the single-phase inverter is circularly corrected, so that the real-time accuracy of the second phase to be tracked (i.e., the accuracy of the acquired host phase) is effectively ensured, and further, each single-phase inverter can perform phase correction based on the corrected second phase to be tracked, so as to ensure that each single-phase inverter reliably and stably performs parallel operation synchronously.

In one possible implementation, after determining whether the synchronization signal received by the single-phase inverter at the time i is at a rising edge/falling edge, the method further includes:

If the synchronization signal received by the single-phase inverter at the time i is not at the rising edge/falling edge, i=i+1 is returned to execute the step of acquiring the second to-be-tracked phase angle of the host at the time i based on the interrupt period of the control unit in the single-phase inverter and the subsequent steps.

In this embodiment, please refer to fig. 1 to 4 together, when the synchronization signal received by the single-phase inverter at the time i is not at the rising edge/falling edge, the second phase angle to be tracked at the next time of the time i is calculated, i.e. let i=i+1, and the step of "obtaining the second phase angle to be tracked by the host at the time i based on the interrupt period of the control unit in the single-phase inverter" is skipped, according to the following stepsThe second phase angle to be tracked by the host at the current instant i is calculated. In this embodiment, when the single-phase inverter detects that the synchronization signal is not at a rising edge or a falling edge, the second to-be-tracked phase angle at the current time i is continuously and circularly updated until the synchronization signal is at the rising edge or the falling edge, and the second to-be-tracked phase angle is corrected, so as to ensure that the phase of the host acquired by the single-phase inverter is completely the same as the actual phase of the host, and further ensure that each single-phase inverter slave machine can perform phase synchronization based on the acquired host phase with high precision, thereby realizing parallel synchronization of all single-phase inverters in a parallel synchronization system of the single-phase inverter.

In one possible implementation manner, before correcting the second to-be-tracked phase angle at the time i based on the first preset value, before obtaining the second to-be-tracked phase angle correction value at the time i, the method further includes:

judging whether the frequency corresponding to the synchronous signal meets a second preset frequency range or not.

And if the frequency corresponding to the synchronous signal meets the second preset frequency range, correcting the second pseudo tracking phase angle at the moment i based on the first preset value to obtain a first pseudo tracking phase angle correction value at the moment i.

If the frequency corresponding to the synchronizing signal does not meet the second preset frequency range, i=i+1 is returned to execute the step of acquiring the second phase angle to be tracked of the host at the moment i based on the interrupt period of the control unit in the single-phase inverter and the subsequent steps.

In this embodiment, referring to fig. 1 to 4 together, before correcting the second pseudo tracking phase angle at the time i, it may be further determined whether the working frequency of the host is normal at this time, and after circularly obtaining the second pseudo tracking phase angle several times, it is considered that the working frequency of the host may be abnormal, so that at this time, the frequency corresponding to the synchronization signal may be determined based on the second preset frequency range, so as to ensure that the phases of the following single-phase inverter slaves are synchronous and are all phases of the host with normal frequency. The second preset frequency range may be, for example, 49.5hz to 50.5hz or 49.8hz to 50.2hz or a frequency fluctuation range that may exist when the frequency of the other host is normal, which is not limited in the present application. When the frequency corresponding to the synchronizing signal meets a second preset frequency range, the operation of the host computer is proved to be normal at the moment, so that the second pseudo tracking phase angle at the current moment (namely moment i) is corrected based on the first preset value, and a second pseudo tracking phase angle correction value at the current moment is obtained. The first preset value may be, for exampleOr alternativelyThe application is not limited in this regard. When the frequency corresponding to the synchronous signal does not meet the second preset frequency range, it is proved that the host machine is abnormal in operation (the possible abnormal conditions can be that the working frequency of the host machine is greatly fluctuated or the host machine is powered down, and the like), at the moment, i=i+1 is enabled to be based on the interrupt period of the control unit in the single-phase inverter again, a second to-be-tracked phase angle of the host machine at the moment i is acquired, and then whether the synchronous signal is on the rising edge/the falling edge or not and whether the second to-be-tracked phase angle is corrected or not are judged again. Therefore, the accuracy of the host phase synchronized by each single-phase inverter slave machine when the host machine operates normally is effectively ensured, and further the parallel operation synchronization of each single-phase inverter is also effectively ensured.

In one possible implementation manner, while obtaining the second to-be-tracked phase angle of the host at the time i based on the interrupt period of the control unit in the single-phase inverter, the method further includes:

Phase synchronizing the current phase angle of the single-phase inverter according to the second to-be-tracked phase angle correction value includes:

based on the second to-be-tracked phase angle correction value and the interruption period of the moment i, the second to-be-tracked phase angle of the host at the moment i+1 is obtained, and based on the current phase angle and the interruption period of the moment i, the current phase angle of the single-phase inverter at the moment i+1 is obtained.

And calculating a second difference absolute value between the current phase angle at the moment i+1 and the second to-be-tracked phase angle at the moment i+1.

And when the absolute value of the second difference is larger than a preset threshold, adjusting the current phase angle of the moment i+1 according to a preset step length to obtain a current phase angle adjusting value of the moment i+1 so as to perform phase synchronization according to the current phase angle adjusting value of the moment i+1.

In this embodiment, please refer to fig. 1 to 4 together, when the second to-be-tracked phase angle of the host at the time i is obtained each time, the single-phase inverter also obtains the current phase angle of the host at the time i based on the interrupt period of the control unit in the host, after the second to-be-tracked phase angle of the host at the time i is corrected, the obtained second to-be-tracked phase angle correction value can effectively ensure the accuracy of the phase angle to be followed by each single-phase inverter slave, at this time, based on the corrected second to-be-tracked phase angle (i.e., the second to-be-tracked phase angle correction value at the time i) at the time i and the interrupt period of the single-phase inverter control unit, the current phase angle of the host at the next time (i.e., the time i+1) is obtained based on the updated current phase angle after the time i and the interrupt period, at this time, the absolute value of the second to-be-tracked phase angle of the single-phase inverter at the next time (i+1) is calculated, and when the absolute value of the absolute difference between the current phase angle of the time i+1 and the second to-be-tracked phase angle of the host is not adjusted to the current phase angle of the host is not adjusted to be the current phase angle 1 at the time i+1, and the phase angle of the current phase angle is adjusted to be the current phase 1 is not adjusted to be the current phase 1. In this embodiment, whether the single-phase inverter is synchronous with the phase of the host computer at this moment is determined by determining whether the absolute value of the second difference between the phase of the single-phase inverter and the phase of the host computer at the current moment is greater than a preset threshold value, and if not, the phase of the single-phase inverter is adjusted stepwise based on a preset step length, so that real-time synchronization of the phase of the single-phase inverter and the phase of the host computer can be effectively ensured.

In this embodiment, the current phase angle at time i+1 may be adjusted in a stepwise manner according to θ "(t _i+1)＝θ'(t_i+1) +flag×Δθ, to obtain the current phase angle adjustment value at time i+1. Where θ "(t _i+1) represents the current phase angle adjustment value at time i+1, θ' (t _i+1) represents the current phase angle at time i+1, flag=1 or flag= -1, represents the adjustment direction, and Δθ represents the preset step size. Illustratively, the preset step size may be: And the appropriate phase step size, as the present application is not limited thereto. In this embodiment, by adjusting the phase of the single-phase inverter in a stepwise manner, the real-time synchronization between the single-phase inverter and the phase of the host computer can be effectively ensured.

In one possible implementation manner, when the absolute value of the second difference is greater than the preset threshold, the current phase angle at the time i+1 is adjusted according to the preset step length, and the value of the adjustment direction is determined in the case that the current phase angle adjustment value at the time i+1 is obtained:

It is determined whether the current phase angle at time i+1 is less than the second to-be-tracked phase angle at time i+1.

And when the current phase angle at the moment i+1 is smaller than the second to-be-tracked phase angle at the moment i+1, judging whether the absolute value of the second difference value is larger than a third judging condition.

If the second difference absolute value is greater than the third judgment condition, flag= -1.

If the absolute value of the second difference is not greater than the third judgment condition, flag=1.

And judging whether the absolute value of the second difference is larger than a fourth judgment condition when the current phase angle at the moment i+1 is not smaller than the second to-be-tracked phase angle at the moment i+1.

If the second difference absolute value is greater than the fourth judgment condition, flag=1.

If the absolute value of the second difference is not greater than the fourth judgment condition, flag= -1.

In this embodiment, considering that when the phase of the single-phase inverter is adjusted to be synchronous with the phase of the host computer in a stepwise manner, the phase shift left or the phase shift right may affect the synchronization period of the phase of the host computer in which the single-phase inverter is successfully synchronized, it may be first determined that the phase shift left or the phase shift right can enable the single-phase inverter to synchronize with the phase of the host computer in the minimum step adjustment times or the shortest synchronization period, so that the efficiency of the phase of the synchronous host computer of the single-phase inverter is effectively ensured, and further the parallel operation of all the single-phase inverters is also facilitated. Therefore, when the absolute value of the second difference is greater than the preset threshold, and the current phase angle of the moment i+1 is adjusted according to the preset step length to obtain the current phase angle adjustment value of the moment i+1, the adjustment direction may be determined in such a manner that, first, it is determined whether the current phase angle of the moment i+1 is smaller than the second to-be-tracked phase angle of the moment i+1, and when the current phase angle of the moment i+1 is smaller than the second to-be-tracked phase angle of the moment i+1, it is determined whether the absolute value of the second difference is greater than the third determination condition. For example, the current phase angle at time i+1 is represented by θ ' (t _i+1), the second to-be-tracked phase angle at time i+1 is represented by θ ¹(t_i+1), the second difference absolute value is D ' = |d|= |θ ' (t _i+1)-θ¹(t_i+1) |, the third judgment condition may be e= |2pi+d|= |2pi+θ ' (t _i+1)-θ¹(t_i+1) |, and if the second difference absolute value D ' is greater than the third judgment condition E, flag= -1. If the second difference absolute value D' is not greater than the third judgment condition E, flag=1. And judging whether the absolute value of the second difference is larger than a fourth judgment condition when the current phase angle at the moment i+1 is not smaller than the second to-be-tracked phase angle at the moment i+1. For example, the fourth judgment condition may be e= |2pi-d= |2pi- θ ' (t _i+1)+θ¹(t_i+1) |, if the second difference absolute value D ' is greater than the fourth judgment condition E, flag=1, and if the first difference absolute value D ' is not greater than the second judgment condition E, flag= -1.

The embodiment of the invention provides a parallel synchronization method of single-phase inverters, which is applied to each single-phase inverter in a parallel synchronization system of the single-phase inverter, wherein the single-phase inverter comprises at least two single-phase inverters connected in parallel; the method comprises the steps of judging whether mains supply is normal, correcting a first to-be-tracked phase angle according to a high-low level signal output by a zero-crossing detection unit in a single-phase inverter to obtain a first to-be-tracked phase angle correction value, carrying out phase synchronization on a current phase angle of the single-phase inverter according to the first to-be-tracked phase angle correction value, obtaining a second to-be-tracked phase angle correction value according to the synchronization signal after the mains supply is abnormal and the single-phase inverter is a master or after the mains supply is abnormal and the single-phase inverter is a slave and the single-phase inverter is preempted to a master position in a single-phase inverter parallel synchronization system, generating a synchronization signal according to the phase of the single-phase inverter and sending the synchronization signal to each slave in the single-phase inverter parallel synchronization system, and carrying out phase synchronization on the current phase angle of the single-phase inverter according to the second to-be-tracked phase angle correction value after the mains supply is abnormal and the single-phase inverter is a slave and the synchronization signal sent by the master in the single-phase inverter parallel synchronization system is received. In the embodiment of the invention, the phase of the standard phase angle corresponding to the mains voltage or the single-phase inverter serving as a host is used as the target phase followed by the phase of each single-phase inverter, each single-phase inverter adjusts the own phase based on the standard phase angle until the own phase of each single-phase inverter and the phase corresponding to the standard phase angle meet the preset condition, and the parallel synchronization of all the single-phase inverters connected in parallel is realized, and the parallel synchronization of each single-phase inverter is not realized through the mains self/sampling circuit, so that the problem that the phase-locked angle deviation is possibly caused by the harmonic content caused by the interference of the mains self/sampling circuit is also effectively avoided, and the reliable operation of the parallel synchronization system of the single-phase inverter is further improved.

According to the parallel operation synchronization method of the single-phase inverter, provided by the embodiment of the invention, only the high and low levels obtained by the zero-crossing detection/synchronization signal hardware are used as the trigger source of phase following, so that the influence of the interference of a sampling circuit and the harmonic wave contained in the mains supply can be effectively avoided, the integral calculated amount is smaller, the performance requirement on the control unit MCU is lower, and the hardware cost of a product is reduced.

It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present invention.

On the other hand, the embodiment of the invention provides a parallel operation synchronization system of single-phase inverters, and fig. 5 is a schematic structural diagram of the parallel operation synchronization system of the single-phase inverters provided by the embodiment of the invention, as shown in fig. 5, and the system comprises at least two single-phase inverters in the second aspect.

The output end of the output isolation unit in each single-phase inverter is connected with the CAP port of the control unit in the other single-phase inverter.

In this embodiment, as shown in fig. 5, the parallel operation synchronization system of the single-phase inverters includes three single-phase inverters, where each single-phase inverter is internally provided with the same configuration, so as to ensure that when the mains supply is abnormal and no host is in the system, a single-phase inverter can preempt the host position to become the host, and further provide a standard phase for phase synchronization for each slave.

On the other hand, fig. 6 is a schematic structural diagram of a single-phase inverter parallel synchronization device according to an embodiment of the present invention, and as shown in fig. 6, the single-phase inverter parallel synchronization device is applied to each single-phase inverter in a single-phase inverter parallel synchronization system including at least two single-phase inverters connected in parallel.

The single-phase inverter parallel operation synchronization device 6 includes:

The utility power judging module 601 is configured to judge whether the utility power is normal.

The phase following mains supply module 602 is configured to correct the first to-be-tracked phase angle according to the high-low level signal output by the zero-crossing detection unit in the single-phase inverter if the mains supply is normal, obtain a first to-be-tracked phase angle correction value, and perform phase synchronization on the current phase angle of the single-phase inverter according to the first to-be-tracked phase angle correction value.

And the synchronization signal determining module 603 is configured to generate a synchronization signal according to a phase of the single-phase inverter after the single-phase inverter is preempted to a master station in the parallel synchronization system of the single-phase inverter if the utility power is abnormal and the single-phase inverter is a master station, or if the utility power is abnormal and the single-phase inverter is a slave station, and send the synchronization signal to each slave station in the parallel synchronization system of the single-phase inverter.

The phase following master module 604 is configured to correct the second to-be-tracked phase angle according to the synchronization signal after the single-phase inverter is a slave and the synchronization signal sent by the master in the parallel operation synchronization system of the single-phase inverter is received if the utility power is abnormal, obtain a second to-be-tracked phase angle correction value, and perform phase synchronization on the current phase angle of the single-phase inverter according to the second to-be-tracked phase angle correction value.

On the other hand, the embodiment of the invention provides a single-phase inverter which comprises a control unit, a zero crossing detection unit and an output isolation unit.

The control unit comprises a memory for storing a computer program, a processor for calling and running the computer program, and a computer program for executing the steps of the method as described above in the first aspect or any of the possible implementations of the first aspect.

In this embodiment, referring to fig. 4 and 7 together, the single-phase inverter provided by the embodiment of the invention includes a control unit, a zero-crossing detection unit and an output isolation unit, wherein an input end of the zero-crossing detection unit is connected with a mains supply, an output end of the zero-crossing detection unit is connected with an input end of the control unit, an output end of the control unit is connected with an input end of the output isolation unit, and an output end of the output isolation unit is connected with a CAP port of the control unit. In addition, the zero-crossing detection unit further comprises a differential sampling circuit and a comparison circuit, the output isolation unit further comprises a signal amplification circuit and a signal isolation circuit, specifically, the input end of the differential sampling circuit is connected with the mains supply, the output end of the differential sampling circuit is connected with the input end of the comparison circuit, the output end of the comparison circuit is connected with the input end of the control unit, the output end of the control unit is connected with the input end of the signal amplification circuit, the output end of the signal amplification circuit is connected with the input end of the signal isolation circuit, and the input end of the signal isolation circuit is connected with the CAP port of the control unit.

Fig. 7 is a schematic structural diagram of a control unit according to an embodiment of the present invention. As shown in fig. 7, the control unit 7 of this embodiment comprises a processor 70, a memory 71 and a computer program 72 stored in said memory 71 and executable on said processor 70. The steps of the single-phase inverter parallel operation synchronization method embodiments described above, such as steps 101 through 104 shown in fig. 1, are implemented by the processor 70 when executing the computer program 72. Or the processor 70, when executing the computer program 72, performs the functions of the modules of the apparatus embodiments described above, such as the functions of the modules 601-604 shown in fig. 6.

By way of example, the computer program 72 may be partitioned into one or more modules/units that are stored in the memory 71 and executed by the processor 70 to complete the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions for describing the execution of the computer program 72 in the control unit 7. For example, the computer program 72 may be split into modules 601 to 604 shown in fig. 6.

The control unit 7 may be a computing device such as a desktop computer, a notebook computer, a palm computer, a cloud server, etc. The control unit 7 may include, but is not limited to, a processor 70, a memory 71. It will be appreciated by those skilled in the art that fig. 7 is merely an example of the control unit 7 and does not constitute a limitation of the control unit 7, and may comprise more or less components than shown, or may combine certain components, or different components, e.g. the control unit may further comprise input and output devices, network access devices, buses, etc.

The Processor 70 may be a central processing unit (Central Processing Unit, CPU), or may be another general purpose Processor, a digital signal Processor (DIGITAL SIGNAL Processor, DSP), an Application SPECIFIC INTEGRATED Circuit (ASIC), a Field-Programmable gate array (Field-Programmable GATE ARRAY, FPGA) or other Programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory 71 may be an internal storage unit of the control unit 7, such as a hard disk or a memory of the control unit 7. The memory 71 may also be an external storage device of the control unit 7, such as a plug-in hard disk, a smart memory card (SMART MEDIA CARD, SMC), a Secure Digital (SD) card, a flash memory card (FLASH CARD) or the like, which are provided on the control unit 7. Further, the memory 71 may also include both an internal memory unit and an external memory device of the control unit. The memory 71 is used for storing the computer program as well as other programs and data required by the control unit. The memory 71 may also be used for temporarily storing data that has been output or is to be output.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, the specific names of the functional units and modules are only for distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/control unit and method may be implemented in other manners. For example, the apparatus/control unit embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical function division, and there may be additional divisions in actual implementation, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated modules/units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present invention may implement all or part of the flow of the method of the above embodiment, or may be implemented by instructing related hardware by a computer program, where the computer program may be stored in a computer readable storage medium, and the computer program may implement the steps of the single-phase inverter parallel operation synchronization method embodiment when executed by a processor. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the computer readable medium may include content that is subject to appropriate increases and decreases as required by jurisdictions in which such content is subject to legislation and patent practice, such as in certain jurisdictions in which such content is not included as electrical carrier signals and telecommunication signals.

The foregoing embodiments are merely illustrative of the technical solutions of the present invention, and not restrictive, and although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that modifications may still be made to the technical solutions described in the foregoing embodiments or equivalent substitutions of some technical features thereof, and that such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A single-phase inverter parallel synchronization method, characterized in that the single-phase inverter parallel synchronization method is applied to each single-phase inverter in a single-phase inverter parallel synchronization system including at least two single-phase inverters connected in parallel;

Judging whether the commercial power is normal or not;

If the commercial power is abnormal and the single-phase inverter is a slave machine, correcting a second to-be-tracked phase angle according to the synchronous signal after receiving the synchronous signal sent by the master machine in the single-phase inverter parallel operation synchronous system, obtaining a second to-be-tracked phase angle correction value, and carrying out phase synchronization on the current phase angle of the single-phase inverter according to the second to-be-tracked phase angle correction value;

The method for correcting the first phase angle to be tracked according to the high-low level signal output by the zero-crossing detection unit in the single-phase inverter to obtain a first phase angle correction value to be tracked comprises the following steps:

based on an interruption period of a control unit in the single-phase inverter, acquiring a first quasi-tracking phase angle of the mains voltage at a moment i, wherein i is a positive integer;

judging whether the high-low level signal received by the single-phase inverter at the moment i is at a rising edge/a falling edge or not;

If the high-low level signal received by the single-phase inverter at the moment i is at the rising edge/the falling edge, correcting the first pseudo tracking phase angle of the moment i based on a first preset value to obtain a first pseudo tracking phase angle correction value of the moment i;

or correcting the second to-be-tracked phase angle according to the synchronous signal to obtain a second to-be-tracked phase angle correction value, including:

based on the interrupt period of the control unit in the single-phase inverter, acquiring a second to-be-tracked phase angle of the host at a moment i, wherein i is a positive integer;

Judging whether the synchronous signal received by the single-phase inverter at the moment i is at a rising edge/falling edge or not;

2. The single-phase inverter parallel operation synchronization method according to claim 1, further comprising, after determining whether the high-low level signal received by the single-phase inverter at time i is on a rising/falling edge:

If the high-low level signal received by the single-phase inverter at the moment i is not at the rising edge/falling edge, making i=i+1, and returning to execute the step and the subsequent steps of acquiring the first to-be-tracked phase angle of the mains voltage at the moment i based on the interrupt period of the control unit in the single-phase inverter;

Or after determining whether the synchronization signal received by the single-phase inverter at time i is on a rising/falling edge, further comprising:

If the synchronization signal received by the single-phase inverter at the time i is not at the rising edge/falling edge, i=i+1 is returned to execute the step of acquiring the second phase angle to be tracked of the host at the time i based on the interrupt period of the control unit in the single-phase inverter and the subsequent steps.

3. The single-phase inverter parallel operation synchronization method according to claim 1, further comprising, before correcting the first pseudo tracking phase angle of the time i based on the first preset value, obtaining the first pseudo tracking phase angle correction value of the time i:

Judging whether the frequency corresponding to the high-low level signal meets a first preset frequency range or not;

if the frequency corresponding to the high-low level signal meets a first preset frequency range, correcting the first pseudo tracking phase angle of the time i based on a first preset value to obtain a first pseudo tracking phase angle correction value of the time i;

If the frequency corresponding to the high-low level signal does not meet the first preset frequency range, making i=i+1, and returning to execute the step and the subsequent steps of acquiring a first to-be-tracked phase angle of the mains voltage at the moment i based on the interrupt period of the control unit in the single-phase inverter;

Or before correcting the second pseudo tracking phase angle at the moment i based on the first preset value to obtain a second pseudo tracking phase angle correction value at the moment i, the method further comprises:

judging whether the frequency corresponding to the synchronous signal meets a second preset frequency range or not;

If the frequency corresponding to the synchronous signal meets a second preset frequency range, correcting the second to-be-tracked phase angle at the moment i based on the first preset value to obtain a first to-be-tracked phase angle correction value at the moment i;

If the frequency corresponding to the synchronization signal does not meet the second preset frequency range, i=i+1 is returned to execute the step of acquiring the second phase angle to be tracked of the host at the moment i based on the interrupt period of the control unit in the single-phase inverter and the subsequent steps.

4. The parallel operation synchronization method of a single-phase inverter according to claim 1, wherein acquiring a first to-be-tracked phase angle of a mains voltage at a time i based on an interruption period of a control unit in the single-phase inverter, further comprises:

based on the interrupt period, acquiring the current phase angle of the single-phase inverter at the moment i;

the phase synchronizing the current phase angle of the single-phase inverter according to the first to-be-tracked phase angle correction value includes:

Acquiring a first to-be-tracked phase angle of the mains voltage at a moment i+1 based on a first to-be-tracked phase angle correction value at the moment i and the interrupt period, and acquiring a current phase angle of the single-phase inverter at the moment i+1 based on a current phase angle at the moment i and the interrupt period;

Calculating a first difference absolute value between the current phase angle at the moment i+1 and a first to-be-tracked phase angle at the moment i+1;

When the absolute value of the first difference is larger than a preset threshold, adjusting the current phase angle of the moment i+1 according to a preset step length to obtain a current phase angle adjusting value of the moment i+1 so as to perform phase synchronization according to the current phase angle adjusting value of the moment i+1;

or based on the interrupt period of the control unit in the single-phase inverter, acquiring the second pseudo tracking phase angle of the host at the moment i, and simultaneously, further comprising:

said phase synchronizing the current phase angle of the single-phase inverter based on the second pseudo-tracking phase angle correction value comprises:

Acquiring a second to-be-tracked phase angle of the host at the moment i+1 based on the second to-be-tracked phase angle correction value at the moment i and the interrupt period, and acquiring a current phase angle of the single-phase inverter at the moment i+1 based on the current phase angle at the moment i and the interrupt period;

Calculating a second difference absolute value between the current phase angle at the moment i+1 and a second to-be-tracked phase angle at the moment i+1;

5. The parallel operation synchronization method of a single-phase inverter according to claim 4, wherein the step of adjusting the current phase angle at the time i+1 according to a preset step length to obtain the current phase angle adjustment value at the time i+1 includes:

According to θ "(t _i+1)＝θ'(t_i+1) +flag×Δθ, the current phase angle of the time i+1 is adjusted, and the current phase angle adjustment value of the time i+1 is obtained;

Wherein θ "(t _i+1) represents a current phase angle adjustment value of time i+1, θ' (t _i+1) represents a current phase angle of time i+1, flag=1 or flag= -1, represents an adjustment direction, and Δθ represents the preset step size.

6. The parallel operation synchronization method of a single-phase inverter according to claim 5, wherein when the absolute value of the first difference is greater than a preset threshold, the current phase angle at the time i+1 is adjusted according to a preset step length, and the value of the adjustment direction is determined in the following manner when the current phase angle adjustment value at the time i+1 is obtained:

Judging whether the current phase angle at the moment i+1 is smaller than the first to-be-tracked phase angle at the moment i+1;

When the current phase angle at the moment i+1 is smaller than the first to-be-tracked phase angle at the moment i+1, judging whether the absolute value of the first difference value is larger than a first judging condition or not;

if the first difference absolute value is greater than the first judgment condition, flag= -1;

if the first difference absolute value is not greater than the first judgment condition, flag=1;

when the current phase angle at the moment i+1 is not smaller than the first to-be-tracked phase angle at the moment i+1, judging whether the absolute value of the first difference value is larger than a second judging condition;

If the first difference absolute value is greater than the second judgment condition, flag=1;

If the first difference absolute value is not greater than the second judgment condition, flag= -1;

Or when the absolute value of the second difference is greater than a preset threshold, adjusting the current phase angle of the moment i+1 according to a preset step length, and determining the value of the adjusting direction under the condition that the current phase angle adjusting value of the moment i+1 is obtained, wherein the determining mode of the value of the adjusting direction is as follows:

judging whether the current phase angle at the moment i+1 is smaller than the second to-be-tracked phase angle at the moment i+1;

When the current phase angle at the moment i+1 is smaller than the second to-be-tracked phase angle at the moment i+1, judging whether the absolute value of the second difference value is larger than a third judging condition or not;

if the second difference absolute value is greater than the third judgment condition, flag= -1;

if the absolute value of the second difference is not greater than the third judgment condition, flag=1;

when the current phase angle at the moment i+1 is not smaller than the second to-be-tracked phase angle at the moment i+1, judging whether the absolute value of the second difference value is larger than a fourth judging condition;

If the second difference absolute value is greater than the fourth judgment condition, flag=1;

and if the absolute value of the second difference is not greater than the fourth judgment condition, flag= -1.

7. The single-phase inverter is characterized by comprising a control unit, a zero crossing detection unit and an output isolation unit;

The control unit comprises a memory for storing a computer program, a processor for calling and running the computer program, and a computer program for executing the method according to any one of claims 1 to 6;

8. A parallel operation synchronization system of single-phase inverter is characterized by comprising at least two single-phase inverters as set forth in claim 7;

9. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method according to any of the preceding claims 1 to 6.