CN119891862A

CN119891862A - Motor rotor initial position identification method, system, equipment and storage medium

Info

Publication number: CN119891862A
Application number: CN202510064343.2A
Authority: CN
Inventors: 巩凤珺; 王华杰; 裴志远; 曾频
Original assignee: Weichai Power Co Ltd
Current assignee: Weichai Power Co Ltd
Priority date: 2025-01-15
Filing date: 2025-01-15
Publication date: 2025-04-25

Abstract

The invention discloses a method, a system, equipment and a storage medium for identifying the initial position of a motor rotor, and relates to the field of motor control, wherein the method comprises the steps of injecting pulse voltage signals into a stator of a motor to enable stator current to generate a stator magnetic field, and simultaneously enabling a rotor permanent magnet to generate a rotor magnetic field; and the initial position of the motor rotor is identified according to the current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions. By injecting a pulsed voltage signal into the motor stator, the direction and magnitude of the stator current is precisely controlled to measure the interaction between the stator and rotor magnetic fields in different relative directions. This interaction is characterized by a current response variation factor, thereby enabling accurate identification of the initial position of the motor rotor.

Description

Motor rotor initial position identification method, system, equipment and storage medium

Technical Field

The invention relates to the field of motor control, in particular to a motor rotor initial position identification method, a system, equipment and a storage medium.

Background

In a permanent magnet synchronous motor, accurate knowledge of the position of the rotor is critical to the control of the motor. The initial position of the rotor is typically unknown at the start of the motor. In modern industry, a common method for identifying the initial position of a motor rotor is a high-frequency square wave voltage injection method (HFI), and a current response is obtained by injecting a high-frequency square wave voltage into a motor stator winding, so as to estimate the position of the rotor.

Although the high-frequency square wave voltage injection method is widely used in industry, the method has problems in identifying the initial position of the rotor, a plurality of convergence points need to be subjected to polarity identification, the polarity identification scheme at present cannot accurately identify the polarity of the magnetic pole, and the motor is in reverse rotation. The current mode directly compares the current responses corresponding to the two injection voltages, and if the current responses are small or the difference between the two injection current responses is small, the polarity discrimination errors are easy to be caused by current fluctuation or sampling deviation.

Disclosure of Invention

The main object of the present invention is to provide a method, system, apparatus and storage medium for identifying the initial position of a motor rotor, which precisely controls the direction and magnitude of the stator current by injecting a pulse voltage signal into the motor stator, so as to measure the interaction between the stator magnetic field and the rotor magnetic field in different opposite directions. This interaction is characterized by a current response variation factor, thereby enabling accurate identification of the initial position of the motor rotor.

In order to achieve the above object, the embodiment of the present application provides the following technical solutions:

according to a first aspect of an embodiment of the present application, there is provided a method for identifying an initial position of a rotor of an electric machine, the method including:

injecting pulse voltage signals into a stator of the motor, so that stator current generates a stator magnetic field, and simultaneously, a rotor permanent magnet generates a rotor magnetic field;

calculating current response change factors of the stator magnetic field and the rotor magnetic field in different relative directions in a preset time by controlling the direction and the magnitude of the stator current;

and identifying the initial position of the motor rotor according to the current response change factors in the different opposite directions.

Optionally, when the stator magnetic field and the rotor magnetic field are in the same direction, by controlling the direction and the magnitude of the stator current, calculating the current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions within a predetermined time includes:

gradually reducing the stator current to 0 according to a set gradient, and continuously increasing to a negative value of the set current reversely according to the set gradient and maintaining the set stable duration;

and calculating a current response change factor of the stator current in the preset time.

Optionally, when the stator magnetic field is opposite to the rotor magnetic field, by controlling the direction and the magnitude of the stator current, calculating the current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions within a predetermined time, including:

gradually reducing the stator current to 0 according to a set gradient, continuously increasing to a positive value of the set current according to the set gradient, and maintaining a set stable duration;

Optionally, said calculating a current response variation factor of said stator current for said predetermined time includes:

measuring the direct-axis high-frequency response current of each sampling point in the preset time;

calculating the direct-axis high-frequency response current accumulated values of all sampling points at each measuring moment;

And obtaining a current response average value according to the direct-axis high-frequency response current accumulated values of all the sampling points and the number of the sampling points, and taking the current response average value as the current response change factor.

Optionally, identifying the initial position of the motor rotor according to the current response change factors in the different opposite directions includes:

Determining the absolute value of a current response change factor under the condition that the stator magnetic field and the rotor magnetic field are in the same direction as a first current factor;

determining the absolute value of a current response change factor under the condition that the stator magnetic field and the rotor magnetic field are opposite in direction as a second current factor;

if the first current factor is larger than the second current factor, the initial position of the motor rotor is N pole;

and if the first current factor is smaller than the second current factor, the initial position of the motor rotor is an S pole.

Optionally, the method further comprises the step of controlling the direction and the magnitude of the stator current to enable the stator magnetic field to be the same as the rotor magnetic field, and specifically comprises the following steps:

converting a stator current from a three-phase coordinate system to a two-phase rotational coordinate system, wherein a stator magnetic field is aligned with a rotor magnetic field, wherein the stator current is decomposed into a d-axis component and a q-axis component that are parallel and perpendicular to the rotor magnetic field, respectively;

calculating a d-axis current component and a q-axis current component according to the motor control requirement, and generating corresponding control signals;

converting the voltage components under the two-phase rotating coordinate system back to a three-phase coordinate system to obtain three-phase voltage components;

generating a pulse width modulation signal according to the three-phase voltage component to control motor phase current;

The actual phase current of the motor is monitored in real time, and the d-axis current component is aligned with the rotor magnetic field by adjusting the pulse width modulation signal, and the q-axis current component is used for controlling the torque of the motor.

Optionally, the method further comprises the step of controlling the direction and the magnitude of the stator current to enable the stator magnetic field to be opposite to the rotor magnetic field, and specifically comprises the following steps:

Calculating a d-axis current component and a q-axis current component according to the motor control requirement, wherein the d-axis current component is adjusted so that the stator magnetic field and the rotor magnetic field are opposite in direction;

Generating a corresponding control signal according to the calculated d-axis current component and q-axis current component, wherein the d-axis control signal is adjusted to be opposite to the rotor magnetic field direction;

The actual phase current of the motor is monitored in real time, and the d-axis current component is opposite to the rotor magnetic field by adjusting the pulse width modulation signal.

According to a second aspect of an embodiment of the present application, there is provided a motor rotor initial position identification system, the system including:

the magnetic field generating module is used for injecting pulse voltage signals into a stator of the motor so that stator current generates a stator magnetic field and the rotor permanent magnet generates a rotor magnetic field;

the current response calculation module is used for calculating current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions in a preset time by controlling the direction and the magnitude of the stator current;

And the position identification module is used for identifying the initial position of the motor rotor according to the current response change factors in different opposite directions.

According to a third aspect of embodiments of the present application there is provided an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor executing the computer program to implement the method of the first aspect.

According to a fourth aspect of embodiments of the present application, there is provided a computer readable storage medium having stored thereon computer readable instructions executable by a processor to implement the method of the first aspect described above.

In summary, the embodiment of the application provides a method, a system, equipment and a storage medium for identifying an initial position of a motor rotor, which are characterized in that a stator current generates a stator magnetic field and a rotor permanent magnet generates a rotor magnetic field by injecting a pulse voltage signal into a stator of the motor, current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions within a preset time are calculated by controlling the direction and the magnitude of the stator current, and the initial position of the motor rotor is identified according to the current response change factors in the different opposite directions. By injecting a pulsed voltage signal into the motor stator, the direction and magnitude of the stator current is precisely controlled to measure the interaction between the stator and rotor magnetic fields in different relative directions. This interaction is characterized by a current response variation factor, thereby enabling accurate identification of the initial position of the motor rotor.

Drawings

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

The structures, proportions, sizes, etc. shown in the present specification are shown only for the purposes of illustration and description, and are not intended to limit the scope of the invention, which is defined by the claims, so that any structural modifications, changes in proportions, or adjustments of sizes, which do not affect the efficacy or the achievement of the present invention, should fall within the scope of the invention.

Fig. 1 is a flowchart of a method for identifying an initial position of a motor rotor according to an embodiment of the present application;

Fig. 2a, fig. 2b, fig. 2c, fig. 2d are schematic diagrams of a polarity determining principle according to an embodiment of the present application;

FIG. 3 is a logic flow diagram of a polarity determination system according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a trapezoidal wave current provided by an embodiment of the present application;

Fig. 5 is a schematic diagram of a motor rotor initial position recognition system according to an embodiment of the present application;

fig. 6 shows a block diagram of an electronic device according to an embodiment of the present application;

fig. 7 shows a diagram of a computer-readable storage medium provided by an embodiment of the present application.

The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that all directional indicators (such as up, down, left, right, front, and rear are used in the embodiments of the present invention) are merely for explaining the relative positional relationship, movement conditions, and the like between the components in a certain specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicators are changed accordingly.

Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "connected," "fixed," and the like are to be construed broadly, and for example, "fixed" may be fixedly connected, detachably connected, or integrally formed, mechanically connected, electrically connected, directly connected, indirectly connected via an intervening medium, or in communication between two elements or in an interaction relationship between two elements, unless otherwise explicitly specified. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.

In the method provided by the embodiment of the application, the polarity (N pole or S pole) of the rotor is identified by injecting specific current waveforms (high-frequency square wave voltage and low-frequency square wave current) on the D axis (straight axis) of the motor, estimating the position of the rotor through a position observer and utilizing the magnetic saturation characteristic of the motor. The time for detecting the rotor position can be reduced, and the accuracy of detection is improved.

The current demand on the D-axis is given in the form of a trapezoidal wave, rather than the conventional low frequency square wave signal. The waveform design aims to reduce the overcurrent risk caused by abrupt change of the required current and improve the identification precision and safety while enhancing the motor inductance saturation effect. After the D-axis required current reaches a preset value, a waiting time is increased to ensure the current to be stable. And then, the D-axis high-frequency current response is accumulated to calculate an average value, so that the reliability of data is improved, and the problem of polarity judgment misjudgment caused by current fluctuation or sampling error is reduced.

Fig. 1 shows a method for identifying an initial position of a rotor of a motor, which includes:

Step 101, injecting pulse voltage signals into a stator of a motor to enable stator current to generate a stator magnetic field and rotor permanent magnets to generate a rotor magnetic field;

102, calculating current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions in a preset time by controlling the direction and the magnitude of the stator current;

And 103, identifying the initial position of the motor rotor according to the current response change factors in the different opposite directions.

The technical scheme of the embodiment of the application aims to develop a method for identifying the initial position of a motor rotor, which utilizes the interaction between a stator magnetic field and a rotor magnetic field to determine the initial position of the rotor. By injecting pulse voltage signals into the motor stator and controlling the direction and the magnitude of stator current, the method can measure current response change factors in different opposite directions, and further identify the initial position of the rotor. This approach aims to improve the accuracy and efficiency of motor control, particularly during motor start-up and fault diagnosis phases.

In a possible implementation manner, when the stator magnetic field and the rotor magnetic field are in the same direction, in step 102, by controlling the direction and the magnitude of the stator current, a current response variation factor of the stator magnetic field and the rotor magnetic field in different opposite directions within a predetermined time is calculated, including:

Gradually increasing the stator current to a positive value of the set current according to a set gradient and maintaining the set stable duration, gradually decreasing the stator current to 0 according to the set gradient, continuously reversely increasing to a negative value of the set current according to the set gradient and maintaining the set stable duration, and calculating a current response change factor of the stator current within the preset time. Whether the stator magnetic field is opposite to the rotor magnetic field or not, a positive stator current is needed to be injected first, a negative stator current is further injected, and further, the high-frequency current response amplitude corresponding to the two injected currents is compared.

In one possible implementation, when the stator magnetic field is opposite to the rotor magnetic field, in step 102, by controlling the direction and magnitude of the stator current, a current response variation factor of the stator magnetic field and the rotor magnetic field in different opposite directions for a predetermined time is calculated, including:

Gradually reducing the stator current to 0 according to a set gradient, continuously increasing the stator current to a positive value of the set current according to the set gradient and maintaining the set stable duration, and calculating a current response change factor of the stator current in the preset time.

Assuming that a servo motor of an industrial robot is provided, it is necessary to precisely control the initial position of the arm portion thereof in order to perform a precise operation. Before the motor is started, pulse voltage signals are injected into the motor stator by the method, and a stator magnetic field is generated. At the same time, the rotor permanent magnets generate a rotor magnetic field. By controlling the direction and magnitude of the stator current, the interaction of the stator magnetic field and the rotor magnetic field in the same and opposite directions is simulated, and the current response variation factor is calculated. These factors reflect the strength and nature of the interaction of the two magnetic fields. By comparing these factors, the initial position of the rotor can be determined, thereby ensuring that the motor can be started from the correct position, enabling accurate control. The method not only improves the accuracy of robot operation, but also reduces the fault risk caused by position errors and enhances the stability and reliability of the system.

In a possible implementation manner, in step 102, the calculating a current response variation factor of the stator current within the predetermined time includes:

Measuring the direct-axis high-frequency response current of each sampling point in the preset time, calculating the direct-axis high-frequency response current accumulated value of all the sampling points at each measuring moment, and obtaining a current response average value as the current response change factor according to the direct-axis high-frequency response current accumulated value of all the sampling points and the number of the sampling points.

The initial position of the rotor is determined by measuring and calculating the direct-axis high-frequency response current of the stator current in detail. The method obtains a current response change factor by measuring, accumulating and calculating an average value of the direct-axis high-frequency response current of each sampling point in a preset time, so as to identify the rotor position. It is assumed that in a traction motor of an electric vehicle, an initial position of a rotor needs to be determined before starting to optimize a starting process. Using the method described above, the direct-axis high-frequency response current of each sampling point for a predetermined time is measured in step 102, and then these current values are accumulated, and an average value is calculated as a current response variation factor. If the stator magnetic field is in the same direction as the rotor magnetic field, a larger current response variation factor is desired, and if the directions are opposite, a smaller current response variation factor is desired. The initial position of the rotor can be determined by comparing the factors, so that the starting strategy of the motor is optimized, the energy consumption and abrasion during starting are reduced, and the performance and reliability of the whole vehicle are improved.

In a possible implementation manner, in step 103, identifying the initial position of the motor rotor according to the current response variation factors in the different opposite directions includes:

The method comprises the steps of determining an absolute value of a current response change factor under the condition that the stator magnetic field and the rotor magnetic field are in the same direction as each other as a first current factor, determining an absolute value of a current response change factor under the condition that the stator magnetic field and the rotor magnetic field are in opposite directions as a second current factor, determining an initial position of a motor rotor as an N pole if the first current factor is larger than the second current factor, and determining an initial position of the motor rotor as an S pole if the first current factor is smaller than the second current factor.

The initial position of the motor rotor is identified by comparing the current response variation factors for the different relative directions. By determining the current response change factors when the stator magnetic field and the rotor magnetic field are in the same or opposite directions and comparing the current response change factors, the initial position of the rotor can be accurately judged to be the N pole or the S pole. It is assumed that first, in the case where the stator magnetic field and the rotor magnetic field are in the same direction, the absolute value of the current response variation factor is measured and calculated, and is determined as the first current factor. Then, in the case where the stator magnetic field is opposite to the rotor magnetic field, the absolute value of the current response variation factor is measured and calculated, and is determined as the second current factor. The initial position of the rotor can be determined by comparing the magnitudes of the two factors. If the first current factor is larger than the second current factor, the initial position of the rotor is N pole, and if the first current factor is smaller than the second current factor, the initial position of the rotor is S pole.

In one possible implementation mode, the method further comprises the steps of controlling the direction and the magnitude of the stator current to enable the stator magnetic field to be the same as the rotor magnetic field, specifically comprising the steps of converting the stator current from a three-phase coordinate system to a two-phase rotation coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field, decomposing the stator current into a d-axis component and a q-axis component which are respectively parallel and perpendicular to the rotor magnetic field, calculating the d-axis current component and the q-axis current component according to the motor control requirement and generating corresponding control signals, converting the voltage components under the two-phase rotation coordinate system back to the three-phase coordinate system to obtain three-phase voltage components, generating pulse width modulation signals according to the three-phase voltage components to control motor phase currents, and monitoring the actual phase currents of the motor in real time, wherein the d-axis current components are aligned with the rotor magnetic field by adjusting pulse width modulation signals, and the q-axis current components are used for controlling the torque of the motor.

In one possible implementation, the method further comprises controlling the direction and magnitude of the stator current such that the stator magnetic field is opposite to the rotor magnetic field, specifically comprising converting the stator current from a three-phase coordinate system to a two-phase rotating coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field, wherein the stator current is decomposed into a d-axis component and a q-axis component which are respectively parallel and perpendicular to the rotor magnetic field, calculating the d-axis current component and the q-axis current component according to the requirements of motor control, adjusting the d-axis current component such that the stator magnetic field is opposite to the rotor magnetic field, generating a corresponding control signal according to the calculated d-axis current component and q-axis current component, wherein the d-axis control signal is adjusted to be opposite to the rotor magnetic field, converting the voltage component in the two-phase rotating coordinate system back to the three-phase coordinate system to obtain a three-phase voltage component, generating a pulse width modulation signal according to the three-phase voltage component, so as to control the motor phase current, monitoring the actual phase current of the motor in real time, and adjusting the pulse width modulation signal such that the d-axis current component is opposite to the rotor magnetic field.

The relative direction of the stator magnetic field and the rotor magnetic field is adjusted by controlling the direction and the magnitude of the stator current, so that the initial position of the rotor is identified. The method comprises two embodiments, namely, the stator magnetic field and the rotor magnetic field are in the same direction by controlling the stator current, and the stator magnetic field and the rotor magnetic field are in opposite directions by controlling the stator current. By the two modes, the current response change factor can be accurately measured, and the position of the rotor can be judged according to the current response change factor.

The method for identifying the initial position of the motor rotor provided by the embodiment of the application is described in detail below with reference to the accompanying drawings.

In the embodiment of the application, the rotor polarity is judged by utilizing the nonlinear saturation characteristic of the stator core of the permanent magnet synchronous motor and using a pulse voltage signal injection method. The principle of polarity judgment is that constant voltage is injected into a stator D axis, a stator current generates a magnetic field psi s, a rotor permanent magnet generates a magnetic field psi f, when the two magnetic fields are in the same direction, a magnetism assisting effect is generated on a magnetic field synthesized by an air gap, the magnetic saturation degree of a stator core is increased, the magnetic resistance of the stator is increased, the inductance of a winding is reduced, the winding current is inversely proportional to the inductance, and therefore the winding current is increased, otherwise, the two magnetic fields are opposite in direction, a demagnetizing effect is generated, the saturation degree of the stator core is weakened, the magnetic resistance is reduced, the inductance is increased, and the winding current is reduced.

Fig. 2a, 2b, 2c, 2d show the effect of two different magnetic field directions on the magnetic saturation level of the stator core. Fig. 2a and 2b show the case where the magnetic fields are in the same (assisted) and opposite (demagnetized), respectively. Under the condition of magnetism assistance, the magnetic resistance of a stator is increased, the inductance is reduced, and the current is increased, while under the condition of magnetism removal, the magnetic resistance is reduced, the inductance is increased, and the current is reduced.

Fig. 2c and 2d show the relationship between the inductance L and the flux linkage ψ when the rotor polarity is identified by injecting currents in different directions in a Permanent Magnet Synchronous Motor (PMSM). These two figures are quantitative descriptions of the effect of magnetic saturation in this method. In fig. 2c, the horizontal axis (B) represents the flux linkage ψ, which is a measure of the magnetic flux in the motor. The vertical axis (H) represents the magnetic field strength, which is proportional to the current. Lambda _f represents the flux linkage of the permanent magnet. Lambda _f+λ_inj(+U_L) indicates that when the direction of the injected current is the same as the direction of the magnetic field of the permanent magnet (assist), the total flux linkage increases, the inductance L decreases, resulting in an increase in current. Lambda _f-λ_inj(-U_L) indicates that when the injection current direction is opposite to the permanent magnet field direction (demagnetizing), the total flux linkage decreases, the inductance L increases, resulting in a decrease in current. In fig. 2c it can be seen that the two solid lines represent the inductance change in the case of the assist and demagnetization, respectively. The dashed line indicates the change in inductance without the injected current. Fig. 2d is similar to fig. 2c, with different current injection strategies or different motor parameters. In fig. 2d, the solid and dashed lines also show the inductance change under different current injection conditions. By comparing these curves, the effect of current injection on inductance can be observed, which is then used to identify the polarity of the rotor. The influence of current injection on the motor magnetic saturation effect is intuitively demonstrated by showing the relation between the inductance L and the flux linkage ψ. The polarity of the rotor can be distinguished by this effect, since different polarities lead to different degrees of magnetic saturation and inductance variations. The method utilizes the physical characteristics of the motor, and realizes the quick and accurate identification of the initial position of the rotor by accurately controlling the current injection.

On the basis of original high-frequency square wave injection, after the estimated D-axis direction fundamental wave required current is gradually increased from 0 to a given I _Dreq, the D-axis fundamental wave required current is always 0, and the required current reaches the given value, waiting for a period of time t1, stabilizing the current, accumulating the D-axis high-frequency current response in a t2 time period, and calculating the D-axis high-frequency current response average value of the current working condition in the t2 time period, and recording as I _DHi1.

If the direction of the injection current is the N pole direction of the rotor, the magnetic field generated by the stator current is the same as the magnetic field generated by the rotor permanent magnet, so that the magnetic resistance is increased, the inductance Ld is reduced, and the D-axis high-frequency current response is large. And continuously reducing the D-axis continuous demand current to 0 according to the same gradient, reversely increasing to a given value-I _Dreq, waiting for a period of time t1 after the demand current reaches the given value, accumulating the D-axis high-frequency current response in the t2 time period after the demand current is stabilized, and calculating the D-axis high-frequency current response average value of the current working condition in the t2 time period, and recording as I _DHi2.

If the direction of the injection current is the S pole direction of the rotor, the magnetic field generated by the stator current is opposite to the magnetic field generated by the rotor permanent magnet, so that the demagnetizing effect is realized, the magnetic resistance is reduced, the inductance Ld is increased, and the D-axis high-frequency current response is small. Comparing I _DHi1 with I _DHi2, if I _DHi1|>|I_DHi2, the rotor position can be judged as N pole, i.e. the identification angle is the actual angle, otherwise, the rotor position is S pole, i.e. the identification angle is 180 degrees different from the actual angle.

And magnetizing and demagnetizing the motor by giving the D-axis required current in a trapezoidal wave form, enhancing the inductance saturation effect of the motor, waiting for a period of time after the D-axis required current reaches a preset current and stabilizing the current, and accumulating and calculating an average value of the D-axis high-frequency current response. The polarity of the rotor is determined by comparing the D-axis high frequency current responses (I _DHi1 and I _DHi2) when currents are injected in different directions. If I _DHi1|>|I_DHi2, the rotor position is N pole, otherwise S pole. The reliability of the data is improved, the problem of polarity discrimination misdiscrimination caused by current fluctuation or sampling errors is reduced, and the accuracy of polarity discrimination is improved.

Fig. 3 illustrates a system logic flow diagram of polarity determination, depicting a control flow of a Permanent Magnet Synchronous Motor (PMSM) rotor initial position identification method. The system regulates current through a current loop PI controller, and controls IPMS (interior permanent magnet synchronous motor) using inverse Park conversion and SVPWM (space vector pulse width modulation). Three-phase currents (Ia, ib, ic) of the motor can be monitored by Park and Clark conversion. If the D-axis current (I _d) is less than 0, the system adjusts the angle θ to ensure that the current direction is correct.

At the beginning of the system, the rotor position of a Permanent Magnet Synchronous Motor (PMSM) is unknown.

In the first stage, the current loop PI controller regulates D-axis (straight axis) and q-axis (quadrature axis) currents of the motor.

In the figure, it receives the target current values (Id and Iq) and outputs control signals (ud and uq) to adjust the current of the motor. Id is the D-axis current and Iq is the q-axis current. In the control of the PMSM, the current loop PI controller sets the target current Id to 0 and iq to 0 to achieve the magnetic field orientation control.

A pulse voltage signal is injected into the D-axis of the stator to generate a magnetic field ψs. The PI controller calculates a required current value according to the magnetic field ψs generated as needed, and outputs a control signal (ud, uq) to adjust the current of the motor. After inverse Park conversion, the control signal output by the current loop PI controller can be used to determine the direction of the current, so as to infer the relationship between the magnetic field ψs and the magnetic field ψf generated by the rotor permanent magnet.

And the second stage, namely converting the current component in the d-q coordinate system into the current component in the three-phase static coordinate system by inverse Park conversion.

Third stage space vector pulse width modulation SVPWM is a PWM technique for controlling PMSM that generates PWM signals from the inverse Park converted current components to control the phase currents of the motor.

The fourth stage is that the interior permanent magnet synchronous motor IPMSM is a controlled motor model that receives the PWM signals generated by the SVPWM and generates three-phase currents (Ia, ib, ic).

The fifth stage, clark transformation, converts the three-phase currents (Ia, ib, ic) into current components (I _DHi1 and I _DHi2) in a two-phase stationary coordinate system (α - β coordinate system). This is a pre-step in Park conversion because Park conversion requires as input the current in the two-phase stationary coordinate system.

The Clark transformation converts the three-phase currents (Ia, ib, ic) into current components in a two-phase stationary coordinate system, which can then be used to calculate the high frequency current response of the D-axis. After the D-axis demand current gradually increases to I _Dreq, the system waits for a time t1 to stabilize the current, then accumulates the D-axis high frequency current response over a period of t2, and calculates an average I _DHi1.

The sixth stage Park transformation converts the current components in the two-phase stationary coordinate system (α - β coordinate system) into current components (Id, iq) in the rotating coordinate system (d-q coordinate system).

The Park-transformed d-q coordinate system current components (Id, iq) are fed into the current loop PI controller. The controller adjusts the control signal to regulate the current of the motor based on the difference between the set target current value (typically Id is 0, iq is also 0 at start-up) and the actual current value. After the current loop PI controller outputs the control signal, the inverse Park transform converts the control signal in the d-q coordinate system back to the three-phase stationary coordinate system to generate a PWM signal suitable for motor driving. Finally, the SVPWM module generates PWM signals according to the signals after inverse Park conversion, and controls phase currents of the motor. The polarity of the rotor can be determined by injecting current into the stator D-axis and monitoring the D-axis high frequency current response. Park transformation is used in this process to convert three-phase currents into current components in the d-q coordinate system for more accurate control and monitoring of the currents.

The controller adjusts the output signal such that the D-axis demand current decreases to 0 and increases back to-I _Dreq. The system again waits for time t1 to stabilize the current and then adds up the D-axis high frequency current response over a period of time t2 and calculates the average I _DHi2.

And in the seventh stage, the difference making module can judge the position of the rotor by comparing the absolute values of the I _DHi1 and the I _DHi2. If I _DHi1|>|I_DHi2, the rotor position is N pole, otherwise S pole. This allows the system to determine the polarity of the rotor and thus correctly identify the initial position of the rotor.

In the eighth stage, if Id <0, i.e. the D-axis current is negative, the system adjusts the angle θ to ensure the current direction is correct.

The control flow realizes the quick and accurate identification of the initial position of the rotor by accurately controlling the current of the motor and utilizing the magnetic saturation characteristic of the PMSM. Through the current loop PI controller and SVPWM, the system is able to dynamically adjust the current of the motor in response to changes in rotor position. Whereas the Clark and Park transforms are used to monitor the current and calculate the rotor position. The design of the whole system aims at improving the accuracy of rotor position detection and the robustness of the system.

The current loop PI controller can adjust the current of the motor according to the requirements of trapezoidal wave current, and the inverse Park conversion and SVPWM module can generate corresponding control signals according to the adjustment. Fig. 4 shows a schematic diagram of a trapezoidal wave current. The trapezoidal current is a non-sinusoidal waveform that remains for a period of time after reaching a maximum value and then gradually decreases back to zero. Such waveforms may reduce abrupt changes in current, thereby reducing the risk of current ripple and overcurrent. In fig. 4, the current is gradually increased from 0 to a preset maximum (I _Dreq), which is linear and reduces the abrupt change in current. The current is held at a maximum value for a period of time (t 1), which allows the current to stabilize, reducing the impact of current fluctuations on the measurement. Then the current gradually decreases back to 0, which process is also linear. After the current stabilizes, the system will collect data on the D-axis high frequency current response over a period of time (t 2). The collected data is accumulated and an average is calculated, which average (I _DHi1) is used for subsequent polarity determination.

In this method, the D-axis demand current is set to a trapezoidal wave instead of a rectangular wave to avoid current abrupt change, improve dynamic following effect, and reduce current fluctuation and overcurrent risk. Compared with a rectangular wave, the trapezoidal wave can provide smoother current change, and the influence caused by current abrupt change is reduced. The magnetic saturation effect of the motor can be better controlled through the trapezoidal wave, so that the accuracy of polarity discrimination is improved. The D-axis required current is given to be trapezoidal wave, so that the motor inductance saturation effect can be enhanced, and the accuracy of polarity discrimination can be improved. After the current is stable, by waiting for a period of time (t 1) and calculating the average value of the D-axis high-frequency current response in the t2 period of time, the reliability of the data can be improved, and erroneous judgment caused by current fluctuation or sampling errors can be reduced. Advantages of this approach include reduced rotor position detection time, improved detection accuracy, interference suppression, and increased system robustness. Through the technical means, the accuracy and the reliability of the identification of the initial position of the rotor of the permanent magnet synchronous motor can be effectively improved.

In summary, the embodiment of the application provides a method for identifying an initial position of a motor rotor, which comprises the steps of injecting pulse voltage signals into a stator of the motor to enable stator current to generate a stator magnetic field and simultaneously enable a rotor permanent magnet to generate a rotor magnetic field, calculating current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions within a preset time by controlling the direction and the magnitude of the stator current, and identifying the initial position of the motor rotor according to the current response change factors in the different opposite directions. By injecting a pulsed voltage signal into the motor stator, the direction and magnitude of the stator current is precisely controlled to measure the interaction between the stator and rotor magnetic fields in different relative directions. This interaction is characterized by a current response variation factor, thereby enabling accurate identification of the initial position of the motor rotor.

Based on the same technical concept, the embodiment of the application also provides a motor rotor initial position identification system, as shown in fig. 5, the system comprises:

a magnetic field generating module 501, configured to inject a pulse voltage signal into a stator of the motor, so that a stator current generates a stator magnetic field, and a rotor permanent magnet generates a rotor magnetic field;

A current response calculation module 502, configured to calculate a current response variation factor of the stator magnetic field and the rotor magnetic field in different opposite directions within a predetermined time by controlling the direction and the magnitude of the stator current;

a position identifying module 503, configured to identify an initial position of the motor rotor according to the current response change factors in the different opposite directions.

The embodiment of the application also provides electronic equipment corresponding to the method provided by the embodiment. Referring to fig. 6, a diagram of an electronic device according to some embodiments of the present application is shown. The electronic device 20 may comprise a processor 200, a memory 201, a bus 202 and a communication interface 203, wherein the processor 200, the communication interface 203 and the memory 201 are connected through the bus 202, a computer program capable of running on the processor 200 is stored in the memory 201, and the processor 200 executes the method provided by any one of the foregoing embodiments of the present application when running the computer program.

The memory 201 may include a high-speed random access memory (RAM: random Access Memory), and may further include a non-volatile memory (non-volatile memory), such as at least one disk memory. The communication connection between the system network element and the at least one other network element is implemented through at least one physical port (which may be wired or wireless), and the internet, wide area network, local network, metropolitan area network, etc. may be used.

Bus 202 may be an ISA bus, a PCI bus, an EISA bus, or the like. The buses may be classified as address buses, data buses, control buses, etc. The memory 201 is configured to store a program, and the processor 200 executes the program after receiving an execution instruction, and the method disclosed in any of the foregoing embodiments of the present application may be applied to the processor 200 or implemented by the processor 200.

The processor 200 may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method may be performed by integrated logic circuits of hardware in the processor 200 or by instructions in the form of software. The processor 200 may be a general-purpose processor including a central processing unit (Central Processing Unit, CPU for short), a network processor (Network Processor, NP for short), etc., or may be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, or discrete hardware components. The disclosed methods, steps, and logic blocks in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be embodied directly in the execution of a hardware decoding processor, or in the execution of a combination of hardware and software modules in a decoding processor. The software modules may be located in a random access memory, flash memory, read only memory, programmable read only memory, or electrically erasable programmable memory, registers, etc. as well known in the art. The storage medium is located in the memory 201, and the processor 200 reads the information in the memory 201, and in combination with its hardware, performs the steps of the above method.

The electronic device provided by the embodiment of the application and the method provided by the embodiment of the application have the same beneficial effects as the method adopted, operated or realized by the electronic device and the method provided by the embodiment of the application due to the same inventive concept.

The present application further provides a computer readable storage medium corresponding to the method provided in the foregoing embodiments, referring to fig. 7, the computer readable storage medium is shown as an optical disc 30, on which a computer program (i.e. a program product) is stored, where the computer program, when executed by a processor, performs the method provided in any of the foregoing embodiments.

It should be noted that examples of the computer readable storage medium may also include, but are not limited to, a phase change memory (PRAM), a Static Random Access Memory (SRAM), a Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), a Read Only Memory (ROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), a flash memory, or other optical or magnetic storage medium, which will not be described in detail herein.

The computer-readable storage medium provided by the above-described embodiments of the present application has the same advantageous effects as the method adopted, operated or implemented by the application program stored therein, for the same inventive concept as the method provided by the embodiments of the present application.

It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.

The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structural changes made by the specification and drawings of the present invention or direct/indirect application in other related technical fields are included in the scope of the present invention.

Claims

1. A method for identifying an initial position of a rotor of an electric machine, the method comprising:

2. The method of claim 1, wherein said calculating current response variation factors of said stator magnetic field and said rotor magnetic field in different relative directions for a predetermined time by controlling the direction and magnitude of said stator current when said stator magnetic field is the same as said rotor magnetic field, comprises:

3. The method of claim 1, wherein said calculating current response variation factors of said stator magnetic field and said rotor magnetic field in different opposite directions for a predetermined time by controlling the direction and magnitude of said stator current when said stator magnetic field is opposite to said rotor magnetic field comprises:

4. A method according to any one of claims 1-3, wherein said calculating a current response variation factor of said stator current over said predetermined time period comprises:

5. The method of claim 4, wherein identifying the initial position of the motor rotor based on the current response variation factors for the different relative directions comprises:

6. The method of claim 1, further comprising controlling the direction and magnitude of the stator current such that the stator magnetic field is in the same direction as the rotor magnetic field, comprising:

7. The method of claim 1, further comprising controlling the direction and magnitude of the stator current such that the stator magnetic field is opposite to the rotor magnetic field, comprising:

8. A motor rotor initial position identification system, the system comprising:

9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the method of any of claims 1-7.

10. A computer readable storage medium having stored thereon computer readable instructions executable by a processor to implement the method of any of claims 1-7.