CN105024613A - Obtaining method of motor off-line resistance value, controller and air conditioner - Google Patents

Abstract

The invention discloses an obtaining method of a motor off-line resistance value, a controller and an air conditioner. The obtaining method of the motor off-line resistance value comprises, when a motor is electrified and is not started, according to a plurality of preset reactive currents of a d axis of the motor, determining voltages of the d axis corresponding to the preset reactive currents of the d axis, and, according to a plurality of preset active currents of a q axis of the motor, determining voltages of the q axis corresponding to the preset active currents of the q axis; and, according the preset reactive currents of the d axis, the voltages of the d axis, the preset active currents of the q axis and the voltages of the q axis, obtaining the off-line resistance value of the motor. On the condition that no cost increases, the method can obtain the off-line resistance value at a starting stage of the motor, obtaining time of the off-line resistance value is short, and precision of the off-line resistance value is high.

Description

Motor offline resistance value obtaining method, controller and air conditioner

Technical Field

The invention relates to the technical field of motor driving, in particular to a motor offline resistance value obtaining method, a controller and an air conditioner.

Background

For drives employing vector control strategies, there is a strong dependence on motor parameters. Therefore, obtaining accurate motor parameters plays a crucial role in improving the motor control efficiency and reducing the motor energy consumption. The resistance is also an important parameter of the motor, and the resistance participates in the calculation in the processes of design of a current loop controller, calculation without a position sensor, voltage compensation and the like, so that the accurate motor parameter acquisition is necessary.

At present, the parameters of the motor are generally obtained through no-load or locked rotor experiments, but the method is generally completed manually, so that not only is the labor cost and the cost of a testing instrument increased, but also the testing error is larger.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the method for acquiring the motor offline resistance value, the controller and the air conditioner, and the testing precision of the motor offline resistance value is improved under the condition of not increasing any cost.

In a first aspect, the present invention provides a method for obtaining an offline resistance value of a motor, including:

when a motor is powered on and is not started, determining the voltage of a d axis corresponding to a plurality of preset reactive currents of the d axis of the motor according to a plurality of preset reactive currents of the d axis, and determining the voltage of a q axis corresponding to a plurality of preset active currents of the q axis of the motor according to a plurality of preset active currents of the q axis;

and obtaining the offline resistance value of the motor according to the plurality of preset reactive currents of the d axis, the voltage of the d axis, the plurality of preset active currents of the q axis and the voltage of the q axis.

Optionally, the preset multiple reactive currents of the d-axis of the motor include: a first reactive current, a second reactive current and a third reactive current;

correspondingly, the determining the voltage of the d-axis corresponding to the preset reactive currents of the d-axis according to the preset reactive currents of the d-axis of the motor includes:

and determining a first voltage, a second voltage and a third voltage which sequentially correspond to the first reactive current, the second reactive current and the third reactive current according to the first reactive current, the second reactive current and the third reactive current.

Optionally, the q-axis preset multiple reactive currents of the motor include: a first active current, a second active current, and a third active current;

correspondingly, the determining the voltage of the q-axis corresponding to a plurality of preset active currents of the q-axis according to a plurality of preset active currents of the q-axis of the motor includes:

and determining a fourth voltage, a fifth voltage and a sixth voltage which sequentially correspond to the first active current, the second active current and the third active current according to the first active current, the second active current and the third active current.

Optionally, the obtaining an offline resistance value of the motor according to a plurality of preset reactive currents of the d axis, a voltage of the d axis, a plurality of preset active currents of the q axis, and a voltage of the q axis includes:

obtaining an offline resistance value of the d axis according to a plurality of preset reactive currents of the d axis and the voltage of the d axis, and obtaining an offline resistance value of the q axis according to a plurality of preset active currents of the q axis and the voltage of the q axis;

and obtaining the offline resistance value of the motor according to the offline resistance value of the d axis and the offline resistance value of the q axis.

Optionally, the obtaining the offline resistance value of the d-axis according to the preset multiple reactive currents of the d-axis and the voltage of the d-axis includes:

according toAcquiring an offline resistance value of a first d axis;

according toAcquiring an off-line resistance value of a second d axis;

according to R_d＝(R_d1+R_d2) Acquiring an off-line resistance value of the d axis;

wherein,which represents the first reactive current, is,which represents the second reactive current and is,which represents the third reactive current and is,which represents the first voltage, is provided by the first voltage,which represents the second voltage, is provided,representing a third voltage, R representing a predetermined line impedance, R_d1Representing the off-line resistance value, R, of the first d-axis_d2Representing the off-line resistance value, R, of the second d-axis_dRepresenting the off-line resistance value of the d-axis.

Optionally, the obtaining of the offline resistance value of the q axis according to a plurality of active currents preset for the q axis and the voltage of the q axis includes:

according toAcquiring an offline resistance value of a first q axis;

according toAcquiring an offline resistance value of a second q axis;

according to R_q＝(R_q1+R_q2) Acquiring an offline resistance value of the q axis;

wherein,which represents the first active current, is,representing the second powerThe flow of the stream(s),which represents the third active current, is,which represents the fourth voltage, is provided,which represents the voltage of the fifth voltage, is,representing a sixth voltage, R being a predetermined line impedance, R_q1Representing the off-line resistance value of the first q-axis, R_q2Representing the off-line resistance value of the second q-axis, R_qRepresenting the off-line resistance value of the q-axis.

Optionally, before determining, according to a plurality of preset reactive currents of a d-axis of the motor, a voltage of the d-axis corresponding to the plurality of preset reactive currents of the d-axis and determining, according to a plurality of preset active currents of a q-axis of the motor, a voltage of the q-axis corresponding to the plurality of preset active currents of the q-axis, the method further includes:

acquiring a first environment temperature of the current environment, and comparing the first environment temperature with a second environment temperature of the motor before the last power-on starting;

and if the value of the temperature change of the first environment temperature relative to the second environment temperature exceeds the value of a preset temperature change range, executing the step of determining the voltage of the d axis and the voltage of the q axis.

Optionally, after the offline resistance value of the motor is obtained according to the preset reactive currents of the d axis, the preset voltage of the d axis, the preset active currents of the q axis, and the preset voltage of the q axis, the method further includes:

judging whether the off-line resistance value of the motor is within a preset off-line resistance value range or not;

and if the off-line resistance value of the motor is not in the range of the preset off-line resistance value, executing the step of determining the voltage of the d axis and the voltage of the q axis.

In a second aspect, the present invention also provides a controller, comprising:

the device comprises a first determining module, a second determining module and a control module, wherein the first determining module is used for determining the voltage of a d axis corresponding to a plurality of preset reactive currents of the d axis of a motor according to the preset reactive currents of the d axis of the motor when the motor is powered on and is not started;

the second determining module is used for determining the voltage of the q axis corresponding to a plurality of active currents preset on the q axis according to a plurality of active currents preset on the q axis of the motor when the motor is powered on and is not started;

the obtaining module is used for obtaining the offline resistance value of the motor according to the multiple preset reactive currents of the d axis, the voltage of the d axis, the multiple preset active currents of the q axis and the voltage of the q axis.

In a third aspect, the present invention also provides an air conditioner comprising a motor, a temperature sensor and the controller as claimed in claim 9, the motor and the temperature sensor being connected to the controller;

the controller is used for acquiring an offline resistance value of the motor when the motor is powered on and is not started;

the temperature sensor is used for detecting a third environment temperature when the motor is powered on and is not started;

the controller is further configured to compare the third ambient temperature with a fourth ambient temperature before the motor is powered on and started last time, and determine whether to reacquire the offline resistance value of the motor.

According to the technical scheme, the invention provides the method for obtaining the off-line resistance value of the motor, the controller and the air conditioner, the method comprises the steps of inputting a plurality of preset reactive currents and a plurality of preset active currents into a d axis and a q axis of the motor respectively, determining the voltage of the d axis corresponding to the reactive currents and the voltage of the q axis corresponding to the active currents, and obtaining the off-line resistance value of the motor according to the reactive currents, the voltage of the d axis, the active currents and the voltage of the q axis.

Drawings

Fig. 1 is a schematic flow chart of a method for obtaining an offline resistance value of a motor according to an embodiment of the present invention;

fig. 2 is a block diagram of off-line parameter self-diagnosis control according to an embodiment of the present invention;

3A-3C are graphs of a plurality of preset reactive currents on d-axis, a preset active current on q-axis and a given motor speed, respectively, according to an embodiment of the present invention;

FIG. 4 is a graph of phase a current before and during start-up of a motor according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a controller according to an embodiment of the present invention.

Detailed Description

The following further describes embodiments of the invention with reference to the drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

Fig. 1 shows a schematic flow chart of a method for obtaining an offline resistance value of a motor according to an embodiment of the present invention, and as shown in fig. 1, the method includes the following steps:

101. when the motor is powered on and is not started, determining the voltage of the d axis corresponding to a plurality of preset reactive currents of the d axis of the motor according to a plurality of preset reactive currents of the d axis, and determining the voltage of the q axis corresponding to a plurality of preset active currents of the q axis of the motor according to a plurality of preset active currents of the q axis.

It can be understood that when the motor is powered on and is not started, the motor performs an open loop process by using a vector to control the speed therein, and the given electrical angular speed is 0, and the rotor of the motor is in a static state at this time.

The preset reactive currents may be understood as at least two reactive currents, the preset active currents may be understood as at least two active currents, and the reactive currents and the active currents are preset current values mainly used for calculating a voltage value corresponding to each current value.

102. And obtaining the offline resistance value of the motor according to the plurality of preset reactive currents of the d axis, the voltage of the d axis, the plurality of preset active currents of the q axis and the voltage of the q axis.

According to the method, the preset reactive currents and the preset active currents are respectively input to the d axis and the q axis of the motor, the voltage of the d axis corresponding to the reactive current and the voltage of the q axis corresponding to the active current are determined, and the off-line resistance value of the motor is obtained according to the reactive current, the voltage of the d axis, the active current and the voltage of the q axis.

Specifically, in step 101, according to a plurality of preset reactive currents of the d-axis of the motor, the voltage of the d-axis corresponding to the preset reactive currents of the d-axis is determined, where as shown in fig. 2, the given current of the d-axis isThe actual current is I_dObtaining voltage after PI regulationThen will beAnd a decoupling term RI_d-ωL_qI_qThe sum of which gives the voltage V of the d axis_d(ii) a Similarly, according to a plurality of active currents preset on the q axis of the motor, determining the voltage of the q axis corresponding to the plurality of active currents preset on the q axis, as shown in fig. 2, where the given current of the q axis isThe actual current is I_qObtaining voltage after PI regulationThen will beAnd a decoupling term RI_q+ωL_d I_d+ωK_eThe sum of which yields the voltage V of the q-axis_qIn an implementation process, according to a plurality of preset reactive currents of a d axis of the motor in other manners, the voltage of the d axis corresponding to the plurality of preset reactive currents of the d axis may be determined, and according to a plurality of preset active currents of a q axis of the motor, the voltage of the q axis corresponding to the plurality of preset active currents of the q axis may be determined.

The above method is described in detail below by way of specific examples.

It should be noted that, in the following embodiments, the off-line resistance of the permanent magnet synchronous motor is calculated in detail, and the type of the motor is not limited in the present embodiment, and the off-line resistance value may be obtained by other types of motors by the following method.

In the off-line resistance calculation, a method of calculating the resistance of the d axis and the q axis and then averaging is adopted to avoid calculation errors caused by uncertain factors. Meanwhile, in order to improve the calculation accuracy, external factors such as tube voltage drop of the resistor, line impedance, dead time and the like are fully considered. The specific calculation process is as follows:

the motor vector equation obtained with the rotor field orientation rotating at the rotor synchronous speed is as follows:

<math> <mrow> <mfenced open = '[' close = ']'> <mtable> <mtr> <mtd> <msub> <mi>V</mi> <mi>d</mi> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>V</mi> <mi>q</mi> </msub> </mtd> </mtr> </mtable> </mfenced> <mo>=</mo> <mfenced open = '[' close = ']'> <mtable> <mtr> <mtd> <mrow> <mi>R</mi> <mo>+</mo> <msub> <mi>pL</mi> <mi>d</mi> </msub> </mrow> </mtd> <mtd> <mrow> <mo>-</mo> <msub> <mi>&omega;L</mi> <mi>q</mi> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>&omega;L</mi> <mi>d</mi> </msub> </mrow> </mtd> <mtd> <mrow> <mi>R</mi> <mo>+</mo> <msub> <mi>pL</mi> <mi>q</mi> </msub> </mrow> </mtd> </mtr> </mtable> </mfenced> <mo>*</mo> <mfenced open = '[' close = ']'> <mtable> <mtr> <mtd> <msub> <mi>I</mi> <mi>d</mi> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>I</mi> <mi>q</mi> </msub> </mtd> </mtr> </mtable> </mfenced> <mo>+</mo> <mfenced open = '[' close = ']'> <mtable> <mtr> <mtd> <mn>0</mn> </mtd> </mtr> <mtr> <mtd> <mi>&omega;</mi> <msub> <mi>K</mi> <mi>e</mi> </msub> </mtd> </mtr> </mtable> </mfenced> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein v is_dVoltage, v, representing the d-axis_qVoltage representing the q-axis, L_dInductance representing the d-axis, L_qInductance representing the q-axis, I_dCurrent representing d-axis, I_qRepresenting the q-axis current, R representing the off-line resistance of the machine, p representing the derivative term, ω representing the angular speed of the rotor, K_eRepresenting the back emf coefficient.

In consideration of the system stability when the rotor is stopped, that is, when the rotor angular velocity ω is 0, the above equation (1) may be equivalent to the following expression:

$\left[\begin{array}{c}{V}_d\\ V_q\end{array}\right]=\left[\begin{array}{cc}R& 0\\ 0& R\end{array}\right]*\left[\begin{array}{c}{I}_d\\ I_q\end{array}\right]---\left(2\right)$

if the tube voltage drop of the resistor and the voltage drop equivalent to the dead time are set as e, and the line impedance is equivalent to r, the above equation (2) can be equivalent to the following equation (3):

$\left[\begin{array}{c}{V}_d\\ V_q\end{array}\right]=\left[\begin{array}{cc}{R}_d+r& 0\\ 0& R_q+r\end{array}\right]*\left[\begin{array}{c}{I}_d\\ I_q\end{array}\right]+\left[\begin{array}{c}{e}_d\\ e_q\end{array}\right]---\left(3\right)$

wherein R is_dResistance representing d-axis, R_qResistance representing the q-axis, e_dComponent on d-axis of the tube voltage drop and dead time equivalent voltage drop representing resistance, e_qThe component of the q-axis of the tube voltage drop representing the resistance and the dead time equivalent voltage drop.

According to the formula (3), since I_dAnd I_qFor a given parameter, v_dAnd v_qIs composed of_dAnd I_qThe line impedance R may be an empirically obtained parameter (the resistance equivalent resistance is generally equal to 0.1 Ω according to the test result), and therefore, it is desirable to calculate R_dAnd R_qNeed to determine e_dAnd e_q，e_dAnd e_qAre unknown, so two equations are necessary to calculate the resistance Rd or Rq. In order to reduce the pressure drop e thus equivalent_dAnd e_qThe induced error therefore necessitates that the given current settings be relatively close. Taking d-axis as an example, two equations are shown in the following equation (4):

$\left\{\begin{array}{c}{V}_{d1}=(R_d+r)I_{d1}+e_d\\ V_{d2}=(R_d+r)I_{d2}+e_d\end{array}\right.---\left(4\right)$

wherein, V_d1First voltage representing d-axis，V_d2A second voltage, I, representing the d-axis_d1First current, I, representing d-axis_d2A second current representing the d-axis.

The resistance component of the d-axis can be calculated from equation (4):

R_d＝(V_d1-V_d2)/(I_d1-I_d2)-r (5)

similarly, the resistance component of the q-axis can be calculated:

R_q＝(V_q1-V_q2)/(I_q1-I_q2)-r (6)

wherein, V_q1A first voltage, V, representing the q-axis_q2A second voltage, I, representing the q-axis_q1First current, I, representing the q-axis_q2Representing a second current of the q-axis.

The final resistance value can be calculated according to the formulas (5) and (6):

R＝(R_d+R_q)/2 (7)

by the method, in order to enable the resistance value to be calculated more accurately, three reactive currents of a given d axis are adopted in the following embodiment, resistance components of two d axes are calculated, and then the calculated resistances of the two d axes are averaged to calculate the resistance of the d axis; similarly, three active currents of a given q axis are adopted to calculate the resistance of two q axes, then the calculated resistance of the two q axes is averaged to calculate the resistance of the q axis, and finally the resistance of the d axis and the resistance of the q axis are averaged to calculate the final resistance value. The number of the given reactive current and the active current is not limited in this embodiment, and the current may be a single value or a linearly increasing current value, which is exemplified below.

First, given the three reactive currents of the d-axis include: first reactive currentSecond reactive currentAnd a third reactive currentAccording to the first idle currentSecond reactive currentAnd a third reactive currentDetermining the first reactive currentSecond reactive currentAnd a third reactive currentSequentially corresponding first voltagesSecond voltageAnd a third voltageThe three active currents for the q-axis of a given machine include: first active currentSecond active currentAnd a third active currentAccording to the first active currentSecond active currentAnd a third active currentDetermining a first active currentSecond active currentAnd a third active currentCorresponding fourth voltage in turnFifth voltageAnd a sixth voltage

According to the preset first idle current of the d axisSecond reactive currentThird reactive currentFirst voltageSecond voltageAnd a third voltageAnd acquiring the off-line resistance value of the d axis.

As shown in fig. 3A, 3B, and 3C, during the time (0-t1) interval: the reactive current and the active current are respectively linearly increased according to given curvesAndwill be provided withAs a result of the first reactive current,as the first active current, the given motor speed is 0 at this time.

At the interval of time (t1-t 2): given reactive and active current maintenanceAndthe given motor speed is 0 at this time. The following relations are provided:

$\left\{\begin{array}{c}{V}_{d1}^{*}=(R_d+r)I_{d1}^{*}+e_d\\ V_{q1}^{*}=(R_q+r)I_{q1}^{*}+e_q\end{array}\right.---\left(8\right)$

at the interval of time (t2-t 3): given reactive and active currentThe current increases linearly according to a given curveAndwill be provided withAs a second reactive current, willAs a second active current, the given motor speed is now 0.

At the interval of time (t3-t 4): given reactive and active current maintenanceAndthe given motor speed is 0 at this time. The following relations are provided:

$\left\{\begin{array}{c}{V}_{d2}^{*}=(R_d+r)I_{d2}^{*}+e_d\\ V_{q2}^{*}=(R_q+r)I_{q2}^{*}+e_q\end{array}\right.---\left(9\right)$

at the interval of time (t4-t 5): the given reactive current and the active current are linearly increased according to a given curveAndwill be provided withAs a third reactive current, willAs the third active current, the given motor speed is 0 at this time.

At times greater than t 5: given reactive and active current maintenanceAndthe given motor speed is 0 at this time. The following relations are provided:

$\left\{\begin{array}{c}{V}_{d3}^{*}=(R_d+r)I_{d3}^{*}+e_d\\ V_{q3}^{*}=(R_q+r)I_{q3}^{*}+e_q\end{array}\right.---\left(10\right)$

wherein the first resistance component R of the d-axis_d1And a second resistance component R of d-axis_d2Comprises the following steps: first reactive currentSecond reactive currentThird reactive currentFirst voltageSecond voltageAnd a third voltageAnd acquiring the off-line resistance value of the d axis.

According to the first reactive currentSecond reactive currentFirst voltageAnd a second voltageCalculating the off-line resistance R of the first d-axis_d1；

$R_{d1}=(V_{d1}^{*}-V_{d2}^{*})/(I_{d1}^{*}-I_{d2}^{*})-r---\left(11\right)$

Wherein r is a preset line impedance, and is generally 0.1 Ω;

according to the second reactive currentThird reactive currentSecond voltageAnd a third voltageCalculating the off-line resistance R of the second d-axis_d2；

$R_{d2}=(V_{d3}^{*}-V_{d2}^{*})/(I_{d3}^{*}-I_{d2}^{*})-r---\left(12\right)$

Wherein r is a preset line impedance, and is generally 0.1 Ω;

off-line resistance R according to the first d-axis_d1And a second d-axis off-line resistance R_d2Calculating the off-line resistance value R of the d axis_d；

R_d＝(R_d1+R_d2)/2 (13)

Similarly according to the first active currentSecond active currentThird active currentA fourth voltageFifth voltageAnd a sixth voltageAnd acquiring the offline resistance value of the q axis.

According to the first active currentSecond active currentA fourth voltageFifth voltageCalculating the offline resistance value R of the first q axis_q1；

$R_{q1}=(V_{q1}^{*}-V_{q2}^{*})/(I_{q1}^{*}-I_{q2}^{*})-r---\left(14\right)$

Wherein r is a preset line impedance, and is generally 0.1 Ω;

according to the second active currentThird active currentFifth voltageAnd a sixth voltageCalculating the off-line resistance R of the second q-axis_q2；

$R_{q2}=(V_{q3}^{*}-V_{q2}^{*})/(I_{q3}^{*}-I_{q2}^{*})-r---\left(15\right)$

Wherein r is a preset line impedance, and is generally 0.1 Ω;

off-line resistance R according to the first q-axis_q1And off-line resistance R of the second q-axis_q2Calculating the off-line resistance value R of the q axis_q；

Wherein R is_q＝(R_q1+R_q2)/2 (16)

And obtaining the offline resistance value of the motor according to the offline resistance value of the d axis and the offline resistance value of the q axis. That is, the final calculated resistance value is obtained according to the formula (13) and the formula (16), where R ═ R (R) is shown in the formula (7)_d+R_q)/2。

The method fully considers factors such as line equivalent circuit impedance, tube voltage drop, dead time and the like, eliminates unknown quantities of the factors through given current, and finally calculates the resistance value.

Fig. 4 shows graphs of phase a current before and at the time of starting of a motor provided by the embodiment of the invention, wherein the horizontal axis represents time and the vertical axis represents the magnitude of current, as shown in fig. 4, the current given in the method comprises three platforms, the current amplitudes of the platform 1, the platform 2 and the platform 3 are respectively 5A, 6A and 7A, and the operation time of each platform is 0.1s, so that the stabilized current is relatively close to the voltage drop e which ensures the equivalent of tube voltage drop and dead time.

By substituting R to 0.1 Ω and related parameters, it is found that the calculated resistance R is 1.03 Ω, and the manufacturer-specified value is 1.05 Ω, and the control accuracy can be controlled within 5%.

Meanwhile, when t is 1s, the motor current is operated according to a certain frequency. As can be seen from FIG. 3, the whole process of obtaining the off-line resistance of the motor only needs 1s of time, and the operation is simple and strong.

Because the resistor is used as a key parameter of the motor to be more sensible to the temperature, when the working condition changes, if factory parameters are adopted for operation, certain errors can be generated in system control. Therefore, it is necessary to update the parameters again.

In this embodiment, in step 101, when the motor is powered on and is not started, before determining the voltage of the d-axis corresponding to a plurality of preset reactive currents of the d-axis of the motor according to a plurality of preset reactive currents of the d-axis, and determining the voltage of the q-axis corresponding to a plurality of preset active currents of the q-axis of the motor according to a plurality of preset active currents of the q-axis, the method further includes steps, which are not shown in fig. 1:

103. acquiring a first environment temperature of the current environment, and comparing the first environment temperature with a second environment temperature of the motor before the last power-on starting;

104. if the value of the temperature change of the first environment temperature relative to the second environment temperature exceeds the value of a preset temperature change range, determining the voltage of the d axis and the voltage of the q axis, namely determining the voltage of the d axis corresponding to a plurality of preset reactive currents of the d axis of the motor according to a plurality of preset reactive currents of the d axis, and determining the voltage of the q axis corresponding to a plurality of preset active currents of the q axis of the motor according to a plurality of preset active currents of the q axis.

For example, if the first ambient temperature is 50 ℃, the second ambient temperature is 30 ℃ and the preset temperature variation range is ± 10 ℃, then when the first ambient temperature is detected to be 50 ℃, the temperature variation of the second ambient temperature 30 ℃ stored before the motor is powered on and started last time is found to be 20 ℃, and the 20 ℃ is greater than the preset temperature variation range by ± 10 ℃, so that in order to avoid the problems that the resistance calculation is inaccurate due to the ambient temperature, and the current control, the speed estimation, the compensation amount of the voltage model and the like during the motor starting are influenced, the off-line resistance value of the motor needs to be recalculated by the above method.

The method for updating the resistance according to the change of the environmental temperature. Meanwhile, the final average value is used as the calculated resistance value by calculating d-axis and q-axis resistances and averaging the results. The method can effectively avoid the problem of inaccurate resistance calculation caused by uncertain factors.

Furthermore, after the step 102 of obtaining the offline resistance value of the motor according to the preset multiple reactive currents of the d axis, the preset voltage of the d axis, the preset multiple active currents of the q axis and the preset voltage of the q axis, the method further includes the steps not shown in fig. 1:

105. judging whether the off-line resistance value of the motor is within a preset off-line resistance value range or not;

106. if the offline resistance value of the motor is not within the range of a preset offline resistance value, the step of determining the voltage of the d axis and the voltage of the q axis is executed, namely the step of determining the voltage of the d axis corresponding to a plurality of preset reactive currents of the d axis according to a plurality of preset reactive currents of the d axis of the motor, and the step of determining the voltage of the q axis corresponding to a plurality of preset active currents of the q axis of the motor according to a plurality of preset active currents of the q axis of the motor. And recording the current temperature and the resistance value for storage for use in the next calculation.

The method judges the calculated resistance value, and if the resistance value is not in the given range, the resistance value is calculated again. The problem of inaccurate resistance calculation caused by uncertain factors is effectively avoided.

Fig. 5 is a schematic structural diagram of a controller according to an embodiment of the present invention, and as shown in fig. 5, the controller includes: a first determining module 51, a second determining module 52 and an obtaining module 53;

the first determining module 51 is configured to determine, when the motor is powered on and is not started, a voltage of a d-axis corresponding to a plurality of preset reactive currents of the d-axis of the motor according to the preset reactive currents of the d-axis;

a second determining module 52, configured to determine, when the motor is powered on and is not started, a voltage of a q-axis corresponding to a plurality of active currents preset for the q-axis according to a plurality of reactive currents preset for the q-axis of the motor;

the first obtaining module 53 is configured to obtain an offline resistance value of the motor according to a plurality of preset reactive currents of the d axis, a voltage of the d axis, a plurality of preset active currents of the q axis, and a voltage of the q axis.

In a preferred embodiment of this embodiment, the preset plurality of reactive currents of the d-axis of the motor include: a first reactive current, a second reactive current and a third reactive current;

correspondingly, the first determining module 51 is specifically configured to:

and determining a first voltage, a second voltage and a third voltage which sequentially correspond to the first reactive current, the second reactive current and the third reactive current according to the first reactive current, the second reactive current and the third reactive current.

For example, according to the first idle currentSecond reactive currentFirst voltageAnd a second voltageCalculating the off-line resistance R of the first d-axis_d1；

Whereinr is a preset line impedance;

according to the second reactive currentThird reactive currentSecond voltageAnd a third voltageCalculating the off-line resistance R of the second d-axis_d2；

Whereinr is a preset line impedance;

off-line resistance R according to the first d-axis_d1And a second d-axis off-line resistance R_d2Calculating the off-line resistance value R of the d axis_d；

Wherein R is_d＝(R_d1+R_d2)/2。

In a preferred implementation manner of this embodiment, the preset multiple active currents of the q-axis of the electric machine include: a first active current, a second active current, and a third active current;

correspondingly, the second determining module 52 is specifically configured to:

and determining a fourth voltage, a fifth voltage and a sixth voltage which sequentially correspond to the first active current, the second active current and the third active current according to the first active current, the second active current and the third active current.

For example, according to the first active currentSecond active currentA fourth voltageFifth voltageCalculating the offline resistance value R of the first q axis_q1；

Whereinr is a preset line impedance;

according to the second active currentThird active currentFifth voltageAnd a sixth voltageCalculating the off-line resistance R of the second q-axis_q2；

Whereinr is a preset line impedance;

off-line resistance R according to the first q-axis_q1And off-line resistance R of the second q-axis_q2Calculating the off-line resistance value R of the q axis_q；

Wherein R is_q＝(R_q1+R_q2)/2。

In a preferred implementation manner of this embodiment, the first obtaining module 53 is specifically configured to:

obtaining an offline resistance value of the d axis according to a plurality of preset reactive currents of the d axis and the voltage of the d axis, and obtaining an offline resistance value of the q axis according to a plurality of preset active currents of the q axis and the voltage of the q axis;

and obtaining the offline resistance value of the motor according to the offline resistance value of the d axis and the offline resistance value of the q axis.

Before the first determining module 51 determines the voltage of the d-axis corresponding to a plurality of preset reactive currents of the d-axis of the motor according to a plurality of preset reactive currents of the d-axis, and the second determining module 52 determines the voltage of the q-axis corresponding to a plurality of preset active currents of the q-axis of the motor according to a plurality of preset active currents of the q-axis, the controller further includes modules not shown in the figure: a second obtaining module 54, a comparing module 55;

a second obtaining module 54, configured to obtain a first ambient temperature of the current environment;

a comparing module 55, configured to compare the first ambient temperature with a second ambient temperature before the motor is powered on and started last time;

the first determining module 51 is configured to determine, according to a plurality of preset reactive currents of a d axis of the motor, a voltage of the d axis corresponding to the plurality of preset reactive currents of the d axis when the comparing module 55 compares that a value of the temperature change of the first environment temperature relative to the second environment temperature exceeds a value of a preset temperature change range, and the second determining module 52 determines, according to a plurality of preset active currents of a q axis of the motor, a voltage of the q axis corresponding to the plurality of preset active currents of the q axis.

After the first obtaining module 53 is configured to obtain the offline resistance value of the motor according to the preset multiple reactive currents of the d axis, the preset voltage of the d axis, the preset multiple active currents of the q axis, and the preset voltage of the q axis, the controller further includes a module not shown in the figure: a decision module 56;

the judging module 56 is used for judging whether the offline resistance value of the motor is within a preset offline resistance value range;

the device comprises a first determining module 51, a second determining module 52 and a control module, wherein the first determining module 51 is used for determining the voltage of a d axis corresponding to a plurality of preset reactive currents of the d axis of the motor according to a plurality of preset reactive currents of the d axis of the motor when the off-line resistance value of the motor is not in the range of the preset off-line resistance value, and the second determining module 52 is used for determining the voltage of a q axis corresponding to a plurality of preset active currents of the q axis of the motor according to a plurality of preset active currents of the q axis of the motor.

The controller corresponds to the method for acquiring the offline resistance value of the motor one by one, and details of implementation of each module in the controller are not described in detail in this embodiment.

The embodiment of the invention also provides an air conditioner, which comprises a motor, a temperature sensor and the controller, wherein the motor and the temperature sensor are connected with the controller, and the electrode, the temperature sensor and the controller can be arranged in an outdoor unit of the air conditioner.

The controller is used for acquiring an offline resistance value of the motor when the motor is powered on and is not started;

the temperature sensor is used for detecting a third environment temperature when the motor is powered on and is not started;

the controller is further configured to compare the third ambient temperature with a fourth ambient temperature before the motor is powered on and started last time, and determine whether to reacquire the offline resistance value of the motor.

It can be understood that when the variation between the third ambient temperature and the fourth ambient temperature before the last power-on start of the motor exceeds the preset temperature variation range, the offline resistance value of the motor is obtained again according to the method, otherwise, the offline resistance value of the motor is not obtained again.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A method for obtaining an offline resistance value of a motor is characterized by comprising the following steps:

when a motor is powered on and is not started, determining the voltage of a d axis corresponding to a plurality of preset reactive currents of the d axis of the motor according to a plurality of preset reactive currents of the d axis, and determining the voltage of a q axis corresponding to a plurality of preset active currents of the q axis of the motor according to a plurality of preset active currents of the q axis;

and obtaining the offline resistance value of the motor according to the plurality of preset reactive currents of the d axis, the voltage of the d axis, the plurality of preset active currents of the q axis and the voltage of the q axis.

2. The method of claim 1, wherein the predetermined plurality of reactive currents for the d-axis of the electric machine comprises: a first reactive current, a second reactive current and a third reactive current;

correspondingly, the determining the voltage of the d-axis corresponding to the preset reactive currents of the d-axis according to the preset reactive currents of the d-axis of the motor includes:

and determining a first voltage, a second voltage and a third voltage which sequentially correspond to the first reactive current, the second reactive current and the third reactive current according to the first reactive current, the second reactive current and the third reactive current.

3. The method of claim 2, wherein the predetermined plurality of reactive currents for the q-axis of the electric machine comprises: a first active current, a second active current, and a third active current;

correspondingly, the determining the voltage of the q-axis corresponding to a plurality of preset active currents of the q-axis according to a plurality of preset active currents of the q-axis of the motor includes:

and determining a fourth voltage, a fifth voltage and a sixth voltage which sequentially correspond to the first active current, the second active current and the third active current according to the first active current, the second active current and the third active current.

4. The method of claim 3, wherein the obtaining the offline resistance value of the electric machine according to the preset multiple reactive currents of the d-axis, the preset multiple voltage of the d-axis, the preset multiple active currents of the q-axis and the preset voltage of the q-axis comprises:

obtaining an offline resistance value of the d axis according to a plurality of preset reactive currents of the d axis and the voltage of the d axis, and obtaining an offline resistance value of the q axis according to a plurality of preset active currents of the q axis and the voltage of the q axis;

and obtaining the offline resistance value of the motor according to the offline resistance value of the d axis and the offline resistance value of the q axis.

5. The method according to claim 4, wherein the obtaining of the off-line resistance value of the d-axis according to a plurality of preset reactive currents of the d-axis and the voltage of the d-axis comprises:

according to $R_{d1}=(V_{d1}^{*}-V_{d2}^{*})/(I_{d1}^{*}-I_{d2}^{*})-r,$ Acquiring an offline resistance value of a first d axis;

according to $R_{d2}=(V_{d3}^{*}-V_{d2}^{*})/(I_{d3}^{*}-I_{d2}^{*})-r,$ Acquiring an off-line resistance value of a second d axis;

according to R_d＝(R_d1+R_d2) Acquiring an off-line resistance value of the d axis;

wherein,which represents the first reactive current, is,which represents the second reactive current and is,which represents the third reactive current and is,which represents the first voltage, is provided by the first voltage,which represents the second voltage, is provided,representing a third voltage, R representing a predetermined line impedance, R_d1Representing the off-line resistance value, R, of the first d-axis_d2Representing the off-line resistance value, R, of the second d-axis_dRepresenting the off-line resistance value of the d-axis.

6. The method according to claim 4, wherein the obtaining the off-line resistance value of the q-axis according to a plurality of active currents preset by the q-axis and the voltage of the q-axis comprises:

according to $R_{q1}=(V_{q1}^{*}-V_{q2}^{*})/(I_{q1}^{*}-I_{q2}^{*})-r,$ Acquiring an offline resistance value of a first q axis;

according to $R_{q2}=(V_{q3}^{*}-V_{q2}^{*})/(I_{q3}^{*}-I_{q2}^{*})-r,$ Acquiring an offline resistance value of a second q axis;

according to R_q＝(R_q1+R_q2) Acquiring an offline resistance value of the q axis;

wherein,which represents the first active current, is,which represents the second active current, is,which represents the third active current, is,which represents the fourth voltage, is provided,which represents the voltage of the fifth voltage, is,representing a sixth voltage, R being a predetermined line impedance, R_q1Representing the off-line resistance value of the first q-axis, R_q2Representing the off-line resistance value of the second q-axis, R_qRepresenting the off-line resistance value of the q-axis.

7. The method according to any one of claims 1-6, wherein before determining the voltage of the d-axis corresponding to a predetermined plurality of reactive currents of the d-axis of the electric machine according to a predetermined plurality of reactive currents of the d-axis and determining the voltage of the q-axis corresponding to a predetermined plurality of active currents of the q-axis according to a predetermined plurality of active currents of the q-axis of the electric machine, the method further comprises:

acquiring a first environment temperature of the current environment, and comparing the first environment temperature with a second environment temperature of the motor before the last power-on starting;

and if the value of the temperature change of the first environment temperature relative to the second environment temperature exceeds the value of a preset temperature change range, executing the step of determining the voltage of the d axis and the voltage of the q axis.

8. The method according to any one of claims 1-6, wherein after obtaining the offline resistance value of the electric machine according to the preset multiple reactive currents of the d-axis, the preset voltage of the d-axis, the preset multiple active currents of the q-axis and the preset voltage of the q-axis, the method further comprises:

judging whether the off-line resistance value of the motor is within a preset off-line resistance value range or not;

and if the off-line resistance value of the motor is not in the range of the preset off-line resistance value, executing the step of determining the voltage of the d axis and the voltage of the q axis.

9. A controller, comprising:

the device comprises a first determining module, a second determining module and a control module, wherein the first determining module is used for determining the voltage of a d axis corresponding to a plurality of preset reactive currents of the d axis of a motor according to the preset reactive currents of the d axis of the motor when the motor is powered on and is not started;

the second determining module is used for determining the voltage of the q axis corresponding to a plurality of active currents preset on the q axis according to a plurality of active currents preset on the q axis of the motor when the motor is powered on and is not started;

the obtaining module is used for obtaining the offline resistance value of the motor according to the multiple preset reactive currents of the d axis, the voltage of the d axis, the multiple preset active currents of the q axis and the voltage of the q axis.

10. An air conditioner comprising a motor, a temperature sensor and the controller of claim 9, wherein the motor and the temperature sensor are both connected to the controller;

the controller is used for acquiring an offline resistance value of the motor when the motor is powered on and is not started;

the temperature sensor is used for detecting a third environment temperature when the motor is powered on and is not started;

the controller is further configured to compare the third ambient temperature with a fourth ambient temperature before the motor is powered on and started last time, and determine whether to reacquire the offline resistance value of the motor.