Permanent magnet synchronous motor static initial position estimation method and stator inductance identification method

Abstract

This invention provides a method for estimating the static initial position of a permanent magnet synchronous motor and a method for identifying the stator inductance. Rated positive and negative pulse voltages are sequentially injected into the windings of phases AB, BC, and CA of the motor. The response current values ​​of each phase under the rated positive and negative pulse voltages are recorded, and the current response difference ΔI between phases AB, BC, and CA in the three-phase stationary coordinate system is calculated. ab ΔI bc and ΔI ca The Clark transformation is performed on the current response difference between each phase to obtain the current response difference ΔI in the α-β axis two-phase stationary coordinate system. α and ΔI β Based on ΔI α and ΔI β Calculate the initial rotor position θ. Based on the calculated initial rotor position, calculate the stator inductance of the permanent magnet synchronous motor. This invention obtains the rotor position directly from the current pulse response through coordinate transformation and solution, eliminating intermediate conversion steps, reducing data loss, and ensuring data accuracy.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of motor control, and relates to a static initial position estimation method of a permanent magnet synchronous motor and a stator inductance identification method. BACKGROUND

[0002] Direct-drive permanent magnet wind generators are widely used in wind power plants due to stable performance and high economic benefits. However, due to the limitation of the volume of the unit, it is difficult to obtain sufficient installation space for position sensors and other devices, and therefore sensorless control strategies are increasingly applied to the field of wind power. The sensorless control strategies for permanent magnet synchronous motors include observer control, switching control and variable structure control, and these methods all need to accurately estimate the initial position of the rotor. Meanwhile, accurate identification of the initial position is also a key problem related to the performance of the motor system. If the detection deviation is large, the motor may have problems such as reduced load capacity, out-of-step and even start failure during the starting stage, which may easily cause safety hazards. Therefore, the identification of the initial position of the rotor of the permanent magnet synchronous motor has always been one of the research hotspots with theoretical significance and economic benefits.

[0003] At present, the identification of the initial position of the rotor mainly adopts two methods of high-frequency injection and instantaneous pulse.

[0004] The high-frequency injection includes high-frequency rotating voltage injection and pulse voltage injection, and the initial position of the rotor is obtained by injecting a high-frequency signal, measuring the current response of the stator winding, and then filtering and calculating the current signal. For example, the initial position detection method of the sensorless permanent magnet synchronous motor disclosed in CN113114077A injects a high-frequency square wave voltage into the d-axis, and estimates the initial position of the rotor according to the high-frequency response current signal. This kind of method can theoretically obtain high estimation accuracy, but the algorithm is complex, and a PI controller is needed for online adjustment or a filter is needed to process the high-frequency signal, which increases the hardware cost.

[0005] The instantaneous pulse position identification method includes the table lookup method and the inductance matrix method, and the initial position of the rotor is obtained by injecting an equal-width pulse into the winding and according to the transient current response. For example, the table lookup method uses a pre-obtained current response and rotor angle table to obtain the rotor position, and this method needs to be pre-tested, is complex to operate and has low accuracy. For example, the inductance matrix method obtains the inductance matrix through the transient current response, and then calculates the rotor position from the inductance matrix. This method is complex to calculate, and due to sampling deviation, inductance matrix conversion and other reasons, it has high requirements for sampling and signal conditioning circuits. SUMMARY

[0006] The application aims to at least solve one of the above technical problems, and provides a static initial position estimation method of a permanent magnet synchronous motor and a stator inductance identification method.

[0007] To achieve the above object, the technical scheme adopted by the present application is:

[0008] A static initial position estimation method of a permanent magnet synchronous motor, comprising the following steps:

[0009] Injecting a rated positive pulse voltage and a rated negative pulse voltage to the motor AB phase, BC phase and CA phase winding in turn, the rated positive pulse voltage and the rated negative pulse voltage being the voltage when the output current of each phase reaches the rated current of the motor;

[0010] In the case of injecting the rated positive pulse voltage and the rated negative pulse voltage to each phase, recording the response current value of each phase under the rated positive pulse voltage and the rated negative pulse voltage, subtracting the response current of each phase under the rated positive pulse voltage from the response current of each phase under the rated negative pulse voltage, and calculating the current response difference value of the AB phase, the BC phase and the CA phase in the three-phase stationary coordinate system 、 and ;

[0011] Performing Clark transformation on the current response difference value of each phase to obtain the current response difference value in the two-axis stationary coordinate system and ;

[0012] Based on and calculating the initial position angle of the rotor :

[0013] .

[0014] In some embodiments of the present application, the method further comprises a magnetic pole direction verification step:

[0015] When the sector of the initial position angle of the rotor is 30°-90°, a positive pulse voltage is input to the A phase and the B phase according to the voltage vector U3, and a negative pulse voltage is input to the C phase, the output current Ic- of the C phase is measured; then a negative pulse voltage is input to the A phase and the B phase according to the voltage vector U4, and a positive pulse voltage is input to the C phase, the output current Ic+ of the C phase is measured; if Ic->Ic+, it is determined that the calculated value of the position angle is accurate;

[0016] When the sector of the initial position angle of the rotor is 210°-270°, a positive pulse voltage is input to the A phase and the B phase according to the voltage vector U3, and a negative pulse voltage is input to the C phase, the output current Ic- of the C phase is measured; then a negative pulse voltage is input to the A phase and the B phase according to the voltage vector U4, and a positive pulse voltage is input to the C phase, the output current Ic+ of the C phase is measured; if Ic+>Ic-, it is determined that the calculated value of the position angle is accurate;

[0017] ​When the sector where the initial position angle of the rotor is located is 90°~150°, positive pulse voltage is input to the A phase C phase according to the voltage vector U5, negative pulse voltage is input to the B phase, the B phase output current Ib- is measured; then negative pulse voltage is input to the A phase C phase according to the voltage vector U6, positive pulse voltage is input to the B phase, the B phase output current Ib+ is measured; if Ib- > Ib+, it is determined that the position angle calculation value is accurate.

[0018] When the sector where the initial position angle of the rotor is located is 270°~330°, positive pulse voltage is input to the A phase C phase according to the voltage vector U5, negative pulse voltage is input to the B phase, the B phase output current Ib- is measured; then negative pulse voltage is input to the A phase C phase according to the voltage vector U6, positive pulse voltage is input to the B phase, the B phase output current Ib+ is measured; if Ib+ > Ib-, it is determined that the position angle calculation value is accurate.

[0019] When the sector where the initial position angle of the rotor is located is 150°~210°, positive pulse voltage is input to the B phase C phase according to the voltage vector U2, negative pulse voltage is input to the A phase, the A phase output current Ia- is measured; then negative pulse voltage is input to the B phase C phase according to the voltage vector U1, positive pulse voltage is input to the A phase, the A phase output current Ia+ is measured; if Ia+ > Ia-, it is determined that the position angle calculation value is accurate.

[0020] When the sector where the initial position angle of the rotor is located is 330°~360° or 0°~30°, positive pulse voltage is input to the B phase C phase according to the voltage vector U2, negative pulse voltage is input to the A phase, the A phase output current Ia- is measured; then negative pulse voltage is input to the B phase C phase according to the voltage vector U1, positive pulse voltage is input to the A phase, the A phase output current Ia+ is measured; if Ia- > Ia+, it is determined that the position angle calculation value is accurate.

[0021] The second embodiment of the application further provides a permanent magnet synchronous motor stator inductance identification method, characterized by comprising the following steps:

[0022] The initial position angle of the rotor is calculated by using the method;

[0023] The AB phase winding inductance, the BC phase winding inductance and the CA phase winding inductance are calculated:

[0024]

[0025] Wherein: is the pulse width, is the average value of the winding AB phase current in a unit pulse width, is the average value of the winding BC phase current in a unit pulse width, is the average value of the winding CA phase current in a unit pulse width, is the change amount of the winding AB phase current in a unit pulse width, The change in the BC phase current of the winding within a unit pulse width. This represents the change in the CA phase current of the winding within a unit pulse width.

[0026] Three-phase wire inductance and Shaft inductance relationship:

[0027]

[0028] in: for Shaft inductor, for Shaft inductance;

[0029] Further calculations , for:

[0030] .

[0031] Compared with the prior art, the method provided by this invention has the following advantages:

[0032] (1) This invention improves the instantaneous pulse injection method and provides a detection method that directly obtains the rotor position using the difference in transient current response. This method does not require a large number of preliminary experiments to obtain a reference table as in the lookup table method, nor does it require a large number of complex calculations as in the inductance matrix method. By transforming and solving the coordinates, the rotor position is directly obtained from the current pulse response, eliminating the intermediate conversion steps, reducing data loss, and ensuring data accuracy. At the same time, this method only requires the use of existing equipment and does not generate additional hardware expenses. It is simple and easy to implement and has high practical value.

[0033] (2) Moreover, the present invention provides a simple and easy method for determining rotor magnetic poles, which can be used to verify whether the initial angle of the rotor is correctly determined, ensure the accuracy of the initial angle identification, and improve the robustness and anti-interference ability of the system. After obtaining the initial position, the present invention can easily calculate the stator inductance by formula, avoiding the need for external inductance detection equipment or complex matrix transformation.

[0034] (3) After obtaining the initial position, the present invention can easily calculate the stator inductance by formula, avoiding the need for external inductance detection equipment and reducing hardware overhead. At the same time, it does not require complex inductance matrix transformation, reducing the amount of calculation. Meanwhile, a single control strategy can realize multiple functions such as motor rotor initial position identification, rotor polarity verification, and inductance parameter identification, which is conducive to reducing the overall calculation amount and hardware overhead of the system and facilitating the integrated design of functions.

[0035] Other features and advantages of the present application will be set forth in the descriptions that follow, and in part will be apparent from the description, or can be learned by practice of the application. The purposes and other advantages of the present application will be realized and attained by the structures particularly pointed out in the written description and claims hereof. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0037] Figure 1 It is a structure schematic diagram of permanent magnet wind power generator control system.

[0038] Figure 2 It is an implementation flow chart of permanent magnet synchronous motor initial position estimation and stator inductance identification.

[0039] Figure 3 It is an equivalent principle diagram of permanent magnet synchronous motor initial position estimation and stator inductance identification.

[0040] Figure 4 It is a three-phase pulse injection schematic diagram for pole direction identification. DETAILED DESCRIPTION

[0041] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clearly, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not used to limit the present application.

[0042] The present application provides a kind of permanent magnet synchronous motor static initial position estimation method and inductance identification mode, overall flow reference Figure 2 It can be used for the auxiliary control of direct-drive permanent magnet wind power generator, to solve the problems of motor rotor initial position estimation and stator inductance identification.

[0043] The structure of direct-drive permanent magnet wind power generator system is as shown in Figure 1 The main parts include machine-side input reactor, machine-side IGBT module, support capacitor, network-side IGBT module, network-side output reactor, voltage and current sampling circuit and controller. These parts belong to prior art, and will not be described again.

[0044] The first embodiment of the present application provides a kind of permanent magnet synchronous motor static initial position estimation method, and the present application is based on the salient pole characteristics of permanent magnet motor, stator inductance changes with the change of rotor magnetic pole position, and then the rotor position information can be obtained by using this characteristic.

[0045] First, the principle of the method for estimating the initial position of the stator according to the present invention will be introduced.

[0046] This invention is based on the principle of salient polarity. By applying an external voltage to the bus support capacitor of the permanent magnet generator set and controlling the switching sequence of the PWM module of the generator set's inverter, two-phase voltage pulses can be applied to the stator winding of the permanent magnet motor. Figure 3 As shown. The motor windings can be equivalent to an RL circuit, and the zero-state response shows that:

[0047] (1)

[0048] In the formula Rated pulse voltage, For winding resistance, For pulse response current, For phase inductance, For time.

[0049] From formula (1), it can be seen that by applying a voltage pulse, the current pulse response of the corresponding winding can be measured. Neglecting the winding resistance, we can obtain:

[0050] (2)

[0051] Traditional identification methods fall into two main categories. One involves deriving the inductance matrix of each winding from the current pulse response and then performing complex calculations to determine the rotor position angle. The other method directly records the relationship between the current response and rotor position, obtains a table comparing the rotor position angle and current response through numerous experiments, and then uses a lookup table to determine the rotor position angle. For the first method, the inductance matrix calculation and conversion are quite complex, and data accuracy is easily lost during the complex conversion process. The second method requires extensive preliminary work, and due to operational and sampling errors, the accuracy of the lookup table method is difficult to guarantee.

[0052] This invention provides a novel method for directly obtaining the rotor position angle from the current pulse response using the current difference without going through an inductor matrix. The static initial position estimation method for permanent magnet synchronous motors provided by this invention specifically includes the following steps.

[0053] S1: Inject the rated positive pulse voltage and the rated negative pulse voltage into the AB phase, BC phase and CA phase windings of the motor in sequence. The rated positive pulse voltage and the rated negative pulse voltage are the voltages that make the output current of each phase reach the rated current of the motor.

[0054] The rated pulse voltage can be obtained by the following method. In some embodiments of the present application: the rated pulse voltage can be obtained by the following method. Inject a U-phase positive pulse and a V-phase negative pulse into the AB-phase winding, and record the u-phase current pulse response Iu; gradually increase the pulse width until Iu is greater than the rated current value of the motor, at which point the pulse width is the selected pulse width, corresponding to the rated positive pulse voltage and the rated negative pulse voltage of each phase.

[0055] S2: record the response current values of each phase under the rated positive pulse voltage and the rated negative pulse voltage, subtract the response current of each phase under the rated positive pulse voltage from the response current of each phase under the rated negative pulse voltage, and calculate the current response difference values of the AB-phase, BC-phase and CA-phase in the three-phase stationary coordinate system 、 and .

[0056] Specifically, after obtaining the rated pulse value, maintain the pulse width, and sequentially inject a U-phase positive pulse and a V-phase negative pulse into the AB-phase winding, a V-phase positive pulse and a U-phase negative pulse, respectively, to obtain positive pulse response currents and negative pulse response currents ; inject a V-phase positive pulse and a W-phase negative pulse into the BC-phase winding, a W-phase positive pulse and a V-phase negative pulse, respectively, to obtain positive pulse response currents and negative pulse current responses ; inject a W-phase positive pulse and a U-phase negative pulse into the CA-phase winding, a U-phase positive pulse and a W-phase negative pulse, respectively, to obtain positive pulse response currents and negative pulse current responses ; obtain the current response difference values of the AB-phase, BC-phase and CA-phase in the three-phase stationary coordinate system 、 and .

[0057] Perform Clark transformation on the current response difference values of each phase to obtain current response difference values in the two-axis stationary coordinate system and ;

[0058] (3)

[0059] Calculate the initial position of the rotor based on and :

[0060] (4)

[0061] ​The method for obtaining the rotor position angle is simple in operation, without the need of calculating a complex intermediate inductance matrix, and the rotor position angle can be directly obtained from the current pulse response by using the current difference value.

[0062] Hereinafter, the calculation process of the initial position of the rotor will be described in detail.

[0063] The phase positive and negative current response difference values and the phase inductance have the following relationship

[0064] (5)

[0065] Wherein: is the positive direction pulse response current of the AB phase winding, is the negative direction pulse response current of the AB phase winding; is the positive direction pulse response current of the BC phase winding, is the negative direction pulse response current of the BC phase winding; is the positive direction pulse response current of the CA phase winding, is the negative direction pulse response current of the CA phase winding; and is the inductance of the AB phase winding; and is the inductance of the BC phase winding; and is the inductance of the CA phase winding; is the rated pulse voltage;

[0066] That is, the phase current response difference value is calculated based on the bus voltage and the phase winding inductance.

[0067] Wherein: further, the following relationship conditions exist:

[0068] The AB phase winding inductance satisfies condition one:

[0069] (6)

[0070] The BC phase winding inductance satisfies condition two:

[0071] (7)

[0072] The CA phase winding inductance satisfies condition three:

[0073] (8)

[0074] Wherein: is the constant component of the line inductance, is the first harmonic amplitude of the line inductance, is the second harmonic amplitude of the line inductance;

[0075] Substitute formula (6) - (8) into formula (5) to obtain:

[0076] (9)

[0077] (10)

[0078] (11)

[0079] Since the following inequality relationship exists in formula (9) - (11):

[0080] , , Satisfy condition four:

[0081] (12)

[0082] (13)

[0083] Substitute condition four formula into (9) - (11) to obtain:

[0084] (14)

[0085] (15)

[0086] (16)

[0087] Arrange formula (14) - (16) to obtain the direct relationship between the winding AB, BC, CA phase positive and negative current difference and the rotor position:

[0088] (17)

[0089] Carry out Clark transformation on formula (17) to obtain:

[0090] (18)

[0091] Further, the initial position of the rotor can be obtained:

[0092] (19)

[0093] From formula (19), the initial angle of the motor can be directly obtained from the current difference without complex inductance calculation. Moreover, the obtained angle only presents a periodic change once with the rotor position in a period of 1 electrical angle, and the position angle of 0° - 360° can be directly calculated without the NS pole judgment process.

[0094] Through the above method, the rotor position angle can be accurately identified in theory, but due to the influence of sampling deviation, external interference and other factors, an occasional detection deviation may be too large in actual use, and a simple method for checking whether the torque angle is identified correctly by judging the NS pole direction is provided.

[0095] The rotor pole direction checking is performed by detecting the rotor position angle value, selecting the direction of applying three-phase pulse to the motor stator winding A, B and C, then obtaining the positive and negative current pulse responses, and judging the pole direction by comparing the positive and negative current amplitude, so as to check whether the rotor position angle identification is correct. The three-phase pulse injection schematic diagram is shown in Figure 4

[0096] In some embodiments of the application, the pole direction checking step is as follows.

[0097] According to the sector position of the calculated rotor initial position angle, the positive pulse signal or the negative pulse signal is selected to be applied to the motor winding according to the rule, and the output current is compared to judge the accuracy of the calculation result of the rotor initial position angle; according to Figure 4 As shown in the table 1, the three-phase pulse injection implementation rule is shown. According to the interval of the rotor position angle value, the pulse signal is applied to the motor winding, if the synthesized magnetic motive force of the winding and the rotor magnetic motive force are in the same direction, the positive pulse signal is applied to the motor winding, at this time the inductance value decreases, then the current response speed increases; the reverse pulse signal is applied to the motor winding, then the synthesized magnetic motive force of the winding and the rotor magnetic motive force are in the opposite direction, at this time the inductance value increases, then the current response speed decreases. Therefore, if the pulse response current test result is consistent with table 1, it is considered that the initial position angle detection is correct, and the next operation can be performed; if the test result is inconsistent with table 1, it is considered that the initial position angle detection deviation is too large, then the position angle detection needs to be performed again. When the rotor position angle is in other sectors, the checking is performed according to table 1.

[0098]

[0099] The specific embodiment flow is described as follows.

[0100] When the sector of the rotor initial position angle is 30°~90°, the positive pulse voltage is input to the A phase and the B phase according to the voltage vector U3, the negative pulse voltage is input to the C phase, the C phase output current Ic- is measured; then the negative pulse voltage is input to the A phase and the B phase according to the voltage vector U4, the positive pulse voltage is input to the C phase, the C phase output current Ic+ is measured; if Ic->Ic+, it is determined that the position angle calculation value is accurate;

[0101] ​When the sector where the initial position angle of the rotor is located is 210°~270°, positive pulse voltage is input to phase A and phase B according to voltage vector U3, and negative pulse voltage is input to phase C, and the output current Ic- of phase C is measured; then negative pulse voltage is input to phase A and phase B according to voltage vector U4, and positive pulse voltage is input to phase C, and the output current Ic+ of phase C is measured; if Ic+>Ic-, it is determined that the calculated value of the position angle is accurate.

[0102] When the sector where the initial position angle of the rotor is located is 90°~150°, positive pulse voltage is input to phase A and phase C according to voltage vector U5, and negative pulse voltage is input to phase B, and the output current Ib- of phase B is measured; then negative pulse voltage is input to phase A and phase C according to voltage vector U6, and positive pulse voltage is input to phase B, and the output current Ib+ of phase B is measured; if Ib- > Ib+, it is determined that the calculated value of the position angle is accurate.

[0103] When the sector where the initial position angle of the rotor is located is 270°~330°, positive pulse voltage is input to phase A and phase C according to voltage vector U5, and negative pulse voltage is input to phase B, and the output current Ib- of phase B is measured; then negative pulse voltage is input to phase A and phase C according to voltage vector U6, and positive pulse voltage is input to phase B, and the output current Ib+ of phase B is measured; if Ib+>Ib-, it is determined that the calculated value of the position angle is accurate.

[0104] When the sector where the initial position angle of the rotor is located is 150°~210°, positive pulse voltage is input to phase B and phase C according to voltage vector U2, and negative pulse voltage is input to phase A, and the output current Ia- of phase A is measured; then negative pulse voltage is input to phase B and phase C according to voltage vector U1, and positive pulse voltage is input to phase A, and the output current Ia+ of phase A is measured; if Ia+>Ia-, it is determined that the calculated value of the position angle is accurate.

[0105] When the sector where the initial position angle of the rotor is located is 330°~360° or 0°~30°, positive pulse voltage is input to phase B and phase C according to voltage vector U2, and negative pulse voltage is input to phase A, and the output current Ia- of phase A is measured; then negative pulse voltage is input to phase B and phase C according to voltage vector U1, and positive pulse voltage is input to phase A, and the output current Ia+ of phase A is measured; if Ia- > Ia+, it is determined that the calculated value of the position angle is accurate.

[0106] The second embodiment of the application further provides a method for identifying the stator inductance of a permanent magnet synchronous motor, comprising the following steps.

[0107] The initial position angle of the rotor is calculated by using the method disclosed in the first embodiment;

[0108] The inductances of the AB phase winding, the BC phase winding and the CA phase winding are calculated:

[0109] (20)

[0110] Wherein: for the pulse width, for the average value of the winding AB phase current in a unit pulse width, for the average value of the winding BC phase current in a unit pulse width, for the average value of the winding CA phase current in a unit pulse width, for the variation of the winding AB phase current in a unit pulse width, for the variation of the winding BC phase current in a unit pulse width, for the variation of the winding CA phase current in a unit pulse width; for the winding resistance;

[0111] the three-phase line inductance and the shaft inductance relationship:

[0112] (21)

[0113] wherein: for the shaft inductance, for the shaft inductance;

[0114] further calculating , for:

[0115] (22)

[0116] (23)

[0117] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for estimating the static initial position of a permanent magnet synchronous motor, characterized in that, The method comprises the following steps: injecting rated positive pulse voltage and rated negative pulse voltage to the motor AB phase, BC phase and CA phase winding in sequence, the rated positive pulse voltage and the rated negative pulse voltage being the voltage when the phase output current reaches the motor rated current; In the case where the respective rated positive pulse voltage and the rated negative pulse voltage are injected into each phase, the response current values of each phase at the rated positive pulse voltage and the rated negative pulse voltage are recorded, the response current of each phase at the rated negative pulse voltage is subtracted from the response current of each phase at the rated positive pulse voltage, and the current response difference values of the AB phase, the BC phase, and the CA phase in the three-phase stationary coordinate system are calculated , and ; The Clark transformation is performed on the response difference of each phase current to obtain The response difference of the current in the two-phase stationary coordinate system of the shaft and ; Based on And Calculate the initial position angle of the rotor : ； further comprising a magnetic pole direction checking step: when the sector where the rotor initial position angle is located is 30°-90°, a positive pulse voltage is input to the A phase and the B phase according to the voltage vector U3, and a negative pulse voltage is input to the C phase, and the C phase output current Ic- is measured; then a negative pulse voltage is input to the A phase and the B phase according to the voltage vector U4, and a positive pulse voltage is input to the C phase, and the C phase output current Ic+ is measured; if Ic->Ic+, it is determined that the position angle calculation value is accurate; when the sector where the rotor initial position angle is located is 210°-270°, a positive pulse voltage is input to the A phase and the B phase according to the voltage vector U3, and a negative pulse voltage is input to the C phase, and the C phase output current Ic- is measured; then a negative pulse voltage is input to the A phase and the B phase according to the voltage vector U4, and a positive pulse voltage is input to the C phase, and the C phase output current Ic+ is measured; if Ic+>Ic-, it is determined that the position angle calculation value is accurate; when the sector where the rotor initial position angle is located is 90°-150°, a positive pulse voltage is input to the A phase and the C phase according to the voltage vector U5, and a negative pulse voltage is input to the B phase, and the B phase output current Ib- is measured; then a negative pulse voltage is input to the A phase and the C phase according to the voltage vector U6, and a positive pulse voltage is input to the B phase, and the B phase output current Ib+ is measured; if Ib->Ib+, it is determined that the position angle calculation value is accurate; when the sector where the rotor initial position angle is located is 270°-330°, a positive pulse voltage is input to the A phase and the C phase according to the voltage vector U5, and a negative pulse voltage is input to the B phase, and the B phase output current Ib- is measured; then a negative pulse voltage is input to the A phase and the C phase according to the voltage vector U6, and a positive pulse voltage is input to the B phase, and the B phase output current Ib+ is measured; if Ib+>Ib-, it is determined that the position angle calculation value is accurate; when the sector where the rotor initial position angle is located is 150°-210°, a positive pulse voltage is input to the B phase and the C phase according to the voltage vector U2, and a negative pulse voltage is input to the A phase, and the A phase output current Ia- is measured; then a negative pulse voltage is input to the B phase and the C phase according to the voltage vector U1, and a positive pulse voltage is input to the A phase, and the A phase output current Ia+ is measured; if Ia+>Ia-, it is determined that the position angle calculation value is accurate; when the sector where the rotor initial position angle is located is 330°-360° or 0°-30°, a positive pulse voltage is input to the B phase and the C phase according to the voltage vector U2, and a negative pulse voltage is input to the A phase, and the A phase output current Ia- is measured; then a negative pulse voltage is input to the B phase and the C phase according to the voltage vector U1, and a positive pulse voltage is input to the A phase, and the A phase output current Ia+ is measured; if Ia->Ia+, it is determined that the position angle calculation value is accurate; wherein the positive and negative current response difference of each phase and the phase inductance have the following relationship: ； wherein: is the AB phase winding positive direction impulse response current, is the AB phase winding negative direction impulse response current; is the BC phase winding positive direction impulse response current, is the BC phase winding negative direction impulse response current; is the CA phase winding positive direction impulse response current, is the CA phase winding negative direction impulse response current; and is the AB phase winding inductance; and is the BC phase winding inductance; and is the CA phase winding inductance; is the rated impulse voltage; wherein: the AB phase winding inductance satisfies condition one: the BC phase winding inductance satisfies condition two: the CA phase winding inductance satisfies condition three: wherein: is the line inductance constant component, is the line inductance first harmonic amplitude, is the line inductance second harmonic amplitude, is the rotor initial position angle; by substituting condition one, condition two and condition three into the relationship formula of the positive and negative current response difference of each phase and the phase inductance, the following formula can be obtained: further, the following inequality relationship can be obtained: , , Satisfies condition four: ； ； Substitute the conditional four formula into the formula of , , , ； ； ； Further, the direct relationship between the positive and negative current difference of the windings AB, BC and CA and the rotor position can be obtained: ； The direct relationship between the current difference and the rotor position is Clark-transformed to obtain: ； The initial position of the rotor can be further obtained: 。 2. The method of claim 1, wherein, The method for obtaining the rated positive pulse voltage and the rated negative pulse voltage comprises: Injecting a positive pulse of phase U and a negative pulse of phase V into the AB phase winding, and recording the pulse response Iu of the u phase current; Gradually increasing the pulse width until Iu is greater than the rated current value of the motor, at which point the pulse width is the selected pulse width, corresponding to the rated positive pulse voltage and the rated negative pulse voltage of each phase.

3. A method for permanent magnet synchronous motor stator inductance identification, characterized in that, The method comprises the following steps: Calculating the initial position angle of the rotor by the method of claim 1 or 2; Calculating the inductance of the AB phase winding, the inductance of the BC phase winding and the inductance of the CA phase winding: ； wherein: is the pulse width, is the average value of the winding AB phase current in a unit pulse width, is the average value of the winding BC phase current in a unit pulse width, is the average value of the winding CA phase current in a unit pulse width, is the variation of the winding AB phase current in a unit pulse width, is the variation of the winding BC phase current in a unit pulse width, is the variation of the winding CA phase current in a unit pulse width; is the winding resistance; Three-phase line inductance and axial inductance relationship: wherein: is axial inductance, is axial inductance; Further extrapolation , is: 。

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