Permanent magnet synchronous motor demagnetization detection method and apparatus, terminal and storage medium

Abstract

The present invention relates to the technical field of motor drive control, and aims to solve the problems in the prior art that generally an external Rogowski coil is required to accurately acquire current information, resulting in higher hardware cost, increased implementation complexity, and inability to achieve rapid detection. Disclosed are a permanent magnet synchronous motor demagnetization detection method and apparatus, a terminal and a storage medium. The method comprises: before a permanent magnet synchronous motor is started, generating a positive and negative symmetrical high-frequency square wave voltage detection signal by means of a main control chip in a motor driver; and, by means of an inverter unit in the motor driver, injecting the high-frequency square wave voltage detection signal into a d-axis of a motor rotation coordinate system d-q. The present invention can accurately achieve the diagnosis of the health condition of permanent magnets of permanent magnet synchronous motors. The present invention can complete demagnetization detection within hundreds of milliseconds before operation of the vehicle, thus having no impact on operation of the vehicle. In addition, the present invention has low requirements for hardware and can be implemented on motor drivers having conventional hardware topologies, thus facilitating engineering implementation and popularization and application.

Description

A permanent magnet synchronous motor demagnetization detection method, device, terminal and storage medium TECHNICAL FIELD

[0001] The present application relates to a kind of permanent magnet synchronous motor demagnetization detection method, device, terminal and storage medium, belong to motor drive control technical field. BACKGROUND

[0002] Permanent magnet synchronous motor is widely used in electric engineering machinery vehicle, mine truck, new energy commercial vehicle by virtue of high efficiency, high power density, good speed regulation performance and other significant advantages.

[0003] However, permanent magnet synchronous motor rotor permanent magnet is sensitive to temperature.When motor occurs frequently locked rotor, overload operation, temperature detection failure and other adverse factors, high temperature generated by stator coil is conducted to rotor permanent magnet, which can cause irreversible demagnetization of permanent magnet even complete demagnetization.Secondly, strong vibration impact under adverse driving, operating conditions can cause the direction of permanent magnet internal magnetic domain to change, which can also cause permanent magnet demagnetization.In addition, when motor operates at very high speed, excessive field weakening current can also cause permanent magnet demagnetization.Permanent magnet synchronous motor demagnetization failure can cause serious reduction of motor performance, scrap motor and other consequences.For the occasion of using permanent magnet synchronous motor as electric vehicle drive motor, motor demagnetization can seriously affect vehicle torque safety, endanger the safety of driver and surrounding personnel and property, so permanent magnet synchronous motor demagnetization detection work is usually required.

[0004] The permanent magnet synchronous motor demagnetization detection method of prior art usually needs external Rogowski coil to accurately collect current information, which has high hardware cost, is difficult to implement, and cannot realize rapid detection, affecting the practicability of the method and being inconvenient for popularization and application. SUMMARY

[0005] The present application aims to overcome the deficiencies in the prior art, and provides a permanent magnet synchronous motor demagnetization detection method, device, terminal and storage medium, which solves the problem of the prior art permanent magnet synchronous motor demagnetization detection method, which usually needs external Rogowski coil to accurately collect current information, has high hardware cost, is difficult to implement, and cannot realize rapid detection, affecting the practicability of the method.

[0006] To solve the above technical problems, the present application is realized by the following technical scheme:

[0007] In the first aspect, the present application provides a permanent magnet synchronous motor demagnetization detection method, comprising the following steps:

[0008] Before starting the permanent magnet synchronous motor, a positive and negative symmetrical high-frequency square wave voltage detection signal is generated by the main control chip in the motor driver;

[0009] Injecting a high-frequency square wave voltage detection signal into a d-axis of a motor rotating coordinate system d-q through an inverter unit in a motor driver;

[0010] Collecting three-phase currents of the permanent magnet synchronous motor through a current sensor, transforming the collected three-phase currents to the motor rotating coordinate system d-q through coordinate transformation, and obtaining a single-period saturation current difference value of the d-axis;

[0011] Continuously injecting a certain period, calculating a saturation current cumulative value according to the single-period saturation current difference value;

[0012] Comparing the saturation current cumulative value with a set threshold value, and determining whether the permanent magnet synchronous motor has an electromagnetic fault according to a comparison result, so as to complete the demagnetization detection of the permanent magnet synchronous motor.

[0013] Further, the high-frequency square wave voltage detection signal is as follows:

[0014] In the formula, U inj is an amplitude of the injected voltage signal, t is time, T inj is an injection period of the high-frequency signal, n is a period number of the injected signal, u inj is the high-frequency square wave voltage detection signal.

[0015] Further, the high-frequency square wave voltage detection signal is injected into the d-axis of the motor rotating coordinate system d-q, as follows:

[0016] In the formula, u d is a high-frequency voltage excitation signal injected under the d-axis of the motor rotating coordinate system d-q; u q is a high-frequency voltage excitation signal injected under the q-axis of the motor rotating coordinate system d-q.

[0017] Further, the coordinate transformation of the collected three-phase currents to the motor rotating coordinate system d-q specifically includes:

[0018] Transforming the three-phase currents to a two-phase stationary coordinate system α-β, and obtaining current signals under the two-phase stationary coordinate system α-β;

[0019] Transforming the current signals under the two-phase stationary coordinate system α-β to the motor rotating coordinate system d-q.

[0020] Further, the three-phase currents of the permanent magnet synchronous motor are collected through the current sensor, the collected three-phase currents are transformed to the motor rotating coordinate system d-q through coordinate transformation, and the single-period saturation current difference value of the d-axis is obtained, specifically including:

[0021] Sampling the currents at a preset time, collecting the three-phase currents iA i B and i C ;

[0022] By performing the following coordinate transformation, i A i B and i C Transform to the two-phase stationary coordinate system α-β:

[0023] In the formula: i α i β The current signal is in the two-phase stationary coordinate system α-β.

[0024] By performing the following coordinate transformation, i α i β Transform to the motor rotating coordinate system dq:

[0025] In the formula: i d For the current signal along the d-axis in the rotating coordinate system dq of the motor, i q Let θ be the current signal along the q-axis in the rotating coordinate system dq of the motor. c This is the rotor magnetic pole position signal;

[0026] exist Current is sampled at specific times, and the collected three-phase current is transformed into the motor rotating coordinate system dq through coordinate transformation to obtain the d-axis current i. d1 ;

[0027] At t=(n-1)T inj Current is sampled at specific times, and the collected three-phase current is transformed into the motor rotating coordinate system dq through coordinate transformation to obtain the d-axis current i. d2 ;

[0028] The single-cycle saturation current difference along the d-axis is calculated using the following formula:

[0029] I n =i d2 +i d1

[0030] In the formula: I n This represents the single-cycle saturation current difference along the d-axis.

[0031] Furthermore, the continuous injection for a certain period of time, and the calculation of the cumulative saturation current value based on the difference in saturation current during a single period, specifically includes:

[0032] In the first injection cycle, n is 1: I1 = i d2 +i d1

[0033] Continuously perform M injection cycles to obtain I1, I2, I3, …, I n … M ; I1, I2, I3, …, I n … M Perform accumulation to obtain a saturation current accumulation value ∑I M .

[0034] Further, the saturation current accumulation value is compared with a set threshold value, and whether the permanent magnet synchronous motor has an electromagnetic fault is determined according to a comparison result, and specifically includes:

[0035] If the saturation current accumulation value is not less than the set threshold value, it is determined that the permanent magnet synchronous motor does not have an electromagnetic fault;

[0036] If the saturation current accumulation value is less than the set threshold value, it is determined that the permanent magnet synchronous motor has an electromagnetic fault.

[0037] In a second aspect, the application provides a permanent magnet synchronous motor demagnetization detection device, and the device includes:

[0038] A generation module: before starting the permanent magnet synchronous motor, a positive-negative symmetrical high-frequency square wave voltage detection signal is generated by a master control chip in a motor driver;

[0039] An input module: the high-frequency square wave voltage detection signal is injected into a d-axis of a motor rotating coordinate system d-q through an inverter unit in the motor driver;

[0040] A first calculation module: three-phase currents of the permanent magnet synchronous motor are collected through a current sensor, the collected three-phase currents are transformed to the motor rotating coordinate system d-q through coordinate transformation, and a single-cycle saturation current difference value of the d-axis is obtained;

[0041] A second calculation module: a certain cycle is continuously injected, and a saturation current accumulation value is calculated according to the single-cycle saturation current difference value;

[0042] A detection module: the saturation current accumulation value is compared with a set threshold value, and whether the permanent magnet synchronous motor has an electromagnetic fault is determined according to a comparison result, so as to complete the demagnetization detection of the permanent magnet synchronous motor.

[0043] In a third aspect, the application provides a terminal including a processor and a storage medium;

[0044] The storage medium is used for storing instructions;

[0045] The processor is used for operating according to the instructions to perform steps of the method according to the first aspect.

[0046] In a fourth aspect, a computer readable storage medium has a computer program stored thereon, and the program is executed by a processor to implement steps of the method according to the first aspect.

[0047] Compared with the prior art, the present application has the following beneficial effects:

[0048] 1. The permanent magnet synchronous motor demagnetization detection method can accurately diagnose the health status of the permanent magnet synchronous motor permanent magnet, and can complete the demagnetization detection within a few hundred milliseconds before the vehicle runs, without affecting the vehicle operation and work, and the hardware requirement is not high, and the method can be completed on a conventional hardware topology motor driver, facilitating engineering implementation and popularization and application.

[0049] 2. The permanent magnet synchronous motor demagnetization detection method can realize effective detection of the demagnetization of the permanent magnet synchronous motor permanent magnet without using any additional auxiliary equipment and instruments, and the existing mainstream motor driver on the market does not have the diagnosis capability of the demagnetization fault of the permanent magnet synchronous motor, and the scheme plays a positive role in improving the torque safety of the vehicle, reducing the accident rate, and improving the product competitiveness. BRIEF DESCRIPTION OF DRAWINGS

[0050] Fig. 1 is a flowchart of a permanent magnet synchronous motor demagnetization detection method according to an embodiment of the present application;

[0051] Fig. 2 is a motor coordinate system diagram of a permanent magnet synchronous motor demagnetization detection method according to an embodiment of the present application;

[0052] Fig. 3 is a whole block diagram of a permanent magnet synchronous motor demagnetization detection method according to an embodiment of the present application;

[0053] Fig. 4 is a three-phase inverter hardware topology structure diagram of a permanent magnet synchronous motor demagnetization detection method according to an embodiment of the present application;

[0054] Fig. 5 is a demagnetization detection signal processing flowchart of a permanent magnet synchronous motor demagnetization detection method according to an embodiment of the present application. DETAILED DESCRIPTION

[0055] The technical scheme of the present application will be described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific features in the embodiments and the specific features in the embodiments are detailed descriptions of the technical scheme of the present application, and are not limitations of the technical scheme of the present application. In the case of no conflict, the technical features in the embodiments and the embodiments can be combined with each other.

[0056] The term "and / or", only describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which means that there are three kinds of situations, that is, A exists alone, A and B exist together, and B exists alone. In addition, the character " / " generally represents that the front and rear associated objects are in an "or" relationship.

[0057] Embodiment one:

[0058] As shown in Figures 1-5, the application provides a permanent magnet synchronous motor demagnetization detection method, comprising the following steps:

[0059] Before starting the permanent magnet synchronous motor, a positive and negative symmetrical high-frequency square wave voltage detection signal is generated by a main control chip in the motor driver;

[0060] The high-frequency square wave voltage detection signal is injected into the d-axis of the motor rotating coordinate system d-q by an inverter unit in the motor driver;

[0061] The three-phase current of the permanent magnet synchronous motor is collected by a current sensor, and the collected three-phase current is transformed to the motor rotating coordinate system d-q by coordinate transformation, and the single-cycle saturation current difference of the d-axis is obtained;

[0062] The saturation current cumulative value is calculated according to the single-cycle saturation current difference;

[0063] The saturation current cumulative value is compared with the set threshold value, and whether the permanent magnet synchronous motor has electromagnetic failure is determined according to the comparison result, so as to complete the demagnetization detection of the permanent magnet synchronous motor.

[0064] Specifically, under normal circumstances, the permanent magnet magnetic field is at the critical saturation point of the magnetic circuit, i.e. the "knee point", if the positive and negative symmetrical voltage excitation produces positive and negative asymmetrical current response, if the motor permanent magnet demagnetization occurs obviously, the permanent magnet magnetic field is in the linear region, if the symmetrical voltage is injected, the response current will also show the characteristics of positive and negative symmetry, the application utilizes this feature to realize demagnetization detection.

[0065] Wherein, Figure 2 is a schematic diagram of the motor coordinate system involved in the application, which includes the relative relationship of the permanent magnet N-S magnetic pole, three-phase static A-B-C coordinate system, two-phase static coordinate system α-β, and motor rotating coordinate system d-q, wherein, the α-axis of the two-phase static coordinate system is defined as the same direction as the A-axis of the three-phase static coordinate system, the d-axis of the motor rotating coordinate system is defined as the same direction as the N-pole of the permanent magnet, and θ c is the angle between the N-pole of the rotor permanent magnet and the A-axis.

[0066] Figure 3 is a block diagram of the application; in the figure, is the voltage command value in the two-phase static coordinate system, i A , i B , and i C are motor current sampling values, i α , i β are current values in the two-phase static coordinate system, i d is the current value in the motor rotating coordinate system, and ∑I M is the saturation current cumulative value.

[0067] Figure 4 is a three-phase inverter hardware topology, which adopts a general three-phase inverter bridge structure, is composed of a DC side supporting capacitor, A phase upper and lower bridge arms, B phase upper and lower bridge arms, and C phase upper and lower bridge arms, and is connected to a permanent magnet synchronous motor junction box through a three-phase power line bundle.

[0068] Figure 5 is a demagnetization detection signal processing flowchart, n is the cycle number of the injected signal, M is the number of cycles of the injected signal, and x is the two d-axis current numbers obtained by coordinate transformation in a single injection cycle.

[0069] The application can realize effective detection of the demagnetization of the permanent magnet of the permanent magnet synchronous motor without using any additional auxiliary equipment, and the existing mainstream motor driver on the market does not have the diagnosis capability of the demagnetization fault of the permanent magnet synchronous motor, and the scheme plays a positive role in improving the torque safety of the vehicle, reducing the accident rate, and improving the product competitiveness.

[0070] In one embodiment, the high-frequency square wave voltage detection signal is as follows:

[0071] In the formula, U inj is the amplitude of the injected voltage signal, t is time, T inj is the injection period of the high-frequency signal, n is the cycle number of the injected signal, u inj is the high-frequency square wave voltage detection signal.

[0072] In one embodiment, the high-frequency square wave voltage detection signal is injected into the d-axis of the motor rotating coordinate system d-q, and is as follows:

[0073] In the formula, u d is the high-frequency voltage excitation signal injected into the d-axis of the motor rotating coordinate system d-q; u q is the high-frequency voltage excitation signal injected into the q-axis of the motor rotating coordinate system d-q.

[0074] In one embodiment, the collected three-phase current is transformed to the motor rotating coordinate system d-q through coordinate transformation, and specifically includes:

[0075] The three-phase current is transformed to the two-phase stationary coordinate system alpha-beta, and the current signal in the two-phase stationary coordinate system alpha-beta is obtained;

[0076] The current signal in the two-phase stationary coordinate system alpha-beta is transformed to the motor rotating coordinate system d-q.

[0077] In one embodiment, the three-phase current of the permanent magnet synchronous motor is collected by a current sensor, the collected three-phase current is transformed to the motor rotating coordinate system d-q through coordinate transformation, and the single-cycle saturation current difference of the d-axis is obtained, and specifically includes: In one embodiment, the three-phase current of the permanent magnet synchronous motor is collected by a current sensor, the collected three-phase current is transformed to the motor rotating coordinate system d-q through coordinate transformation, and the single-cycle saturation current difference of the d-axis is obtained, and specifically includes:

[0078] The current sampling is performed at a preset time, and the three-phase current i A , i B and i C of the permanent magnet synchronous motor are collected by the current sensor

[0079] The i A , i B and i C are transformed to the two-phase stationary coordinate system α-β by the following coordinate transformation:

[0080] In the formula: i α , i β are the current signals in the two-phase stationary coordinate system α-β

[0081] The i α , i β are transformed to the motor rotating coordinate system d-q by the following coordinate transformation:

[0082] In the formula: i d is the current signal of the d-axis in the motor rotating coordinate system d-q, i q is the current signal of the q-axis in the motor rotating coordinate system d-q, and θ c is the rotor magnetic pole position signal

[0083] The current sampling is performed at the time t , and the collected three-phase current is transformed to the motor rotating coordinate system d-q by coordinate transformation to obtain the d-axis current i d1 ;

[0084] The current sampling is performed at the time t inj , and the collected three-phase current is transformed to the motor rotating coordinate system d-q by coordinate transformation to obtain the d-axis current i d2 ;

[0085] The single-period saturated current difference of the d-axis is calculated by the following formula: I n = i d2 + i d1

[0086] In the formula: I n is the single-period saturated current difference of the d-axis

[0087] In one embodiment, the saturated current cumulative value is calculated according to the single-period saturated current difference in the period, and specifically includes:

[0088] In the first injection period, n is 1: I1= i d2 + i d1

[0089] Continuously perform M injection cycles to obtain I1, I2, I3, …, I n … M ; I1, I2, I3, …, I n … M Perform accumulation to obtain a saturation current accumulation value ΣI M .

[0090] One embodiment, the saturation current accumulation value is compared with a set threshold, and whether the permanent magnet synchronous motor has an electromagnetic fault is determined according to the comparison result, specifically comprising:

[0091] If the saturation current accumulation value is not less than the set threshold, it is determined that the permanent magnet synchronous motor has not occurred electromagnetic fault;

[0092] If the saturation current accumulation value is less than the set threshold, it is determined that the permanent magnet synchronous motor has an electromagnetic fault.

[0093] Specifically, the saturation current accumulation value ΣI M is compared with the set threshold, and if the saturation current accumulation value ΣI M is greater than or equal to the set threshold, it means that the nonlinear characteristics of the motor d-axis magnetic circuit saturation are obvious, the permanent magnet flux linkage is still near the critical saturation point, and demagnetization has not occurred, that is, no electromagnetic fault has occurred; if the saturation current accumulation value ΣI M is less than the set threshold, it means that the motor d-axis magnetic circuit has not occurred saturation, and the permanent magnet flux linkage is in the linear region, and it is determined that demagnetization fault has occurred.

[0094] The application can accurately diagnose the health status of the permanent magnet synchronous motor permanent magnet; the application can complete demagnetization detection within a few hundred milliseconds before the vehicle runs, without affecting the vehicle operation and work, and the application has low requirements for hardware and can be completed on a conventional hardware topology motor driver, facilitating engineering implementation and popularization and application.

[0095] Embodiment two:

[0096] The application further provides a permanent magnet synchronous motor demagnetization detection device, which comprises:

[0097] A generating module generates a positive-negative symmetrical high-frequency square wave voltage detection signal through a main control chip in a motor driver before starting the permanent magnet synchronous motor;

[0098] An input module injects the high-frequency square wave voltage detection signal into the d-axis of the motor rotating coordinate system d-q through an inverter unit in the motor driver;

[0099] A first calculation module collects three-phase currents of the permanent magnet synchronous motor through a current sensor, transforms the collected three-phase currents to the motor rotating coordinate system d-q through coordinate transformation, and obtains a single-cycle saturation current difference value of the d-axis;

[0100] The second calculation module: continuously injects a certain period, and calculates a saturation current accumulation value according to a single-period saturation current difference value;

[0101] The detection module: compares the saturation current accumulation value with a set threshold value, and determines whether the permanent magnet synchronous motor has an electromagnetic fault according to a comparison result, so as to complete the demagnetization detection of the permanent magnet synchronous motor.

[0102] Embodiment three:

[0103] The embodiment of the application further provides a terminal, including a processor and a storage medium.

[0104] The storage medium is used for storing instructions.

[0105] The processor is used for operating according to the instructions to execute the steps of the method in the embodiment one.

[0106] Embodiment four:

[0107] The embodiment of the application further provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the steps of the method in the embodiment one.

[0108] Since the storage medium provided by the embodiment of the application can execute the method provided by the embodiment one of the application, it has the corresponding function modules and beneficial effects of the executed method.

[0109] Those skilled in the art should understand that the embodiments of the application can be provided as a method, a system, or a computer program product. Therefore, the application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0110] The application is described with reference to flowcharts and / or block diagrams according to the method, device (system), and computer program product of the embodiments of the application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device for implementing the functions specified in one or more flows in the flowcharts and / or one or more blocks in the block diagrams.

[0111] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart or flowsheets and / or block or blocks of the block diagrams.

[0112] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheets and / or block or blocks of the block diagrams.

[0113] The above description is only preferred embodiments of the present application, it should be pointed out that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can also be made, which should be considered as the protection scope of the present application.

Claims

1. A method for detecting demagnetization of a permanent magnet synchronous motor, characterized in that, Includes the following steps: Before the permanent magnet synchronous motor starts, a high-frequency square wave voltage detection signal with positive and negative symmetry is generated by the main control chip in the motor driver; The high-frequency square wave voltage detection signal is injected into the d-axis of the motor rotating coordinate system dq through the inverter unit in the motor driver; The three-phase current of the permanent magnet synchronous motor is collected, and the collected three-phase current is transformed into the motor rotating coordinate system dq through coordinate transformation, and the single-cycle saturation current difference of the d-axis is obtained. Continuous injection for a certain period of time, and calculation of the cumulative value of saturation current based on the difference of saturation current in a single period; The accumulated value of saturation current is compared with a set threshold, and the comparison result is used to determine whether the permanent magnet synchronous motor has an electromagnetic fault, so as to complete the demagnetization detection of the permanent magnet synchronous motor.

2. The method for detecting demagnetization of a permanent magnet synchronous motor according to claim 1, characterized in that, The high-frequency square wave voltage detection signal is as follows: In the formula: U inj The amplitude of the injected voltage signal is T, where t is time. inj U represents the injection period of the high-frequency signal, where n is the period number of the injected signal, and u... inj It is a high-frequency square wave voltage detection signal.

3. The method for detecting demagnetization of a permanent magnet synchronous motor according to claim 2, characterized in that, The high-frequency square wave voltage detection signal is injected into the d-axis of the motor's rotating coordinate system dq, as shown in the following formula: In the formula: u d A high-frequency voltage excitation signal injected into the d-axis of the motor's rotating coordinate system dq; u q A high-frequency voltage excitation signal is injected into the q-axis of the motor's rotating coordinate system dq.

4. The method for detecting demagnetization of a permanent magnet synchronous motor according to claim 3, characterized in that, The process of transforming the acquired three-phase current into the motor rotating coordinate system dq through coordinate transformation specifically includes: The three-phase current is transformed into a two-phase stationary coordinate system α-β, and the current signal in the two-phase stationary coordinate system α-β is obtained. The current signal in the two-phase stationary coordinate system α-β is transformed into the motor rotating coordinate system dq.

5. The method for detecting demagnetization of a permanent magnet synchronous motor according to claim 4, characterized in that, The process of acquiring the three-phase current of the permanent magnet synchronous motor through a current sensor, transforming the acquired three-phase current to the motor's rotating coordinate system dq through coordinate transformation, and obtaining the single-cycle saturation current difference along the d-axis specifically includes: Current sampling is performed at preset times, and the three-phase current i of the permanent magnet synchronous motor is collected by a current sensor. A i B and i C ; By performing the following coordinate transformation, i A i B and i C Transform to the two-phase stationary coordinate system α-β: In the formula: i α i β The current signal is in the two-phase stationary coordinate system α-β. By performing the following coordinate transformation, i ɑ i β Transform to the motor rotating coordinate system dq: In the formula: i d For the current signal along the d-axis in the rotating coordinate system dq of the motor, i q Let θ be the current signal along the q-axis in the rotating coordinate system dq of the motor. c This is the rotor magnetic pole position signal; exist Current is sampled at specific times, and the collected three-phase current is transformed into the motor rotating coordinate system dq through coordinate transformation to obtain the d-axis current i. d1 ; At t=(n-1)T inj Current is sampled at specific times, and the collected three-phase current is transformed into the motor rotating coordinate system dq through coordinate transformation to obtain the d-axis current i. d2 ; The single-cycle saturation current difference along the d-axis is calculated using the following formula: I n =i d2 +i d1 In the formula: I n This represents the single-cycle saturation current difference along the d-axis.

6. The method for detecting demagnetization of a permanent magnet synchronous motor according to claim 5, characterized in that, The continuous injection for a certain period of time, and the calculation of the cumulative saturation current value based on the difference in saturation current in a single period, specifically includes: In the first injection cycle, n is 1: I1=i d2 +i d1 Execute M injection cycles consecutively to obtain I1, I2, I3...I n …I M ; I1, I2, I3...I n …I M Accumulate the values ​​to obtain the accumulated saturation current ∑I. M .

7. The method for detecting demagnetization of a permanent magnet synchronous motor according to claim 1, characterized in that, The step of comparing the accumulated saturation current value with a set threshold and determining whether the permanent magnet synchronous motor has experienced an electromagnetic fault based on the comparison result specifically includes: If the accumulated value of the saturation current is not less than the set threshold, it is determined that the permanent magnet synchronous motor has not experienced an electromagnetic fault. If the accumulated saturation current is less than the set threshold, the permanent magnet synchronous motor is determined to have an electromagnetic fault.

8. A demagnetization detection device for a permanent magnet synchronous motor, characterized in that, The device includes: Generation module: Before the permanent magnet synchronous motor starts, the main control chip in the motor driver generates a positive and negative symmetrical high-frequency square wave voltage detection signal; Input module: The high-frequency square wave voltage detection signal is injected into the d-axis of the motor rotating coordinate system dq through the inverter unit in the motor driver; The first calculation module collects the three-phase current of the permanent magnet synchronous motor through a current sensor, transforms the collected three-phase current to the motor rotating coordinate system dq through coordinate transformation, and obtains the single-cycle saturation current difference of the d-axis. Second calculation module: Continuously inject for a certain period of time, and calculate the cumulative value of saturation current based on the difference of saturation current in a single period; Detection module: Compares the accumulated value of saturation current with a set threshold, and determines whether the permanent magnet synchronous motor has an electromagnetic fault based on the comparison result, so as to complete the demagnetization detection of the permanent magnet synchronous motor.

9. A terminal, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1 to 7.

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