Detecting Faults in Field Oriented Controlled Permanent Magnet Synchronous Motors

Abstract

The present application relates to detecting faults in a field-oriented controlled permanent magnet synchronous motor. In the described example, a system (200) includes a proportional integral derivative (PID) regulator (203). The system (200) also includes a fault detection unit (214) for receiving at least two outputs from the PID regulator (203). The at least two outputs include at least two rotor reference frame (D-Q) currents. The fault detection unit (214) is also used to generate a detection signal based on the at least two rotor reference frame currents. The detection signal identifies the fault based on a fault detection signal amplitude value of the amplitude amplitude of each of the at least two rotor reference frame D-Q currents. The fault detection unit (214) is used to identify the presence of a permanent magnet motor fault based on a comparison between the fault detection signal amplitude value and an amplitude threshold. Further, a fault location feature is used to locate the fault.

Description

[0001] This application is a divisional application of Chinese patent application 201580054183.8 filed on October 7, 2015 and entitled “Detecting Faults in Field Oriented Controlled Permanent Magnet Synchronous Motors”. Technical Field

[0002] The present disclosure relates generally to electronic circuits, and more particularly to methods and circuits for detecting faults in field oriented control (FOC) permanent magnet synchronous motors (PMSMs) and drives. Background Art

[0003] Electric motors are used in a range of applications, including industrial applications, household appliances, automotive traction, pumps and fans, and aerospace applications. Most of these applications require safe and reliable operation of the machine and any associated drive systems. Failures in electric motors can occur for many reasons, including mechanical vibration, thermal cycling, thermal shock, manufacturing defects, and improper maintenance. Detecting motor failures can prevent damage to the machine, drive electronics, personnel, and other equipment. Summary of the invention

[0004] In a first example, a system includes a proportional-integral-derivative (PID) regulator. The system also includes a fault detection unit. The fault detection unit is used to receive at least two outputs from the PID regulator. The at least two outputs include at least two rotor reference frame currents (DQ currents). The fault detection unit is also used to determine the amplitude magnitude of each of the at least two rotor reference frame currents. The fault detection unit is also used to generate a detection signal based on the at least two rotor reference frame currents. The detection signal identifies a single amplitude magnitude value based on the amplitude magnitude of each of the at least two rotor reference frame currents. The fault detection unit is used to identify the presence of a permanent magnet motor / drive fault based on a comparison between the fault detection signal amplitude value and a predefined threshold.

[0005] In a second example, a fault detection unit includes a threshold detector for receiving at least two outputs from a proportional integral derivative (PID) regulator and for determining an amplitude magnitude of each of at least two rotor reference frame currents. The at least two outputs include at least two rotor reference frame currents. The fault detection unit also includes a detection signal generation unit for generating a detection signal based on the at least two rotor reference frame currents. The detection signal identifies a single amplitude magnitude value based on the amplitude magnitude of each of the at least two rotor reference frame currents. The fault detection unit also includes a comparator for comparing the signal amplitude value with a preset threshold value to identify the presence of a permanent magnet motor fault.

[0006] In a third example, a method includes receiving at least two outputs from a proportional integral derivative (PID) regulator, and determining an amplitude magnitude of each of the at least two rotor reference frame currents. The at least two outputs include at least two rotor reference frame currents. The method also includes determining an amplitude magnitude of each of the at least two rotor reference frame currents. The method also includes generating a detection signal based on the at least two rotor reference frame currents. The detection signal identifies a fault based on an amplitude value of the signal of each of the at least two rotor reference frame currents. The method includes identifying the presence of a permanent magnet motor / drive fault based on a comparison between the signal amplitude value and a preset threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is an example block diagram of a system with a field oriented control (FOC) permanent magnet synchronous motor (PMSM) according to the present disclosure.

[0008] Figure 2 is an example block diagram of a system for detecting faults in FOC PMSM motors and drives according to the present disclosure.

[0009] Figure 3A is an example block diagram of a DQ current signature (rotor reference frame current signature) according to the present disclosure.

[0010] Figure 3B is an example block diagram of phase current characterization according to the present disclosure.

[0011] Figure 4 is an example block diagram of a fault detection unit according to the present disclosure.

[0012] Figure 5 is a flow chart of an example fault detection method according to the present disclosure. DETAILED DESCRIPTION

[0013] Permanent Magnet Synchronous Motor (PMSM) is increasingly being used due to power density, efficiency gains and simplicity of control algorithms. Field Oriented Control (FOC) is a control algorithm used for PMSM control due to its simplicity. Listed below are some typical faults that can occur in a PMSM drive system.

[0014] Table 1: Failure modes of PMSM motor drive system

[0015] Machine failure Drive failure Bearing failure Switch failure Winding failure (in-phase) Single leg failure Winding failure (phase to phase) Multiphase failure Magnet failure The switch is short-circuited to the phase Open phase fault Switch shorted to ground

[0016] A winding short circuit in a rotating PMSM is essentially a loop of a conductor rotating in a magnetic field. The conductor loop is induced as voltage creates a current flow in a low resistance path. Current in excess of the winding rated current can flow in the conductor loop, even at low speeds caused by the low resistance. Exceeding the rated current of the winding can cause the machine to overheat and can result in a potentially hazardous environment. Immediate detection of winding faults will prevent damage to the machine, drive electronics, personnel, and other equipment.

[0017] Figure 1 is an example block diagram of a system 100 having a field oriented control (FOC) permanent magnet synchronous motor (PMSM) according to the present disclosure. Figure 1 As shown, the system 100 includes a rotor reference frame current regulation scheme and I dq To V dq The converter unit 102 (hereinafter referred to as the RC unit 102), the rotor reference frame voltage form (V dq ) to phase voltage form (V abcs ) conversion unit 101 (hereinafter referred to as line voltage to phase voltage conversion unit 101), a pulse width modulation (PWM) generation unit 108, an inverter 104, a permanent magnet motor 106, a DC motor or any mechanism 107 for loading (hereinafter referred to as machine 107) and a proportional integral derivative (PID) regulator 103. The PID regulator 103 includes an error calculation unit 110. The system also includes a Clarke and Park (CP) conversion unit 112.

[0018] RC unit 102 receives two line current forms (I dq ), and convert the two line current forms into two rotor reference frame voltage forms (V dq ). RC unit 102 transmits the two rotor reference frame voltage forms to unit 101. Unit 101 converts the two rotor reference frame voltage forms into phase voltage forms (V abcs The phase voltage form is provided to the PWM generation unit 108. The PWM generation unit 108 controls the width of the pulse based on the modulator signal information, in other words, controls the pulse duration.

[0019] The inverter 104 receives the phase voltage form from the PMW generation unit 108 and converts the direct current (DC) power into alternating current (AC) power. In this example, the inverter 104 represents a three-phase inverter that converts the DC power into a three-phase AC power provided to the motor 106. The inverter 104 includes any suitable structure for converting power from a DC form into an AC form. For example, the inverter 104 may include one or more transistor switches driven using a pulse width modulation (PWM) signal.

[0020] Motor 106 represents a permanent magnet motor that operates using a voltage provided by inverter 104. Motor 106 includes a rotor having magnets embedded in or connected to the rotor. Motor 106 also includes a stator having a plurality of teeth around which a conductive winding is wound. The winding is selectively energized and de-energized based on a signal from inverter 104, which produces a rotating magnetic field that rotates the rotor. Motor 106 drives machine 107. The motor can drive machine 107 with, for example, a drive shaft and one or more gears.

[0021] The system 100 further includes a proportional integral derivative (PID) regulator 103. In one embodiment, the PID regulator 103 is a proportional integral (PI) regulator. The controller includes the PID regulator 103 having an error calculation unit 110 and a Clarke and Park (CP) transformation unit 112. The CP transformation unit 112 receives the balanced three-phase AC current from the inverter 104 in the stator reference frame and converts the balanced three-phase AC current in the stator frame into two currents (I q and I d , Q and D axis currents). The CP transformation unit 112 transmits the two line currents to the error calculation unit 110. The error calculation unit 110 adjusts the two line currents which are then fed to the RC unit 102.

[0022] The RC unit 102, the unit 101, and the PWM generation unit 108 together control the operation of the inverter 104, thereby controlling the operation of the motor 106. For example, the PWM generation unit 108 generates a PWM signal that drives the transistor switches in the inverter 104. By controlling the duty cycle of the PWM signal, the PWM generation unit 108 controls the three-phase voltage provided by the inverter 104 to the motor 106.

[0023] In this example, the RC unit 102 receives as input a command speed signal ω * , which identifies the desired speed of the motor 106. The RC unit 102 also receives as input feedback from the PID regulator 103, where the feedback identifies the estimated motor speed, rotor position, or other characteristic (or characteristics) of the motor 106. The PWM generator 108 uses the input to generate a PWM signal for driving the transistor switches in the inverter 104.

[0024] Figure 1 The various components in can be combined or further subdivided. For example, one or more of components 101, 102, 104 and 108 can be integrated into motor 106 itself.

[0025] Figure 2 is an example block diagram of a system 200 for detecting faults in a field oriented control (FOC) permanent magnet synchronous motor (PMSM) according to the present disclosure. Figure 2 As shown, the system 200 includes an RC unit 202, a rotor reference frame voltage to phase voltage conversion unit 201, a PWM generation unit 208, an inverter 204, a permanent magnet motor 206, a machine 207, and a PID regulator 203. The PID regulator 203 includes an error calculation unit 210 and a Clark and Park (CP) conversion unit 212. Each of these components of the system 200 is similar to Figure 1 The corresponding RC unit 102, line voltage to phase voltage conversion unit 101, PWM generation unit 108, inverter 104, permanent magnet motor 106, machine 107 and PID regulator 103 including error calculation unit 110 and CP conversion unit 112 are the same or similar.

[0026] The system 200 also includes a fault detection unit 214. The fault detection unit 214 detects the presence of a fault in the permanent magnet motor 206 by executing a detection algorithm based on the rotor reference frame current signature (DQ current signature) due to the machine imbalance caused by the fault. For example, for control purposes, the motor is considered to be a balanced three-phase machine. The FOC algorithm relies on a balanced machine controlled by a set of balanced three-phase currents. When the CP transformation unit 212 is activated, the balanced three-phase currents in the stator reference frame are transformed into two DC-like signals (non-sinusoidal) in the rotor reference frame. After a transition period, each of the two DC signals is in a steady state.

[0027] If a fault is present, the three-phase current will be unbalanced during steady-state operation, and the CP transformation unit 212 does not generate two DC signals in the rotor reference frame at steady state. In this case, the unbalanced motor has a rotor reference frame current in which a sinusoidal component is superimposed on a DC component. The fault detection unit 214 identifies the sinusoidal component superimposed on the DC component and determines that a fault exists, such as based on the amplitude value of the sinusoidal component.

[0028] Figure 3A is an example block diagram of a DQ current according to the present disclosure. Similar variations are reflected in the PID controller error output and control signal output, which are used for fault diagnosis and location. The fault detection unit 214 detects the presence of a fault. For example, Figure 3A As shown, the fault detection unit 214 receives a plurality of DQ current values ​​over a period of time to generate a DQ current signature. From the 0.48 second mark until the 0.5 second mark, the fault detection unit 214 determines that the motor and phase currents are balanced when the DQ current signature is in a steady state. At the 0.5 second mark, the DQ current signature changes from a steady state current to a sinusoidal current. The rotor reference frame PID regulator output is also affected by the sinusoidal current. The fault detection unit 214 determines that the motor and phase currents are unbalanced because the DQ current error is not in a steady state, thereby indicating that a fault exists.

[0029] Figure 3B is an example block diagram of phase current features according to the present disclosure. The fault detection unit 214 derives the DQ current features from the phase current features, for example, after the fault detection unit 214 determines that a fault exists. The derived DQ current features have the same or similar phase current features provided to the motor 206 from the inverter 204. By deriving the DQ current features from the phase features, the fault detection unit 214 can identify the type of fault. For example, Figure 3A The derived DQ current characteristics follow Figure 3B Phase current characteristics. Figure 3B As shown, from the 0.48 second mark to the 0.5 second mark, the derived phase current signatures show three sinusoidal current signatures (phases A, B, and C) with the same or similar amplitudes reflecting steady-state DQ current signatures within the same time frame. At the 0.5 second mark, the phase current signatures change so that the phase B current signature has zero amplitude, while the phase A and phase C current signatures have amplitudes reflecting the use of Figure 3A The increased amplitude of the sinusoidal DQ current signature identifies a fault condition.

[0030] The DQ current and rotor position are used together to locate the fault occurrence. The rotor position can be estimated or obtained via a rotor position sensor. For example, a specific configuration or pattern of phase current characteristics can identify switch failures, single leg failures, switch disconnect failures, switch short circuit to ground failures, and other failures. Based on the identification of the fault type, the fault detection unit 214 can determine the location of the fault.

[0031] In addition, the fault detection unit 214 uses an algorithm to detect the faulty phase. The faulty phase identification scheme is based on the phase shift induced in the function "f" relative to the actual rotor position due to the fault condition. Assuming a fault on phase "C", the following is derived:

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] If the actual electrical angle is known, the phase shift in the above signal "f" can be extracted. The phase shift will indicate the faulty winding / phase.

[0040]

[0041] Figure 2 The various components in can be combined or further subdivided. For example, one or more of components 201, 202, 204 and 208 can be incorporated into motor 206 itself.

[0042] Figure 4 is an example block diagram of a fault detection unit 414 according to the present disclosure. The design details of the fault detection unit 414 may be incorporated into Figure 2 Of course, these design details can be incorporated into other fault detection units operating in other systems. Figure 4 As shown, the fault detection unit 414 includes a threshold detector 416 , a detection signal generating unit 418 , a comparator 420 , a fault counter 422 , and a detection threshold storage unit 424 .

[0043] Threshold detector 416 is derived from a proportional integral derivative (PID) regulator (e.g. Figure 2 The PID regulator 203 of the motor 206 receives at least two outputs. The at least two outputs include at least two rotor reference frame DQ current features. The threshold detector 416 determines the amplitude magnitude of each of the at least two rotor reference frame DQ currents to enable the fault detection circuit. For example, when the motor 206 is balanced, the threshold detector 416 will determine that the amplitude of each of the at least two rotor reference frame DQ currents is equal to zero or close to zero because the rotor reference frame current is in a steady state. When the motor 206 is unbalanced, the threshold detector 416 will determine that the amplitude magnitude of each of the at least two rotor reference frame DQ currents is a value significantly greater than zero because the rotor reference frame current is not in a steady state. After the at least two rotor reference frame DQ current features pass through the threshold detector 416, the at least two rotor reference frame DQ current features are received by the detection signal generation unit 418.

[0044] The detection signal generation unit 418 receives at least two rotor reference frame DQ current features and generates a detection signal based on the at least two rotor reference frame DQ current features. Therefore, the detection signal is a single signal that is a combination of the D current feature and the Q current feature. The detection signal is based on the amplitude magnitude of each of the at least two rotor reference frame DQ current features, and a single amplitude magnitude value is identified from the single signal. The detection signal generation unit 418 calculates the single amplitude magnitude value to provide an accurate amplitude magnitude value. The detection signal generation unit 418 can generate the detection signal using the following equation:

[0045] I d_error x / (I d_error x +Iq_error x ); x=1,2,3,…

[0046] After the detection signal generating unit 418 generates the detection signal, the detection signal generating unit 418 transmits the detection signal to the comparator 420 .

[0047] The comparator 420 receives the detection signal and compares the single amplitude amplitude value of the detection signal with the amplitude threshold to identify the presence of a permanent magnet motor fault. For example, if the single amplitude amplitude value is greater than the amplitude threshold, a fault exists. The detection threshold storage unit 424 stores the amplitude threshold and provides the amplitude threshold to the comparator 420 for signal comparison.

[0048] The fault detection unit 414 also includes a fault counter 422. The fault counter 422 verifies that a fault exists. For example, after determining that a first fault exists, the fault counter 422 counts the number of subsequent fault signal threshold crossings detected at the comparator 420. When the fault counter 422 detects a predetermined number of subsequent faults, the fault counter 422 verifies that a fault exists. The fault counter 422 may verify that a fault exists after detecting at least one subsequent fault. The fault counter 422 may verify that a fault exists after detecting a predetermined number of faults within a predetermined time period. The fault counter 422 may verify that a fault exists when a predetermined number of consecutive fault signal threshold crossings are detected within a predetermined time period. The fault counter 422 may verify that a fault exists when a percentage of faults to non-faults is detected within a predetermined time period.

[0049] Figure 5 is a flow chart of an example fault detection method 500 according to the present disclosure. In step 502, the fault detection unit 414 receives at least two outputs or output streams from a proportional integral derivative (PID) regulator. The at least two outputs include at least two rotor reference frame currents or current characteristics. In step 504, the fault detection unit 414 determines the amplitude magnitude of each of the at least two rotor reference frame currents. In step 506, the fault detection unit 414 generates a detection signal based on the at least two rotor reference frame currents. The detection signal identifies a single amplitude magnitude value based on the amplitude magnitude of each of the at least two rotor reference frame currents. In step 508, the fault detection unit 414 identifies the presence of a fault based on a comparison between the single amplitude magnitude value and an amplitude threshold. For example, the fault detection unit 414 may compare the single amplitude magnitude value with the amplitude threshold and determine whether a fault exists based on the comparison. In step 510, the fault detection unit 414 verifies the presence of a permanent magnet motor fault by comparing a predetermined amount of subsequent single amplitude magnitude values ​​with the amplitude threshold.

[0050] although Figure 5A series of steps are shown, but the various steps in each figure can overlap, occur in parallel, occur in a different order, or occur any number of times. In addition, one or more steps of method 500 can be removed, or other steps can be added to method 500. Method 500 is described as being performed by fault detection unit 414, but method 500 can be performed by any other suitable unit, device, or system.

[0051] In some embodiments, the various functions described above are implemented or supported by a computer program formed from a computer readable program code and contained in a computer readable medium. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disk (DVD), or any other type of memory. "Non-transitory" computer readable media excludes wired, wireless, optical, or other communication links that transmit instantaneous electrical signals or other signals. Non-transitory computer readable media include media in which data can be permanently stored and media in which data can be stored and rewritten later, such as rewritable optical disks or erasable memory devices.

[0052] The terms "application" and "program" as used herein refer to one or more computer programs, software components, instruction sets, procedures, functions, objects, classes, instances, related data, or portions thereof, suitable for implementation in suitable computer code (including source code, object code, or executable code).

[0053] Modifications are possible in the described embodiments, and other embodiments are possible within the scope of the invention.

Claims

1. A fault detection system, comprising: Proportional integral derivative regulator; as well as A fault detection circuit is coupled to the PID regulator and includes: A threshold detector is configured to: receiving at least two outputs from the PID regulator, wherein the at least two outputs include at least a first rotor reference frame current characteristic of a first rotor reference frame current and a second rotor reference frame current characteristic of a second rotor reference frame current; and Determine a first magnitude I of the amplitude of the first rotor reference frame current d_error and a second magnitude I of the amplitude of the second rotor reference frame current q_error ; A detection signal generating unit, which is coupled to the threshold detector and configured to generate a detection signal, wherein the detection signal is based on the first amplitude I of the amplitude of the first rotor reference frame current. d_error and the second amplitude I of the amplitude of the second rotor reference frame current q_error To identify a single amplitude magnitude value, wherein the fault detection circuit is configured to generate the detection signal using the following formula: I d_error x / (I d_error x +I q_error x ), where x is an integer greater than 1; and A comparator is coupled to the detection signal generating unit and is configured to compare the single amplitude magnitude value with an amplitude threshold to identify the presence of a permanent magnet motor fault.

2. The fault detection system of claim 1 , wherein the presence of the permanent magnet motor fault is verified by comparing a predetermined amount of subsequent single amplitude magnitude values ​​to the amplitude threshold, and the predetermined amount of subsequent single amplitude magnitude values ​​comprises at least one subsequent single amplitude magnitude value.

3. The fault detection system according to claim 1, wherein the fault detection circuit is further configured to: after identifying the presence of the permanent magnet motor fault, derive a three-phase stator reference frame current from at least the first rotor reference frame current and the second rotor reference frame current, and identify the drive fault type based on the three-phase stator reference frame current.

4. The fault detection system of claim 3, wherein the drive fault type comprises at least one of the following: a switch failure fault, a single leg failure, a multi-phase failure, a switch disconnection fault, a switch short circuit to phase fault, or a switch short circuit to ground fault.

5. The fault detection system of claim 3, wherein the fault detection circuit is further configured to identify a permanent magnet motor fault type based on the drive fault type, and the permanent magnet motor fault type includes at least one of a bearing failure, an intra-phase winding failure, an inter-phase winding failure, a magnet failure, or an open-phase fault. 6 . The fault detection system of claim 1 , wherein the PID regulator is a component of a Field Oriented Control (FOC) Permanent Magnet Synchronous Motor (PMSM).

7. A fault detection circuit comprising: A threshold detector is configured to: receiving at least a first rotor reference frame current characteristic of the first rotor reference frame current and a second rotor reference frame current characteristic of the second rotor reference frame current; and Determine a first magnitude I of the amplitude of the first rotor reference frame current d_error and the second amplitude I of the amplitude of the second rotor reference frame current q_error ; A detection signal generating unit, which is coupled to the threshold detector and configured to generate a detection signal, wherein the detection signal is based on the first amplitude I of the amplitude of the first rotor reference frame current. d_error and the second amplitude I of the amplitude of the second rotor reference frame current q_error To identify a single amplitude magnitude value, wherein the fault detection circuit is configured to generate the detection signal using the following formula: I d_error x / (I d_error x +I q_error x ), where x is an integer greater than 1; as well as A comparator is coupled to the detection signal generating unit and is configured to compare the single amplitude magnitude value with an amplitude threshold to identify the presence of a permanent magnet motor fault.

8. The fault detection circuit of claim 7, wherein the presence of the permanent magnet motor fault is identified if the single amplitude magnitude value is greater than the amplitude threshold.

9. The fault detection circuit of claim 8, further comprising a counter that verifies the presence of the permanent magnet motor fault by counting a predetermined number of subsequent single amplitude magnitude values ​​greater than the amplitude threshold.

10. The fault detection circuit of claim 7, wherein the permanent magnet motor fault is a stator winding fault.

11. The fault detection circuit of claim 7, wherein the fault detection circuit is configured to: derive a three-phase stator reference frame current from the first rotor reference frame current and the second rotor reference frame current after a certain number of instances in which the comparison indicates the presence of a permanent magnet motor fault, and determine a drive fault type based on the three-phase stator reference frame current.

12. The fault detection circuit of claim 11, wherein the drive fault type comprises at least one of a switch failure fault, a single leg failure, a multi-phase failure, a switch open fault, a switch short circuit to phase fault, or a switch short circuit to ground fault.

13. The fault detection circuit of claim 11, wherein the fault detection circuit is configured to identify a permanent magnet motor fault type based on the drive fault type, and the permanent magnet motor fault type includes at least one of a bearing failure, an intra-phase winding failure, an inter-phase winding failure, a magnet failure, or an open-phase fault.

14. A fault detection method, comprising: receiving at least a first rotor reference frame current characteristic of a first rotor reference frame current and a second rotor reference frame current characteristic of a second rotor reference frame current; Determine a first magnitude I of the amplitude of the first rotor reference frame current d_error and the second amplitude I of the amplitude of the second rotor reference frame current q_error ; Generate a detection signal, wherein the detection signal is based on the first amplitude I of the amplitude of the first rotor reference frame current d_error and the second amplitude I of the amplitude of the second rotor reference frame current q_error to identify a single amplitude value, wherein generating the detection signal comprises generating the detection signal using the following formula: I d_error x / (I d_error x +I q_error x ), where x is an integer greater than 1; as well as The presence of a permanent magnet motor fault is identified based on a comparison between the single amplitude magnitude value and an amplitude threshold. 15 . The fault detection method of claim 14 , wherein identifying the presence of the permanent magnet motor fault comprises determining whether the single amplitude magnitude value is greater than the amplitude threshold. 16 . The fault detection method of claim 14 , further comprising verifying the presence of the permanent magnet motor fault by comparing a predetermined number of subsequent single amplitude magnitude values ​​to the amplitude threshold.

17. The fault detection method according to claim 14 further includes deriving a three-phase stator reference frame current from at least the first rotor reference frame current and the second rotor reference frame current after identifying the presence of the permanent magnet motor fault, and identifying the drive fault type based on the three-phase stator reference frame current.

18. The fault detection method according to claim 17, wherein the drive fault type comprises at least one of the following items: a switch failure fault, a single leg failure, a multi-phase failure, a switch disconnection fault, a switch short circuit to a phase fault, and a switch short circuit to a ground fault.

19. The fault detection method according to claim 17 further comprises identifying a permanent magnet motor fault type based on the drive fault type, the permanent magnet motor fault type comprising at least one of a bearing failure, an intra-phase winding failure, an inter-phase winding failure, a magnet failure and an open-phase fault.

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