SRM switching tube short circuit fault dynamic diagnosis method using current slope monitoring
By monitoring the current slope and current value during the conduction and non-conduction intervals of a switched reluctance motor, and combining this with position signals, the problem of low accuracy and precision in traditional switching transistor short-circuit fault diagnosis is solved, achieving fast and accurate switching transistor short-circuit fault diagnosis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-01-09
- Publication Date
- 2026-04-07
AI Technical Summary
Traditional switching transistor short-circuit fault diagnosis techniques suffer from low precision and accuracy, especially in determining short-circuit faults in the conduction range, which can easily lead to motor damage.
By employing a current slope monitoring method, the slope of the current sensor's detected waveform and the current value are calculated in the conducting and non-conducting regions of the switched reluctance motor, respectively. Combined with the position signal, this enables rapid and accurate diagnosis of short-circuit faults in the switching transistor.
It enables rapid and accurate diagnosis of short-circuit faults in switching transistors without affecting current detection, improving diagnostic accuracy and response speed, and allowing for quick location of faulty switching transistors.
Smart Images
Figure CN115932651B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of switched reluctance motor control, and particularly relates to a SRM switch tube short circuit fault dynamic diagnosis method using current slope monitoring. BACKGROUND
[0002] Switched reluctance motor is widely used in daily life and industrial manufacturing field due to its simple structure, low cost, high reliability, good speed regulation and a series of advantages. In daily life, switched reluctance motor is used in food processors, blenders, vacuum cleaners and the like, and the switched reluctance motor is often used in our daily life. Therefore, more and more attention is paid to improving the reliability of switched reluctance motor.
[0003] The traditional switch tube short circuit fault diagnosis technology has the problems of low precision and low accuracy, especially in judging the switch tube short circuit fault in the conduction interval. The switch tube short circuit fault in the conduction interval is easy to cause the sudden increase of current, which is easy to damage the motor and related equipment, thereby causing huge economic loss. Therefore, it is extremely important to quickly and accurately diagnose the switch tube short circuit fault in this area. SUMMARY
[0004] The purpose of the application is to provide a method which is convenient, accurate and can quickly and accurately diagnose the switch tube short circuit fault. In view of the problems of low precision and low accuracy of the traditional switch tube short circuit fault diagnosis technology, especially the technical pain point of diagnosis lag in judging the switch tube short circuit fault in the conduction interval, the change of current slope in the test stage after the fault occurs in the conduction interval is used to quickly and accurately diagnose the short circuit fault.
[0005] Technical scheme: The application is a SRM switch tube short circuit fault dynamic diagnosis method using current slope monitoring. The asymmetric half-bridge power converter of the switched reluctance motor is used. In the conduction interval of each phase of the switched reluctance motor, the upper switch tube of each phase bridge arm corresponding to the power converter is used as a chopping tube, and the lower switch tube is used as a conduction tube. In combination with the chopping control signal and the current measurement waveform of each phase, each phase is taken as a target phase, and the following steps are executed to quickly diagnose the switch tube short circuit fault of the target phase.
[0006] Step A: The target phase is detected by a current sensor to obtain a detection current value i csa and a detection waveform slope di csa / dt;
[0007] Step B: The position signal of the target phase is obtained according to the position sensor, and the position region of the target phase is judged to be in the conduction region or the non-conduction region through the position signal.
[0008] Step C: When the target phase is in the conduction region, the detection current value i csa The absolute value is used to obtain the winding current value. If the winding current value exceeds the preset chopper limit, a short-circuit fault test is triggered. In the short-circuit fault test, the slope di of the detected waveform is used as the reference. csa / dt diagnoses short-circuit faults in the switching transistors of the target phase;
[0009] Step D: When the target phase is in the non-conducting region, based on the detected waveform slope di csa / dt and combined with the electrical detection current value i csa The symbols are used together to diagnose short-circuit faults in the target phase switching transistors.
[0010] Furthermore, in step A, the current sensor is connected to the target phase in the following way: the current sensor passes through one end of the chopper tube in the target phase in the forward direction and connects it to one end of the winding of the target phase, and then passes through the current sensor in the forward direction to connect to the cathode of the lower diode in the target phase.
[0011] Furthermore, step A specifically includes:
[0012] Step A-1: Detect the current signal on the target phase winding of the switched reluctance motor using a current sensor, and acquire the detected current value i. csa And by detecting the current value i csa Calculate the slope di of the detected waveform csa / dt;
[0013] Step A-2: Based on the target phase detection current value i csa The current is collected and combined with the preset upper and lower chopping thresholds of the current in the target phase conduction area to achieve current chopping control of the target phase; the lower switch of the target phase conduction area is kept on, and when the target phase current value rises to the upper chopping threshold, the upper switch of the target phase is turned off to reduce the target phase current value; when the target phase current value drops to the lower chopping threshold, the upper switch of the target phase is turned on to increase the target phase current value.
[0014] Furthermore, step C specifically includes:
[0015] Step C-1: When the target phase is in the conduction region, the detection current value i csa The absolute value is taken to obtain the winding current value. If the winding current value exceeds 20% of the preset chopping limit, the test stage is entered and the process jumps to step C-2. If the abnormality is not detected, the upper and lower switching transistors of the phase are diagnosed as operating normally and the process jumps to step C-3.
[0016] Step C-2: After entering the testing phase, forcibly turn off the upper and lower switches S1 and S2 of the target phase and begin calculating the slope di of the sensor-detected waveform during the testing process. csa / dt, if the slope di of the waveform detected by the current sensor csa If / dt is negative, it indicates that the lower switch S2 is not short-circuited, the current decreases, and the diagnosis is a short-circuit fault in the upper switch S1. The test ends and jumps to step C-3; if the slope di of the waveform detected by the current sensor is... csa If / dt is positive, it indicates that the current still rises after turning off the upper switch S1 and the lower switch S2, which is diagnosed as a dual-transistor short circuit fault. The test ends and jumps to step C-3; if the slope di of the waveform detected by the current sensor is positive... csa If / dt equals 0, the diagnostic process remains in step C-2 and continues to calculate the slope di of the current sensor detection waveform at the next moment. csa / dt until the slope di of the waveform detected by the current sensor csa If / dt is positive or negative, check again whether it meets the judgment condition in step C-2;
[0017] Step C-3: This diagnosis ends. If the target phase is still in the conduction area, proceed to the next diagnosis; if the target phase enters the non-conducting area, jump to the non-conducting area diagnosis step D.
[0018] Furthermore, step D specifically includes:
[0019] Step D-1: When the current sensor detects the current value i csa The slope di of the detected waveform is less than 0. csa When / dt is less than 0, it is determined that the lower switch S2 is short-circuited, and the process jumps to step D-2; when the current sensor detects the current value i csa The slope di of the detected waveform is less than 0. csa / dt is greater than 0 or a current sensor detects the current value i csa The slope di of the detected waveform is equal to 0. csa When / dt equals 0, it is determined that the upper switch S1 and the lower switch S2 are working normally, and the process jumps to step D-2; when the current sensor detects the current value i csa The slope di of the detected waveform is greater than 0. csa When / dt is less than 0, it is determined that the upper switch S1 is short-circuited, and the process jumps to step D-2; if the current sensor detects the current value i, it indicates that the current is short-circuited. csa The slope di of the detected waveform is less than 0. csa / dt equals 0 or a current sensor detects the current value i csa The slope di of the detected waveform is greater than 0. csa / dt equals 0 or a current sensor detects the current value i csa The slope di of the detected waveform is equal to 0. csaIf / dt is not equal to 0, the diagnostic process remains at step D-1 and continues to detect the current value i detected by the current sensor at the next moment. csa And calculate the slope di of the current sensor detection waveform at the next moment. csa / dt, and once again determine whether the judgment condition in step D-1 is met;
[0020] Step D-2: This diagnosis ends. If the target phase is still in the non-conductive region, proceed to the next diagnosis. If the target phase enters the conductive region, proceed to the conductive region diagnosis step C.
[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:
[0022] (1) This invention enables rapid diagnosis of short-circuit faults in switching transistors without affecting current detection. The controller can still obtain the actual phase current value through the current sensor.
[0023] (2) To address the issues of low precision and accuracy in traditional switching transistor short-circuit fault diagnosis techniques, particularly the diagnostic lag in determining short-circuit faults in the conduction interval, this paper proposes a method to rapidly and accurately diagnose short-circuit faults by utilizing the change in current slope during the testing phase after a fault occurs in the conduction interval. This scheme offers advantages such as high accuracy, fast response speed, and ease of implementation.
[0024] (3) For short-circuit faults of switching transistors in non-conducting regions, the faulty switching transistor can be quickly located by calculating the slope of the waveform detected by the sensor and combining the positive and negative values of the measured values. Attached Figure Description
[0025] Figure 1 This is the topology of an asymmetric half-bridge power converter and the wiring diagram of the current sensor.
[0026] Figure 2 This is the overall logic flowchart for short-circuit fault diagnosis;
[0027] Figure 3 This is a flowchart of the logic for diagnosing short-circuit faults in the conduction zone;
[0028] Figure 4 This is a flowchart of the logic for diagnosing short-circuit faults in the non-conductive zone. Detailed Implementation
[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings.
[0030] This invention presents a dynamic diagnostic method for short-circuit faults of SRM switching transistors using current slope monitoring. Based on the fault characteristics corresponding to the phase current waveforms of the switched reluctance motor in each short-circuit fault of the switching transistor, it achieves real-time and rapid diagnosis of short-circuit faults in each phase of the switching transistor. The motor adopts single-transistor current chopper control. In phase A, the upper switching transistor S1 is set as the chopper transistor and the lower switching transistor S2 as the conducting transistor; in phase B, the upper switching transistor S3 is set as the chopper transistor and the lower switching transistor S4 as the conducting transistor; and in phase C, the upper switching transistor S5 is set as the chopper transistor and the lower switching transistor S6 as the conducting transistor.
[0031] like Figure 1 As shown, this figure illustrates the topology of an asymmetric half-bridge power converter and the wiring diagram of the current sensor. The current sensor used in this design is constructed by passing one end of a chopper tube's wire forward through the sensor and connecting it to one end of the winding, then passing it forward through the sensor again and connecting it to the cathode of the lower diode. Based on this current sensor connection, different current loops can be distinguished by the sign of the sensor's current measurement. Under normal operating conditions of the switching transistors, taking phase A as an example, when this phase is in the conduction region, if the chopper S1 drive signal P... s1 =1 and the drive signal P of the conducting transistor S2 is 1. s2 When P = 1, the current rises rapidly. Since the current flows through the current sensor in the positive direction, the measured value is positive. s1 =0 and P s2 When P = 1, the phase current decreases. Since the current flows through the current sensor in the negative direction, its measured value is negative. When this phase is disconnected, P... S1 P S2 Always set to 0, S1 and S2 are off. The current drops rapidly through the freewheeling diodes D2 and D1, causing rapid demagnetization of this phase. Since the current flows through the current sensor in the negative direction, its measured value is negative. Furthermore, because this current sensor connection only affects the sign of the current without changing its amplitude, the actual winding current value can be obtained by taking the absolute value of the current sensor's measurement.
[0032] The short-circuit fault identification scheme and specific diagnostic scheme are as follows:
[0033] Based on the classification and simplification of the short-circuit fault location and the fault type of the switching transistor, it can be seen that there are 15 types of short-circuit faults in the power switching transistors of the switched reluctance motor, namely: short circuit of A-phase chopper S1 in the conducting area, short circuit of A-phase chopper S1 in the non-conducting area, short circuit of A-phase conducting transistor S2, short circuit of both A-phase transistors in the conducting area, short circuit of both A-phase transistors in the non-conducting area, short circuit of B-phase chopper S3 in the conducting area, short circuit of B-phase chopper S3 in the non-conducting area, short circuit of B-phase conducting transistor S4, short circuit of B-phase dual transistors in the conducting area, short circuit of B-phase dual transistors in the non-conducting area, short circuit of C-phase chopper S5 in the conducting area, short circuit of C-phase chopper S5 in the non-conducting area, short circuit of C-phase conducting transistor S6, short circuit of C-phase dual transistors in the conducting area, and short circuit of C-phase dual transistors in the non-conducting area. Because each phase of the asymmetrical half-bridge operates independently, there are a total of five types of short-circuit faults in phase A. The following section will use phase A as an example to develop corresponding diagnostic solutions for these five different short-circuit faults.
[0034] Under single-tube current chopper control, when a short-circuit fault occurs in the conduction region, there are two types of short-circuit faults: short circuit in chopper tube S1 and short circuit in both tubes. Since a short circuit in conductor tube S2 does not affect the current in the conduction region, it is not considered.
[0035] If chopper S1 is short-circuited, and the current in that phase exceeds the chopper upper limit while it is in the conduction region, then P s1 Set to 0, P s2 With the setting to 1, because chopper S1 is short-circuited, S1 remains in the on state, and the current continues to rise in the conduction region. If both tubes are short-circuited, when the current in the conduction region exceeds the chopper's upper limit, P... s1 Set to 0, P s2 Set to 1. Since both upper and lower switching transistors S1 and S2 are short-circuited, S1 and S2 remain in the on state. In this state, the current also rises rapidly. However, this short-circuit fault has a more severe impact on the motor than the short-circuit fault of chopper transistor S1. The sudden increase in current caused by the double short circuit may damage the motor and related equipment. Because both types of switching transistor short-circuit faults cause the phase current to continuously increase in the conduction region, a short-circuit fault test is performed when the short-circuit current exceeds the chopper limit by 20% to distinguish between the two types of short-circuit faults.
[0036] During the testing phase, the gate signals of both upper and lower switching transistors S1 and S2 are set to 0, i.e., S1 = S2 = 0. If the short-circuit fault in the switching transistors is a short-circuit fault of chopper S1, then because the gate signal of conducting transistor S2 is set to 0, it is disconnected. This phase experiences zero-voltage freewheeling through the chopper S1 and diode D1 circuit, resulting in a decrease in the current detection value and a negative slope of the detected waveform. If the short-circuit fault in the switching transistors is a double-transistor short-circuit fault, then because both chopper S1 and conducting transistor S2 are short-circuited, this phase is forced to remain in the positive voltage excitation stage through the switching transistors S1 and S2 circuit in the conduction region, resulting in an increase in the current detection value and a positive slope of the detected waveform. Therefore, the sign of the slope during the test can be used to distinguish between chopper S1 short-circuit faults and double-transistor short-circuit faults occurring in the conduction region. The changes in current slope before and after the test are shown in Table 1, where di csa / dt refers to the rate of change of the current sensor measurement value with time t, where "+" represents a positive slope and "-" represents a negative slope.
[0037] Table 1 Changes in current slope before and after the test.
[0038]
[0039] When a short circuit fault occurs in the non-conducting region, there are three types of short circuit faults: chopper S1 short circuit, conducting S2 short circuit, and dual-tube short circuit.
[0040] In the non-conducting region, when the switching transistor is operating normally, the current measurement value gradually rises from near the negative chopper limit to 0, meaning that the phase undergoes negative voltage demagnetization through diodes D1 and D2. If chopper S1 is short-circuited, the phase continues to flow through the chopper S1 and diode D1 circuit due to the short circuit, and the current measurement value becomes positive at the instant the short circuit occurs, with the slope of the detected waveform being negative. If conductor S2 is short-circuited, the phase continues to flow through the conductor S2 and diode D2 circuit due to the short circuit, and the current measurement value does not change significantly before and after the short circuit occurs, but the slope of the final detected waveform is negative because of the short circuit of conductor S2. If both transistors are short-circuited, the phase undergoes positive voltage excitation through the switching transistor S1 and S2 circuit due to the short circuit of both upper and lower switching transistors S1 and S2, and the current measurement value becomes positive at the instant the short circuit occurs, with the slope of the detected waveform being positive. Therefore, based on the sign of the slope during the test, short circuits of chopper S1, conducting tube S2, and both tubes occurring in the non-conducting region can be distinguished. The changes in current slope and current value sign before and after the short circuit fault are shown in Table 2. Wherein, i a Indicates the winding current, i csa This indicates the measured value from the current sensor, and the drive signal P. s1 and P s2 These are the drive signals for the upper transistor S1 and the lower transistor S2, respectively.
[0041] Table 2 Changes in current slope and sign before and after short-circuit fault.
[0042]
[0043] like Figure 2 As shown, this diagram is the overall logic flowchart for short-circuit fault diagnosis. The determination of the conducting and non-conducting regions is based on the setting of the turn-on and turn-off angles. When the rotor position angle θ of the motor is within (θ... on ,θ off When the current slope is within the conducting range, the system determines it to be in the conducting range. Otherwise, it is in the non-conducting range. In the conducting range, the system diagnoses short-circuit faults of the switching transistor by calculating the rate of change of the measured value; in the non-conducting range, the system diagnoses short-circuit faults of the switching transistor by calculating the current slope in real time in the non-conducting region of the motor and combining it with the positive or negative value of the sensor measurement.
[0044] like Figure 3 As shown, this diagram is a flowchart of the short-circuit fault diagnosis logic in the conduction region. In the conduction region, short-circuit fault diagnosis of the switching transistor is performed by calculating the rate of change of measured values. Taking phase A as an example, the following steps are executed in real time:
[0045] Step A: Sample the current of phase A and perform current chopping control on the motor to keep the current constant in the conduction region.
[0046] Step A-1: Detect the current signal on the A-phase winding of the motor using a current sensor and collect the A-phase current value.
[0047] Step A-2: Phase A winding is conducting between 0-17°, and the controller performs single-tube current chopping control. The implementation is as follows: An upper chopping threshold is set for the current in the conduction range of this phase. When the current rises to the upper chopping threshold, chopper S1 for that phase is turned off to reduce the current. Simultaneously, a lower chopping threshold is set for the current in the same conduction range. When the current drops to the lower threshold, chopper S1 for that phase is turned on to increase the current. Meanwhile, during the switching process of chopper S1, conductor S2 remains conducting.
[0048] Step B: When the position signal detects that the phase is in the conduction range, proceed to step C.
[0049] Step C: Measure the phase current in real time during the conduction interval. If winding current is detected (the winding current can be measured by the current sensor value i),... csa If the absolute value obtained is greater than the chopper limit by more than 20%, then proceed to the testing phase and jump to step D; if no abnormality is detected, then the upper and lower switching transistors of that phase are diagnosed as operating normally and jump to step E.
[0050] Step D: After entering the testing phase, the upper and lower switches S1 and S2 of that phase are forcibly turned off, and the slope of the sensor-detected waveform during the test begins to be calculated. If the slope of the sensor-detected waveform is negative, it indicates that the conducting tube S2 has not experienced a short circuit fault, the current decreases, and the diagnosis is a short circuit fault in the chopper tube S1. The test ends and jumps to step E. If the slope of the sensor-detected waveform is positive, it indicates that the current still increases after turning off the upper and lower switches S1 and S2. The diagnosis is a double-tube short circuit fault, the test ends, and jumps to step E. If the slope of the sensor-detected waveform is equal to 0, the diagnostic process remains in step D and continues to calculate the slope of the sensor-detected waveform at the next moment until the slope of the sensor-detected waveform shows both positive and negative values. Then, it is determined again whether the judgment condition in step D is met.
[0051] Step E: This diagnosis ends. If the phase is still in the conducting region, proceed to the next diagnosis; if the phase enters the non-conducting region, jump to the non-conducting region diagnosis step.
[0052] like Figure 4 As shown, this diagram is a flowchart of the short-circuit fault diagnosis logic in the non-conducting region. By calculating the current slope in real time within the non-conducting region of the motor and combining this with the sign of the sensor measurements, short-circuit fault diagnosis is performed on the switching transistor. Taking phase A as an example, the following steps are executed in real time:
[0053] Step A: Sample the A-phase current and perform current chopping control on the motor.
[0054] Step A-1: Detect the current signal on the A-phase winding of the motor using a current sensor and collect the A-phase current value.
[0055] Step A-2: Phase A winding is conducting between 0-17°, and the controller performs single-tube current chopping control. The implementation is as follows: An upper chopping threshold is set for the current in the conduction range of this phase. When the current rises to the upper chopping threshold, chopper S1 for that phase is turned off to reduce the current. Simultaneously, a lower chopping threshold is set for the current in the same conduction range. When the current drops to the lower threshold, chopper S1 for that phase is turned on to increase the current. Meanwhile, during the switching process of chopper S1, conductor S2 remains conducting.
[0056] Step B: When the position signal detects that the phase is in the non-conducting range, proceed to step C.
[0057] Step C: Real-time detection of sensor values in the non-conductive region and calculation of the slope di of the sensor detection waveform. csa / dt. Real-time diagnosis of short-circuit faults in switching transistors. When the sensor detection value is less than 0 and the slope of the detection waveform is less than 0, it is determined that the conducting transistor S2 is short-circuited, and the process jumps to step D; when the sensor detection value is less than 0 and the slope of the detection waveform is greater than 0, or when the sensor detection value is equal to 0 and the slope of the detection waveform is equal to 0, it is determined that switching transistors S1 and S2 are working normally, and the process jumps to step D; when the sensor detection value is greater than 0 and the slope of the detection waveform is greater than 0, it is determined that switching transistors S1 and S2 are short-circuited, and the process jumps to step D; when the sensor detection value is greater than 0 and the slope of the detection waveform is less than 0, it is determined that the conducting transistor S1 is short-circuited, and the process jumps to step D. If the detected sensor value is less than 0 and the slope of the detected waveform is equal to 0, or the detected sensor value is greater than 0 and the slope of the detected waveform is equal to 0, or the detected sensor value is equal to 0 and the slope of the detected waveform is not equal to 0, the diagnostic process remains in step C, and the sensor value at the next moment is detected and the slope of the detected waveform at the next moment is calculated. Then, it is determined again whether the judgment condition in step C is met.
[0058] Step D: This diagnosis ends. If the phase is still in the non-conductive region, proceed to the next diagnosis; if the phase enters the conductive region, jump to the conductive region diagnosis step.
Claims
1. A dynamic diagnostic method for short-circuit faults in SRM switching transistors using current slope monitoring, characterized in that, Using an asymmetrical half-bridge power converter for a switched reluctance motor, when each phase of the switched reluctance motor is in the conduction range, the upper switch of each phase bridge arm of the power converter acts as a chopper and the lower switch acts as a conductor. Combining the chopper control signal and current measurement waveform measured for each phase, the following steps are performed with each phase as the target phase to achieve rapid diagnosis of short-circuit faults in the target phase switch. Step A: Detect the target phase using a current sensor to obtain the detected current value. i csa And detect the waveform slope d i csa / d t In step A, the current sensor is connected to the target phase in the following way: the current sensor passes through one end of the wire of the chopper tube in the target phase in the forward direction and is connected to one end of the winding of the target phase, and then passes through the current sensor in the forward direction and is connected to the cathode of the lower diode in the target phase. Step B: Obtain the position signal of the target phase from the position sensor, and determine whether the target phase is in a conductive or non-conductive region based on the position signal. If the target phase is in a conductive region, proceed to step C; if the target phase is in a non-conductive region, proceed to step D. Step C: Detect the current value i csa The absolute value is used to obtain the winding current value. If the winding current value exceeds the preset chopper limit, a short-circuit fault test is triggered. In the short-circuit fault test, the slope d of the detected waveform is used as the basis for the test. i csa / d t Diagnose short-circuit faults in the switching transistors of the target phase; Step D: Based on the detected waveform slope d i csa / d t Combined with electrical detection current value i csa The symbols are used together to diagnose short-circuit faults in the target phase switching transistors.
2. The dynamic diagnosis method for short-circuit faults of SRM switching transistors using current slope monitoring as described in claim 1, characterized in that, Step A specifically includes: Step A-1: Detect the current signal on the target phase winding of the switched reluctance motor using a current sensor and collect the detected current value. i csa And by detecting the current value i csa Calculate the slope d of the detected waveform i csa / d t ; Step A-2: Detect current value based on target phase i csa The current is collected and combined with the preset upper and lower chopping thresholds of the current in the target phase conduction area to achieve current chopping control of the target phase; the lower switch of the target phase conduction area is kept on, and when the target phase current value rises to the upper chopping threshold, the upper switch of the target phase is turned off to reduce the target phase current value; when the target phase current value drops to the lower chopping threshold, the upper switch of the target phase is turned on to increase the target phase current value.
3. The dynamic diagnosis method for short-circuit faults of SRM switching transistors using current slope monitoring as described in claim 1, characterized in that, Step C specifically includes: Step C-1: When the target phase is in the conduction region, the detection current value is... i csa The absolute value is taken to obtain the winding current value. If the winding current value exceeds 20% of the preset chopping limit, the test stage is entered and the process jumps to step C-2. If no abnormality is detected, the upper and lower switching transistors of the phase are diagnosed as operating normally and the process jumps to step C-3. Step C-2: After entering the testing phase, forcibly turn off the upper and lower switches S1 and S2 of the target phase and begin calculating the slope d of the sensor detection waveform during the testing process. i csa / d t If the slope d of the waveform detected by the current sensor i csa / d t If the value is negative, it indicates that there is no short circuit fault in the lower switch S2. The current decreases, and the diagnosis is a short circuit fault in the upper switch S1. The test ends and jumps to step C-3. If the slope d of the waveform detected by the current sensor is... i csa / d t If the value is positive, it indicates that the current continues to rise after turning off the upper switch S1 and the lower switch S2, which is diagnosed as a dual-transistor short circuit fault. The test ends and jumps to step C-3; if the slope d of the waveform detected by the current sensor is positive... i csa / d t If the value is 0, the diagnostic process remains at step C-2 and continues to calculate the slope d of the current sensor detection waveform at the next moment. i csa / d t Until the current sensor detects the slope d of the waveform i csa / d t If a positive or negative result is obtained, determine again whether the judgment condition in step C-2 is met; Step C-3: This diagnosis ends. If the target phase is still in the conduction area, proceed to the next diagnosis; if the target phase enters the non-conducting area, jump to the non-conducting area diagnosis step D.
4. The dynamic diagnosis method for short-circuit faults of SRM switching transistors using current slope monitoring according to claim 1, characterized in that, Step D specifically includes: Step D-1: When the current sensor detects the current value i csa The slope d of the detected waveform is less than 0. i csa / d t When the value is less than 0, it is determined that the lower switch S2 is short-circuited, and the process jumps to step D-2; when the current value detected by the current sensor is detected... i csa The slope d of the detected waveform is less than 0. i csa / d t Greater than 0 or detected current value by current sensor i csa The slope d of the detected waveform is equal to 0. i csa / d t When the value equals 0, it is determined that the upper switch S1 and the lower switch S2 are working normally, and the process jumps to step D-2; when the current value detected by the current sensor is detected... i csa The slope d of the detected waveform is greater than 0. i csa / d t If the value is less than 0, it is determined that the upper switch S1 is short-circuited, and the process jumps to step D-2; if the current value detected by the current sensor is detected, the process jumps to step D-2. i csa The slope d of the detected waveform is less than 0. i csa / d t The current value detected by the current sensor is equal to 0 or is detected. i csa The slope d of the detected waveform is greater than 0. i csa / d t The current value detected by the current sensor is equal to 0 or is detected. i csa The slope d of the detected waveform is equal to 0. i csa / d t If the current value is not equal to 0, the diagnostic process remains at step D-1 and continues to detect the current value detected by the current sensor at the next moment. i csa And calculate the slope d of the current sensor detection waveform at the next moment. i csa / d t Then, determine again whether the judgment conditions in step D-1 are met; Step D-2: This diagnosis ends. If the target phase is still in the non-conductive region, proceed to the next diagnosis. If the target phase enters the conductive region, proceed to the conductive region diagnosis step C.