Switching fault tolerant control method for five-level power converter of switched reluctance motor

Abstract

The application provides a kind of switch reluctance motor five-level power converter switch tube fault tolerance control method, belong to switch reluctance motor control field.Utilize this fault tolerance control method, without additional switching device and measurement sensor device, only need to change the position of conducting switch tube, combine fault switch tube and motor rotor position, comprehensive judge the switch tube that needs to be turned on in fault tolerance control, stop using fault tube and turn on corresponding switch tube according to the judgment result, can make motor winding current flow quickly normal.This application fault tolerance control method algorithm is simple, small amount of calculation, fast response, can effectively reduce the current distortion after power converter open-circuit fault, realize better torque ripple control, so as to realize the smooth control of motor speed, improve the stability and reliability of electric drive system.

Description

Technical Field

[0001] This invention belongs to the field of switched reluctance motor control technology, specifically relating to a fault-tolerant control method for the switching transistor of a five-level power converter for a switched reluctance motor. Background Technology

[0002] Switched reluctance motors are motors designed based on the principle of minimum reluctance. Their doubly salient pole structure and rotor design without permanent magnets / windings give them significant advantages under extreme operating conditions. The concentrated winding of their stator windings not only reduces manufacturing complexity but also endows them with stable operation in harsh environments such as high temperatures and high vibrations. Therefore, they are widely used in aerospace propulsion systems and new energy vehicle drive systems.

[0003] As the core unit of energy conversion, the reliability of the power converter directly determines the overall performance of the motor system. Although various fault-tolerant strategies have been developed for traditional two-level / three-level topologies, with the evolution of multi-level technology, five-level power converters have shown breakthrough potential in improving system efficiency and extending device life due to their unique advantages such as voltage harmonic suppression capability and reduced voltage stress on power devices. However, the increase in the number of levels leads to an exponential increase in the number of switching transistors. Existing fault-tolerant control strategies cannot dynamically reconstruct the switching transistor conduction logic, resulting in insufficient current path reconstruction capability under fault conditions and difficulty in coping with the multimodal fault characteristics of the five-level structure. To address this, fault-tolerant control methods for five-level power converters have been developed. However, existing methods all require a large number of additional power devices and sensors, which not only significantly increases the system size and cost but also results in high algorithm complexity, slow response, and a long time lag between fault diagnosis and compensation control, potentially leading to secondary fault risks such as increased current distortion rate and aggravated torque ripple. Summary of the Invention

[0004] The purpose of this invention is to solve the aforementioned problems in the fault-tolerant control technology for switching transistors in five-level power converters of switched reluctance motors, and to provide a fault-tolerant control method that only changes the position of the switching transistor's on-signal. This method eliminates the need for additional switching devices and measuring sensors. By determining the location of the fault point in the faulty power converter, it can achieve fault tolerance for different switching transistor faults, stop the use of the faulty transistor, ensure the rapid and normal flow of motor winding current, reduce motor torque ripple, and improve the stability and reliability of the motor system.

[0005] To achieve the above objectives, the technical solution provided by this invention is:

[0006] A fault-tolerant control method for switching transistors in a five-level power converter for a switched reluctance motor is provided. The five-level power converter includes a three-phase power switching transistor group and common switching transistors for the phase windings. The three-phase power switching transistor group includes power switching transistors A1, A2, and A3 for phase A, B1, B2, and B3 for phase B, and C1, C2, and C3 for phase C. The common switching transistors for the phase windings are S1, S2, and S3. The method includes the following steps:

[0007] Step 1: Measure the current of each phase winding to determine if a fault has occurred. If a fault is determined to have occurred, proceed to Step 2; if no fault is determined to have occurred, proceed to Step 12.

[0008] Step 2: Determine whether the fault occurs in one of the switching transistors A1, B1, and C1. If yes, proceed to step 3; otherwise, proceed to step 5.

[0009] Step 3: Determine whether the rotor position is within the corresponding A, B, or C phase forward current turn-on range. If it is within the turn-on range, proceed to step 4; otherwise, proceed to step 12.

[0010] Step 4: Force A3, B3, C3 and S2 to connect the turn-on signals of A1, B1 and C1, and change the current originally flowing through A1, B1 and C1 to flow to A3, B3 and C3, and then go to step 13;

[0011] Step 5: Determine if the fault point occurs in one of A2, B2, or C2. If yes, proceed to step 6; otherwise, proceed to step 8.

[0012] Step 6: Determine whether the rotor position is within the corresponding A, B, C opposite current on-state interval. If it is within the on-state interval, proceed to step 7; otherwise, proceed to step 12.

[0013] Step 7: Force A3, B3, C3 and S1 to connect the turn-on signals of A2, B2 and C2, and change the current originally flowing through A2, B2 and C2 to flow to A3, B3 and C3, and then go to step 13;

[0014] Step 8: Determine if the fault occurs in S1. If yes, proceed to step 9; otherwise, proceed to step 10.

[0015] Step 9: Force S3 to connect to the turn-on signal of S1, converting the current originally flowing through S1 to flow to S3, and then proceed to step 13.

[0016] Step 10: Determine whether the fault point occurs at S2. If yes, proceed to step 11; otherwise, proceed to step 12.

[0017] Step 11: Force S3 to connect to the turn-on signal of S2, change the current originally flowing through S2 to flow to S3, and then proceed to step 13.

[0018] Step 12: Connect the turn-on signals of each switch normally without modification;

[0019] Step 13: End fault tolerance control.

[0020] Furthermore, the winding turn-on interval refers to the fixed turn-on angle and turn-off angle of each phase winding of a switched reluctance motor throughout the entire electrical angle cycle, and the interval between these two angles is the turn-on interval of a certain phase winding.

[0021] Furthermore, positive current refers to the current flowing from the power converter into the positive terminal of the winding and out from the negative terminal of the winding during the turn-on period.

[0022] Furthermore, reverse current refers to the current flowing from the power converter into the negative terminal of the winding and out from the positive terminal of the winding during the turn-on period.

[0023] The advantages of this invention are:

[0024] The fault-tolerant control method for a five-level power converter in a switched reluctance motor proposed in this invention requires no additional switching devices or measuring sensors. It only requires changing the position of the conducting switching transistor, combining the faulty switching transistor with the motor rotor position, and comprehensively determining the switching transistor that needs to be turned on for fault-tolerant control. By disabling the faulty transistor and turning on the corresponding switching transistor based on the determination result, the motor winding current can be quickly and normally circulated. Therefore, the fault-tolerant control method of this invention has a simple algorithm, low computational load, and fast response. It can effectively reduce current distortion after an open-circuit fault in the power converter, achieve better torque ripple control, and thus achieve smooth motor speed control, improving the stability and reliability of the electric drive system. Attached Figure Description

[0025] The above and / or other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, in which:

[0026] Figure 1 This is the circuit schematic of a five-level power converter for a switched reluctance motor.

[0027] Figure 2 This is a flowchart of the fault-tolerant control method of the present invention;

[0028] Figure 3 This refers to the motor's output torque under healthy conditions of the power converter;

[0029] Figure 4 The waveform of the motor speed under the healthy state of the power converter;

[0030] Figure 5 This refers to the motor's output torque under power converter failure conditions.

[0031] Figure 6 The waveform of the motor speed under power converter failure conditions;

[0032] Figure 7 This refers to the output torque of the motor under fault-tolerant control of the power converter.

[0033] Figure 8 This is the motor speed waveform under fault-tolerant control of the power converter. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments thereof. It should be noted that the following detailed description of the present invention is for illustrative purposes only and is not intended to limit the scope of the invention.

[0035] This invention addresses the shortcomings of existing five-level power converters, which require a large number of additional power devices and sensors for fault-tolerant control, leading to increased motor system size and cost, as well as exacerbated torque ripple. It proposes a fault-tolerant control method for the switching transistors of a five-level power converter for switched reluctance motors. Primarily applied to switched reluctance motor drive systems, this method eliminates the need for additional switching devices and measurement sensors, effectively reduces current distortion, and achieves better torque ripple control.

[0036] After the fault location of the power converter is determined, the faulty switch cannot be turned on or off normally, remaining in a high-resistance off state. To maintain the normal flow of winding current in the motor drive system, this invention proposes a fault-tolerant control method for switching the conduction loop, which achieves freewheeling of winding current by changing the position of the switched-on switch.

[0037] Reference Figure 1 The five-level power converter has a large number of switching transistors, including three-phase power switching transistor groups and phase winding common switching transistors. The three-phase power switching transistor groups include power switching transistors A1, A2, and A3 for phase A, power switching transistors B1, B2, and B3 for phase B, and power switching transistors C1, C2, and C3 for phase C. The phase winding common switching transistors include switching transistors S1, S2, and S3.

[0038] Reference Figure 2 The fault-tolerant control method for the switching transistor of a five-level power converter for a switched reluctance motor provided by the present invention includes the following steps:

[0039] Step S1: Measure the current of each phase winding to determine if a fault has occurred. If a fault is determined to have occurred, proceed to step S2. If no fault is determined to have occurred, proceed to step S12.

[0040] Step S2: Determine whether the fault point occurs in one of the switching transistors A1, B1, and C1. If yes, proceed to step S3; otherwise, proceed to step S5.

[0041] Step S3: Determine whether the rotor position is within the corresponding A, B, C phase forward current turn-on range. If it is within the turn-on range, proceed to step S4; otherwise, proceed to step S12.

[0042] Step S4: Force A3, B3, C3 and S2 to connect the turn-on signals of A1, B1 and C1, and change the current originally flowing through A1, B1 and C1 to flow to A3, B3 and C3, and then proceed to step S13.

[0043] Step S5: Determine whether the fault point occurs in one of A2, B2, or C2. If yes, proceed to step S6; otherwise, proceed to step S8.

[0044] Step S6: Determine whether the rotor position is within the corresponding A, B, C opposite current on-state interval. If it is within the on-state interval, proceed to step S7; otherwise, proceed to step S12.

[0045] Step S7: Force A3, B3, C3 and S1 to connect the turn-on signals of A2, B2 and C2, and change the current originally flowing through A2, B2 and C2 to flow to A3, B3 and C3, and then proceed to step S13;

[0046] Step S8: Determine whether the fault point occurs in S1. If yes, proceed to step S9; otherwise, proceed to step S10.

[0047] Step S9: Force S3 to connect the turn-on signal of S1, convert the current originally flowing through S1 to flow to S3, and then proceed to step S13.

[0048] Step S10: Determine whether the fault point occurs in S2. If yes, proceed to step S11; otherwise, proceed to step S12.

[0049] Step S11: Force S3 to connect the turn-on signal of S2, change the current originally flowing through S2 to flow to S3, and then proceed to step S13.

[0050] Step S12: The turn-on signals of each switch are connected normally without modification;

[0051] Step S13: End fault tolerance control.

[0052] It should be noted that the fault judgment method mentioned in the above control process can be implemented using known mature technologies; this article only describes the fault-tolerant control process.

[0053] In this invention, the winding open-circuit interval refers to the fixed on-angle and off-angle of each phase winding of the switched reluctance motor throughout the entire electrical angle cycle. The interval between these two angles constitutes the open-circuit interval of a certain phase winding. The open-circuit interval can be given by the control program, and the interval is determined by monitoring the position information fed back by the position sensor, thereby calculating whether the current position is within the open-circuit interval.

[0054] Furthermore, forward current refers to the current flowing from the positive terminal of the winding into the power converter and flowing out from the negative terminal within the open-circuit period. In summary, the forward current open-circuit period refers to the winding open-circuit period where current flows in from the positive terminal and out from the negative terminal. Reverse current refers to the current flowing from the negative terminal of the winding into the power converter and flowing out from the positive terminal within the open-circuit period.

[0055] As described above, the fault-tolerant control method of this invention combines the faulty switch and the motor rotor position to comprehensively determine the switch that needs to be turned on for fault-tolerant control. By deactivating the faulty switch and turning on the corresponding switch according to the determination result, the motor winding current can be quickly and normally circulated. Therefore, the fault-tolerant control method of this invention has a simple algorithm, low computational load, and fast response. It can effectively reduce current distortion after an open-circuit fault occurs in the power converter, achieve better torque ripple control, and thus achieve smooth control of motor speed, improving the stability and reliability of the electric drive system.

[0056] The following examples further illustrate the fault-tolerant control method for the switching transistor of the five-level power converter for the switched reluctance motor provided by this invention.

[0057] Figure 3 The waveform diagram shows the total electromagnetic torque output of the motor when the power converter is functioning correctly. It can be seen that the output torque is relatively stable. Figure 4 The actual speed of the motor is shown when the power converter is not malfunctioning, and it can be seen that it can be stabilized at 500 rpm. Figure 5 The total electromagnetic torque output by the motor after the power converter fails shows a large torque fluctuation. Figure 6 This is the actual motor speed after the power converter malfunctions; the speed fluctuates greatly and is very unstable. Figure 7 After incorporating the fault-tolerant control proposed in this invention, it can be seen that when the power converter fails, the output torque of the motor fluctuates significantly less compared to when no fault-tolerant control is added. Figure 8 After incorporating the fault-tolerant control proposed in this invention, the actual motor speed can be stabilized at 500 rpm when the power converter fails, significantly reducing speed fluctuations after the fault. Therefore, this example verifies the effectiveness of the proposed method, which can reduce torque ripple in the motor output after an open-circuit fault in the converter, achieving smooth motor speed control.

[0058] Finally, it should be noted that the features mentioned and / or shown in the above description of exemplary embodiments of the present invention can be combined in the same or similar manner with one or more other embodiments, combined with features in other embodiments, or substituted for corresponding features in other embodiments. These combined or substituted technical solutions should also be considered to be included within the scope of protection of the present invention.

Claims

1. A fault-tolerant control method for switching transistors in a five-level power converter for a switched reluctance motor, wherein the five-level power converter includes a three-phase power switching transistor group and common switching transistors for the phase windings, the three-phase power switching transistor group includes power switching transistors A1, A2, and A3 for phase A, power switching transistors B1, B2, and B3 for phase B, and power switching transistors C1, C2, and C3 for phase C, and the common switching transistors for the phase windings are S1, S2, and S3, characterized in that, The method includes the following steps: Step 1: Measure the current of each phase winding to determine if a fault has occurred. If a fault is determined to have occurred, proceed to Step 2; if no fault is determined to have occurred, proceed to Step 12. Step 2: Determine if the fault occurs in one of the switching transistors A1, B1, and C1. If yes, proceed to step 3; otherwise, proceed to step 5. Step 3: Determine whether the rotor position is within the corresponding A, B, or C phase forward current turn-on range. If it is within the turn-on range, proceed to step 4; otherwise, proceed to step 12. Step 4: Force A3, B3, C3 and S2 to connect the turn-on signals of A1, B1 and C1, and change the current originally flowing through A1, B1 and C1 to flow to A3, B3 and C3, and then go to step 13; Step 5: Determine if the fault point occurs in one of A2, B2, or C2. If yes, proceed to step 6; otherwise, proceed to step 8. Step 6: Determine whether the rotor position is within the corresponding A, B, C opposite current on-state interval. If it is within the on-state interval, proceed to step 7; otherwise, proceed to step 12. Step 7: Force A3, B3, C3 and S1 to connect the turn-on signals of A2, B2 and C2, and change the current originally flowing through A2, B2 and C2 to flow to A3, B3 and C3, and then go to step 13; Step 8: Determine if the fault occurs in S1. If yes, proceed to step 9; otherwise, proceed to step 10. Step 9: Force S3 to connect to the turn-on signal of S1, converting the current originally flowing through S1 to flow to S3, and then proceed to step 13. Step 10: Determine whether the fault point occurs at S2. If yes, proceed to step 11; otherwise, proceed to step 12. Step 11: Force S3 to connect to the turn-on signal of S2, change the current originally flowing through S2 to flow to S3, and then proceed to step 13. Step 12: Connect the turn-on signals of each switch normally without modification; Step 13: End fault tolerance control.

2. The fault-tolerant control method for the switching transistor of a five-level power converter for a switched reluctance motor according to claim 1, characterized in that, The winding turn-on interval refers to the fixed turn-on angle and turn-off angle of each phase winding of a switched reluctance motor throughout the entire electrical angle cycle. The interval between these two angles is the turn-on interval of a certain phase winding.

3. The fault-tolerant control method for the switching transistor of a five-level power converter for a switched reluctance motor according to claim 2, characterized in that, Forward current refers to the current flowing from the power converter into the positive terminal of the winding and out from the negative terminal of the winding during the open-circuit period.

4. The fault-tolerant control method for the switching transistor of a five-level power converter for a switched reluctance motor according to claim 2, characterized in that, Reverse current refers to the current flowing from the power converter into the negative terminal of the winding and out from the positive terminal of the winding during the turn-on period.

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