Novel fault-tolerant power converter for double-stator switched reluctance motor and fault diagnosis method

Abstract

The invention discloses a novel fault-tolerant power converter for a double-stator switched reluctance motor and a fault diagnosis method, and the power converter can realize three operation modes: single-winding operation, winding series operation and winding parallel operation. A novel fault diagnosis method is provided by combining the characteristics of the operation mode of the novel fault-tolerant power converter. According to the method, fault diagnosis after an open-circuit fault of a switch tube in each state is realized through reconstruction design of a part of branches of the power converter and additional arrangement of a current sensor for fault diagnosis, the position of the fault switch tube is accurately positioned, and meanwhile, the running state can be quickly switched to ensure continuous and normal running of the motor. And the fault-tolerant capability of the driving system is obviously enhanced.

Description

Technical Field

[0001] The present invention relates to a novel fault-tolerant power converter for a dual-stator switched reluctance motor, and in particular to a power converter structure and a fault diagnosis fault-tolerant operation method. Background Art

[0002] Switched reluctance motors (SRMs) offer advantages such as high reliability, low cost, simple structure, high starting torque, and a wide speed regulation range, making them promising applications in a variety of fields, including aerospace, electric vehicles, and textile engineering. However, traditional SRMs suffer from low power density and high torque ripple. To address these shortcomings, a dual-stator SRM has been proposed. This novel SRM effectively reduces torque ripple and increases power density. Because traditional asymmetric half-bridge power converters struggle to meet the driving requirements of dual-stator SRMs, further improvements in power converter topology are urgently needed. Summary of the Invention

[0003] To address the above technical issues, the present invention provides a novel fault-tolerant power converter for a dual-stator switched reluctance motor and proposes a novel fault diagnosis method. This method, through the reconfiguration of some branches of the power converter and the addition of a fault diagnosis current sensor, enables fault diagnosis after an open-circuit fault in a switching tube under various conditions. While accurately locating the faulty switching tube, it also enables fault-tolerant operation by dynamically switching operating modes, significantly enhancing the drive system's fault tolerance while ensuring torque output continuity.

[0004] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention discloses a new fault-tolerant power converter for a dual-stator switched reluctance motor, which is suitable for dual-stator switched reluctance motors. The motor can be roughly divided into three categories: radial dual-stator, axial dual-stator, and axial-radial dual-stator. Since each phase of the motor has two windings, the operating modes of the fault-tolerant power converter can be divided into: winding series operation mode, single winding operation mode, and winding parallel operation mode. Among them, the winding series operation mode can be divided into A1-A2 winding series operation mode and A2-A1 winding series operation mode according to the current flow path and the power switching device used. The single winding operation mode can also be divided into A1 winding single operation mode and A2 winding single operation mode.

[0006] The present invention is that the disclosed novel fault-tolerant power converter includes a DC power supply module U s , a boost capacitor, 9 diodes and 15 switches. Since phases A, B and C are connected in parallel and have the same structure, phase A is taken as an example: Among them, the DC power supply U sIn parallel with the boost capacitor, phases A, B, and C are all connected in parallel across the capacitor. Compared to the traditional asymmetric half-bridge power converter, the proposed new fault-tolerant power converter adds two power switching devices (S3, S4) with anti-parallel diodes, a power switching device (S5) without an anti-parallel diode, and a freewheeling diode (D3) in each phase. The power switching device can be a power device such as an IGBT or MOSFET, and the diode can be a fast recovery type or a Schottky type. The new power converter disclosed in the present invention uses an IGBT power switching device and a fast recovery diode. The connection relationship is as follows: the collector of S3 is connected to the positive pole of the DC bus, and its emitter is respectively connected to the positive end of the winding coil A2 and the cathode of the freewheeling diode D3; the freewheeling diode D3 is located below S3 and is respectively connected to the negative end of the winding coil A1 and the collector of another power switch tube located below it, namely S4. The collector of S4 is connected to the negative terminal of winding A1, and its emitter is connected to the negative terminal of the DC bus. The collector of S5 is connected to the negative terminal of winding A2, the anode of freewheeling diode D1 located above it, and the collector of S2. Its emitter is connected to the positive terminal of winding A1 and the cathode of freewheeling diode D2 located below it. The collector of S1 is connected to the positive terminal of the DC bus, the cathode of freewheeling diode D1, and the collector of S3. The emitter of S1 is connected to the positive terminal of winding A1. The collector of S2 is connected to the negative terminal of winding A2, and the emitter of S2 is connected to the negative terminal of the DC bus. If a power switching device MOSFET is used instead, its drain corresponds to the collector of the IGBT, and its source corresponds to the emitter of the IGBT. The other connection relationships remain unchanged. Since the present invention is mainly applicable to the winding series operation mode and the single winding operation mode, the winding parallel operation mode will not be discussed further.

[0007] The present invention is that when a fault-tolerant power converter operates in winding series operation mode, the power switching devices used are S1, S2, S3, S4, and S5, and the freewheeling diodes used are D1, D2, and D3. Depending on the power switching devices used and the order in which current flows, the winding series operation mode is divided into: A1-A2 winding series operation and A2-A1 winding series operation. When the fault-tolerant power converter is in the A1-A2 winding series operation mode, the power switching devices S1 and S2 are turned on, and the current first flows through the A1 winding and then through the A2 winding, forming a closed loop. When the fault-tolerant power converter is in the A2-A1 winding series operation mode, the power switching devices S3, S4, and S5 are turned on, and the current first flows through the A2 winding and then through the A1 winding, forming a closed loop.

[0008] The present invention is that when the fault-tolerant power converter operates in a single-winding operation mode, the power switching devices used are S1, S2, S3, and S4, and the freewheeling diodes used are D1, D2, and D3. The single-winding operation mode is divided into an A1 winding single operation mode and an A2 winding single operation mode.

[0009] In a second aspect, the present invention discloses a fault analysis method for a fault-tolerant power converter for a dual-stator switched reluctance motor based on the aforementioned method. If the switch tube is in the on state in a certain normal operating mode, then an open-circuit fault in that operating mode will affect the current operating mode, with the excitation state changing to the freewheeling state, and the freewheeling state changing to the demagnetization state. If the switch tube is in the off state in a certain normal operating mode, then an open-circuit fault in that operating mode will not affect the current operating mode, that is, open-circuit faults of the demagnetized switch tube are not considered. Taking phase A as an example, the possible fault conditions and fault tolerance conditions of the fault-tolerant power converter under various operating modes are analyzed.

[0010] The present invention is characterized in that when the fault-tolerant power converter operates in a dual-winding series operation mode, when operating in the A1-A2 winding series operation mode, the conducting switches include S1 and S2. In the excitation state, if switch S1 experiences an open-circuit fault, only switch S2 is conducting, and windings A1 and A2 form a closed loop through D3, S2, and D2, i.e., the excitation state changes to the S2 freewheeling state. When switch S2 experiences an open-circuit fault, only switch S1 is conducting, and windings A1 and A2 form a closed loop through D3, D1, and S1, i.e., the excitation state changes to the S1 freewheeling state. In the S1 freewheeling state, the only switching tube that is turned on is S1. When an open-circuit fault occurs in S1, all switching tubes are in the off state, and windings A1 and A2 can only perform demagnetization work, that is, the S1 freewheeling state changes to the demagnetization state; when in the S2 freewheeling state, the only switching tube that is turned on is S2. When an open-circuit fault occurs in S2, all switching tubes are in the off state, and windings A1 and A2 can only perform demagnetization work, that is, the S2 freewheeling state changes to the demagnetization state.

[0011] The present invention is characterized in that when the fault-tolerant power converter operates in the A2-A1 winding series operation mode, the conductive switches include S3, S4, and S5. At this time, the newly added IGBT without anti-parallel diode is turned on to provide excitation and freewheeling channels, playing an important role. In the excitation state, if switch S5 has an open circuit fault, when switches S3 and S4 are turned on, winding A2 forms a closed loop through S3 and D1, and winding A1 forms a closed loop through S4 and D2, that is, the state changes from the excitation state to the S3 and S4 freewheeling state. When switch S3 has an open circuit fault, when switches S4 and S5 are turned on, S4 is turned off, and windings A1 and A2 form a closed loop through D3 and S5, that is, the state changes from the excitation state to the S5 freewheeling state. When switch S4 has an open circuit fault, when switches S3 and S5 are turned on, S3 is turned off, and the state change is consistent with the open circuit fault of S3. When the fault-tolerant power converter operates in the S5 freewheeling state, the only switch tube that is turned on is S5. When an open-circuit fault occurs in the switch tube S5, all switch tubes are in the off state, and windings A1 and A2 can only perform demagnetization work; when in the S3 and S4 freewheeling states, the only switch tubes that are turned on are S3 and S4. When an open-circuit fault occurs in the switch tube S3 or S4, all switch tubes are in the off state, and windings A1 and A2 operate in the demagnetization state.

[0012] The present invention is characterized in that when the fault-tolerant power converter operates in the A1 single-winding operation mode, the conductive switches include S1 and S4. If switch S1 experiences an open-circuit fault, winding A1 forms a closed loop through S4 and D2, switching from an excitation state to an S4 freewheeling state. If switch S4 experiences an open-circuit fault, winding A1 forms a closed loop through S1, D3, and S3's anti-parallel diode, switching from an excitation state to an S1 freewheeling state.

[0013] The present invention is characterized in that when the fault-tolerant power converter operates in the A2 single-winding operation mode, the conductive switches include S2 and S3. If switch S2 experiences an open-circuit fault, winding A2 forms a closed loop through S3 and D1, switching from an excitation state to an S3 freewheeling state. If switch S3 experiences an open-circuit fault, winding A2 forms a closed loop through the anti-parallel diodes S2 and S4 and D3, switching from an excitation state to an S2 freewheeling state.

[0014] In a third aspect, the present invention discloses a fault diagnosis method and fault-tolerant operation mechanism for a novel fault-tolerant power converter for a dual-stator switched reluctance motor based on the aforementioned method. The fault diagnosis and fault-tolerant operation process of the novel power converter are as follows: First, the system's current operating mode is detected and determined in real time. When an open-circuit fault signal is given, the system performs a comprehensive judgment based on the fault diagnosis process and generates a corresponding fault diagnosis flag. To ensure system stability, this diagnostic flag is delayed for one sampling cycle and then outputs a mode switching control signal to enable rapid switching to another operating mode. For example, if a fault occurs in the dual-winding series operation mode (A1-A2 winding series operation), the fault-tolerant power converter will rapidly and fault-tolerantly switch to the A2-A1 winding series operation mode. In the single-winding operation mode, if a fault occurs in the A1 winding single-operation power switch, the fault-tolerant power converter will rapidly and fault-tolerantly switch to the A2 winding single-operation mode or the winding series operation mode. If a fault occurs in the A2 winding single-operation power switch, the fault-tolerant power converter will rapidly and fault-tolerantly switch to the A1 winding single-operation mode or the winding series operation mode.

[0015] The present invention is that the fault diagnosis method is implemented by analyzing the three-phase phase current and the current changes of some branches before and after the open circuit fault of the switch tube through four current sensors. Taking phase A as an example, the A-phase current can be obtained by winding a current sensor around any winding branch of phase A. The configuration of the current sensor of phases B and C is consistent with that of phase A to obtain the three-phase phase current. On the basis of obtaining the three-phase phase current, another current sensor is added to realize the diagnosis of the open circuit fault of the switch tube under various operating modes. For the current sensor for fault diagnosis, the branch current measured by it includes the branch currents of the three phases A, B and C. If you want to perform fault diagnosis on the open circuit fault of the switch tube of a certain phase separately, you need to obtain the separate branch current of the corresponding phase. After comprehensive analysis, the separate branch current i before and after the phase A switch tube fault can be obtained. gA As shown in Table 2.

[0016] The present invention is that in any state of the four modes of winding series operation and single operation, i gA Under the same operating state, the results of normal state and open circuit fault are different, and the measurement results under different switch tube faults are also different. gA By comparing with the reference current value under the fault state, the open circuit fault of the switch tube can be detected, and the position of the faulty switch tube can be accurately located.

[0017] The present invention is that after generating a fault diagnosis flag, after a sampling period of delay processing, the fault-tolerant power converter outputs a mode switching control signal to achieve rapid switching to another operating mode, thereby achieving fault-tolerant operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a topological diagram of a novel fault-tolerant power converter for a dual-stator switched reluctance motor according to the present invention.

[0019] Figure 2 These are four working state diagrams of the novel fault-tolerant power converter A1-A2 winding series operation mode for the dual-stator switched reluctance motor of the present invention.

[0020] Figure 3 These are four working state diagrams of the A2-A1 winding series operation mode of the novel fault-tolerant power converter for the dual-stator switched reluctance motor of the present invention.

[0021] Figure 4 These are four working state diagrams of the A1 winding single operation mode of the new fault-tolerant power converter for the dual-stator switched reluctance motor of the present invention.

[0022] Figure 5 These are four working state diagrams of the A2 winding single operation mode of the new fault-tolerant power converter for the dual-stator switched reluctance motor of the present invention.

[0023] Figure 6 This is a topology diagram of a novel fault-tolerant power converter for a dual-stator switched reluctance motor reconstructed based on the fault diagnosis method of the present invention.

[0024] Figure 7 This is a waveform diagram of the fault diagnosis and fault-tolerant operation experiment of the new fault-tolerant power converter for the dual-stator switched reluctance motor of the present invention in the excitation state of the winding series operation mode.

[0025] Figure 8 This is a waveform diagram of the fault diagnosis and fault-tolerant operation experiment of the new fault-tolerant power converter for the dual-stator switched reluctance motor of the present invention under the excitation state of the single winding operation mode. DETAILED DESCRIPTION

[0026] The present invention will be described in further detail below with reference to the accompanying drawings.

[0027] The object of study in this example is a new fault-tolerant power converter for a dual-stator switched reluctance motor. Figure 1 As shown, the disclosed novel fault-tolerant power converter includes a DC power supply module U s , a boost capacitor, 9 diodes and 15 switches. Since phases A, B and C are in parallel and have the same structure, phase A is taken as an example: Among them, the DC power supply U sIn parallel with the boost capacitor, phase A, phase B, and phase C are all connected in parallel at both ends of the capacitor. Compared with the traditional asymmetric half-bridge power converter, two power switching devices with anti-parallel diodes (S3, S4), a power switching device without anti-parallel diodes (S5) and a freewheeling diode (D3) are added in each phase. The power switching device can be a power device such as IGBT, MOSFET, etc., and the diode can be a fast recovery type or Schottky type. The new power converter disclosed in the present invention uses IGBT type power switching devices and fast recovery diodes. Its connection relationship is: DC power supply U s In parallel with the boost capacitor, phases A, B, and C are all connected in parallel across the capacitor. S3's collector is connected to the DC bus's positive terminal, and its emitter is connected to the positive terminal of winding A2 and the cathode of freewheeling diode D3. Freewheeling diode D3 is located below S3, with one end connected to the negative terminal of winding A1 and the other end connected to the collector of power switch S4. S4's collector is connected to the negative terminal of winding A1, and its emitter is connected to the negative terminal of the DC bus. S5's collector is connected to the negative terminal of winding A2, the anode of freewheeling diode D1, and the collector of S2, while its emitter is connected to the positive terminal of winding A1 and the cathode of freewheeling diode D2. S1's collector is connected to the DC bus's positive terminal, the cathode of freewheeling diode D1, and the collector of S3, while its emitter is connected to the positive terminal of winding A1. S2's collector is connected to the negative terminal of winding A2, and its emitter is connected to the negative terminal of the DC bus. If a MOSFET is used instead, its drain corresponds to the collector of the IGBT, and its source corresponds to the emitter of the IGBT, with all other connections remaining unchanged. The operating states of the new fault-tolerant power converter are shown in Table 1.

[0028] The proposed new fault-tolerant power converter can realize the dual-winding series operation mode, which is divided into two types: A1-A2 winding series operation and A2-A1 winding series operation. The difference between these two series operation modes is that the power switching tubes used are different and the current flow order is different. Figure 2(a) shows a schematic diagram of the excitation and freewheeling circuits for the motor operating in the A1-A2 series winding operation mode. In the excitation state, power switches S1 and S2 are turned on, and windings A1 and A2 are connected via diode D3, forming a complete series excitation circuit with the upper and lower switches S1 and S2. Switches S3, S4, and S5 are always off. The gate drive signals for power switches S1 and S2 are set by the driver circuit, while the gate signals for switches S3, S4, and S5 are always set to "0" by the driver circuit, keeping them off. This ensures that motor phase A operates in the A1-A2 series winding operation mode. Phases B and C follow the same drive control method as phase A. When S1 is in the freewheeling state, S2 is closed, and current flows through windings A1 and A2, freewheeling diodes D3 and D1, and power switch S1 to form a freewheeling circuit. When S2 is in the freewheeling state, S1 is closed, and the current flows through the winding coils A1 and A2, the freewheeling diodes D3 and D2, and the power switch device S2 to form a freewheeling loop. Figure 2 (b) shows the demagnetization state in the A1-A2 series operation mode, where all power switches are off and the two windings are demagnetized via freewheeling diodes D1, D2, and D3. All four states of the A1-A2 series operation mode utilize a traditional asymmetric half-bridge power converter's excitation and demagnetization circuits with the addition of an additional diode to implement excitation, freewheeling, and demagnetization.

[0029] Figure 3 (a) shows a schematic diagram of the excitation and freewheeling circuits for the motor operating in the A2-A1 series winding operation mode. As can be seen from the figure, the main difference between the excitation state in the A2-A1 series winding operation mode and the excitation state in the A1-A2 series winding operation mode is that the latter first excites through winding A1, then through a diode, and then through winding A2, while the former first excites through winding A2, then through an IGBT, and then through winding A1. The S5, S3, and S4 freewheeling states in the A2-A1 series winding operation mode are also quite unique, differing significantly from the freewheeling states of traditional asymmetric half-bridge converters. S5 freewheeling uses an additional diode and IGBT to achieve series freewheeling, while S3 and S4 freewheeling uses the upper and lower transistors of the two windings A1 and A2, respectively. The demagnetization state in the A2-A1 series winding operation mode is consistent with the demagnetization state in the A1-A2 series winding operation mode, both using an additional diode for series demagnetization.

[0030] Figure 4 A schematic diagram of the new fault-tolerant power converter operating in the A1 winding single operation state is given. Figure 4 (a) is the excitation state and freewheeling state of A1 winding in single operation mode. Figure 4(b) shows the demagnetization state of winding A1 in standalone operation mode. During excitation, power switches S1 and S4 conduct, exciting winding A1. When S1 is in freewheeling mode and S4 is off, winding A1 forms a loop with freewheeling diode D3, S3's antiparallel diode, and S1 to achieve freewheeling current. When S4 is in freewheeling mode and S1 is off, winding A1 forms a loop with freewheeling current D2 and S4 to achieve freewheeling current. During demagnetization, winding A1 is demagnetized through the loop of antiparallel diodes D2, D3, and S3.

[0031] Figure 5 A schematic diagram of the new fault-tolerant power converter operating in the A2 winding single operation state is given. Figure 5 (a) is the excitation state and freewheeling state of A2 winding in single operation mode. Figure 5 (b) is the demagnetization state of the A2 winding in the single operation mode. During excitation, the power switch devices S2 and S3 are turned on, and the A2 winding is excited. When S2 is in the freewheeling state, S3 is turned off. At this time, the A2 winding forms a loop through the freewheeling diode D3, the anti-parallel diode S4, and S2 to achieve freewheeling. When S3 is in the freewheeling state, S2 is turned off. At this time, the A2 winding forms a loop through D1 and S3 to achieve freewheeling. Figure 4 and 5 It can be seen that the excitation state and S4 freewheeling state of the single-winding A1 operating mode, as well as the excitation state and S3 freewheeling state of the single-winding A2 operating mode, are similar to the excitation and freewheeling states of a traditional asymmetric half-bridge converter, and all achieve turn-on and turn-off through two power switching devices. However, the freewheeling and demagnetization states of the single-winding A1 operating mode S1, and the freewheeling and demagnetization states of the single-winding A2 operating mode S2, in addition to the freewheeling and demagnetization of the traditional asymmetric half-bridge converter, also require the freewheeling and demagnetization of a power switching device through an anti-parallel diode.

[0032] The fault diagnosis method used in this example uses four current sensors to analyze the three-phase currents and the partial branch phase currents before and after the open circuit fault of each switch tube to achieve fault diagnosis. Figure 6As shown, fault diagnosis is achieved by reconstructing and designing some branches and winding three-phase current detection current sensors and fault diagnosis current sensors. Taking phase A as an example, the current of phase A can be obtained by winding a current sensor around any winding branch of phase A. The current sensors of phases B and C are configured in the same way as those of phase A to obtain the three-phase current. On the basis of obtaining the three-phase current, another current sensor is added to realize the diagnosis of the open circuit fault of the switch tube under various operating modes. This method explores and selects three branches of each phase in the fault-tolerant converter topology for fault diagnosis, and merges and simplifies the two branches of each phase, a total of six branches, into two branches, so that the original nine branches can be simplified into five branches. For the current sensor for fault diagnosis, the branch current measured includes the branch currents of phases A, B and C. If you want to realize the fault diagnosis of the open circuit fault of the switch tube of a certain phase separately, you need to parse the separate branch current of the corresponding phase. The separate branch current of phase A i gA Affected by the operating status of phases B and C, after analyzing the four operating modes, gA With the phase currents i of phases A, B and C A 、i B and i C The relationship between the switch tube open circuit fault and the gA with i A relationship.

[0033] It can be seen from Table 2 that in any state of series and single winding operation mode, i gA The results of normal and open circuit faults are different in the same state, and the measurement results under different switch tube faults are also different. gA By comparing with the reference current value under the fault state, the open circuit fault of the switching tube is detected, and the position of the faulty switching tube can be accurately located. The fault diagnosis method for phases B and C is consistent with that for phase A.

[0034] Furthermore, after comprehensive fault diagnosis, a corresponding fault diagnostic flag is generated. To ensure system stability, this diagnostic flag is delayed for one sampling period before outputting a mode switching control signal. This enables rapid switching to another mode, thus achieving fault-tolerant operation.

[0035] Specifically, the fault-tolerant operation process is:

[0036] In the A1-A2 series winding operation mode, when the power converter is operating in the excitation state, an open-circuit fault in one phase switch will cause the currents in the other two phases to increase and the motor torque to enter the zero torque region, i.e., phase loss operation. To avoid phase loss operation, simply detecting the fault quickly is not enough. Here, the operating mode is switched in the next sampling cycle after the open-circuit fault is detected, namely, from the A1-A2 series winding operation mode to the A2-A1 series winding operation mode. Therefore, if an S1 or S2 open-circuit fault occurs in the excitation state, the power converter will smoothly switch to the A2-A1 series winding operation mode in the next sampling cycle. When the power converter is operating in the freewheeling state, an open-circuit fault in one phase switch will also cause the currents in the other two phases to increase and the motor torque to enter the zero torque region, i.e., phase loss operation. Therefore, after an S1 or S2 open-circuit fault occurs, the power converter will smoothly switch to the A2-A1 series winding operation mode in the next sampling cycle. The above is the fault-tolerant operation of the power converter in the A1-A2 winding series operation mode, and the fault-tolerant operation of the power converter in the A2-A1 winding series operation mode can be compared to the above process.

[0037] Similarly, when a power converter operates in single-winding mode, an open-circuit fault in one phase switch, whether in the excitation or freewheeling state, will cause the current in the other two phases to increase and the motor torque to enter the zero torque region, i.e., phase loss operation. To avoid phase loss operation, simply detecting the fault quickly is not enough. Here, the consideration is to switch the operating mode in the next sampling cycle after detecting the open-circuit fault. This means switching from single-winding mode to dual-winding series mode, or from one single-winding mode to another, such as switching from winding A1 alone to winding A2 alone.

[0038] Based on the above examples, the feasibility and effectiveness of the proposed new fault-tolerant power converter and fault diagnosis method are further verified through simulation experiments.

[0039] In the switching tube fault diagnosis and fault-tolerant switching experiment under the excitation state of the winding series operation mode, Figure 7 (a) shows the experimental waveform of the A1-A2 winding series excitation state switching to the A2-A1 winding series excitation state when an open circuit fault occurs. Figure 7 (b) shows the experimental waveforms of switching from the A2-A1 series excitation state to the A1-A2 series excitation state after an open-circuit fault occurs. The figure demonstrates accurate fault diagnosis and relatively stable fault-tolerant operation in the series excitation state. When a switching transistor fails, the power converter can stably switch operating modes. This verifies the accuracy and effectiveness of the fault diagnosis method and fault-tolerant operation.

[0040] In the switch tube fault diagnosis and fault-tolerant switching experiment under the excitation state of single winding operation mode, Figure 8 (a) shows the experimental waveform diagram of the single winding A1 excitation operation mode switching to the single winding A2 excitation operation mode when an open circuit fault occurs. Figure 8 (b) shows the experimental waveforms of switching to single-winding A1 excitation mode after an open-circuit fault occurs in single-winding A2 excitation operation. The figure demonstrates accurate fault diagnosis and relatively stable fault-tolerant operation in the single-winding excitation mode. When a switching transistor fails, the power converter can stably switch operating modes. This verifies the accuracy and effectiveness of the fault diagnosis method and fault-tolerant operation.

[0041] The above is an example of the verification experiment of the present invention. The other fault conditions proposed by the present invention have been verified by experiments and can basically achieve accurate fault diagnosis and stable fault-tolerant operation, verifying the accuracy of the proposed fault diagnosis method and the effectiveness of fault-tolerant operation.

[0042] As can be seen from the above, the present invention proposes a new fault-tolerant power converter topology suitable for dual-stator switched reluctance motors, enabling both series winding operation and single-winding operation. Based on this new fault-tolerant power converter, a novel fault diagnosis method is proposed. By reconfiguring some branches of the power converter and adding an additional fault diagnosis current sensor, fault diagnosis is achieved after an open-circuit fault of a switch tube in various states. This method accurately locates the faulty switch tube and rapidly switches the operating state to ensure continued normal operation of the motor. The effectiveness of the fault-tolerant operation of the new fault-tolerant power converter and the accuracy of the fault diagnosis method are verified.

[0043] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may make various changes, modifications, substitutions, and variations to these embodiments without departing from the principles and purpose of the present invention. However, any simple modifications, equivalent variations, and modifications to the above embodiments made in accordance with the technical essence of the present invention, without departing from the scope of the present invention, are still within the scope of the present invention.

[0044] Table 1 Working status of the new fault-tolerant power converter

[0045] Table 2 Before and after the switch tube open circuit fault in four operating modes gA In the description provided herein, numerous specific details are described. However, it is understood that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description. Furthermore, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are also intended to fall within the scope of protection of the present invention and form different embodiments. For example, in the above embodiments, those skilled in the art will be able to use them in combination based on the known technical solutions and the technical problems to be solved by this application. The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments using the above-mentioned technical contents without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A novel fault-tolerant power converter applicable to a dual-stator switched reluctance motor, characterized by: The motor is a special type of switched reluctance motor, the core feature of which is the coordinated or independent operation of the inner and outer stators. Combined with a multi-mode control strategy, it significantly improves power density, efficiency and fault tolerance. Generally, the double-stator structure is divided into: radial double stator, axial double stator, and axial-radial double stator. In the power converter, each phase has two windings: taking phase A as an example, there are stator winding A1 and stator winding A2. The windings can be operated in series, parallel, or as a single winding.

2. The disclosed novel power converter includes a DC power supply module U s , a boost capacitor, 9 diodes and 15 switches. Since phases A, B and C are in parallel and have the same structure, phase A is taken as an example: DC power supply U s In parallel with the boost capacitor, phase A, phase B, and phase C are all connected in parallel at both ends of the capacitor; the proposed new fault-tolerant power converter is based on the traditional asymmetric half-bridge power converter, and adds two power switching devices (S3, S4) with anti-parallel diodes, a power switching device (S5) without anti-parallel diodes, and a freewheeling diode (D3) in each phase; the power switching device can be a power device such as IGBT, MOSFET, etc., and the diode can be a fast recovery type or Schottky type; the new power converter disclosed in the present invention is illustrated by taking the IGBT power switching device and the fast recovery diode as an example, and its connection relationship is: the collector of S3 is connected to the positive pole of the DC bus, and its emitter is respectively connected to the positive end of the winding coil A2 and the cathode of the freewheeling diode D3; the freewheeling diode D3 is located below S3, and is respectively connected to the negative end of the winding coil A1 and the cathode of the freewheeling diode D3 The collector of another power switch device below it, namely S4, is connected; the collector of S4 is connected to the negative end of the winding coil A1, and its emitter is connected to the negative pole of the DC bus; the collector of S5 is connected to the negative end of the winding coil A2, the anode of the freewheeling diode D1 located above it, and the collector of S2, and its emitter is connected to the positive end of the winding coil A1, the cathode of the freewheeling diode D2 located below it, and the emitter of S1; the collector of S1 is connected to the positive pole of the DC bus, the cathode of the freewheeling diode D1, and the collector of S3, and the emitter of S1 is connected to the positive end of the winding coil A1; the collector of S2 is connected to the negative end of the winding coil A2, and the emitter of S2 is connected to the negative pole of the DC bus; if the power switching device MOSFET is used instead, its drain corresponds to the collector of the IGBT, and the source corresponds to the emitter of the IGBT, and the other connection relationships remain unchanged.

3. The novel power converter according to claim 2, characterized in that: When the motor is in dual-winding series operation mode, the power switches used are S1, S2, S3, S4, and S5, and the freewheeling diodes used are D1, D2, and D3. Two modes can be divided based on the power switches used and the order in which current flows under the excitation state. In the A1-A2 winding series operation mode, the power switches used are S1 and S2, and the freewheeling diodes used are D1, D2, and D3. Under the excitation state, the current first flows through the A1 winding and then through the A2 winding, forming a closed loop. In the A2-A1 winding series operation mode, the power switches used are S3, S4, and S5, and the freewheeling diodes used are D1, D2, and D3. Under the excitation state, the current first flows through the A2 winding and then through the A1 winding, forming a closed loop.

4. The novel fault-tolerant power converter according to claim 2, characterized in that: When the motor is in single-winding operation mode, the power switching devices used are S1, S2, S3, and S4, and the freewheeling diodes used are D1, D2, and D3; according to the different windings and power switching devices used, it can be divided into two modes: when the A1 winding is in single-winding operation mode, the power switching devices used are S1 and S4, and the freewheeling diodes used are D2 and D3; when the A2 winding is in single-winding operation mode, the power switching devices used are S2 and S3, and the freewheeling diodes used are D1 and D3.

5. The novel fault-tolerant power converter according to claim 2, characterized in that: When the motor is in the winding parallel operation mode, the power switching devices used are S1, S2, S3, and S4, and the freewheeling diodes used are D1, D2, and D3.

6. A novel fault-tolerant power converter fault diagnosis and fault-tolerant operation method applicable to a dual-stator switched reluctance motor, characterized by: First, all possible open-circuit fault conditions of the fault-tolerant power converter are analyzed. Then, four current sensors are used to parse the three-phase currents and the current changes of some branches before and after the open-circuit fault of the switch tube to perform fault diagnosis. Finally, a fault diagnosis flag is generated and a mode switching control signal is output after a sampling cycle delay. The fault-tolerant power converter quickly switches to another operating mode.

7. The fault characteristics of the novel fault-tolerant power converter according to claim 6 when an open-circuit fault occurs in the A1-A2 winding series operation mode are as follows: in the excitation state, the conductive switches include S1 and S2; when the switch S1 has an open-circuit fault, only the switch S2 is conductive, and the windings A1 and A2 form a closed loop through D3, S2, and D2, that is, the excitation state changes to the S2 freewheeling state; when the switch S2 has an open-circuit fault, only the switch S1 ... D1 and S1 form a closed loop, that is, the state changes from the excitation state to the S1 freewheeling state; in the S1 freewheeling state, the only switching tube that is turned on is S1. When an open-circuit fault occurs in S1, all switching tubes are in the off state, and windings A1 and A2 can only perform demagnetization work, that is, the state changes from the S1 freewheeling state to the demagnetization state; when in the S2 freewheeling state, the only switching tube that is turned on is S2. When an open-circuit fault occurs in S2, all switching tubes are in the off state, and windings A1 and A2 can only perform demagnetization work, that is, the state changes from the S2 freewheeling state to the demagnetization state.

8. The novel fault-tolerant power converter according to claim 6 is characterized by the following when an open-circuit fault occurs in the A2-A1 winding series operation mode: in the excitation state, the conductive switches include S3, S4, and S5; when the switch S5 has an open-circuit fault, when the switches S3 and S4 are conductive, the winding A2 forms a closed loop through S3 and D1, and the winding A1 forms a closed loop through S4 and D2, that is, the excitation state changes to the S3 and S4 freewheeling state; when the switch S3 has an open-circuit fault, when the switches S4 and S5 are conductive, S4 is cut off, and the windings A1 and A2 form a closed loop through D3 and S5, that is, the excitation state changes to the S3 and S4 freewheeling state. 5 freewheeling state; when an open-circuit fault occurs on switch tube S4, switch tubes S3 and S5 are turned on while S3 is cut off, and the state change is consistent with an open-circuit fault on S3; when in the S5 freewheeling state, only switch tube S5 is turned on. When an open-circuit fault occurs on switch tube S5, all switch tubes are turned off, and windings A1 and A2 can only perform demagnetization work, that is, the S5 freewheeling state changes to the demagnetization state; when in the S3 and S4 freewheeling states, switch tubes S3 and S4 are turned on. When an open-circuit fault occurs on switch tube S3 or S4, all switch tubes are turned off, and windings A1 and A2 can only perform demagnetization work, that is, the S3 and S4 freewheeling state changes to the demagnetization state.

9. The novel fault-tolerant power converter according to claim 6 is characterized in that when an open circuit fault occurs in a winding-only operation mode: When in the A1 winding single operation mode, the switching tubes that are turned on in the excitation state include S1 and S4. When the power switch device S1 or S4 has an open circuit fault, the power converter will change to the S4 or S1 freewheeling state; and if an open circuit fault occurs in the freewheeling state, the power converter will change to the demagnetization state; when in the A2 winding single operation mode, when the power switch device S2 or S3 has an open circuit fault in the excitation state, the power converter will change to the S3 or S2 freewheeling state; and if an open circuit fault occurs in the freewheeling state, the power converter will change to the demagnetization state.

10. According to the novel fault-tolerant operation method of the fault-tolerant power converter described in claim 6, when an open-circuit fault occurs in a power switching device, the power converter will perform the following mode switching: if the A1-A2 winding series operation mode fails, it will fault-tolerantly switch to the A2-A1 winding series operation mode; if the A2-A1 winding series operation mode fails, it will fault-tolerantly switch to the A1-A2 winding series operation mode; if the A1 winding single operation mode fails, it will switch to the A2 winding single operation mode or the winding series operation mode; if the A2 winding single operation mode fails, it will switch to the A1 winding single operation mode or the winding series operation mode.

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