A three-level ANPC bridge arm IGBT open circuit fault modeling method based on FPGA

Abstract

The present invention relates to a modeling method for an ANPC converter, specifically a FPGA-based three-level ANPC bridge arm IGBT short-circuit fault modeling method. A FPGA-based three-level ANPC bridge arm IGBT short-circuit fault modeling method first analyzes the corresponding current paths under each switching sequence of the power device under normal operating conditions and bridge arm IGBT short-circuit fault conditions to obtain corresponding expressions of output voltage and current, designs a bridge arm model including the IGBT short-circuit fault state, and then sets the fault mode to trigger a switch to facilitate switching the fault state during normal operating conditions. The constructed FPGA-based three-level ANPC bridge arm IGBT short-circuit fault model has fast computing speed and high accuracy, and the real-time simulation step length can reach 100ns. It can not only test the three-level controller under normal operating conditions, but also provide operating condition testing under the bridge arm IGBT short-circuit fault mode.

Description

Technical Field

[0001] The present invention relates to a modeling method for an ANPC converter, in particular to a three-level ANPC bridge arm IGBT open circuit fault modeling method based on FPGA. Background Art

[0002] As power device switching frequencies increase, the application of multilevel inverters is becoming increasingly widespread. The active neutral point clamped (ANPC) three-level topology effectively overcomes the uneven loss distribution problem of the NPC topology and offers simple control, making it increasingly widely used in the modern new energy industry.

[0003] Currently, model-based development is becoming increasingly mainstream for power electronics controller development. Hardware-in-the-loop (HIL) simulation is a typical testing method within this development model. HIL simulation connects a physical controller with a virtual model of the controlled plant (implemented using real-time simulation hardware). This allows for cost-effective and efficient testing of controller functionality and performance. Furthermore, HIL simulation offers advantages in destructive testing, reducing the cost of replacing damaged components.

[0004] Currently, the main circuit of a three-level ANPC converter is typically built using components and switch modules from the SimPowerSystems module library in MATLAB simulation software. Because the IGBT / Diode models included in the SimPowerSystems module library are electrical models that incorporate parasitic parameters and are relatively complex, they are typically used for offline simulation. In real-time online simulation, using components and modules from the SimPowerSystems module library to build the main circuit results in a limited simulation step size due to the model's complexity and high computational complexity. Improving simulation accuracy requires compiling and downloading the model to the FPGA board, but the SimPowerSystems module library does not support this compilation and downloading capabilities.

[0005] Patent CN102710153A, "Modeling Method for Single-Phase Bridge-Type Three-Level Rectifier," discloses a modeling method for a single-phase bridge-type three-level rectifier. This method is simple and computationally intensive. However, this modeling method only models a single-phase three-level rectifier under normal operating conditions and does not consider IGBT short-circuit fault conditions, making it incapable of simulating fault conditions. Summary of the Invention

[0006] The present invention provides a three-level ANPC bridge arm IGBT short-circuit fault modeling method. This method does not consider parasitic parameters and derives the current-voltage relationship between the device in the on and off states. The model has high accuracy and can be compiled and downloaded to an FPGA board for real-time simulation. This solves the problem that the main circuit model built in the SimPowerSystems module library is complex and cannot be downloaded.

[0007] The present invention is implemented using the following technical solution: a FPGA-based three-level ANPC bridge arm IGBT short-circuit fault modeling method. First, by analyzing the corresponding current paths under each switching sequence of the power device under normal operating conditions and bridge arm IGBT short-circuit fault conditions, the corresponding expressions of output voltage and current are obtained, and a bridge arm model including the IGBT short-circuit fault state is designed. Then, the fault mode is set to trigger a switch to facilitate switching the fault state during normal operating conditions.

[0008] The above-mentioned FPGA-based three-level ANPC bridge arm IGBT open circuit fault modeling method includes six switch states: P, OU1, OU2, OL1, OL2, and N in the current path;

[0009] In the P switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 110001, and the output voltage is +Udc / 2. If iT1=iT2=iac, iac≥0; if -iD1=-iD2=-iac, iac<0;

[0010] In the OU1 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010010, and the output voltage is 0. If -iD5=iT2=iac, iac≥0; if -iD2=iT5=-iac, iac<0;

[0011] In the OU2 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010110, and the output voltage is 0. If -iD5=iT2=iac, iac≥0; if -iD2=iT5=-iac, iac<0;

[0012] In the OL1 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001001, and the output voltage is 0. If -iD3=iT6=iac, iac≥0; if -iD6=iT3=-iac, iac<0;

[0013] In the OL2 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 101001, and the output voltage is 0. If -iD3=iT6=iac, iac≥0; if -iD6=iT3=-iac, iac<0;

[0014] In the N switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001110, and the output voltage is -Udc / 2. If -iD3=-iD4=iac, iac≥0; if iT3=iT4=-iac, iac<0;

[0015] iT1, iT2, iT3, iT4, iT5, iT6 are the currents of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 respectively; -iD1, -iD2, -iD3, -iD4, -iD5, and -iD6 are the currents of the diodes D1, D2, D3, D4, D5, and D6 respectively; iac is the bridge arm output current; and Udc is the DC side voltage.

[0016] The above-mentioned FPGA-based three-level ANPC bridge arm IGBT short-circuit fault modeling method includes seven short-circuit states: T1 short-circuit, T2 short-circuit 1, T2 short-circuit 2, T2 short-circuit 3, T5 short-circuit 1T, T5 short-circuit 2, and T5 short-circuit 3.

[0017] When T1 is in the off state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010001. If the output voltage is 0, -iD5=iT2=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0.

[0018] In the T2 disconnect 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 100001. If the output voltage is 0, there is no current path. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0;

[0019] In the T2 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000010. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD2=iT5=-iac, iac<0.

[0020] In the T2 open circuit 3 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000110. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD2=iT5=-iac, iac<0.

[0021] In the T5 off-circuit 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010000. If the output voltage is 0, -iD5=iT2=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0.

[0022] In the T5 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010100. If the output voltage is 0, -iD5=iT2=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0.

[0023] In the T5 circuit breaker 3 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001100, and the output voltage is -Udc / 2. If -iD3=-iD4=iac, iac≥0; if iT3=iT4=-iac, iac<0.

[0024] The above-mentioned FPGA-based three-level ANPC bridge arm IGBT short-circuit fault modeling method includes seven short-circuit states: T4 short-circuit, T3 short-circuit 1, T3 short-circuit 2, T3 short-circuit 3, T6 short-circuit 1T, T5 short-circuit 2, and T6 short-circuit 3.

[0025] When T4 is in the off state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001010. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD6=iT3=-iac, iac<0.

[0026] In the T3 off-circuit 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000001. If the output voltage is 0, -iD3=iT6=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0.

[0027] In the T3 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 100001. If the output voltage is 0, -iD3=iT6=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0.

[0028] In the T3 disconnect state 3, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000110. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, there is no current path;

[0029] In the T6 disconnect 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 110000, and the output voltage is Udc / 2. If iT1=iT2=iac, iac≥0, and if -iD1=-iD2=-iac, iac<0;

[0030] In the T6 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001000. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD6=iT3=-iac, iac<0.

[0031] In the T6 circuit breaker 3 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 101000. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD6=iT3=-iac, iac<0.

[0032] The above-mentioned FPGA-based three-level ANPC bridge arm IGBT short-circuit fault modeling method uses the Xilinx model library in MATLAB to build a model. The built model is an FPGA-based model, which can be compiled and downloaded to the FPGA board and can be used with the controller for real-time semi-physical simulation verification.

[0033] The FPGA-based three-level ANPC bridge arm IGBT short-circuit fault modeling method has the following beneficial effects:

[0034] 1) The model includes normal operating conditions and bridge arm IGBT short-circuit fault conditions, and the fault conditions can be switched;

[0035] 2) The logic of each working condition model is clear, the structure is simple, and it is easy to verify;

[0036] 3) The three-level ANPC bridge arm does not consider parasitic parameters, but adopts logic modeling, which is simple and takes up less resources;

[0037] 4) This bridge arm model can be encapsulated as a module and can be used alone or combined into single-phase, three-phase and other topological applications, which is universal;

[0038] 5) The model can be compiled and downloaded to the FPGA board, and can be used with the controller for real-time semi-physical simulation verification. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the block diagram of the three-level ANPC bridge arm IGBT open circuit fault model.

[0040] Figure 2 This is the topology diagram of the three-level ANPC bridge arm circuit.

[0041] Figure 3 Schematic diagram of the ANPC current path.

[0042] Figure 4 This is the typical current flow diagram corresponding to the ANPC three-level upper bridge arm IGBT short-circuit fault.

[0043] Figure 5 This is the schematic diagram of the three-phase ANPC inverter circuit.

[0044] Figure 6 This is the FPGA model diagram of the three-phase three-level ANPC inverter with motor.

[0045] Figure 7 The figure is a Simpower model diagram of a three-phase three-level ANPC inverter with a motor for comparison.

[0046] Figure 8 This is the waveform of the three-phase stator current of the motor.

[0047] Figure 9 The following is a comparison diagram of the current waveforms of IGBT1~IGBT6 in the U-phase bridge arm of the inverter.

[0048] Figure 10 This is a comparison chart of the motor U-phase current and line voltage waveforms.

[0049] Figure 11 The comparison diagram of the DC side current waveform of the inverter.

[0050] Figure 12 This is the waveform of the three-phase stator current of the motor.

[0051] Figure 13 The following is a comparison diagram of the current waveforms of IGBT1~IGBT6 in the U-phase bridge arm of the inverter.

[0052] Figure 14 This is a comparison chart of the motor U-phase current and line voltage waveforms.

[0053] Figure 15 The comparison diagram of the DC side current waveform of the inverter.

[0054] Figure 16 This is the waveform of the three-phase stator current of the motor.

[0055] Figure 17 The following is a comparison diagram of the current waveforms of IGBT1~IGBT6 in the U-phase bridge arm of the inverter.

[0056] Figure 18 This is a comparison chart of the motor U-phase current and line voltage waveforms.

[0057] Figure 19 The comparison diagram of the DC side current waveform of the inverter.

[0058] Figure 20 This is the schematic diagram of the single-phase ANPC rectifier circuit.

[0059] Figure 21 This is the FPGA model diagram of the single-phase ANPC rectifier circuit.

[0060] Figure 22 This is the Simpower model diagram of the single-phase ANPC rectifier circuit.

[0061] Figure 23 This is a comparison diagram of the current waveforms of IGBT1 to IGBT6 in the A bridge arm.

[0062] Figure 24 This is a comparison chart of bus voltage, four-quadrant voltage and current, and DC current waveforms.

[0063] Figure 25 This is a comparison diagram of the current waveforms of IGBT1 to IGBT6 in the A bridge arm.

[0064] Figure 26 This is a comparison chart of bus voltage, four-quadrant voltage and current, and DC current waveforms.

[0065] Figure 27 This is a comparison diagram of the current waveforms of IGBT1 to IGBT6 in the A bridge arm.

[0066] Figure 28 This is a comparison chart of bus voltage, four-quadrant voltage and current, and DC current waveforms. DETAILED DESCRIPTION

[0067] The present invention first analyzes the corresponding current paths of each switching sequence of the power device under normal working conditions and bridge arm IGBT short circuit fault conditions, obtains the corresponding expressions of output voltage and current, designs a bridge arm model that includes the IGBT short circuit fault state, and then sets the fault mode to trigger the switch, making it convenient to switch the fault state during normal working conditions. The overall block diagram is as follows Figure 1 shown.

[0068] The three-level ANPC bridge arm circuit topology is as follows Figure 2 As shown, each phase of the ANPC contains six bidirectional switches. These switches form eight current paths—CP1-CP4, CPP, CPP-, CPN, and CPN-—based on the phase current direction and output level, as shown in Figure 3. Current path CPP connects the output level terminal to the DC side's positive current terminal, P, while CPN connects the output level terminal to the DC side's negative current terminal, N. In this case, the converter operates at unity power factor (PF=1). Conversely, current paths CPP- and CPN- produce a PF=-1 operation. Each of these four current paths uniquely corresponds to an output level and current operating state.

[0069] At the midpoint current terminal, the positive phase current has two current paths: CP1 and CP2. Similarly, CP3 and CP4 are the current paths for the negative phase current. As shown in Figure 3, each current path includes two power devices. The current paths CPP and CPN each contain two active switching IGBTs, CP1-CP4 each contain one IGBT and one freewheeling diode, and CPP- and CPN- each contain two freewheeling diodes. The current paths containing active switching IGBTs can be controlled by controlling the power switching devices.

[0070] Through the above analysis of the current path, we can obtain the switching sequence table shown in Table 1. The IGBT / Diode current is in the positive direction from collector to emitter, and the commutation method is as follows:

[0071] Table 1 ANPC bridge arm switching sequence table

[0072]

[0073] As can be seen from the three-level ANPC topology diagram, the ANPC topology is symmetrical. Therefore, when analyzing a single device fault, only the fault conditions on one side above or below the midpoint need to be considered. Only the three devices T1, T2, and T5 on the upper side of the bridge arm need to be analyzed for short circuits. The short circuit analysis of the three devices T3, T4, and T6 on the lower side of the bridge arm is similar to that of T1, T2, and T5. When analyzing a single device short circuit fault, the current outflow direction is defined as the positive direction. Figure 4 This is a typical current flow path diagram when T1, T2 and T5 devices fail.

[0074] It can be seen that Figure 4The current flow path shown in (a) corresponds to the following drive sequence and output voltage: the inverter single-phase output voltage corresponding to the drive sequence is +Udc / 2, current flows out of the output terminal, and T1 has a circuit breaker fault. However, in this case, the inverter bridge arm actually outputs zero potential, rather than the output corresponding to the drive sequence of +Udc / 2; Figure 4 The current flow path shown in (b) corresponds to a drive sequence and output voltage of zero (corresponding to the inverter single-phase output of 0U2 and 0U1). Current flows out of the bridge arm output terminals, and T2 fails. However, in this case, the actual inverter output voltage is -Udc / 2, rather than the zero output corresponding to the drive sequence. Figure 4 The current flow path shown in (c) corresponds to the following drive sequence and output voltage: the inverter's single-phase output voltage corresponding to the drive sequence is zero, current flows out of the output terminals, and T5 has a short circuit fault. However, in this case, the actual inverter output voltage is +Udc / 2, not the zero output corresponding to the drive sequence.

[0075] In summary, when a fully-controlled turn-off device in a bridge arm fails, the actual single-phase output voltage of the bridge arm is different from the output voltage corresponding to the drive sequence, and the current flow path is changed, causing the entire system to malfunction.

[0076] Through the above analysis of the current path, we can obtain the newly added switching sequence table for the ANPC high-arm IGBT short-circuit fault shown in Table 2. The IGBT / Diode current is in the positive direction from collector to emitter, and the commutation method is as follows:

[0077] Table 2 New sequence list of ANPC upper arm IGBT circuit breaker fault

[0078]

[0079] The lower arm is similar to the upper arm. Table 3 shows the newly added switching sequence table for the ANPC lower arm IGBT short-circuit fault. The IGBT / Diode current is in the positive direction from collector to emitter, and the commutation method is as follows:

[0080] Table 3 New sequence list of ANPC lower arm IGBT circuit breaker fault

[0081]

[0082] Implementation example of three-phase inverter model

[0083] Build a three-phase ANPC inverter circuit, the schematic diagram is as follows Figure 5 shown.

[0084] For comparison, a three-phase ANPC inverter circuit based on MATLAB / Simpower model library and a model based on FPGA were built respectively, such as Figure 6 and Figure 7 As shown in the figure, a fault is set to occur at 0.1s.

[0085] Since the main circuit has a vertically symmetrical structure, only the consistency between the FPGA model and the Simpower model under the open-circuit conditions of T1, T2, and T5 among the six IGBTs is analyzed.

[0086] T1 is open

[0087] Depend on Figure 8 It can be seen that after the T1 circuit breaker fault occurs 0.1s, the stator current becomes three-phase unbalanced, iu is negatively biased, and iv and iw are positively biased.

[0088] Depend on Figure 9 It can be seen that after T1 is disconnected, the current of IGBT1 is only the negative diode current, and the forward current is 0.

[0089] Depend on Figures 9-11 It can be seen that the output voltage and DC side current waveforms of the FPGA model and Simpower under normal operating conditions and after T1 circuit breaker fault are almost completely consistent, verifying the correctness of the FPGA model.

[0090] T2 open circuit

[0091] Depend on Figure 12 It can be seen that after the T2 circuit breaker fault occurs at 0.1s, the stator current becomes three-phase unbalanced, iu is negatively biased, and iv and iw are positively biased.

[0092] Depend on Figure 13 It can be seen that after T2 is disconnected, the currents of IGBT1, IGBT2, and IGBT6 are only negative diode currents, and the forward current is 0; the currents of IGBT3, IGBT4, and IGBT5 are only forward IGBT currents, and the negative diode current is 0.

[0093] Depend on Figures 13-15 It can be seen that the output voltage and DC side current waveforms of the FPGA model and Simpower under normal operating conditions and after T2 circuit breaker fault are almost completely consistent, verifying the correctness of the FPGA model.

[0094] T5 circuit breaker

[0095] Depend on Figure 16 It can be seen that after the T1 circuit breaker fault occurs 0.1s, the stator current becomes three-phase unbalanced, iu is positively biased, and iv and iw are negatively biased.

[0096] Depend on Figure 17 It can be seen that after T5 is disconnected, the current of IGBT5 is only the negative diode current, and the forward current is 0.

[0097] Depend on Figures 16-19 It can be seen that the output voltage and DC side current waveforms of the FPGA model and Simpower under normal operating conditions and after T5 circuit breaker fault are almost completely consistent, verifying the correctness of the FPGA model.

[0098] Single-phase Rectification Simulation Model Implementation Example

[0099] Build a single-phase ANPC rectifier circuit, the schematic diagram is as follows Figure 20 shown

[0100] For comparison, a single-phase ANPC rectifier circuit based on MATLAB / Simpower model library and a FPGA-based model were built, such as Figure 21 and Figure 22 As shown in the figure, the waveform is set to start at 0.05s and the fault occurs at 0.1s.

[0101] Since the main circuit has a vertically symmetrical structure, only the consistency between the FPGA model and the Simpower model under the open-circuit conditions of T1, T2, and T5 among the six IGBTs is analyzed.

[0102] T1 is open

[0103] Depend on Figure 23 It can be seen that after T1 is disconnected, the current of IGBT1 is only the negative diode current, and the forward current is 0.

[0104] Depend on Figure 23 、 24 It can be seen that the output bus voltage, four-quadrant voltage and current, and DC side current waveforms of the FPGA model and Simpower under normal operating conditions and after T1 circuit breaker fault are almost completely consistent, verifying the correctness of the FPGA model.

[0105] T2 open circuit

[0106] Depend on Figure 25 It can be seen that after T2 is disconnected, the currents of IGBT1 and IGBT2 are only negative diode currents, and the forward current is 0; the current of IGBT5 is only forward IGBT current, and the negative diode current is 0.

[0107] Depend on Figure 25 、 26 It can be seen that the output bus voltage, four-quadrant voltage and current, and DC side current waveforms of the FPGA model and Simpower under normal operating conditions and after T2 circuit breaker fault are almost completely consistent, verifying the correctness of the FPGA model.

[0108] T5 circuit breaker

[0109] Depend on Figure 27 It can be seen that after T5 is disconnected, the current of IGBT5 is only the negative diode current, and the forward current is 0.

[0110] Depend on Figure 27 、 28 It can be seen that the output bus voltage, four-quadrant voltage and current, and DC side current waveforms of the FPGA model and Simpower under normal operating conditions and after T5 circuit breaker fault are almost completely consistent, verifying the correctness of the FPGA model.

Claims

1. A three-level ANPC bridge arm IGBT open circuit fault modeling method based on FPGA, characterized by: First, by analyzing the current paths corresponding to each switching sequence of the power device under normal operating conditions and bridge arm IGBT short-circuit fault conditions, the corresponding expressions of output voltage and current are obtained. A bridge arm model that includes the IGBT short-circuit fault state is designed. The fault mode is then set to trigger the switch to facilitate switching the fault state during normal operation. The current path includes six switching states: P, OU1, OU2, OL1, OL2, and N. The upper arm IGBT short circuit fault includes seven short circuit states: T1 short circuit, T2 short circuit 1, T2 short circuit 2, T2 short circuit 3, T5 short circuit 1, T5 short circuit 2, and T5 short circuit 3; When T1 is in the off state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010001. If the output voltage is 0, -iD5=iT2=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0. In the T2 disconnect 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 100001. If the output voltage is 0, there is no current path. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0; In the T2 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000010. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD2=iT5=-iac, iac<0. In the T2 open circuit 3 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000110. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD2=iT5=-iac, iac<0. In the T5 off-circuit 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010000. If the output voltage is 0, -iD5=iT2=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0. In the T5 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010100. If the output voltage is 0, -iD5=iT2=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0. In the T5 open circuit 3 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001100, and the output voltage is -Udc / 2. If -iD3=-iD4=iac, iac≥0, and if iT3=iT4=-iac, iac<0; The lower arm IGBT short circuit fault includes seven short circuit states: T4 short circuit, T3 short circuit 1, T3 short circuit 2, T3 short circuit 3, T6 short circuit 1, T6 short circuit 2, and T6 short circuit 3.

2. The FPGA-based three-level ANPC bridge arm IGBT open circuit fault modeling method according to claim 1, characterized in that: In the P switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 110001, and the output voltage is +Udc / 2. If iT1=iT2=iac, iac≥0; if -iD1=-iD2=-iac, iac<0; In the OU1 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010010, and the output voltage is 0. If -iD5=iT2=iac, iac≥0; if -iD2=iT5=-iac, iac<0; In the OU2 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 010110, and the output voltage is 0. If -iD5=iT2=iac, iac≥0; if -iD2=iT5=-iac, iac<0; In the OL1 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001001, and the output voltage is 0. If -iD3=iT6=iac, iac≥0; if -iD6=iT3=-iac, iac<0; In the OL2 switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 101001, and the output voltage is 0. If -iD3=iT6=iac, iac≥0; if -iD6=iT3=-iac, iac<0; In the N switching state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001110, and the output voltage is -Udc / 2. If -iD3=-iD4=iac, iac≥0; if iT3=iT4=-iac, iac<0; iT1, iT2, iT3, iT4, iT5, iT6 are the currents of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 respectively; -iD1, -iD2, -iD3, -iD4, -iD5, and -iD6 are the currents of the diodes D1, D2, D3, D4, D5, and D6 respectively; iac is the bridge arm output current; and Udc is the DC side voltage.

3. The FPGA-based three-level ANPC bridge arm IGBT open circuit fault modeling method according to claim 2, characterized in that: When T4 is in the off state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001010. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD6=iT3=-iac, iac<0. In the T3 off-circuit 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000001. If the output voltage is 0, -iD3=iT6=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0. In the T3 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 100001. If the output voltage is 0, -iD3=iT6=iac, iac≥0. If the output voltage is Udc / 2, -iD1=-iD2=-iac, iac<0. In the T3 disconnect state 3, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 000110. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, there is no current path; In the T6 disconnect 1 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 110000, and the output voltage is Udc / 2. If iT1=iT2=iac, iac≥0, and if -iD1=-iD2=-iac, iac<0; In the T6 disconnect 2 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 001000. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD6=iT3=-iac, iac<0. In the T6 circuit breaker 3 state, the switching sequence of the bidirectional switch devices T1, T2, T3, T4, T5, and T6 is 101000. If the output voltage is -Udc / 2, -iD3=-iD4=iac, iac≥0. If the output voltage is 0, -iD6=iT3=-iac, iac<0.

4. The FPGA-based three-level ANPC bridge arm IGBT open circuit fault modeling method according to claim 3, characterized in that: The model is built using the Xilinx model library in MATLAB. The model built is an FPGA-based model.

Images