High-frequency link AC-DC matrix converter switching tube fault tolerance system and method
By employing a topology that connects power frequency diodes to the abc input and a two-line voltage modulation strategy in the high-frequency chain AC-DC matrix converter, the problem of high fault tolerance cost of the switching transistor in the high-frequency chain AC-DC matrix converter is solved, and low-cost, safe and reliable fault-tolerant operation is achieved.
Patent Information
- Application Number
- CN202511341022.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-19
- Publication Date
- 2025-12-12
AI Technical Summary
Existing fault tolerance methods for switching transistors in high-frequency AC-DC matrix converters are costly, complex in design, and have limited applicability, especially in delta-type input power supplies without a neutral line, where their performance is poor.
Six power frequency diodes are connected to the abc input. Fault-tolerant operation is achieved through topology reconstruction without the need for additional trigger signals. The switching state is optimized by using a two-line voltage modulation strategy to reduce conduction losses.
It achieves low-cost fault-tolerant operation, is suitable for simultaneous failure of up to 6 switching transistors, reduces conduction losses and does not require additional trigger signals, thus improving the safety and reliability of the system.
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Figure CN121124533A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of AC / DC power conversion devices, and in particular to a fault-tolerant system and method for switching transistors in a high-frequency AC-DC matrix converter. Background Technology
[0002] Three-phase high-frequency chain AC-DC matrix converters have advantages such as compact structure, high power density, and electrical isolation, showing promising application prospects in new energy storage systems and electric vehicle charging piles. However, the main circuit of a high-frequency chain AC-DC matrix converter requires multiple bidirectional switches (a total of 12 switching devices), which makes the circuit prone to switching transistor failures and affects its service life. Therefore, designing fault-tolerant strategies is of great significance for improving the safety and reliability of the system.
[0003] Fault-tolerant methods typically employ a redundant phase connected to the abc input phase via a bidirectional thyristor (composed of six unidirectional thyristors), or directly connected to the neutral point O. While direct connection to the neutral point offers lower hardware costs, this method limits the fault-tolerant operating range and incurs higher current stress after fault tolerance. Furthermore, it is unsuitable for delta-type input power supplies without a neutral line. Therefore, in applications requiring high fault tolerance, the method of connecting the redundant phase to the abc input phase is generally preferred.
[0004] like Figure 1 As shown, when a switch fails, the thyristor in the phase containing the faulty switch can be turned on, thereby using a redundant phase to replace the faulty phase and achieve fault tolerance. However, since the fault tolerance method connected to the abc input phases must use semi-controlled thyristors, it will have the following disadvantages:
[0005] 1. An additional trigger signal is required to control the thyristor conduction, which complicates the design of the fault-tolerant system;
[0006] 2. If the trigger signal is not set properly, it can easily lead to further performance degradation after the converter fails.
[0007] 3. Thyristors and their signal triggering devices are relatively expensive, resulting in high fault-tolerance costs for the converter;
[0008] 4. During fault-tolerant operation, the thyristor needs to be connected to an additional circuit, and the current needs to flow through 4 switching transistors and 1 thyristor, which will lead to an increase in conduction loss after fault tolerance.
[0009] 5. If the faulty switching transistors are on the same phase, fault-tolerant operation can be achieved. That is, this fault-tolerant method is only applicable to the case where a maximum of 4 switching transistors fail at the same time.
[0010] Therefore, a fault-tolerant system and method for switching transistors in a high-frequency AC-DC matrix converter are needed. Summary of the Invention
[0011] To address the problem of excessively high fault-tolerance costs in existing technologies, this invention provides a fault-tolerance system and method for switching transistor failures in a high-frequency AC-DC matrix converter. This system requires only six power frequency diodes connected to the abc input and can actively switch to fault-tolerant operation without additional trigger signals after a switching transistor failure, thus achieving low fault-tolerance costs. The specific technical solution is as follows:
[0012] A fault-tolerant switching tube system for a high-frequency AC-DC matrix converter includes a switch array composed of six bidirectional switches, a downstream diode rectifier bridge, and two bidirectional switches. The switch array of six bidirectional switches converts three-phase power frequency AC to single-phase high-frequency AC. A high-frequency transformer is responsible for high-frequency energy transmission and electrical isolation. The downstream diode rectifier bridge converts single-phase high-frequency AC to DC output to the load. The two bidirectional switches have opposite series configurations and are connected to the p-terminal and n-terminal of the transformer, respectively, and are connected to the abc inputs through six diodes.
[0013] Preferably, the diode operates at the input power frequency.
[0014] Preferably, the fault-tolerant system for the switching transistors of the high-frequency AC-DC matrix converter uses diodes to achieve fault-tolerant operation and does not require additional trigger signals.
[0015] A fault-tolerant method for switching transistors in a high-frequency chain AC-DC matrix converter is applied to the fault-tolerant system for switching transistors in the high-frequency chain AC-DC matrix converter described above. When one of the switching transistors experiences an open-circuit fault, all other switching transistors in the upper bridge arm and the redundant switching transistors are turned off, thereby achieving fault-tolerant operation through topology reconfiguration; wherein:
[0016] When a fault occurs in the upper arm, all upper arm switching transistors and redundant switching transistors will be turned off.
[0017] When a fault occurs in the lower bridge arm, turn off all the lower bridge arm switches and redundant switches.
[0018] Preferably, the fault-tolerant system employs a two-line voltage modulation (DLM) strategy.
[0019] Preferably, it includes the following parts:
[0020] Define the input phase voltage of the high-frequency chain AC-DC matrix converter, divide the input period into 12 sectors, and use the DLM strategy to synthesize the output voltage using the maximum and second largest values of the input line voltage, and the output line voltage is zero during the freewheeling phase.
[0021] During the switching cycle, the system adopts an alternating positive and negative operating mode. By setting different switching states, different positive output line voltage values, negative output line voltage values, and zero voltage output values can be obtained in each sector.
[0022] Five operating modes are designed within the switching cycle, each corresponding to a different output line voltage. The order is as follows: maximum positive line voltage → second maximum positive line voltage → zero output freewheeling stage → maximum negative line voltage → zero output freewheeling stage.
[0023] Once the operating mode and its corresponding switching state are determined, the DLM strategy uses the absolute value of the minimum phase voltage and the absolute value of the intermediate phase voltage to obtain the duration of different switching states.
[0024] Further calculate the duration of different states within the switching cycle.
[0025] Preferably, the input phase voltage of the high-frequency AC-DC matrix converter is defined as:
[0026]
[0027] In the formula, u im θ represents the input voltage amplitude, and θ represents the sector angle.
[0028] Preferably, the duration of different switching states is obtained using the absolute values of the minimum phase voltage and the intermediate phase voltage, and the calculation formula is as follows:
[0029]
[0030] In the formula, T s The switching period is denoted by m, where m is the modulation coefficient value, and |u min | and |u med | represents the absolute values of the minimum and second-largest phase voltages within the input sector, T x T y T0 and T1 represent the total duration of the maximum output line voltage state, the second maximum output line voltage state, and the freewheeling phase, respectively.
[0031] Preferably, based on the constraint that the volt-second product of the positive half-switching period and the negative half-switching period is equal, the formula for calculating the duration of each mode is as follows:
[0032]
[0033] By substituting the absolute values of the input phase voltage and line voltage within the corresponding sector, the duration of each operating mode can be obtained.
[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0035] 1. The fault-tolerant system also only has 4 switches to form a redundant structure, and there is no need to increase the number of switches;
[0036] 2. Only 6 diodes need to be connected to the abc input, and it can actively switch to fault tolerance without a trigger signal;
[0037] 3. The six diodes are power frequency (50Hz) diodes, which are inexpensive and result in lower fault tolerance costs;
[0038] 4. During fault-tolerant operation, the current only flows through 3 switching transistors and 1 power frequency diode, resulting in low conduction losses;
[0039] 5. As long as the faulty switching transistors are in the same bridge arm, fault-tolerant operation can be achieved. That is, the proposed method can be applied to up to 6 switching transistors failing at the same time, which is more than the traditional method. Attached Figure Description
[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0041] Figure 1 This is a schematic diagram of a traditional fault-tolerant switching transistor system.
[0042] Figure 2 This is a schematic diagram of the fault-tolerant switching transistor system proposed in this invention;
[0043] Figure 3 The waveform diagram shows the fault-tolerant strategy based on the Matlab / Simulink simulation model.
[0044] Figure 4 For the switching transistor S 11i A schematic diagram illustrating the evolution of the fault-tolerant structure after an open-circuit fault occurs;
[0045] Figure 5 Flowchart for refactoring fault-tolerant structures when different switching transistors fail;
[0046] Figure 6 This is a schematic diagram of sector division within the input cycle;
[0047] Figure 7 This is a typical waveform diagram for fault-tolerant operation;
[0048] Figure 8 Schematic diagram of the fault operation mode (Mode 1);
[0049] Figure 9 Schematic diagram of the fault operation mode (Mode 2);
[0050] Figure 10 Schematic diagram of the fault operation mode (Mode 3);
[0051] Figure 11 Schematic diagram of the fault operation mode (Mode 4);
[0052] Figure 12 Schematic diagram of the faulty operation mode (Mode 5). Detailed Implementation
[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0054] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.
[0055] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.
[0056] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.
[0057] Figure 1 This paper illustrates a traditional fault-tolerant switching transistor system. To reduce fault-tolerant costs without compromising performance, this invention replaces semi-controlled thyristors with uncontrolled power frequency diodes and modifies redundant bridge arms, proposing a fault-tolerant switching transistor system for a high-frequency chain AC-DC matrix converter, and designing a corresponding fault-tolerant operation method.
[0058] In one embodiment of the present invention, such as Figure 2As shown, the high-frequency AC-DC matrix converter's front-end circuit consists of a switching array of six bidirectional switches, converting three-phase power frequency AC to single-phase high-frequency AC. A high-frequency transformer handles high-frequency energy transmission and electrical isolation. The subsequent diode rectifier bridge converts the single-phase high-frequency AC to DC output to the load. Wherein, u a u b and u c For three-phase input voltage, u p and i p For the primary side voltage and current of the high-frequency transformer, u o and i o For output voltage and current, R i L i and C i For the input filter resistor, inductor, and capacitor, L o and C o For the output filter inductor and capacitor, R o This is the load resistance.
[0059] The redundant section in the middle of the circuit includes two bidirectional switches consisting of four switching transistors, and these two bidirectional switches need to have opposite series configurations. Unlike traditional methods, the two bidirectional switches are connected to the p-terminal and n-terminal of the transformer, respectively, and are connected to the abc inputs through six diodes. The diodes operate at the input power frequency (50Hz), thus allowing the use of low-cost diodes to construct a fault-tolerant system.
[0060] like Figure 3 As shown, to verify the correctness and effectiveness of the proposed fault-tolerant method, a simulation experiment based on a Matlab / Simulink simulation model was conducted. The circuit parameters of the simulation model are: input voltage 220V / 50Hz, load resistance 20Ω, modulation coefficient m=0.85, and switching frequency f. s =10kHz, the primary-to-secondary turns ratio of the transformer is 1:1. The period from 0 to 0.05s represents normal operation, and the period from 0.05 to 0.1s represents the switching state of the transistor S. 11i Open circuit fault operation state, 0.1~0.15s is fault-tolerant operation state.
[0061] Figure 3 When the switching transistor S 11iWhen an open-circuit fault occurs, not only is the input current severely distorted, but the DC output voltage / current also exhibits significant ripple, and the volt-second intervals of the high-frequency voltage are unbalanced during the switching cycle. After switching to the proposed fault-tolerant method, the high-frequency chain AC-DC matrix converter can resume normal operation, maintaining the same performance as during normal operation. Furthermore, based on the terminal voltages of the diodes in window 6, it can be determined that the six diodes used in the proposed method are power frequency diodes with an operating frequency of 50Hz, consistent with the grid-side input frequency. Therefore, fault-tolerant operation can be achieved using low-cost diodes without requiring additional trigger signals.
[0062] With the switching transistor S 11i Taking an open circuit fault as an example, such as Figure 4 The diagram shows the evolution of the fault-tolerant structure. When S 11i After the fault occurs, the remaining switches S of the upper bridge arm 11o S 12i S 12o S 13i S 13o And the redundant switching transistor S 14o S 24o All switches are shut down, thus achieving fault-tolerant operation through topology reconfiguration. It should be further noted that when a fault occurs in the upper arm, only the upper arm switches and the redundant switches S need to be switched off. 14o S 24o All switches are turned off; if the fault occurs in the lower bridge arm, only the lower bridge arm switch and the redundant switch S need to be turned off. 14i S 24i Turn off all Figure 5 This is a flowchart illustrating the fault-tolerant structure reconfiguration process when different switching transistors fail. Therefore, by ensuring that the faulty switching transistor is in the same bridge arm, fault-tolerant operation can be achieved even when up to six switching transistors fail simultaneously.
[0063] The fault-tolerant topology has unique properties, with Figure 4 S-type switching transistor 11i Taking a fault-tolerant structure after a fault as an example, we will analyze its operation in detail. In order to ensure that the output DC voltage remains constant and the input current is balanced sinusoidal after fault tolerance, the fault-tolerant system adopts a two-line voltage modulation (DLM) strategy.
[0064] ① Divide the input sector
[0065] First, define the input phase voltage of the high-frequency chain AC-DC matrix converter as:
[0066]
[0067] In the formula u im Let θ be the input voltage amplitude, and θ be the sector angle. The relationship between the magnitudes of the three-phase input voltages is as follows: Figure 6The input cycle is divided into 12 sectors. The DLM strategy uses the maximum and second-largest values of the input line voltage to synthesize the output voltage, and the output line voltage is zero during the freewheeling phase.
[0068] ② Define switch states
[0069] To ensure volt-second balance in the high-frequency transformer, an alternating positive and negative operating mode is required during the switching cycle. By setting different switching states, different positive output line voltage values, negative output line voltage values, and zero-voltage output values can be obtained in each sector. According to... Figure 6 The input sectors are divided into sections. Table 1 summarizes the maximum output line voltage u in sectors 1 to 12. ll_max Second largest output line voltage u ll_med The table shows the corresponding switching states under conditions such as freewheeling and current recovery. Additionally, the symbol "\" in the table indicates no switching state, meaning that there is no switching state in that sector capable of outputting the line voltage value. Therefore, its operating mode will differ from normal operation, requiring a new fault-tolerant operating scheme to be designed.
[0070] Table 1. Switch states and corresponding output line voltages in different sectors.
[0071]
[0072]
[0073] ③ Determine the fault-tolerant operation mode
[0074] Compared to traditional methods, the proposed fault-tolerant topology is an asymmetrical circuit, leading to situations where a certain line voltage cannot be output within each sector. Therefore, the proposed fault-tolerant structure cannot generate symmetrical and equal high-frequency voltages during the positive and negative half-switching cycles, requiring a specific asymmetrical operating mode to achieve dynamic volt-second balance of the high-frequency transformer.
[0075] This invention designs five operating modes within the switching cycle, each corresponding to a different output line voltage. The sequence is as follows: maximum positive line voltage → second maximum positive line voltage → zero output freewheeling stage → maximum negative line voltage → zero output freewheeling stage. Typical operating waveforms are shown below. Figure 7 As shown. In Figure 7 The table below shows the conduction status of different switching transistors under five operating modes in sector 1, consistent with the switching states and output line voltages in Table 1. The switching states for other sectors can also be set according to the table. Figure 7 If the five-segment operation mode shown cannot generate a certain positive second-largest line voltage value, simply change... Figure 7The sequence of the positive and negative half-switching cycles, such as the operating mode sequence in sector 2, is: maximum positive line voltage → zero output freewheeling phase → maximum negative line voltage → second maximum negative line voltage → zero output freewheeling phase. Although the order of action needs to change in different sectors, the duration of different switching states is the same within the switching cycle.
[0076] ④ Calculate the duration of each mode
[0077] Once the operating mode and its corresponding switching state are determined, the DLM strategy uses the absolute value of the minimum phase voltage and the absolute value of the intermediate phase voltage to obtain the duration of different switching states. The calculation formula is as follows:
[0078]
[0079] In the formula, T s The switching period is denoted by m, where m is the modulation coefficient value, and |u min | and |u med | represents the absolute values of the minimum and second-largest phase voltages within the input sector (e.g., if |u exists in sector 1) min |=|u b | and |u med |=|u c Other sectors can also be based on Figure 6 (Obtained). T x T y T0 and T1 represent the total duration of the maximum output line voltage state, the second maximum output line voltage state, and the freewheeling phase, respectively.
[0080] In addition, in order to achieve volt-second balance of the high-frequency transformer after fault tolerance, according to Figure 7 The five-segment structure designed in the middle requires further calculation of the duration of different states within the switching cycle. Based on the constraint that the volt-second product of the positive and negative half-switching cycles is equal, the formulas for calculating the duration of each mode are as follows:
[0081]
[0082] The duration of each operating mode can be obtained by substituting the absolute values of the input phase voltage and line voltage within the corresponding sector into equation (3). Taking sector 1 as an example, a detailed schematic diagram of the operating modes is shown below. Figures 8-12 As shown below, the durations of the five modes and their specific analysis processes are presented.
[0083] 1. Operating Mode 1 (t0~t1):
[0084] The operational status of this work phase is as follows: Figure 8 As shown, at this time, the switching transistor S 14i and bidirectional switch S 23With the circuit turned on and all other switches off, the primary voltage of the high-frequency transformer is:
[0085] u p =u ll_max =u ac (4)
[0086] The duration of this phase is:
[0087]
[0088] 2. Operating Mode 2 (t1~t2):
[0089] The operational status of this work phase is as follows: Figure 9 As shown, this is currently in the positive half-switching cycle, and the switching transistor S... 14i and bidirectional switch S 22 With the circuit turned on and all other switches turned off, the voltage on the primary side of the high-frequency transformer is...
[0090] u p =u ll_med =u ab (6)
[0091] The duration of this phase is
[0092] T mode2 =T y =mT s |u b | / u im (7)3. Operating Mode 3 (t2~t3):
[0093] The operational status of this work phase is as follows: Figure 10 As shown, this is currently in the positive half-switching cycle and the freewheeling phase, and the switching transistor S... 14i and bidirectional switch S 21 With the circuit turned on and all other switches turned off, the voltage on the primary side of the high-frequency transformer is...
[0094] u p =0 (8)
[0095] The duration of this phase is
[0096] T mode3 =(T s -mT s |u b | / u im -mT s |u c | / u im ) / 2 (9)4、Running Mode 4 (t3~t4):
[0097] The operational status of this work phase is as follows: Figure 11As shown, this is the negative half-switching cycle, and the switching transistor S... 24i and bidirectional switch S 21 With the circuit turned on and all other switches turned off, the voltage on the primary side of the high-frequency transformer is...
[0098] u p =-u ll,max =u ca (10)
[0099] The duration of this phase is
[0100]
[0101] 5. Operating Mode 5 (t4~t5):
[0102] The operational status of this work phase is as follows: Figure 12 As shown, at this time, it is in the negative half-switching cycle and the freewheeling phase, and the switching transistor S... 24i and bidirectional switch S 23 With the circuit turned on and all other switches turned off, the voltage on the primary side of the high-frequency transformer is...
[0103] u p =0 (12)
[0104] The duration of this phase is
[0105] T mode5 =(T s -mT s |u b | / u im -mT s |u c | / u im ) / 2 (13)
[0106] After the above 5 operating modes, the following can be formed: Figure 7 The five-segment operation mode is shown. When operating in other sectors, the duration of different operating modes can also be calculated according to formula (3), but attention should be paid to the relationship between the logic values of line voltage and phase voltage in different sectors. After the duration of different modes in all sectors is calculated, it can be further combined with the corresponding switching state to generate drive pulses to control the switching tube to turn on and off, so as to realize the dynamic volt-second balance of the high-frequency transformer in the switching cycle and ensure the safe and stable operation of the proposed high-frequency chain AC-DC matrix converter fault-tolerant system.
[0107] Those skilled in the art will recognize that the units of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the invention.
[0108] In the embodiments provided by the present invention, it should be understood that the division of units is only a logical functional division. In actual implementation, there may be other division methods, such as multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored.
[0109] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.
[0110] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.
[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A fault-tolerant system for switching transistors in a high-frequency AC-DC matrix converter, characterized in that, It includes a switch array consisting of 6 bidirectional switches, a downstream diode rectifier bridge, and 2 bidirectional switches. The switch array consisting of 6 bidirectional switches converts three-phase power frequency AC to single-phase high-frequency AC. The high-frequency transformer is responsible for high-frequency energy transmission and electrical isolation. The downstream diode rectifier bridge converts single-phase high-frequency AC to DC output to the load. The 2 bidirectional switches have opposite series configurations and are connected to the p-terminal and n-terminal of the transformer, respectively, and are connected to the abc input through 6 diodes.
2. The fault-tolerant system for switching transistors of a high-frequency AC-DC matrix converter according to claim 1, characterized in that, The diode operates at the input power frequency.
3. The fault-tolerant system for switching transistors of a high-frequency AC-DC matrix converter according to claim 1, characterized in that, The fault-tolerant system for switching transistors in a high-frequency AC-DC matrix converter uses diodes to achieve fault-tolerant operation and does not require additional trigger signals.
4. A fault-tolerant method for switching transistors in a high-frequency chain AC-DC matrix converter, applied to the fault-tolerant system for switching transistors in a high-frequency chain AC-DC matrix converter as described in any one of claims 1-3, characterized in that, When one of the switching transistors experiences an open-circuit fault, all other switching transistors in the upper arm and the redundant switching transistors are turned off, thereby achieving fault-tolerant operation through topology reconfiguration; where: When a fault occurs in the upper arm, all upper arm switching transistors and redundant switching transistors will be turned off. When a fault occurs in the lower bridge arm, turn off all the lower bridge arm switches and redundant switches.
5. The fault-tolerant method for switching transistors in a high-frequency AC-DC matrix converter according to claim 4, characterized in that, The fault-tolerant system employs a two-line voltage modulation strategy.
6. The fault-tolerant method for switching transistors in a high-frequency AC-DC matrix converter according to claim 4, characterized in that, Includes the following parts: Define the input phase voltage of the high-frequency chain AC-DC matrix converter, divide the input period into 12 sectors, and use the DLM strategy to synthesize the output voltage using the maximum and second largest values of the input line voltage, and the output line voltage is zero during the freewheeling phase. During the switching cycle, the system adopts an alternating positive and negative operating mode. By setting different switching states, different positive output line voltage values, negative output line voltage values, and zero voltage output values can be obtained in each sector. Five operating modes are designed within the switching cycle, each corresponding to a different output line voltage. The order is as follows: maximum positive line voltage → second maximum positive line voltage → zero output freewheeling stage → maximum negative line voltage → zero output freewheeling stage. Once the operating mode and its corresponding switching state are determined, the DLM strategy uses the absolute value of the minimum phase voltage and the absolute value of the intermediate phase voltage to obtain the duration of different switching states. Further calculate the duration of different states within the switching cycle.
7. A fault-tolerant method for switching transistors in a high-frequency AC-DC matrix converter according to claim 6, characterized in that, Define the input phase voltage of the high-frequency AC-DC matrix converter as: In the formula, u im θ represents the input voltage amplitude, and θ represents the sector angle.
8. A fault-tolerant method for switching transistors in a high-frequency AC-DC matrix converter according to claim 7, characterized in that, The duration of different switching states is obtained using the absolute values of the minimum and intermediate phase voltages, and the calculation formula is as follows: In the formula, T s The switching period is denoted by m, where m is the modulation coefficient value, and |u min | and |u med | represents the absolute values of the minimum and second-largest phase voltages within the input sector, T x T y T0 and T1 represent the total duration of the maximum output line voltage state, the second maximum output line voltage state, and the freewheeling phase, respectively.
9. A fault-tolerant method for switching transistors in a high-frequency AC-DC matrix converter according to claim 8, characterized in that, Based on the constraint that the volt-second product of the positive half-switching period and the negative half-switching period is equal, the formulas for calculating the duration of each mode are as follows: By substituting the absolute values of the input phase voltage and line voltage within the corresponding sector, the duration of each operating mode can be obtained.