Isolation matrix converter and control method

Abstract

The present application discloses a separation matrix converter and a control method, the converter includes a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor, the bidirectional switch module is connected in series with the bridge arm capacitor to form a bridge arm of the converter, each bridge arm of the converter includes at least one bidirectional switch module, the primary winding of the transformer is connected in series with the resonant inductor and the resonant capacitor and then connected to both ends of the bridge arm of the converter, the bidirectional switch module includes a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forms two bridge arms of the module, both ends of the clamp capacitor are connected to both ends of the two bridge arms of the module, the clamp capacitor forms a clamp absorption circuit with the two upper bridge arms or the two lower bridge arms of the two bridge arms, the bidirectional switch unit includes at least two controllable switching tubes, the clamp capacitor suppresses voltage spikes generated when the switching tubes in the bidirectional switch module are operated, thereby protecting the switching tubes, further protecting the safety of the entire converter, and improving the reliability of the entire converter.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to a Chinese patent application bearing application number 202210565545.1 and entitled "Isolation matrix converter and control method", filed with the State Intellectual Property Office of the People's Republic of China on May 23, 2022, the entire contents of which are incorporated herein by reference. [Technical field] The present application relates to the technical field of power electronics, and in particular to an isolated matrix converter and a control method. [Background technology]

[0002] The isolation matrix converter generally includes a bidirectional switch and a transformer, and the input end of the transformer further includes a resonant circuit, which generally can realize AC to AC conversion and can also realize AC to DC conversion, for example, the input is AC and the output is DC.

[0003] Please refer to FIG. 1, which is a schematic diagram of an isolated matrix converter provided by the prior art.

[0004] As shown in Figure 1, the input terminal of the separation matrix converter is connected to three-phase AC, and each phase of the separation matrix converter includes a bidirectional switch, that is, the anti-parallel diodes of the two switching tubes connected in series are in the opposite direction, allowing the current to flow in both directions. The primary winding of the transformer is connected in series with an inductor and a capacitor to form an LLC resonance. However, the voltage clamp of the bidirectional switch of the separation matrix converter shown in Figure 1 is the line voltage of the AC power, and when passing through the resonance region, the switching tube will have a large current switching, so the voltage spike may be too high and cause an overvoltage failure of the switching tube. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of this, the embodiments of the present application provide an isolated matrix converter and a control method that can suppress voltage spikes caused when a switching tube operates and protect the switching tube. [Means for solving the problem]

[0006] The present application provides an isolated matrix converter, the isolated matrix converter including a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor; The bidirectional switch module is connected in series with the bridge arm capacitor to form a bridge arm of a converter, and each bridge arm of the converter includes at least one bidirectional switch module; A primary winding of the transformer is connected in series with the resonant inductor and the resonant capacitor, and then connected to both ends of a bridge arm of the converter; The bidirectional switch module includes a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forms two bridge arms of the module, both ends of the clamp capacitor are connected to both ends of the two bridge arms of the module, the clamp capacitor forms a clamp absorption circuit with two upper bridge arms or two lower bridge arms of the two bridge arms, the bidirectional switch unit includes at least two controllable switching tubes, The clamp capacitor is used to suppress voltage spikes that occur when the switching tube in the bidirectional switch module operates.

[0007] Preferably, when the bidirectional switch module includes two controllable switching tubes, the two controllable switching tubes are located in the same two upper bridge arms or the same two lower bridge arms.

[0008] Preferably, the bidirectional switch module includes four controllable switching tubes, including a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube; a first end of the first switching tube and a first end of the third switching tube are both connected to a first end of the clamp capacitor, a second end of the second switching tube and a second end of the fourth switching tube are both connected to a second end of the clamp capacitor, a second end of the first switching tube is connected to the first end of the second switching tube, and a second end of the third switching tube is connected to the first end of the fourth switching tube; A common end of the first switching tube and the second switching tube is a first end of the bidirectional switch module, and a common end of the third switching tube and the fourth switching tube is a second end of the bidirectional switch module.

[0009] Preferably, the bidirectional switch module includes three controllable switching tubes, namely, a first switching tube, a second switching tube, a third switching tube, and a diode, namely, a first diode; The first switching tube and the second switching tube are connected in series to form a first bridge arm of the module, and the third switching tube and the first diode are connected in series to form a second bridge arm of the module.

[0010] Preferably, the bidirectional switch module includes two controllable switching tubes, a first switching tube and a second switching tube, and two diodes, a first diode and a second diode; The first switching tube and the first diode are connected in series to form a first bridge arm of the module, and the second switching tube and the second diode are connected in series to form a second bridge arm of the module.

[0011] Preferably, the converter comprises at least two bidirectional switch modules connected in series; The converter further includes a controller, and the controller specifically controls and operates a controllable switching tube in the bidirectional switch unit such that, when a voltage of the clamp capacitor is greater than a first preset voltage, the clamp capacitor is discharged until the voltage of the clamp capacitor is less than a second preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules, and the first preset voltage is greater than the second preset voltage.

[0012] Preferably, the converter comprises at least two bidirectional switch modules connected in series; The converter further includes a controller, and the controller specifically controls and operates a controllable switching tube in the bidirectional switch unit to charge the clamp capacitor until the voltage of the clamp capacitor is greater than a fourth preset voltage when the voltage of the clamp capacitor is less than a third preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules; The third preset voltage is less than the fourth preset voltage.

[0013] Preferably, when the isolated matrix converter is a three-phase isolated matrix converter, each phase of the three-phase isolated matrix converter includes at least one of the bidirectional switch modules; The converter further includes a controller, and the controller further controls the switching tube that is not subjected to a voltage stress of a phase having a highest absolute value of a phase voltage to always be on, and the switching tube that is subjected to the voltage stress of the highest phase to perform a switching operation at a preset duty ratio; The controller further controls the switching tube of the phase having the second highest absolute value of the phase voltage, which is not subjected to voltage stress when the switching tube of the highest phase is turned on, to be turned on before the bidirectional switch module of the highest phase is turned off, and the switching tube of the second highest phase subjected to voltage stress is turned on after the bidirectional switch module of the highest phase is turned off; The controller further controls so that the switching tube that is not subjected to voltage stress when the bidirectional switch module of the second highest phase, which is the phase having the smallest absolute value of the phase voltage, is turned on is turned on before the bidirectional switch module of the second highest phase is turned off, and the switching tube that is subjected to voltage stress is turned on after the bidirectional switch module of the second highest phase is turned off.

[0014] Preferably, when each of the converter bridge arms includes a plurality of the bidirectional switch units, the plurality of the bidirectional switch units are connected in series.

[0015] Preferably, the secondary winding of the transformer is connected to a rectifier bridge, the rectifier bridge including at least one of a diode or a controllable switching tube.

[0016] Preferably, the transformer includes a plurality of secondary windings, each secondary winding being connected to a corresponding rectifier bridge.

[0017] The present application further provides a control method for a separation matrix converter, the separation matrix converter including a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor, the bidirectional switch module is connected in series with the bridge arm capacitor to form a bridge arm of the converter, each bridge arm of the converter includes at least one bidirectional switch module, a primary winding of the transformer is connected in series with the resonant inductor and the resonant capacitor and then connected to both ends of the bridge arm of the converter, the bidirectional switch module includes a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forms two bridge arms of the module, both ends of the clamp capacitor are connected to both ends of the two bridge arms of the module, the clamp capacitor forms a clamp absorption circuit with two upper bridge arms or two lower bridge arms of the two bridge arms, the bidirectional switch unit includes at least two controllable switching tubes, The method comprises: controlling and operating a switching tube in the bidirectional switch module; and controlling the clamp capacitor to suppress voltage spikes during operation of a switching tube in the bidirectional switch module.

[0018] Preferably, when the bidirectional switch module includes two controllable switching tubes, the two controllable switching tubes are located in the same two upper bridge arms or the same two lower bridge arms.

[0019] Preferably, the bidirectional switch module includes four controllable switching tubes, including a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube; a first end of the first switching tube and a first end of the third switching tube are both connected to a first end of the clamp capacitor, a second end of the second switching tube and a second end of the fourth switching tube are both connected to a second end of the clamp capacitor, a second end of the first switching tube is connected to the first end of the second switching tube, and a second end of the third switching tube is connected to the first end of the fourth switching tube; A common end of the first switching tube and the second switching tube is a first end of the bidirectional switch module, and a common end of the third switching tube and the fourth switching tube is a second end of the bidirectional switch module.

[0020] Preferably, the converter comprises at least two bidirectional switch modules connected in series; The method further includes controlling and operating a controllable switching tube in the bidirectional switch unit to discharge the clamp capacitor until the voltage of the clamp capacitor is less than a second preset voltage when the voltage of the clamp capacitor is greater than a first preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules, wherein the first preset voltage is greater than the second preset voltage.

[0021] Preferably, the converter comprises at least two bidirectional switch modules connected in series; When the voltage of the clamp capacitor is less than a third preset voltage, controlling and operating a controllable switching tube in the bidirectional switch unit to charge the clamp capacitor until the voltage of the clamp capacitor is greater than a fourth preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules; The third preset voltage is less than the fourth preset voltage.

[0022] Preferably, when the isolated matrix converter is a three-phase isolated matrix converter, each phase of the three-phase isolated matrix converter includes at least one of the bidirectional switch modules; The method comprises: A step of controlling so that a switching tube that is not subjected to a voltage stress of a phase having the highest absolute value of a phase voltage is always on, and a switching tube that is subjected to the voltage stress of the highest phase performs a switching operation at a preset duty ratio; A step of controlling the switching tube of the phase having the second highest absolute value of the phase voltage, which is not subjected to voltage stress when the switching tube of the highest phase is turned on, to be turned on before the bidirectional switch module of the highest phase is turned off, and the switching tube of the second highest phase subjected to voltage stress is turned on after the bidirectional switch module of the highest phase is turned off; The method further includes a step of controlling so that the switching tube that is not subjected to voltage stress when the bidirectional switch module of the second highest phase, which is the phase having the smallest absolute value of the phase voltage, is turned on is turned on before the bidirectional switch module of the second highest phase is turned off, and the switching tube that is subjected to voltage stress is turned on after the bidirectional switch module of the second highest phase is turned off.

[0023] Thus, the embodiment of the present application has the following beneficial effects: The separation matrix converter includes a bidirectional switch module, the bidirectional switch module including a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forms two bridge arms of the module, both ends of the clamp capacitor are connected to both ends of the two bridge arms of the module, the clamp capacitor forms a clamp absorption circuit with the two upper bridge arms or the two lower bridge arms of the two bridge arms, the bidirectional switch unit includes at least two controllable switching tubes, and the clamp capacitor can suppress voltage spikes generated by the switching tubes during the operation process, thereby protecting the switching tubes, further protecting the safety of the entire converter, and improving the reliability of the entire converter. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram of an isolated matrix converter provided by the prior art; [Diagram 2] FIG. 2 is a schematic diagram of an isolated matrix converter provided by an embodiment of the present application. [Diagram 3] FIG. 13 is a schematic diagram of yet another isolated matrix converter provided by an embodiment of the present application. [Figure 4] FIG. 2 is a schematic diagram of a bidirectional switch module provided by an embodiment of the present application. [Diagram 5] FIG. 13 is a schematic diagram of yet another bidirectional switch module provided by an embodiment of the present application. [Figure 6] FIG. 13 is a schematic diagram of another bidirectional switch module provided by an embodiment of the present application. [Figure 7] FIG. 13 is a schematic diagram of another bidirectional switch module provided by an embodiment of the present application. [Figure 8] FIG. 13 is a schematic diagram of yet another isolated matrix converter provided by an embodiment of the present application. [Figure 9] FIG. 2 is a schematic diagram of another isolated matrix converter provided by an embodiment of the present application. [Figure 10] 1 is an oscillogram of a three-phase AC voltage provided by an embodiment of the present application. [Figure 11] FIG. 10 is a driving timing diagram of a bidirectional switch module of the isolated matrix converter provided by an embodiment of the present application. [Figure 12A] FIG. 2 is a diagram illustrating the operation principle of a switching operation in a bidirectional switch module provided by an embodiment of the present application. [Figure 12B] FIG. 2 is a diagram illustrating the operation principle of a switching operation in a bidirectional switch module provided by an embodiment of the present application. [Figure 12C] FIG. 2 is a diagram illustrating the operation principle of a switching operation in a bidirectional switch module provided by an embodiment of the present application. [Figure 12D] FIG. 2 is a diagram illustrating the operation principle of a switching operation in a bidirectional switch module provided by an embodiment of the present application. [Figure 13] FIG. 13 is a voltage stress schematic diagram of the off process of Q4 provided by an embodiment of the present application. [Figure 14] 1 is a flowchart of a control method for an isolated matrix converter provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In order to enable those skilled in the art to better understand the technical solution provided by this application, a specific application scenario will be first introduced below.

[0026] The isolated matrix converter provided by the embodiment of the present application may be a DC-AC-DC converter or an AC-AC-DC converter, i.e., the input may be DC or AC, but generally, the output is DC, and the input may be three-phase or one-phase, and the output may be one-phase, i.e., it outputs DC to a load.

[0027] The separated matrix converter provided by the embodiments of the present application is not limited to a specific application scenario. For example, when the transformer of the separated matrix converter includes multiple secondary windings, each secondary winding can be connected to a rectifier bridge, and the output of each rectifier bridge can be connected to a load, for example, for charging new energy vehicles, that is, applied to a charging pile scenario, and each output can be connected to a charging gun to provide DC charging for the new energy vehicles.

[0028] The isolation matrix converter may also provide power for other electrical equipment, for example machine room electrical uses such as servers.

[0029] Furthermore, if a controllable switching tube is included in the rectifier bridge connected to the secondary winding of the transformer of the isolated matrix converter, the isolated matrix converter may be a bidirectional converter, i.e., energy can flow in both directions, for example converting DC to AC or AC to DC.

[0030] Converter Example The isolated matrix converter provided by the embodiment of the present application will be described in detail below with reference to the accompanying drawings, and a three-phase AC input will be taken as an example.

[0031] Please refer to FIG. 2, which is a schematic diagram of an isolated matrix converter provided by an embodiment of the present application.

[0032] The isolated matrix converter provided in this embodiment includes a bidirectional switch module 100, a transformer Tx, a resonant inductor Lr, a resonant capacitor Cr, and a bridge arm capacitor. As shown in FIG. 2 , taking a three-phase AC input as an example, it corresponds to a three-phase bridge arm, where the bridge arm capacitor of phase A is CA, the bridge arm capacitor of phase B is CB, and the bridge arm capacitor of phase C is CC.

[0033] The bidirectional switch module 100 is connected in series with the bridge arm capacitor to form a bridge arm of the converter, and each bridge arm of the separation matrix converter includes at least one bidirectional switch module, and the embodiment of the present application does not specifically limit the number of bidirectional switch modules 100 included in each phase bridge arm, and in FIG. 2, each phase bridge arm includes a plurality of bidirectional switch modules 100 connected in series, for example, the n bidirectional switch modules of the A-phase bridge arm are MA1 to MAn, and by the same principle, the n bidirectional switch modules of the B-phase bridge arm are MB1 to MBn, and the n bidirectional switch modules of the C-phase bridge arm are MC1 to MCn, where n is an integer of 1 or more.

[0034] The upper half bridge arm of each phase in the isolation matrix converter is a bidirectional switch module, and the lower half bridge arm is a bridge arm capacitor, and the bidirectional switch module is connected in series with the bridge arm capacitor to form the entire bridge arm of each phase.

[0035] The primary winding of the transformer is connected in series to the resonant inductor Lr and the resonant capacitor Cr and connected to both ends of the bridge arm of the isolation matrix converter, and the primary winding of the transformer is connected in series to the resonant inductor Lr and the resonant capacitor Cr to form an LLC series resonance.

[0036] The bidirectional switch module includes a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forms two bridge arms of the module, both ends of the clamp capacitor are connected to both ends of the two bridge arms of the module, the clamp capacitor forms a clamp absorption circuit with the two upper bridge arms or the two lower bridge arms of the two bridge arms, the bidirectional switch unit includes at least two controllable switching tubes, The clamp capacitor is used to suppress voltage spikes generated by the switching tube in the bidirectional switch unit during its operation.

[0037] The bidirectional switch module in the isolated matrix converter provided by the embodiment of the present application needs to include at least two controllable switching tubes, that is, it can include four, three, or two, but if it includes only one controllable switching tube, it cannot realize the charging and discharging of the clamp capacitor. If the bidirectional switch module includes two controllable switching tubes, the two controllable switching tubes need to be located in the same two upper bridge arms or two lower bridge arms.

[0038] 2, the bidirectional switch module is taken as an example to include four controllable switching tubes, namely, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4. To form a freewheeling loop, each switching tube includes an anti-parallel diode, that is, the anti-parallel diode of the first switching tube Q1 is D1, the anti-parallel diode of the second switching tube Q2 is D2, the anti-parallel diode of the third switching tube Q3 is D3, and the anti-parallel diode of the fourth switching tube Q4 is D4.

[0039] A first end of the first switching tube Q1 and a first end of the third switching tube Q3 are both connected to a first end of the clamp capacitor C1, a second end of the second switching tube Q2 and a second end of the fourth switching tube Q4 are both connected to a second end of the clamp capacitor C1, a second end of the first switching tube Q1 is connected to a first end of the second switching tube Q2, and a second end of the third switching tube Q3 is connected to a first end of the fourth switching tube Q4; The common end of the first switching tube Q1 and the second switching tube Q2 is a first end of the bidirectional switch module, and the common end of the third switching tube Q3 and the fourth switching tube Q4 is a second end of the bidirectional switch module.

[0040] 2, the output end of the isolated matrix converter is connected to a full-bridge rectifier bridge, and the rectifier bridge includes four diodes, namely, the fourth diode D4, the fifth diode D5, the sixth diode D6, and the seventh diode D7, the fourth diode D4 and the fifth diode D5 are connected in series to form one bridge arm of the rectifier bridge, and the sixth diode D6 and the seventh diode D7 are connected in series to form the other bridge arm of the rectifier bridge. The output end of the rectifier bridge is connected to the output capacitor Cbus.

[0041] 2 only shows that the rectifier bridge includes diodes, the rectifier bridge can also include controllable switching tubes or a mixture of controllable switching tubes and diodes, when the bridge arm of the rectifier bridge includes a controllable switching tube, the isolated matrix converter can realize bidirectional conversion of power, i.e., can realize conversion from DC to AC. One side of the rectifier bridge is the input end.

[0042] In FIG. 2, if each phase bridge arm includes only one bidirectional switch module, as shown in FIG. 3, which is a schematic diagram of yet another isolated matrix converter provided by an embodiment of the present application.

[0043] In FIG. 3, each phase bridge arm includes only one bidirectional switch module, and the rest is the same as FIG. 2, and will not be described here.

[0044] The bidirectional switch modules in FIG. 2 and FIG. 3 are all controllable switching tubes. Below, we will introduce a case where the controllable switching tubes and diodes are mixed.

[0045] In the isolated matrix converter provided by the embodiment of the present application, the bidirectional switch module includes two controllable switching tubes, a first switching tube and a second switching tube, and two diodes, a first diode and a second diode, the first switching tube and the first diode are connected in series to form a first bridge arm of the module, and the second switching tube and the second diode are connected in series to form a second bridge arm of the module. The first switching tube and the second switching tube are merely names of the switching tubes, and do not specifically indicate their positions.

[0046] The embodiment of the present application does not specifically limit the positions of the two diodes, and for example, they may be located on two upper half bridge arms at the same time, or they may be located on two lower half bridge arms at the same time.

[0047] Please refer to FIG. 4, which is a schematic diagram of a bidirectional switch module provided by an embodiment of the present application.

[0048] In Fig. 4, the two upper half bridge arms are controllable switching tubes, and the two lower half bridge arms are diodes as an example, that is, Q1 and Q3 are both controllable switching tubes, D2 and D4 are both diodes, and Q1 includes an anti-parallel diode D1, and Q3 includes an anti-parallel diode D3. A clamp capacitor C1 is connected to both ends of the bridge arms of the module.

[0049] Please refer to FIG. 5, which is a schematic diagram of yet another bi-directional switch module provided by an embodiment of the present application.

[0050] 5, two upper half bridge arms are diodes, and two lower half bridge arms are controllable switching tubes. That is, Q12 and Q14 are both controllable switching tubes, D11 and D13 are both diodes, and Q12 includes an anti-parallel diode D12 and Q14 includes an anti-parallel diode D14. A clamp capacitor C1 is connected to both ends of the bridge arms of the module.

[0051] 4 and 5 both introduce the case where the bidirectional switch module includes two controllable switching tubes and two diodes, and hereinafter, the drawings will be combined to introduce the case where the bidirectional switch module includes three controllable switching tubes and one diode, that is, the bidirectional switch module includes three controllable switching tubes, namely, a first switching tube, a second switching tube and a third switching tube, and one diode, namely, a first diode, and the first switching tube and the second switching tube are connected in series to form a first bridge arm of the module, and the third switching tube and the first diode are connected in series to form a second bridge arm of the module.

[0052] Please refer to FIG. 6, which is a schematic diagram of another bi-directional switch module provided by an embodiment of the present application.

[0053] In Fig. 6, the left bridge arm includes two controllable switching tubes Q1 and Q2, the upper half bridge arm on the right side includes a controllable switching tube Q3, and the lower half bridge arm on the right side includes a diode D4. The anti-parallel diode of Q1 is D1, the anti-parallel diode of Q2 is D2, and the anti-parallel diode of Q3 is D3. A clamp capacitor C1 is connected across both ends of the bridge arm of the module.

[0054] Please refer to FIG. 7, which is a schematic diagram of another bi-directional switch module provided by an embodiment of the present application.

[0055] In Figure 7, the left bridge arm includes two controllable switching tubes Q1 and Q2, the upper half bridge arm on the right side includes a diode D3, and the lower half bridge arm on the right side includes a controllable switching tube Q4. The anti-parallel diode of Q1 is D1, the anti-parallel diode of Q2 is D2, and the anti-parallel diode of Q4 is D4. A clamp capacitor C1 is connected across both ends of the bridge arm of the module.

[0056] It should be noted that Figures 6 and 7 only illustrate the position of one diode, and the diode can be located in any of the four half-bridge arms. Figures 6 and 7 include three controllable switching tubes, which ensures that the voltage of each bidirectional switch module can be controlled, and in particular, the duty ratio of the controllable switching tube can be adjusted to adjust the voltage of the module.

[0057] The secondary winding of the transformer is connected to a rectifier bridge, which includes at least one of a diode or a controllable switching tube.

[0058] When the rectifier bridge includes a diode, refer to FIG. 3, and the transformer in FIG. 3 has only one secondary winding. Below, we will introduce the case where the transformer includes multiple secondary windings.

[0059] The transformer includes multiple secondary windings, each of which is connected to a corresponding rectifier bridge. Since the transformer includes multiple secondary windings, it can correspond to multiple output ports, and the post-converter can be increased to flexibly adjust the voltage and power of each output port.

[0060] Please refer to FIG. 8, which is a schematic diagram of yet another isolated matrix converter provided by an embodiment of the present application.

[0061] 8, the transformer includes n secondary windings, where n is an integer greater than 1, and each winding is connected to a corresponding rectifier bridge. For example, the first rectifier bridge includes four diodes D5-D8, and the output capacitor of the first rectifier bridge is Cbus1. The nth rectifier bridge includes four diodes Dn5-Dn8, and the output capacitor of the nth rectifier bridge is Cbusn.

[0062] The isolated matrix converter shown in Figure 8 can be applied to the charging scenario of electric vehicles, and each rectifier bridge corresponds to one charging gun to charge for electric vehicles. For example, the input voltage of the isolated matrix converter can be AC ​​10kV or AC 35kV.

[0063] The isolated matrix converters introduced above are all exemplified by the rectifier bridge including diodes. Below, we will introduce the case where the rectifier bridge includes a controllable switching tube.

[0064] Please refer to FIG. 9, which is a schematic diagram of another isolated matrix converter provided by an embodiment of the present application.

[0065] 9 includes four controllable switching tubes, namely Q5 to Q8, and each controllable switching tube includes a corresponding anti-parallel diode, namely the anti-parallel diodes of Q5 to Q8 are D5 to D8, respectively. The output capacitor of the rectifier bridge is C1.

[0066] The isolated matrix converter shown in FIG. 9 is connected to the photovoltaic array on the right side, that is, the right side is the input end and the left side is the AC output end, which realizes AC grid connection of photovoltaic power generation.

[0067] The embodiments of the present application do not specifically limit the application scenario of the isolated matrix converter, do not limit the number of bidirectional switch modules, do not limit the number of rectifier bridges and the type of switching tube in the rectifier bridge, and do not limit the type of switching tube in each bidirectional switch module. The various implementation methods introduced above can be freely combined.

[0068] The working principle of the separation matrix converter provided in the embodiment of the present application will be described in detail below with reference to the drawings. The circuit of the separation matrix converter is shown in FIG. 3, and the bidirectional switch module is taken as an example of a controllable switching tube.

[0069] Please refer to FIG. 10, which is an oscillogram of a three-phase AC voltage provided by an embodiment of the present application.

[0070] If the voltage waveform of a three-phase power grid is as shown in Figure 10, the A, B, and C phases differ by 120 degrees in sequence, and when the angle is between 0 and 30 degrees, the absolute value of the A phase voltage is the largest, the absolute value of the B phase is the smallest, and the absolute value of the C phase is the second smallest, and the A phase voltage is opposite to the B phase voltage and the C phase voltage. As shown in the circuit of Figure 3, Q2 and Q4 in the bidirectional switch module are the main switching tubes, and when Q1 and Q3 are turned off, the switching timing of Q2 and Q4 tubes during normal operation is as shown in Figure 11.

[0071] Please refer to FIG. 11, which is a driving timing diagram of a bidirectional switch module of an isolated matrix converter provided by an embodiment of the present application.

[0072] When the isolated matrix converter is a three-phase isolated matrix converter, each phase of the three-phase isolated matrix converter includes at least one bidirectional switch module; The converter further includes a controller. When the three-phase voltages shown in Fig. 10 are combined, the absolute value of the A-phase voltage is the highest, the absolute value of the C-phase voltage is the second highest, and the absolute value of the B-phase voltage is the smallest. In Fig. 11, Qa2 indicates the drive timing of Q2 in the A-phase, Qa4 indicates the drive timing of Q4 in the A-phase, Qc2 indicates the drive timing of Q2 in the C-phase, Qc4 indicates the drive timing of Q4 in the C-phase, Qb2 indicates the drive timing of Q2 in the B-phase, and Qb4 indicates the drive timing of Q4 in the B-phase.

[0073] The controller further controls the switching tube that is not subjected to the voltage stress of the phase having the highest absolute value of the phase voltage to always be on, and the switching tube that is subjected to the voltage stress of the highest phase to operate at a preset duty ratio or a preset switch frequency, for example, the duty ratio is 50%.

[0074] The controller further controls the switching tube of the phase having the second highest absolute value of the phase voltage, which is not subjected to voltage stress when the switching tube of the highest phase is turned on, to turn on before the bidirectional switch module of the highest phase is turned off, and the switching tube of the second highest phase subjected to voltage stress is turned on after the bidirectional switch module of the highest phase is turned off, and both switches are turned off simultaneously, and the Q4 duty ratio is the actual duty ratio of the unit, and the duty ratio is determined according to the relationship between the phase voltage value and the highest phase voltage.

[0075] The controller further controls the switching tube that is not voltage-stressed when the bidirectional switch module of the second highest phase, which is the phase with the smallest absolute value of the phase voltage, is turned on before the bidirectional switch module of the second highest phase is turned off, and the switching tube that is voltage-stressed is turned on after the bidirectional switch module of the second highest phase is turned off. In addition, both switches are turned off at the same time, and the Q2 duty ratio is the actual duty ratio of the unit, and the duty ratio is determined according to the relationship between the phase voltage value and the highest phase voltage value.

[0076] The specific positions of the above switching tubes in the bidirectional switch module can be determined according to the actual topology structure, and different bidirectional switch modules may show different switching tubes, for example, when the upper two half-bridge arms include controllable switching tubes, it is different from when the lower two half-bridge arms include controllable switching tubes. However, regardless of the structure of the bidirectional switch module, the above are divided into switching tubes that are subjected to voltage stress and switching tubes that are not subjected to voltage stress.

[0077] For ease of understanding, the absolute value of the phase voltage of phase A is the highest in the range of 0 to 30 degrees shown in FIG. 10 and will be taken as an example below.

[0078] The controller further controls the second switching tube Q2 of the phase with the highest absolute value of the phase voltage to be turned on, and the fourth switching tube Q4 of the highest phase to perform a switching operation with a preset duty ratio or a preset switching frequency, for example, the preset duty ratio is 50%; The fourth switching tube Q4 of the phase having the second highest absolute value of the phase voltage is turned on before the fourth switching tube Q4 of the highest phase is turned off, and the second switching tube Q2 of the phase having the second highest absolute value of the phase voltage is controlled to be turned on after the fourth switching tube Q4 of the second highest phase is turned off; The second switching tube Q2 of the phase having the smallest absolute value of the phase voltage is controlled to turn on before the second switching tube Q2 and fourth switching tube Q4 of the second highest phase are turned off, and the fourth switching tube Q4 of the phase having the smallest absolute value of the phase voltage is controlled to turn on after the second switching tube Q2 and fourth switching tube Q4 of the second highest phase are turned off.

[0079] The above Q2 and Q4 indicate the second and fourth switching tubes in each phase, and the numbers of the four switching tubes in each phase are the same and are distinguished only by different phases.

[0080] When the converter includes at least two bidirectional switch modules connected in series, the controller specifically controls and operates the controllable switching tube in the bidirectional switch unit such that, when the voltage of the clamp capacitor is greater than a first preset voltage, the clamp capacitor is discharged until the voltage of the clamp capacitor is less than a second preset voltage, and the first preset voltage is greater than the second preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules; When the converter includes at least two bidirectional switch modules connected in series, the controller specifically controls and operates the controllable switching tube in the bidirectional switch unit so that, when the voltage of the clamp capacitor is smaller than a third preset voltage, the clamp capacitor is charged until the voltage of the clamp capacitor is greater than a fourth preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules, and the third preset voltage is smaller than the fourth preset voltage; The second preset voltage is greater than the third preset voltage.

[0081] For the converter provided by this embodiment, when the converter includes at least two bidirectional switch modules connected in series, the operation of the controllable switching tube in the bidirectional switch module can be controlled to charge or discharge the clamp capacitor, and may further include modifying the voltage on the clamp capacitor to achieve voltage balance between the multiple series-connected bidirectional switch modules, and when the voltages are balanced, the voltage stresses of the switching tubes in the multiple bidirectional switch modules are uniform, so that the voltage stress experienced by the switching tube in one bidirectional switch module is not large and the voltage stress experienced by the switching tube in another bidirectional switch module is not small, thereby the switching tube can be better protected.

[0082] Please refer to FIG. 12A to FIG. 12D, which are operation principle diagrams of the switching operation in the bidirectional switch module provided by the embodiment of the present application.

[0083] As shown in Figures 12A to 12D, during the off process of the A-phase switching tube Q4 from 0 to 30 degrees, the working principle of the clamp capacitor C1 is that during the off process of Q4, the parasitic inductor of the loop may oscillate a high voltage spike at Q4, and due to the existence of C1, the voltage spike is limited to the voltage of C1, that is, C1 clamps the spike voltage and effectively suppresses the voltage spike.

[0084] In order to ensure that C1 can effectively protect the controllable switching tube, it is required that the voltage across C1 be controlled within a reasonable range. For example, the normal voltage is set to V0, and when the voltage is higher than the first preset voltage V1, the module enters the overvoltage discharge working mode, when the voltage is lower than the second preset voltage V2, the module exits the overvoltage discharge mode, when the voltage is lower than the third preset voltage V3, the module enters the low voltage charging mode, when the voltage is higher than the fourth preset voltage V4, the module exits the low voltage charging mode. Below, the working process of the clamp capacitor C1 in the charging and discharging mode is introduced when the A phase is at the maximum value (0-30 degrees), the middle value (30-60 degrees), and the minimum value (60-90 degrees) respectively.

[0085] From 0 to 30 degrees, when the voltage of the clamp capacitor C1 of the bidirectional switch module of phase A is lower than V2, the module enters bus undervoltage charging mode, in which the long-pass tube Q2 of the module is turned off, and the module will not start up Q4 when it needs to turn on Q4. The main power loop current charges C1. If the voltage across C1 of the module is higher than V4, the module will continue to enter the long-pass state in the next switching period Q2, and Q4 will switch according to the set logic. If the voltage of the absorbing clamp capacitor C1 of the module is higher than V1, the module enters bus overvoltage discharge mode, in which the long-pass tube Q2 of the module is turned off and Q1 is shut down when Q4 is on, and the loop current charges C1; when each phase bridge arm includes multiple bidirectional switch modules connected in series, when Q4 is turned off, Q1 is turned off and Q2 is turned on at the same time to reduce the voltage stress of other modules of phase A. It continues discharging in the next switching period, and when the voltage of C1 becomes lower than V2, it exits the discharging mode.

[0086] Between 30 and 60 degrees, when the voltage of the clamp capacitor C1 of the bidirectional switch module of A phase is lower than V3, the module enters the bus undervoltage charging mode; during normal operation, the module Q2 turns on at a certain time before the maximum phase Q4 turns off to prepare for the zero voltage turn-on of Q4; in charging mode, Q2 will not turn on, and Q4 will not turn on in this period, and the loop current will still charge C1; if the charging is not completed in this period, the charging will continue in the next switching period until the charging is completed. When the voltage of the absorbing clamp capacitor C1 of the module is higher than V1, the module enters the bus overvoltage discharging mode; when Q2 does not start up, and Q4 needs to start up normally, Q1 will start up when Q4 starts up, and the main loop current will discharge C1; but before the current reverses, the capacitor Cx needs to be discharged.

[0087] Between 60 and 90 degrees, when the voltage of the clamp capacitor C1 of the bidirectional switch module of A phase is lower than V3, the module enters the bus undervoltage charging mode, normally, Q4 turns on before Q2 and Q4 of the middle phase C phase turn on, so as to create a zero-voltage turn-on condition for Q2, and in the charging mode, Q4 and Q2 do not start up together in a cycle. When the voltage of the absorbing clamp capacitor C1 of the module is higher than V1, the module enters the bus overvoltage discharging mode, Q4 turns on normally, but when Q2 turns on normally, Q1 turns on instead of Q2, and at the time when Q2 and Q4 should be turned off normally, Q1 and Q4 are turned off, thereby realizing the discharge to C1.

[0088] Below, we will specifically explain the process by which C1 suppresses the voltage spike when Q4 is turned off.

[0089] In FIG. 12A, the A-phase current enters from Q4, flows through Q2 and D2, and flows out from the upper end of Q2. In this case, both Q1 and Q3 are turned off.

[0090] In Figure 12B, Q4 turns off, Q1 and Q3 remain off, and current charges the junction capacitor Co4 of Q4 and discharges the junction capacitor Co3 of Q3.

[0091] In FIG. 12C, Q4 turns off, Q1 and Q3 continue to remain off, and the voltage formed by the current in the junction capacitor Co4 of Q4 reaches the voltage across the clamp capacitor C1. In this case, Co3 discharges to 0, and then D3 turns on to suppress the spike in the voltage of Q4 and protect the safety of Q4.

[0092] In FIG. 12D, the current flows through the parasitic inductance of the loop (meaning the large loop of the entire isolation matrix converter), and after D3, C1, and D2 resonate to 0, it reverses and charges and discharges the junction capacitors (Co3 and Co4) of Q3 and Q4, until the total voltage of Q4 in all the series-connected bidirectional switch modules reaches the line voltage of the AC input, causing the voltage across Q4 to decrease and the voltage across Q3 to increase.

[0093] Without C1, the voltages of Co3 and Co4 would be large, which would require Q3 and Q4 to be subjected to high voltage stress, which would result in damage if the withstand voltage was exceeded.

[0094] In order to more clearly understand the effect of suppressing spike voltages during operation of the switching tube by the clamp capacitor of the bidirectional switch module in the isolated matrix converter provided by the present application, the following will be presented in detail in conjunction with oscillograms.

[0095] Please refer to FIG. 13, which is a voltage stress diagram of the turn-off process of Q4 provided by an embodiment of the present application.

[0096] 13, due to the presence of the clamp capacitor C1, there exists a flat plateau H in the voltage stress during the turn-off process of Q4, that is, the voltage is clamped, and without the clamp capacitor C1, a high spike voltage will appear during the turn-off process of Q4, which may affect Q4, for example, exceeding the withstand voltage of Q4 and causing damage to Q4. By the same principle, other switching tubes can be protected by C1 from the impact of spike voltage during the switching process.

[0097] The above embodiment is presented by taking the A phase as an example, the operation processes of the switching tubes of other phases and different phase sections are similar, and will not be described here in detail.

[0098] When the switching tubes in the bidirectional switch modules are of a non-fully controlled type (ie, including a combination of a controllable switching tube and a diode), the charge / discharge mode of each bidirectional switch module is controlled only in a specific phase section.

[0099] In the above-described solutions, Q2 and Q4 in the bidirectional switch module are described as the main switches. In actual use, Q1 and Q3 can be used as the main switches, and Q2 and Q4 can be used as the voltage adjusting switching tube of the clamp capacitor C1. The relevant timing needs to be adjusted accordingly, and no further details are given here.

[0100] In the isolated matrix converter provided by the embodiment of the present application, the bidirectional switch module includes a clamp capacitor, so that the clamp capacitor can be used to suppress the spike voltage of the switching tube during the switching process, thereby protecting the switching tube, and further protecting the safety of the entire converter and improving the reliability of the entire converter. In addition, the control of the charge mode and discharge mode of the clamp capacitor can be used to better control the voltage stress of the converter.

[0101] In addition, in the isolated matrix converter provided by the embodiments of the present application, each phase may include a plurality of bidirectional switch modules connected in series, in this way, when the voltage of the bridge arm is high, the voltage received by each bidirectional switch module can be reduced, which further contributes to the selection of the type of controllable switching tube in the bidirectional switch module, and reduces the cost of the converter.

[0102] The bidirectional switch module in the above embodiment is presented in the form of a bridge arm, that is, a two-level topology is taken as an example, and may also be designed as a three-level full bridge or multi-level topology such as I-NPC, A-NPC, etc.

[0103] Method Example Based on the isolated matrix converter provided by the above embodiment, the embodiment of the present application further provides a control method for the isolated matrix converter, which will be described in detail below in conjunction with the drawings.

[0104] Please refer to FIG. 14, which is a flow chart of a control method for an isolated matrix converter provided by an embodiment of the present application.

[0105] Regarding the control method of the separated matrix converter provided by this embodiment, the separated matrix converter includes a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor, the bidirectional switch module is connected in series with the bridge arm capacitor to form a bridge arm of the converter, each bridge arm of the converter includes at least one bidirectional switch module, a primary winding of the transformer is connected in series with the resonant inductor and the resonant capacitor and then connected to both ends of the bridge arm of the converter, the bidirectional switch module includes a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forms two bridge arms of the module, both ends of the clamp capacitor are connected to both ends of the two bridge arms of the module, the clamp capacitor forms a clamp absorption circuit with two upper bridge arms or two lower bridge arms of the two bridge arms, the bidirectional switch unit includes at least two controllable switching tubes, The method comprises: S1401: controlling and operating a switching tube in a bidirectional switch unit; S1402: Controlling the clamp capacitor to suppress a voltage spike occurring during the operation of the switching tube.

[0106] In the control method of the isolated matrix converter provided in the embodiment of the present application, a clamp capacitor is included in the bidirectional switch module. The clamp capacitor can be used to suppress the spike voltage of the switching tube during the switching process, thereby protecting the switching tube and further protecting the safety of the entire converter, and improving the reliability of the entire converter.

[0107] When the bidirectional switch module includes two controllable switching tubes, the two controllable switching tubes are located in the two upper bridge arms or the two lower bridge arms in the same way.

[0108] The bidirectional switch module includes four controllable switching tubes, including a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube; a first end of the first switching tube and a first end of the third switching tube are both connected to a first end of a clamp capacitor, a second end of the second switching tube and a second end of the fourth switching tube are both connected to a second end of the clamp capacitor, a second end of the first switching tube is connected to a first end of the second switching tube, and a second end of the third switching tube is connected to a first end of the fourth switching tube; A common end of the first switching tube and the second switching tube is a first end of the bidirectional switch module, and a common end of the third switching tube and the fourth switching tube is a second end of the bidirectional switch module.

[0109] The method provided by this embodiment includes, when the converter includes at least two bidirectional switch modules connected in series, The method further includes a step of balancing the voltage between the at least two bidirectional switch modules by controlling and operating the controllable switching tubes in the bidirectional switch unit such that, when the voltage of the clamp capacitor is greater than a first preset voltage, the clamp capacitor is discharged until the voltage of the clamp capacitor is less than a second preset voltage, and when the first preset voltage is greater than the second preset voltage and the switching tubes are controlled and operated such that the clamp capacitor is discharged, the bidirectional switch module must include at least three switching tubes.

[0110] The method provided by this embodiment includes, when the converter includes at least two bidirectional switch modules connected in series, Further comprising the step of balancing the voltage between the at least two bidirectional switch modules by controlling and operating a controllable switching tube in a bidirectional switch unit to charge a clamp capacitor until the voltage of the clamp capacitor is greater than a fourth preset voltage, when the voltage of the clamp capacitor is less than a third preset voltage, and the third preset voltage is less than the fourth preset voltage; The second preset voltage is greater than the third preset voltage.

[0111] Regarding the method provided by this embodiment, when the converter includes at least two bidirectional switch modules connected in series, the operation of the controllable switching tube in the bidirectional switch module can be controlled to charge or discharge the clamp capacitor, and may further include modifying the voltage on the clamp capacitor to achieve voltage balance among the multiple series-connected bidirectional switch modules, and when the voltages are balanced, the voltage stresses of the switching tubes in the multiple bidirectional switch modules are uniform, so that the voltage stresses experienced by the switching tubes in some bidirectional switch modules are not large and the voltage stresses experienced by the switching tubes in some bidirectional switch modules are not small, thereby the switching tubes can be better protected.

[0112] When the isolated matrix converter is a three-phase isolated matrix converter, each phase of the three-phase isolated matrix converter includes at least one bidirectional switch module; The method comprises: A step of controlling so that a switching tube that is not subjected to a voltage stress of a phase having the highest absolute value of a phase voltage is always on, and a switching tube that is subjected to the voltage stress of the highest phase performs a switching operation at a preset duty ratio; A step of controlling the switching tube of the phase having the second highest absolute value of the phase voltage, which is not subjected to voltage stress when the switching tube of the highest phase is turned on, to be turned on before the bidirectional switch module of the highest phase is turned off, and the switching tube of the second highest phase subjected to voltage stress is turned on after the bidirectional switch module of the highest phase is turned off; The method further includes a step of controlling so that the switching tube that is not subjected to voltage stress when the bidirectional switch module of the second highest phase, which is the phase having the smallest absolute value of the phase voltage, is turned on is turned on before the bidirectional switch module of the second highest phase is turned off, and the switching tube that is subjected to voltage stress is turned on after the bidirectional switch module of the second highest phase is turned off.

[0113] The above description of the disclosed embodiments will enable one skilled in the art to make or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Thus, the present application is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An isolation matrix converter, comprising: a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor; The bidirectional switch module is connected in series with the bridge arm capacitor to form a bridge arm of a converter, and each bridge arm of the converter includes at least one bidirectional switch module; A primary winding of the transformer is connected in series with the resonant inductor and the resonant capacitor, and then connected to both ends of a bridge arm of the converter; The bidirectional switch module includes a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forms two bridge arms of the module, both ends of the clamp capacitor are connected to both ends of the two bridge arms of the module, the clamp capacitor forms a clamp absorption circuit with the two upper bridge arms or the two lower bridge arms of the two bridge arms, and the bidirectional switch unit includes at least two controllable switching tubes; The clamp capacitor is used to suppress voltage spikes that occur when a switching tube in the bidirectional switch module is operated. A converter comprising:

2. When the bidirectional switch module includes two controllable switching tubes, the two controllable switching tubes are located in the two upper bridge arms or the two lower bridge arms.

2. The converter according to claim 1 .

3. The bidirectional switch module includes four controllable switching tubes, including a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube; a first end of the first switching tube and a first end of the third switching tube are both connected to a first end of the clamp capacitor, a second end of the second switching tube and a second end of the fourth switching tube are both connected to a second end of the clamp capacitor, a second end of the first switching tube is connected to the first end of the second switching tube, and a second end of the third switching tube is connected to the first end of the fourth switching tube; a common end of the first switching tube and the second switching tube is a first end of the bidirectional switch module, and a common end of the third switching tube and the fourth switching tube is a second end of the bidirectional switch module; 3. The converter according to claim 2.

4. The bidirectional switch module includes three controllable switching tubes, namely, a first switching tube, a second switching tube, and a third switching tube, and a diode, namely, a first diode; the first switching tube and the second switching tube are connected in series to form a first bridge arm of the module, and the third switching tube and the first diode are connected in series to form a second bridge arm of the module.

3. The converter according to claim 2.

5. The bidirectional switch module includes two controllable switching tubes, a first switching tube and a second switching tube, and two diodes, a first diode and a second diode; the first switching tube and the first diode are connected in series to form a first bridge arm of the module, and the second switching tube and the second diode are connected in series to form a second bridge arm of the module.

3. The converter according to claim 2.

6. The converter includes at least two bidirectional switch modules connected in series; The converter further includes a controller, and the controller specifically controls and operates a controllable switching tube in the bidirectional switch unit to discharge the clamp capacitor until the voltage of the clamp capacitor is smaller than a second preset voltage when the voltage of the clamp capacitor is larger than a first preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules, and the first preset voltage is larger than the second preset voltage. A converter according to any one of claims 1 to 4.

7. The converter includes at least two bidirectional switch modules connected in series; The converter further includes a controller, and the controller specifically controls and operates a controllable switching tube in the bidirectional switch unit to charge the clamp capacitor until the voltage of the clamp capacitor is greater than a fourth preset voltage when the voltage of the clamp capacitor is less than a third preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules; the third preset voltage is less than the fourth preset voltage; A converter according to any one of claims 1 to 5.

8. When the isolated matrix converter is a three-phase isolated matrix converter, each phase of the three-phase isolated matrix converter includes at least one of the bidirectional switch modules; The converter further includes a controller, and the controller further controls the switching tube that is not subjected to a voltage stress of a phase having a highest absolute value of a phase voltage to always be on, and the switching tube that is subjected to the voltage stress of the highest phase to perform a switching operation at a preset duty ratio; The controller further controls the switching tube of the phase having the second highest absolute value of the phase voltage, which is not subjected to voltage stress when the switching tube of the highest phase is turned on, to be turned on before the bidirectional switch module of the highest phase is turned off, and the switching tube of the second highest phase subjected to voltage stress is turned on after the bidirectional switch module of the highest phase is turned off; The controller further performs control so that a switching tube that is not subjected to voltage stress when the bidirectional switch module of the second highest phase, which is the phase having the smallest absolute value of the phase voltage, is turned on is turned on before the bidirectional switch module of the second highest phase is turned off, and a switching tube that is subjected to voltage stress is turned on after the bidirectional switch module of the second highest phase is turned off. A converter according to any one of claims 2 to 5.

9. When each of the converter bridge arms includes a plurality of the bidirectional switch units, the plurality of the bidirectional switch units are connected in series. A converter according to any one of claims 1 to 7.

10. a secondary winding of the transformer connected to a rectifier bridge, the rectifier bridge including at least one of a diode or a controllable switching tube; A converter according to any one of claims 1 to 7.

11. The transformer includes a plurality of secondary windings, each of which is connected to a corresponding rectifier bridge.

10. The converter according to claim 9.

12. A control method for an isolated matrix converter, the isolated matrix converter comprising: a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor, the bidirectional switch module being connected in series with the bridge arm capacitor to form a bridge arm of the converter, each bridge arm of the converter comprising at least one bidirectional switch module, a primary winding of the transformer being connected in series with the resonant inductor and the resonant capacitor and then connected to both ends of the bridge arm of the converter, the bidirectional switch module comprising a clamp capacitor and a bidirectional switch unit, the bidirectional switch unit forming two bridge arms of the module, both ends of the clamp capacitor being connected to both ends of the two bridge arms of the module, the clamp capacitor forming a clamp absorption circuit with two upper bridge arms or two lower bridge arms of the two bridge arms, the bidirectional switch unit comprising at least two controllable switching tubes, The method comprises: controlling and operating a switching tube in the bidirectional switch module; and controlling the clamp capacitor to suppress voltage spikes during operation of a switching tube in the bidirectional switch module. A control method comprising:

13. When the bidirectional switch module includes two controllable switching tubes, the two controllable switching tubes are located in the two upper bridge arms or the two lower bridge arms.

13. The control method according to claim 12.

14. The bidirectional switch module includes four controllable switching tubes, including a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube; a first end of the first switching tube and a first end of the third switching tube are both connected to a first end of the clamp capacitor, a second end of the second switching tube and a second end of the fourth switching tube are both connected to a second end of the clamp capacitor, a second end of the first switching tube is connected to the first end of the second switching tube, and a second end of the third switching tube is connected to the first end of the fourth switching tube; a common end of the first switching tube and the second switching tube is a first end of the bidirectional switch module, and a common end of the third switching tube and the fourth switching tube is a second end of the bidirectional switch module; 14. The control method according to claim 13.

15. The converter includes at least two bidirectional switch modules connected in series; and controlling and operating a controllable switching tube in the bidirectional switch unit such that, when a voltage of the clamp capacitor is greater than a first preset voltage, the clamp capacitor is discharged until the voltage of the clamp capacitor is less than a second preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules, wherein the first preset voltage is greater than the second preset voltage. The control method according to any one of claims 12 to 13.

16. The converter includes at least two bidirectional switch modules connected in series; When the voltage of the clamp capacitor is less than a third preset voltage, controlling and operating a controllable switching tube in the bidirectional switch unit to charge the clamp capacitor until the voltage of the clamp capacitor is greater than a fourth preset voltage, thereby balancing the voltage between the at least two bidirectional switch modules; the third preset voltage is less than the fourth preset voltage; 15. The control method according to claim 13 or 14.

17. When the isolated matrix converter is a three-phase isolated matrix converter, each phase of the three-phase isolated matrix converter includes at least one of the bidirectional switch modules; The method comprises: controlling the switching tube that is not subjected to the voltage stress of the phase having the highest absolute value of the phase voltage to always be on, and the switching tube that is subjected to the voltage stress of the highest phase to perform a switching operation at a preset duty ratio; A step of controlling a switching tube that is not subjected to voltage stress when the highest phase switching tube of the phase having the second highest absolute value of phase voltage is turned on before the highest phase bidirectional switch module is turned off, and a switching tube that is subjected to voltage stress of the second highest phase is turned on after the highest phase bidirectional switch module is turned off; controlling the switching tube that is not subjected to voltage stress when the bidirectional switch module of the second highest phase, which is the phase having the smallest absolute value of the phase voltage, is turned on before the bidirectional switch module of the second highest phase is turned off, and the switching tube that is subjected to voltage stress is turned on after the bidirectional switch module of the second highest phase is turned off, 14. The control method according to claim 13.

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