Isolation matrix converter and control method

Abstract

The present application discloses an isolated matrix converter and 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 and the bridge arm capacitor are connected in series to form the bridge arm of the converter, and 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 the two ends of the bridge arm of the converter. The bidirectional switch module includes: a clamping capacitor and a bidirectional switch unit. The bidirectional switch unit forms the two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module. The clamping capacitor forms a clamping 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 transistors. The clamping capacitor suppresses voltage spikes generated when the switching transistors in the bidirectional switch module are activated. This protects the switching transistors, and further protects the safety of the entire converter, thereby improving the reliability of the converter.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to an isolation matrix converter and a control method thereof. Background Art

[0002] An isolated matrix converter typically includes a bidirectional switch and a transformer, with a resonant circuit at the input of the transformer. It can generally perform both AC-to-AC and AC-to-DC conversions. For example, if the input is AC, the output is DC.

[0003] See also Figure 1 , which is a schematic diagram of an isolation matrix converter provided by the prior art.

[0004] like Figure 1 As shown, the input end of the isolation matrix converter is connected to three-phase AC power. Each phase of the isolation matrix converter includes a bidirectional switch, that is, the anti-parallel diodes of the two series-connected switches are in opposite directions, allowing current to flow in both the upward and downward directions. The primary winding of the transformer is connected in series with an inductor and a capacitor to form LLC resonance. However, Figure 1 The voltage of the bidirectional switch in the isolated matrix converter shown is clamped to the line voltage of the AC power. When in the over-resonance region, the switch tube will experience large current switching, which may cause excessive voltage spikes and cause overvoltage failure of the switch tube. Summary of the Invention

[0005] In view of this, embodiments of the present application provide an isolated matrix converter and a control method, which can suppress voltage spikes caused by the operation of switching tubes and protect the switching tubes.

[0006] The present application provides a matrix isolation converter, comprising: a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor and a bridge arm capacitor;

[0007] The bidirectional switch module and the bridge arm capacitor are connected in series to form a bridge arm of the converter, and each bridge arm of the converter includes at least one bidirectional switch module;

[0008] The primary winding of the transformer is connected in series with the resonant inductor and the resonant capacitor and then connected to the two ends of the bridge arm of the converter;

[0009] The bidirectional switch module includes: a clamping capacitor and a bidirectional switch unit; the bidirectional switch unit forms two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module; the clamping capacitor and the two upper bridge arms or the two lower bridge arms of the two bridge arms form a clamping absorption circuit; the bidirectional switch unit includes at least two controllable switch tubes;

[0010] The clamping capacitor is used to suppress the voltage spike generated when the switch tube in the bidirectional switch module is in operation.

[0011] Preferably, when the bidirectional switch module includes two controllable switch tubes, the two controllable switch tubes are located in two upper bridge arms or in two lower bridge arms.

[0012] Preferably, the bidirectional switch module includes the following four controllable switch tubes: a first switch tube, a second switch tube, a third switch tube and a fourth switch tube;

[0013] The first end of the first switching transistor and the first end of the third switching transistor are both connected to the first end of the clamping capacitor, the second end of the second switching transistor and the second end of the fourth switching transistor are both connected to the second end of the clamping capacitor, the second end of the first switching transistor is connected to the first end of the second switching transistor, and the second end of the third switching transistor is connected to the first end of the fourth switching transistor;

[0014] The common end of the first switch tube and the second switch tube is the first end of the bidirectional switch module, and the common end of the third switch tube and the fourth switch tube is the second end of the bidirectional switch module.

[0015] Preferably, the bidirectional switch module includes the following three controllable switch tubes and a diode: a first switch tube, a second switch tube, a third switch tube and a first diode;

[0016] The first switch tube and the second switch tube are connected in series to form a first bridge arm of the module, and the third switch tube and the first diode are connected in series to form a second bridge arm of the module.

[0017] Preferably, the bidirectional switch module includes the following two controllable switch tubes and two diodes: a first switch tube and a second switch tube, a first diode and a second diode;

[0018] The first switch tube and the first diode are connected in series to form a first bridge arm of the module, and the second switch tube and the second diode are connected in series to form a second bridge arm of the module.

[0019] Preferably, the converter comprises at least two bidirectional switch modules connected in series;

[0020] The converter also includes a controller; the controller is specifically used to control the controllable switch tube in the bidirectional switch unit to discharge the clamping capacitor until the voltage of the clamping capacitor is less than a second preset voltage when the voltage of the clamping capacitor is greater than a first preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; 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;

[0022] The converter further includes a controller; the controller is specifically configured to control the controllable switch in the bidirectional switch unit to charge the clamping capacitor until the voltage of the clamping capacitor is greater than a fourth preset voltage, so as to balance the voltage between the at least two bidirectional switch modules, when the voltage of the clamping capacitor is less than a third preset voltage;

[0023] The third preset voltage is lower than the fourth preset voltage.

[0024] Preferably, when the matrix isolation converter is a three-phase matrix isolation converter, each phase of the three-phase matrix isolation converter includes at least one bidirectional switch module;

[0025] The converter further includes a controller; the controller is further configured to control the switch tube in the phase with the highest absolute value of phase voltage that is not subjected to voltage stress to be always turned on, and the switch tube in the phase with the highest absolute value of phase voltage that is subjected to voltage stress to switch at a preset duty cycle;

[0026] The controller is further configured to control the switching tubes in the phase with the second highest phase voltage absolute value that are 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 tubes in the second highest phase that are subjected to voltage stress to be turned on after the bidirectional switch module of the highest phase is turned off;

[0027] The controller is also used to control the switch tube that does not bear voltage stress in the phase with the smallest phase voltage absolute value to be turned on before the bidirectional switch module of the next highest phase is turned off when the bidirectional switch module of the next highest phase is turned on, and to control the switch tube that bears voltage stress to be turned on after the bidirectional switch module of the next highest phase is turned off.

[0028] Preferably, when each bridge arm of the converter includes a plurality of the bidirectional switch units, the plurality of the bidirectional switch units are connected in series.

[0029] Preferably, the secondary winding of the transformer is connected to a rectifier bridge, and the rectifier bridge includes at least one of a diode and a controllable switch tube.

[0030] Preferably, the transformer includes a plurality of secondary windings, and each secondary winding is connected to a corresponding rectifier bridge.

[0031] The present application also provides a control method for a matrix isolation converter, the matrix isolation converter comprising: a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor; the bidirectional switch module and the bridge arm capacitor are connected in series to form a bridge arm of the converter, and each bridge arm of the converter comprises 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 the two ends of the bridge arm of the converter; the bidirectional switch module comprises: a clamping capacitor and a bidirectional switch unit; the bidirectional switch unit forms two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module; the clamping capacitor forms a clamping absorption circuit with the two upper bridge arms or the two lower bridge arms of the two bridge arms; the bidirectional switch unit comprises at least two controllable switch tubes;

[0032] The method includes:

[0033] Controlling the action of the switch tube in the bidirectional switch module;

[0034] The clamping capacitor is controlled to suppress voltage spikes when the switch tube in the bidirectional switch module is in operation.

[0035] Preferably, when the bidirectional switch module includes two controllable switch tubes, the two controllable switch tubes are located in two upper bridge arms or in two lower bridge arms.

[0036] Preferably, the bidirectional switch module includes the following four controllable switch tubes: a first switch tube, a second switch tube, a third switch tube and a fourth switch tube;

[0037] The first end of the first switching transistor and the first end of the third switching transistor are both connected to the first end of the clamping capacitor, the second end of the second switching transistor and the second end of the fourth switching transistor are both connected to the second end of the clamping capacitor, the second end of the first switching transistor is connected to the first end of the second switching transistor, and the second end of the third switching transistor is connected to the first end of the fourth switching transistor;

[0038] The common end of the first switch tube and the second switch tube is the first end of the bidirectional switch module, and the common end of the third switch tube and the fourth switch tube is the second end of the bidirectional switch module.

[0039] Preferably, the converter comprises at least two bidirectional switch modules connected in series;

[0040] Also includes:

[0041] When the voltage of the clamping capacitor is greater than a first preset voltage, the controllable switch tube in the bidirectional switch unit is controlled to discharge the clamping capacitor until the voltage of the clamping capacitor is less than a second preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; the first preset voltage is greater than the second preset voltage.

[0042] Preferably, the converter comprises at least two bidirectional switch modules connected in series;

[0043] Also includes:

[0044] When the voltage of the clamping capacitor is less than a third preset voltage, controlling the controllable switch in the bidirectional switch unit to charge the clamping capacitor until the voltage of the clamping capacitor is greater than a fourth preset voltage, so as to balance the voltage between the at least two bidirectional switch modules;

[0045] The third preset voltage is lower than the fourth preset voltage.

[0046] Preferably, when the matrix isolation converter is a three-phase matrix isolation converter, each phase of the three-phase matrix isolation converter includes at least one bidirectional switch module;

[0047] The method further includes:

[0048] The switch tube that is not subjected to voltage stress in the phase with the highest absolute value of the control phase voltage is always turned on, and the switch tube that is subjected to voltage stress in the phase with the highest absolute value of the control phase voltage is switched at a preset duty cycle;

[0049] The switch tube in the phase with the second highest absolute value of the control phase voltage that does not bear voltage stress when the switch tube of the highest phase is turned on is turned on before the bidirectional switch module of the highest phase is turned off, and the switch tube in the second highest phase that bears voltage stress is turned on after the bidirectional switch module of the highest phase is turned off;

[0050] In the phase with the smallest absolute value of the control phase voltage, when the bidirectional switch module of the next highest phase is turned on, the switch tube that does not bear voltage stress is turned on before the bidirectional switch module of the next highest phase is turned off, and the switch tube that bears voltage stress is turned on after the bidirectional switch module of the next highest phase is turned off.

[0051] It can be seen that the embodiments of the present application have the following beneficial effects:

[0052] The matrix isolation converter includes: a bidirectional switch module, which includes: a clamping capacitor and a bidirectional switch unit; the bidirectional switch unit forms the two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module; the clamping capacitor and the two upper bridge arms or the two lower bridge arms of the two bridge arms form a clamping absorption circuit; the bidirectional switch unit includes at least two controllable switching tubes; the clamping capacitor can suppress the voltage spike generated by the switching tube during operation, thereby protecting the switching tube, and further protecting the safety of the entire converter, thereby improving the reliability of the entire converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic diagram of an isolation matrix converter provided by the prior art;

[0054] Figure 2 A schematic diagram of a matrix isolation converter provided in an embodiment of the present application;

[0055] Figure 3 A schematic diagram of another matrix isolation converter provided in an embodiment of the present application;

[0056] Figure 4 A schematic diagram of a bidirectional switch module provided in an embodiment of the present application;

[0057] Figure 5 A schematic diagram of another bidirectional switch module provided in an embodiment of the present application;

[0058] Figure 6 A schematic diagram of another bidirectional switch module provided in an embodiment of the present application;

[0059] Figure 7 A schematic diagram of another bidirectional switch module provided in an embodiment of the present application;

[0060] Figure 8 A schematic diagram of another matrix isolation converter provided in an embodiment of the present application;

[0061] Figure 9 A schematic diagram of another matrix isolation converter provided in an embodiment of the present application;

[0062] Figure 10 The waveform diagram of the three-phase AC voltage provided in the embodiment of the present application;

[0063] Figure 11 A driving timing diagram of a bidirectional switch module of a matrix isolation converter provided in an embodiment of the present application;

[0064] Figures 12A-12D A diagram showing the working principle of the switching action in the bidirectional switch module provided in an embodiment of the present application;

[0065] Figure 13A schematic diagram of voltage stress during the shutdown process of Q4 provided in an embodiment of the present application;

[0066] Figure 14 A flowchart of a control method for a matrix isolation converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] In order to enable those skilled in the art to better understand the technical solution provided by this application, a specific application scenario is first introduced below.

[0068] The matrix isolation converter provided in the embodiments of the present application can function as either a DC-AC-DC converter or an AC-AC-DC converter. This means that the input can be either DC or AC, but the output is generally DC. Furthermore, the input can be three-phase or single-phase, and the output can be single-phase, meaning that DC is delivered to the load.

[0069] The matrix isolation converter provided in the embodiments of the present application is not limited to specific application scenarios. For example, when the secondary winding of the transformer of the matrix isolation converter includes multiple, each secondary winding is connected to a rectifier bridge, and the output of each rectifier bridge can be connected to a load, such as charging a new energy vehicle, that is, applied to a charging pile scenario, each output can be connected to a charging gun to perform DC charging on the new energy vehicle.

[0070] In addition, the matrix isolation converter can also provide power for other electrical equipment, such as servers and other computer rooms.

[0071] In addition, when the rectifier bridge connected to the secondary winding of the transformer of the matrix isolation converter includes a controllable switch tube, the matrix isolation converter can be used as a bidirectional converter, that is, energy can flow in both directions, for example, from DC to AC, or from AC to DC.

[0072] Converter Embodiment

[0073] The matrix isolation converter provided in the embodiments of the present application is described in detail below with reference to the accompanying drawings, taking three-phase AC input as an example.

[0074] See also Figure 2 , which is a schematic diagram of a matrix isolation converter provided in an embodiment of the present application.

[0075] The matrix isolation 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; Figure 2 As shown, taking three-phase AC input as an example, corresponding to the three-phase bridge arm, the bridge arm capacitance of phase A is CA, the bridge arm capacitance of phase B is CB, and the bridge arm capacitance of phase C is CC.

[0076] The bidirectional switch module 100 is connected in series with the bridge arm capacitor to form a bridge arm of the converter. Each bridge arm of the matrix isolation converter includes at least one bidirectional switch module. The embodiment of the present application does not specifically limit the number of bidirectional switch modules 100 included in each phase bridge arm. Figure 2 Each phase bridge arm includes multiple bidirectional switch modules 100 connected in series. For example, the n bidirectional switch modules in the phase A bridge arm are MA1-MAn, respectively. Similarly, the n bidirectional switch modules in the phase B bridge arm are MB1-MBn, respectively. The n bidirectional switch modules in the phase C bridge arm are MC1-MCn, respectively. Where n is an integer greater than or equal to 1.

[0077] The upper half of each phase bridge arm in the matrix isolation converter is a bidirectional switch module, and the lower half of the bridge arm is a bridge arm capacitor. The bidirectional switch module and the bridge arm capacitor are connected in series to form the entire bridge arm of each phase.

[0078] The primary winding of the transformer is connected in series with the resonant inductor Lr and the resonant capacitor Cr and then connected to both ends of the bridge arm of the matrix isolation converter; wherein, the primary winding of the transformer, the resonant inductor Lr and the resonant capacitor Cr are connected in series to form LLC series resonance.

[0079] The bidirectional switch module includes: a clamping capacitor and a bidirectional switch unit; the bidirectional switch unit forms the two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module; the clamping capacitor and the two upper bridge arms or the two lower bridge arms of the two bridge arms form a clamping absorption circuit; the bidirectional switch unit includes at least two controllable switch tubes;

[0080] The clamping capacitor is used to suppress the voltage spike generated by the switch tube in the bidirectional switch unit during operation.

[0081] The bidirectional switch module in the matrix isolation converter provided in the embodiments of the present application must include at least two controllable switching transistors, which can include four, three, or two controllable switching transistors. However, including only one controllable switching transistor cannot realize the charging and discharging of the clamping capacitor. When the bidirectional switch module includes two controllable switching transistors, the two controllable switching transistors must be located in both upper bridge arms or both lower bridge arms.

[0082] Figure 2 In the following, a bidirectional switch module is described as including the following four controllable switch tubes: a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, and a fourth switch tube Q4. To form a freewheeling circuit, each switch tube includes an anti-parallel diode, i.e., the anti-parallel diode of the first switch tube Q1 is D1, the anti-parallel diode of the second switch tube Q2 is D2, the anti-parallel diode of the third switch tube Q3 is D3, and the anti-parallel diode of the fourth switch tube Q4 is D4.

[0083] The first end of the first switch tube Q1 and the first end of the third switch tube Q3 are both connected to the first end of the clamping capacitor C1, the second end of the second switch tube Q2 and the second end of the fourth switch tube Q4 are both connected to the second end of the clamping capacitor C1, the second end of the first switch tube Q1 is connected to the first end of the second switch tube Q2, and the second end of the third switch tube Q3 is connected to the first end of the fourth switch tube Q4;

[0084] The common end of the first switch tube Q1 and the second switch tube Q2 is the first end of the bidirectional switch module, and the common end of the third switch tube Q3 and the fourth switch tube Q4 is the second end of the bidirectional switch module.

[0085] Figure 2 In this example, the output end of the matrix isolation converter is connected to a full-bridge rectifier bridge, and the rectifier bridge includes four diodes, namely, a fourth diode D4, a fifth diode D5, a sixth diode D6, and a seventh diode D7. The fourth diode D4 and the fifth diode D5 are connected in series to form one arm of the rectifier bridge, and the sixth diode D6 and the seventh diode D7 are connected in series to form the other arm of the rectifier bridge. The output end of the rectifier bridge is connected to the output capacitor Cbus.

[0086] Figure 2 The rectifier bridge shown here only illustrates the inclusion of diodes. Alternatively, the rectifier bridge may include controllable switching transistors, or a combination of controllable switching transistors and diodes. When the bridge arms of the rectifier bridge include controllable switching transistors, the matrix isolation converter can achieve bidirectional power conversion, that is, conversion from DC to AC. One side of the rectifier bridge is the input terminal.

[0087] when Figure 2 When each phase bridge arm includes only one bidirectional switch module, Figure 3 As shown in the figure, this figure is a schematic diagram of another matrix isolation converter provided in an embodiment of the present application.

[0088] Figure 3 Each phase bridge arm includes only one bidirectional switch module, and the rest Figure 2 The same, no longer repeated here.

[0089] Figure 2 and Figure 3 The bidirectional switch modules in the figure are all controlled switch tubes. The following describes the mixed case of controlled switch tubes and diodes.

[0090] In the matrix isolation converter provided in the embodiments of the present application, a bidirectional switch module includes the following two controllable switching transistors and two diodes: a first switching transistor and a second switching transistor, and a first diode and a second diode. The first switching transistor and the first diode are connected in series to form a first bridge arm of the module, while the second switching transistor and the second diode are connected in series to form a second bridge arm of the module. The first switching transistor and the second switching transistor are merely names for the switching transistors and do not specifically refer to their positions.

[0091] The embodiment of the present application does not specifically limit the positions of the two diodes. For example, they can be located in both upper half-bridge arms or in both lower half-bridge arms.

[0092] See also Figure 4 , which is a schematic diagram of a bidirectional switch module provided in an embodiment of the present application.

[0093] Figure 4 This example uses two upper-half bridge arms as controllable switches and two lower-half bridge arms as diodes. That is, Q1 and Q3 are both controllable switches, D2 and D4 are both diodes, and Q1 includes an antiparallel diode D1, while Q3 includes an antiparallel diode D3. Clamping capacitor C1 is connected across the bridge arms of the module.

[0094] See also Figure 5 , this figure is a schematic diagram of another bidirectional switch module provided in an embodiment of the present application.

[0095] Figure 5 This example uses diodes in the two upper bridge arms and controllable switches in the two lower bridge arms. That is, Q12 and Q14 are both controllable switches, D11 and D13 are both diodes, and Q12 includes an antiparallel diode D12, while Q14 includes an antiparallel diode D14. Clamping capacitor C1 is connected across the module's bridge arms.

[0096] Figure 4 and Figure 5 The above descriptions all involve two controllable switches and two diodes. The following, with reference to the accompanying figures, describes a bidirectional switch module comprising three controllable switches and one diode. Specifically, the bidirectional switch module includes the following three controllable switches and one diode: a first switch, a second switch, a third switch, and a first diode. The first and second switches are connected in series to form the module's first bridge arm, while the third switch and the first diode are connected in series to form the module's second bridge arm.

[0097] See also Figure 6 , which is a schematic diagram of another bidirectional switch module provided in an embodiment of the present application.

[0098] Figure 6 The left bridge arm includes two controllable switches Q1 and Q2, the upper right bridge arm includes controllable switch Q3, and the lower right bridge arm includes diode D4. Q1's antiparallel diode is D1, Q2's antiparallel diode is D2, and Q3's antiparallel diode is D3. Clamping capacitor C1 is connected across the module's bridge arms.

[0099] See also Figure 7 , this figure is a schematic diagram of another bidirectional switch module provided in an embodiment of the present application.

[0100] Figure 6 The left bridge arm includes two controllable switches Q1 and Q2, the right upper bridge arm includes diode D3, and the right lower bridge arm includes controllable switch Q4. Q1's antiparallel diode is D1, Q2's antiparallel diode is D2, and Q4's antiparallel diode is D4. Clamping capacitor C1 is connected across the module's bridge arms.

[0101] It should be understood that Figure 6 and Figure 7 The position of a diode is only shown as an example. The diode can be located in any of the four half-bridge arms. Figure 6 and Figure 7 It includes three controllable switching tubes, which can ensure that the voltage of each bidirectional switch module can be controlled. Specifically, the voltage of the module can be adjusted by adjusting the duty cycle of the controllable switching tube.

[0102] The secondary winding of the transformer is connected to a rectifier bridge, which includes at least one of a diode and a controllable switch tube.

[0103] When the bridge includes diodes, see Figure 3 ,and Figure 3 The transformer in the figure has only one secondary winding. The following describes the case where the transformer includes multiple secondary windings.

[0104] The transformer includes multiple secondary windings, each connected to a corresponding rectifier bridge. Since the transformer has multiple secondary windings, corresponding to multiple output ports, a subsequent converter can be added to flexibly adjust the voltage and power of each output port.

[0105] See also Figure 8 , this figure is a schematic diagram of another matrix isolation converter provided in an embodiment of the present application.

[0106] Figure 8 The transformer includes n secondary windings, where n is an integer greater than 1. Each winding is connected to a corresponding rectifier bridge. For example, the first rectifier bridge includes four diodes D5-D8, and the output capacitance of the first rectifier bridge is Cbus1. The nth rectifier bridge includes four diodes Dn5-Dn8, and the output capacitance of the nth rectifier bridge is Cbusn.

[0107] Figure 8 The matrix isolation converter shown can be used in electric vehicle charging scenarios. Each rectifier bridge corresponds to a charging connector to charge the electric vehicle. For example, the input voltage of the matrix isolation converter can be AC ​​10kV or AC 35kV.

[0108] The matrix isolation converters described above are all introduced using the rectifier bridge including diodes as an example. The following describes the scenario where the rectifier bridge includes a controllable switch tube.

[0109] See also Figure 9 , this figure is a schematic diagram of another matrix isolation converter provided in an embodiment of the present application.

[0110] Figure 9 The rectifier bridge in FIG. 1 includes four controllable switches, Q5-Q8, each of which includes a corresponding anti-parallel diode, namely D5-D8 for Q5-Q8. The output capacitor of the rectifier bridge is C1.

[0111] Figure 9 The matrix isolation converter shown can be connected to the photovoltaic array on the right side, that is, the right side serves as the input end and the left side serves as the AC output end, thereby realizing AC grid connection of photovoltaic power generation.

[0112] The embodiments of the present application do not specifically limit the application scenarios of the matrix isolation converter, nor do they limit the number of bidirectional switch modules, nor do they limit the number of rectifier bridges, nor do they limit the types of switch tubes in the rectifier bridges, nor do they limit the types of switch tubes in each bidirectional switch module. The various implementation methods introduced above can be freely combined.

[0113] The working principle of the matrix isolation converter provided by the embodiment of the present application is described in detail below with reference to the accompanying drawings. Figure 3 , taking the bidirectional switch module as an example where all the switch tubes are controllable.

[0114] See also Figure 10 , which is a waveform diagram of the three-phase AC voltage provided in an embodiment of the present application.

[0115] Assume that the three-phase grid voltage waveform is as follows Figure 10 As shown, the phase difference between phases A, B and C is 120 degrees. When the phases are 0-30 degrees, the absolute value of the voltage of phase A is the largest, the absolute value of phase B is the smallest, and the absolute value of phase C is the second largest. The voltage of phase A is opposite to that of phase B and phase C. Figure 3 In the circuit shown, Q2 and Q4 in the bidirectional switch module are the main switches, and Q1 and Q3 are turned off. The switching timing of Q2 and Q4 in normal operation is as follows: Figure 11 shown.

[0116] See also Figure 11 , which is a driving timing diagram of the bidirectional switch module of the matrix isolation converter provided in an embodiment of the present application.

[0117] When the matrix isolation converter is a three-phase matrix isolation converter, each phase of the three-phase matrix isolation converter includes at least one bidirectional switch module;

[0118] The converter further includes: a controller;

[0119] Combine Figure 10Among the three-phase voltages shown, the absolute value of phase A voltage is the highest, the absolute value of phase C voltage is the second highest, and the absolute value of phase B voltage is the smallest. Figure 11 , Qa2 represents the driving timing of Q2 of phase A, Qa4 represents the driving timing of Q4 of phase A, Qc2 represents the driving timing of Q2 of phase C, Qc4 represents the driving timing of Q4 of phase C, Qb2 represents the driving timing of Q2 of phase B, and Qb4 represents the driving timing of Q4 of phase B.

[0120] The controller is also used to control the switch tube that is not subjected to voltage stress in the phase with the highest phase voltage absolute value to be always turned on, and the switch tube that is subjected to voltage stress in the highest phase operates at a preset duty cycle or a preset switching frequency; for example, the duty cycle is 50%.

[0121] The controller is also used to control the switch tube in the phase with the second highest phase voltage absolute value that does not bear voltage stress when the highest phase switch tube is turned on to turn on before the bidirectional switch module of the highest phase is turned off, and the switch tube in the second highest phase that bears voltage stress to turn on after the bidirectional switch module of the highest phase is turned off; and the two switches are turned off at the same time, and the duty cycle of Q4 is the actual duty cycle of the unit, which is determined according to the relationship between the phase voltage value and the highest phase voltage.

[0122] The controller is further configured to control, in the phase with the smallest phase voltage absolute value, the switch transistor that is not subject to voltage stress when the bidirectional switch module of the next highest phase is on, to turn on before the bidirectional switch module of the next highest phase turns off, and to control the switch transistor that is subject to voltage stress to turn on after the bidirectional switch module of the next highest phase turns off. Both switches are turned off simultaneously, and the duty cycle of Q2 is the actual duty cycle of the unit, which is determined based on the relationship between the voltage value of that phase and the voltage value of the highest phase.

[0123] The specific positions of the aforementioned switches within the bidirectional switch module can be determined based on the actual topology. Different bidirectional switch modules may refer to different switches, for example, when the upper two half-bridge arms include controllable switches versus when the lower two half-bridge arms include controllable switches. Regardless of the bidirectional switch module's structure, however, the distinction between switches that withstand voltage stress and switches that do not is made.

[0124] For ease of understanding, the following Figure 10 The following is an example of the phase voltage absolute value of phase A being the highest in the range of 0-30 degrees.

[0125] The controller is further configured to control the second switch Q2 of the phase with the highest phase voltage absolute value to be turned on, and the fourth switch Q4 of the highest phase to perform switching at a preset duty cycle or a preset switching frequency; for example, the preset duty cycle is 50%;

[0126] The fourth switch tube Q4 of the phase with the second highest absolute value of the phase voltage is turned on before the fourth switch tube Q4 of the highest phase is turned off, and the second switch tube Q2 of the phase with the second highest absolute value of the phase voltage is turned on after the fourth switch tube Q4 of the second highest phase is turned off;

[0127] The second switch tube Q2 of the phase with the smallest absolute value of the control phase voltage is turned on before the second switch tube Q2 and the fourth switch tube Q4 of the next highest phase are turned off, and the fourth switch tube Q4 of the phase with the smallest absolute value of the control phase voltage is turned on after the second switch tube Q2 and the fourth switch tube Q4 of the next highest phase are turned off.

[0128] Q2 and Q4 above represent the second and fourth switching tubes in each phase. The four switching tubes in each phase have the same label and are distinguished only by different phases.

[0129] When the converter includes at least two bidirectional switch modules connected in series, the controller is specifically configured to control the controllable switch in the bidirectional switch unit to discharge the clamping capacitor until the voltage of the clamping capacitor is less than a second preset voltage when the voltage of the clamping capacitor is greater than a first preset voltage; the first preset voltage is greater than the second preset voltage, so as to balance the voltage between the at least two bidirectional switch modules;

[0130] When the converter includes at least two bidirectional switch modules connected in series, the controller is specifically configured to control the controllable switch in the bidirectional switch unit to charge the clamping capacitor until the voltage of the clamping capacitor is greater than a fourth preset voltage when the voltage of the clamping capacitor is less than a third preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; the third preset voltage is less than the fourth preset voltage,

[0131] The second preset voltage is greater than the third preset voltage.

[0132] The converter provided in this embodiment, when the converter includes at least two bidirectional switch modules connected in series, can charge or discharge a clamping capacitor by controlling the action of a controllable switch tube in the bidirectional switch module, thereby changing the voltage on the clamping capacitor to achieve voltage balance between multiple bidirectional switch modules connected in series. When the voltage is balanced, the voltage stress of the switch tubes in the multiple bidirectional switch modules can be balanced, and the situation where the switch tubes in some bidirectional switch modules are subjected to greater voltage stress and the switch tubes in some bidirectional switch modules are subjected to less voltage stress will not occur, thereby better protecting the switch tubes.

[0133] See also Figures 12A-12D , which is a diagram showing the working principle of the switch action in the bidirectional switch module provided in an embodiment of the present application.

[0134] Figures 12A-12DThe figure shows the turn-off process of the A-phase switch tube Q4 from 0 to 30 degrees, and the working principle of the clamping capacitor C1. During the turn-off process of Q4, the parasitic inductance of the loop may oscillate a high voltage spike on Q4. Due to the presence of C1, the voltage spike is limited to the voltage of C1, that is, C1 clamps the peak voltage, effectively suppressing the voltage spike.

[0135] To ensure that C1 effectively protects the controllable switch, the voltage across C1 must be kept within a reasonable range. For example, the normal voltage is set to V0. When the voltage exceeds a first preset voltage (V1), the module enters overvoltage discharge mode and exits this mode until the voltage drops below a second preset voltage (V2). When the voltage drops below a third preset voltage (V3), the module enters undervoltage charge mode and exits this mode until the voltage exceeds a fourth preset voltage (V4). The following describes the charge and discharge modes of clamping capacitor C1 when phase A is at its maximum (0-30°C), intermediate (30-60°C), and minimum (60-90°C).

[0136] Between 0 and 30 degrees Celsius, when the voltage of the clamping capacitor C1 of the Phase A bidirectional switch module falls below V2, the module enters bus undervoltage charging mode. In this mode, the module's long-pass transistor Q2 is turned off, and Q4 is not turned on when the module needs to turn on Q4. The main power circuit current then charges C1. When the voltage across C1 of the module exceeds V4, Q2 continues to enter the long-pass state in the next switching cycle, and Q4 switches according to the set logic. When the voltage of the module's absorption clamping capacitor C1 exceeds V1, the module enters bus overvoltage discharge mode. In this mode, the module's long-pass transistor Q2 is turned off and Q1 is turned on when Q4 turns on, charging C1 with circuit current. When each phase arm includes multiple bidirectional switch modules connected in series, to reduce voltage stress on other modules in Phase A, Q1 is turned off and Q2 is turned on when Q4 turns off. Discharge continues in the next switching cycle until the voltage of C1 falls below V2, at which point discharge mode exits.

[0137] At 30-60 degrees, when the voltage of the clamping capacitor C1 of the A-phase bidirectional switch module is lower than V3, the module enters the bus undervoltage charging mode. During normal operation, the module Q2 will be turned on some time before the maximum phase Q4 is turned off to prepare for the zero-voltage turn-on of Q4. However, in the charging mode, Q2 is no longer turned on, and Q4 is also not turned on during this cycle, thereby charging C1 through the loop current. If charging is not completed in this cycle, charging will continue in the next switching cycle until charging is completed. When the voltage of the module's absorption clamping capacitor C1 is higher than V1, the module enters the bus overvoltage discharge mode. Q2 is no longer turned on, but when Q4 is normally turned on, Q1 is turned on when Q4 is turned on, and C1 is discharged through the main loop current, but capacitor Cx needs to be discharged before the current reverses.

[0138] At 60-90 degrees, when the voltage of the clamping capacitor C1 of the phase A bidirectional switch module is lower than V3, the module enters the bus undervoltage charging mode. Normally, Q4 will be turned on in advance when Q2 and Q4 are turned on in the intermediate phase C, creating a zero-voltage turn-on condition for Q2. In the charging mode, Q4 and Q2 are not turned on during the cycle. When the voltage of the module's absorption clamping capacitor C1 is higher than V1, the module enters the bus overvoltage discharge mode. Q4 is turned on normally, but Q1 is turned on instead of Q2 when Q2 is turned on normally. When Q2 and Q4 are turned off normally, Q1 and Q4 are turned off to discharge C1.

[0139] The following describes in detail how C1 suppresses voltage spikes during the shutdown process of Q4.

[0140] Figure 12A In the circuit, the A-phase current enters from Q4, flows through Q2 and D2, and flows out from the upper end of Q2. At this time, Q1 and Q3 are both turned off.

[0141] Figure 12B In the case of Q4 being off, Q1 and Q3 remain off. The current charges the junction capacitance Co4 of Q4 and discharges the junction capacitance Co3 of Q3.

[0142] Figure 12C In the circuit, Q4 is turned off, Q1 and Q3 remain off, and the voltage formed on the junction capacitance Co4 of Q4 reaches the voltage across the clamping capacitor C1. At this time, after Co3 discharges to 0, D3 is turned on to suppress the voltage spike of Q4 and protect the safety of Q4.

[0143] Figure 12D In the circuit (referring to the large loop of the entire matrix isolation converter), the current passes through the parasitic inductance of the loop (referring to the large loop of the entire matrix isolation converter), and after D3, C1, and D2 resonate to 0, the junction capacitance of Q3 and Q4 (Co3 and Co4) is charged and discharged in reverse. The voltage across Q4 drops and the voltage across Q3 rises until the total voltage of Q4 in all bidirectional switch modules in series reaches the line voltage of the AC input.

[0144] Without C1, the voltage of Co3 and Co4 will be larger, so Q3 and Q4 need to withstand higher voltage stress, which will cause damage if the withstand voltage is exceeded.

[0145] In order to more clearly understand the effect of the clamping capacitor in the bidirectional switch module in the matrix isolation converter provided in the present application on suppressing the peak voltage when the switch tube is in operation, a detailed introduction is given below with reference to the waveform diagram.

[0146] See also Figure 13 , which is a schematic diagram of voltage stress during the shutdown process of Q4 provided in an embodiment of the present application.

[0147] from Figure 13As can be seen, due to the presence of clamping capacitor C1, Q4 experiences a voltage stress plateau H during the turn-off process, effectively clamping the voltage. Without clamping capacitor C1, Q4 would experience a high voltage spike during the turn-off process, potentially exceeding its withstand voltage and damaging it. Similarly, other switching transistors can also be protected by C1 during the switching process, avoiding voltage spikes.

[0148] The above embodiment is introduced by taking phase A as an example. The working processes of the switches in other phases and different phase intervals are similar and will not be described in detail here.

[0149] When the switch tubes in the bidirectional switch modules are non-fully controlled (ie, comprising a combination of a controllable switch tube and a diode), the charge and discharge modes of each bidirectional switch module are controlled only in a specific phase interval.

[0150] The above solutions are all described with Q2 and Q4 in the bidirectional switch module as the main switches. In actual use, Q1 and Q3 can also be used as the main switches, and Q2 and Q4 can be used as voltage regulation switches for the clamping capacitor C1. The relevant timing needs to be adjusted accordingly, which will not be repeated here.

[0151] In the matrix-isolated converter provided by the present invention, the bidirectional switch module includes a clamping capacitor. This clamping capacitor can suppress the voltage spikes generated by the switch tube during switching, thereby protecting the switch tube and, in turn, the safety of the entire converter, thereby improving the reliability of the converter. Furthermore, by controlling the charging and discharging modes of the clamping capacitor, the voltage stress of the converter can be better controlled.

[0152] In addition, the matrix isolation converter provided in the embodiment of the present application can include multiple bidirectional switch modules connected in series in each phase. In this way, when the bridge arm voltage is high, the voltage borne by each bidirectional switch module can be reduced, which is beneficial to the selection of controllable switch tubes in the bidirectional switch module and reduces the cost of the converter.

[0153] The bidirectional switch module in the above embodiment is described in the form of a bridge arm, that is, a two-level topology. In addition, it can also be designed as a three-level full-bridge or multi-level topology such as I-NPC, A-NPC, etc.

[0154] Method Example

[0155] Based on the matrix isolation converter provided in the above embodiment, an embodiment of the present application further provides a control method for the matrix isolation converter, which is described in detail below with reference to the accompanying drawings.

[0156] See also Figure 14 , which is a flow chart of a control method for a matrix isolation converter provided in an embodiment of the present application.

[0157] This embodiment provides a control method for a matrix isolation converter, wherein the matrix isolation converter includes: a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor; the bidirectional switch module and the bridge arm capacitor are connected in series to form a bridge arm of the converter, and 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 the two ends of the bridge arm of the converter; the bidirectional switch module includes: a clamping capacitor and a bidirectional switch unit; the bidirectional switch unit forms the two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module; the clamping capacitor forms a clamping 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 transistors;

[0158] The method includes:

[0159] S1401: Control the action of the switch tube in the bidirectional switch unit;

[0160] S1402: Control the clamping capacitor to suppress the voltage spike generated during the operation of the switching tube.

[0161] The control method of the matrix isolation converter provided in the embodiment of the present application includes a clamping capacitor in the bidirectional switch module. The clamping capacitor can suppress the peak voltage of the switch tube during the switching process, thereby protecting the switch tube and further protecting the safety of the entire converter, thereby improving the reliability of the entire converter.

[0162] When the bidirectional switch module includes two controllable switch tubes, the two controllable switch tubes are located in the two upper bridge arms or in the two lower bridge arms.

[0163] The bidirectional switch module includes the following four controllable switch tubes: a first switch tube, a second switch tube, a third switch tube and a fourth switch tube;

[0164] The first end of the first switching tube and the first end of the third switching tube are both connected to the first end of the clamping capacitor, the second end of the second switching tube and the second end of the fourth switching tube are both connected to the second end of the clamping capacitor, the second end of the first switching tube is connected to the first end of the second switching tube, and the second end of the third switching tube is connected to the first end of the fourth switching tube;

[0165] The common end of the first switch tube and the second switch tube is the first end of the bidirectional switch module, and the common end of the third switch tube and the fourth switch tube is the second end of the bidirectional switch module.

[0166] The method provided in this embodiment, when the converter includes at least two bidirectional switch modules connected in series, further includes:

[0167] When the voltage of the clamping capacitor is greater than a first preset voltage, the controllable switch tube in the bidirectional switch unit is controlled to discharge the clamping capacitor until the voltage of the clamping capacitor is less than a second preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; the first preset voltage is greater than the second preset voltage; it should be understood that when the switch tube is controlled to discharge the clamping capacitor, the bidirectional switch module needs to include at least three switch tubes.

[0168] The method provided in this embodiment, when the converter includes at least two bidirectional switch modules connected in series, further includes:

[0169] When the voltage of the clamping capacitor is less than the third preset voltage, the controllable switch in the bidirectional switch unit is controlled to charge the clamping capacitor until the voltage of the clamping capacitor is greater than the fourth preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; the third preset voltage is less than the fourth preset voltage,

[0170] The second preset voltage is greater than the third preset voltage.

[0171] The method provided in this embodiment, when the converter includes at least two bidirectional switch modules connected in series, can charge or discharge the clamping capacitor by controlling the action of the controllable switch tubes in the bidirectional switch modules, thereby changing the voltage on the clamping capacitor to achieve voltage balance between multiple bidirectional switch modules connected in series. When the voltage is balanced, the voltage stress of the switch tubes in the multiple bidirectional switch modules can be balanced, and the situation where the switch tubes in some bidirectional switch modules are subjected to greater voltage stress and the switch tubes in some bidirectional switch modules are subjected to less voltage stress will not occur, thereby better protecting the switch tubes.

[0172] When the matrix isolation converter is a three-phase matrix isolation converter, each phase of the three-phase matrix isolation converter includes at least one bidirectional switch module;

[0173] The method further includes:

[0174] The switch tube that is not subjected to voltage stress in the phase with the highest absolute value of the control phase voltage is always turned on, and the switch tube that is subjected to voltage stress in the phase with the highest absolute value of the control phase voltage is switched at a preset duty cycle;

[0175] The switch tube in the phase with the second highest absolute value of the control phase voltage that does not bear voltage stress when the switch tube of the highest phase is turned on is turned on before the bidirectional switch module of the highest phase is turned off, and the switch tube in the second highest phase that bears voltage stress is turned on after the bidirectional switch module of the highest phase is turned off;

[0176] In the phase with the smallest absolute value of the control phase voltage, when the bidirectional switch module of the next highest phase is turned on, the switch tube that does not bear voltage stress is turned on before the bidirectional switch module of the next highest phase is turned off, and the switch tube that bears voltage stress is turned on after the bidirectional switch module of the next highest phase is turned off.

[0177] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A matrix isolation converter, characterized in that: include: Bidirectional switch module, transformer, resonant inductor, resonant capacitor and bridge arm capacitor; The bidirectional switch module and the bridge arm capacitor are connected in series to form a bridge arm of the converter, and 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 the two ends of the bridge arm of the converter; The bidirectional switch module includes: a clamping capacitor and a bidirectional switch unit; the bidirectional switch unit forms two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module; the clamping capacitor and the two upper bridge arms or the two lower bridge arms of the two bridge arms form a clamping absorption circuit; the bidirectional switch unit includes at least two controllable switch tubes; The clamping capacitor is used to suppress the voltage spike generated when the switch tube in the bidirectional switch module is in operation.

2. The converter according to claim 1, characterized in that When the bidirectional switch module includes two controllable switch tubes, the two controllable switch tubes are located in the two upper bridge arms or in the two lower bridge arms.

3. The converter according to claim 2, characterized in that The bidirectional switch module includes the following four controllable switch tubes: a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; The first end of the first switching transistor and the first end of the third switching transistor are both connected to the first end of the clamping capacitor, the second end of the second switching transistor and the second end of the fourth switching transistor are both connected to the second end of the clamping capacitor, the second end of the first switching transistor is connected to the first end of the second switching transistor, and the second end of the third switching transistor is connected to the first end of the fourth switching transistor; The common end of the first switch tube and the second switch tube is the first end of the bidirectional switch module, and the common end of the third switch tube and the fourth switch tube is the second end of the bidirectional switch module.

4. The converter according to claim 2, characterized in that The bidirectional switch module includes the following three controllable switch tubes and a diode: a first switch tube, a second switch tube, a third switch tube and a first diode; The first switch tube and the second switch tube are connected in series to form a first bridge arm of the module, and the third switch tube and the first diode are connected in series to form a second bridge arm of the module.

5. The converter according to claim 2, characterized in that The bidirectional switch module includes the following two controllable switch tubes and two diodes: a first switch tube and a second switch tube, a first diode and a second diode; The first switch tube and the first diode are connected in series to form a first bridge arm of the module, and the second switch tube and the second diode are connected in series to form a second bridge arm of the module.

6. The converter according to any one of claims 1 to 4, characterized in that: The converter includes at least two bidirectional switch modules connected in series; The converter also includes a controller; the controller is specifically used to control the controllable switch tube in the bidirectional switch unit to discharge the clamping capacitor until the voltage of the clamping capacitor is less than a second preset voltage when the voltage of the clamping capacitor is greater than a first preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; the first preset voltage is greater than the second preset voltage.

7. The converter according to any one of claims 1 to 5, characterized in that: The converter includes at least two bidirectional switch modules connected in series; The converter further includes a controller; the controller is specifically configured to control the controllable switch in the bidirectional switch unit to charge the clamping capacitor until the voltage of the clamping capacitor is greater than a fourth preset voltage, so as to balance the voltage between the at least two bidirectional switch modules, when the voltage of the clamping capacitor is less than a third preset voltage; The third preset voltage is lower than the fourth preset voltage.

8. The converter according to any one of claims 2 to 5, characterized in that: When the matrix isolation converter is a three-phase matrix isolation converter, each phase of the three-phase matrix isolation converter includes at least one bidirectional switch module; The converter further includes a controller; the controller is further configured to control the switch tube in the phase with the highest absolute value of phase voltage that is not subjected to voltage stress to be always turned on, and the switch tube in the phase with the highest absolute value of phase voltage that is subjected to voltage stress to switch at a preset duty cycle; The controller is further configured to control the switching tubes in the phase with the second highest phase voltage absolute value that are 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 tubes in the second highest phase that are subjected to voltage stress to be turned on after the bidirectional switch module of the highest phase is turned off; The controller is also used to control the switch tube that does not bear voltage stress in the phase with the smallest phase voltage absolute value to be turned on before the bidirectional switch module of the next highest phase is turned off when the bidirectional switch module of the next highest phase is turned on, and to control the switch tube that bears voltage stress to be turned on after the bidirectional switch module of the next highest phase is turned off.

9. The converter according to any one of claims 1 to 5, characterized in that: When each bridge arm of the converter includes a plurality of the bidirectional switch units, the plurality of the bidirectional switch units are connected in series.

10. The converter according to any one of claims 1 to 5, characterized in that: The secondary winding of the transformer is connected to a rectifier bridge, which includes at least one of a diode and a controllable switch tube.

11. The converter according to claim 9, characterized in that The transformer includes a plurality of secondary windings, and each secondary winding is connected to a corresponding rectifier bridge.

12. A control method for a matrix isolation converter, characterized in that: The matrix isolation converter includes: a bidirectional switch module, a transformer, a resonant inductor, a resonant capacitor, and a bridge arm capacitor; the bidirectional switch module and the bridge arm capacitor are connected in series to form a bridge arm of the converter, and 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 the two ends of the bridge arm of the converter; the bidirectional switch module includes: a clamping capacitor and a bidirectional switch unit; the bidirectional switch unit forms the two bridge arms of the module, and the two ends of the clamping capacitor are connected to the two ends of the two bridge arms of the module; the clamping capacitor and the two upper bridge arms or the two lower bridge arms of the two bridge arms form a clamping absorption circuit; the bidirectional switch unit includes at least two controllable switch tubes; The method includes: Controlling the action of the switch tube in the bidirectional switch module; The clamping capacitor is controlled to suppress voltage spikes when the switch tube in the bidirectional switch module is in operation.

13. The control method according to claim 12, characterized in that: When the bidirectional switch module includes two controllable switch tubes, the two controllable switch tubes are located in the two upper bridge arms or in the two lower bridge arms.

14. The control method according to claim 13, characterized in that: The bidirectional switch module includes the following four controllable switch tubes: a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; The first end of the first switching transistor and the first end of the third switching transistor are both connected to the first end of the clamping capacitor, the second end of the second switching transistor and the second end of the fourth switching transistor are both connected to the second end of the clamping capacitor, the second end of the first switching transistor is connected to the first end of the second switching transistor, and the second end of the third switching transistor is connected to the first end of the fourth switching transistor; The common end of the first switch tube and the second switch tube is the first end of the bidirectional switch module, and the common end of the third switch tube and the fourth switch tube is the second end of the bidirectional switch module.

15. The control method according to any one of claims 12 to 13, characterized in that: The converter includes at least two bidirectional switch modules connected in series; Also includes: When the voltage of the clamping capacitor is greater than a first preset voltage, the controllable switch tube in the bidirectional switch unit is controlled to discharge the clamping capacitor until the voltage of the clamping capacitor is less than a second preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; the first preset voltage is greater than the second preset voltage.

16. The control method according to claim 13 or 14, characterized in that: The converter includes at least two bidirectional switch modules connected in series; Also includes: When the voltage of the clamping capacitor is less than a third preset voltage, controlling the controllable switch in the bidirectional switch unit to charge the clamping capacitor until the voltage of the clamping capacitor is greater than a fourth preset voltage, so as to balance the voltage between the at least two bidirectional switch modules; The third preset voltage is lower than the fourth preset voltage.

17. The control method according to claim 13, characterized in that: When the matrix isolation converter is a three-phase matrix isolation converter, each phase of the three-phase matrix isolation converter includes at least one bidirectional switch module; The method further includes: The switch tube that is not subjected to voltage stress in the phase with the highest absolute value of the control phase voltage is always turned on, and the switch tube that is subjected to voltage stress in the phase with the highest absolute value of the control phase voltage is switched at a preset duty cycle; The switch tube in the phase with the second highest absolute value of the control phase voltage that does not bear voltage stress when the switch tube of the highest phase is turned on is turned on before the bidirectional switch module of the highest phase is turned off, and the switch tube in the second highest phase that bears voltage stress is turned on after the bidirectional switch module of the highest phase is turned off; In the phase with the smallest absolute value of the control phase voltage, when the bidirectional switch module of the next highest phase is turned on, the switch tube that does not bear voltage stress is turned on before the bidirectional switch module of the next highest phase is turned off, and the switch tube that bears voltage stress is turned on after the bidirectional switch module of the next highest phase is turned off.

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