A power conversion circuit and control method

Abstract

The application provides a power conversion circuit and a control method. The power conversion circuit comprises a first power circuit, a second power circuit, a main loop composed of a switching circuit and a main loop switch, and an auxiliary loop composed of a sampling circuit, a discharging circuit and a soft start circuit. The auxiliary loop is additionally provided with a soft start switch for controlling the on-off of the soft start circuit. When the soft start switch and the main loop switch are turned off during the switching of the first power circuit and the second power circuit in the series mode or the parallel mode controlled by the switching circuit, the second port can be completely disconnected from the internal circuit, the discharging of the internal capacitor and the switching between the series mode and the parallel mode will not affect the voltage of the second port, and the second port load will not be damaged. Meanwhile, the energy storage element of the second port will not charge the internal capacitor during the discharging, and the internal battery voltage can be completely discharged.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, and particularly relates to a power conversion circuit and control method. Background Technology

[0002] Traditional power conversion circuits such as Figure 1 As shown, to achieve a wide constant power voltage range, the switching states of switches K1, K2, and K3 are generally controlled to make the outputs of power circuit 1 and power circuit 2 operate in series or parallel mode. When the output voltage is low, K1 is open, and K2 and K3 are closed, so power circuit 1 and power circuit 2 operate in parallel mode; when the output voltage is high, K1 is closed, and K2 and K3 are open, so power circuit 1 and power circuit 2 operate in series mode.

[0003] Deficiencies of existing technology:

[0004] A typical main circuit filter circuit includes at least a filter capacitor and a filter inductor, with the filter capacitor having a much smaller capacitance than C1 and C2. In parallel mode, the voltage across the filter capacitor is the same as the voltage across C1 and C2. In series mode, the voltage across the filter capacitor is the sum of the voltages across C1 and C2. Therefore, when switching from parallel to series mode, the voltage across the filter capacitor will spike. This high voltage can flow back to the DC port through the soft-start circuit, potentially damaging the load connected to the DC port. When switching from series to parallel mode, if the voltages across C1 and C2 are inconsistent, a large current will flow through the switch K2 and K3, which may cause the contacts of K2 and K3 to stick together in severe cases. Therefore, it is desirable to completely discharge the charge on capacitors C1 and C2 and the filter capacitor before the switch K1, K2, and K3 operate. However, when DC+ and DC- are connected to energy storage components such as batteries, even though the main circuit switch K4 is disconnected, the battery is simultaneously charging the capacitors through the soft-start circuit while C1, C2, and the filter capacitor are discharging. Therefore, it is difficult to completely discharge the internal capacitors. Furthermore, the existing technology also has defects in the voltage sampling scheme: in parallel mode, the voltages of the upper and lower branches are the same, representing the output of sampling circuit 1 or sampling circuit 2; in series mode, the result of sampling circuit 1 is the voltage of the lower branch, and the result of sampling circuit 2 minus the result of sampling circuit 1 is the voltage of the upper branch. However, when K1, K2, and K3 are all disconnected, the voltage of the upper branch cannot be sampled, making it impossible to determine the discharge status of capacitor C1 in this situation. Finally, when K1, K2, and K3 are all disconnected, the discharge circuit cannot discharge C1 and C2. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a power conversion circuit and control method. It aims to address the issue in existing technology where the power conversion circuit, in order to achieve a wide constant power voltage range, cannot fully discharge the capacitor during mode switching, leading to switch sticking.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0007] The first aspect of this invention provides a power conversion circuit for realizing power transmission between a first port and a second port. The power conversion circuit includes a main circuit and an auxiliary circuit; wherein:

[0008] The main circuit includes a first power circuit, a second power circuit, a switching circuit, and a main circuit switch;

[0009] A first power circuit and a second power circuit are used to realize power conversion in a power conversion circuit. The output terminal of the first power circuit is connected in parallel with a first output capacitor, and the output terminal of the second power circuit is connected in parallel with a second output capacitor.

[0010] A switching circuit is used to switch between series or parallel modes between the first power circuit and the second power circuit.

[0011] The main circuit switch is used to control the on / off state of the main circuit.

[0012] The auxiliary circuit includes a sampling circuit, a discharge circuit, a soft start circuit, and a soft start switch;

[0013] A sampling circuit is used to sample the capacitor voltages of the first output capacitor and the second output capacitor;

[0014] The discharge circuit is used to discharge the capacitance of the first output capacitor and the second output capacitor.

[0015] The soft start circuit is used to perform soft start control on the main circuit when the main circuit switch is closed.

[0016] A soft start switch is used to control the on / off state of a soft start circuit.

[0017] Furthermore, the sampling circuit includes:

[0018] The first sampling circuit is used to sample and obtain the voltage of the second output capacitor;

[0019] The second sampling circuit is used to sample and obtain the positive voltage of the first output capacitor;

[0020] The third sampling circuit is used to sample and obtain the negative voltage of the first output capacitor.

[0021] Furthermore, it also includes a filter circuit, which is located in the main circuit and is used to filter out ripple in the output voltage.

[0022] Furthermore, the first power circuit and the second power circuit are respectively connected to independent buses at the first port, or share the same bus.

[0023] Furthermore, it also includes an auxiliary power supply connected to a second port, which is used to connect to an energy storage device. The auxiliary circuit can also be connected to other power supplies.

[0024] Furthermore, it also includes a balancing circuit, which is connected in parallel across the two ends of the first output capacitor to balance the impedance of the first output capacitor and the second output capacitor.

[0025] Furthermore, the discharge circuit includes a first discharge circuit, a second discharge circuit, and a third discharge circuit.

[0026] The first discharge circuit is connected in parallel in the main circuit and is used to discharge the first output capacitor and the second output capacitor when the switching circuit is connected.

[0027] The second discharge circuit is connected in parallel across the two ends of the first output capacitor and is used to discharge the first output capacitor when the switching circuit is closed.

[0028] The third discharge circuit is connected in parallel across the two ends of the second output capacitor and is used to discharge the second output capacitor when the switching circuit is closed.

[0029] A second aspect of the present invention provides a control method applied to the power conversion circuit described above, for realizing the power conversion circuit's power-on process, the control method comprising:

[0030] The main circuit switch and soft start switch are controlled to enter the open state, and the discharge circuit discharges the first output capacitor and the second output capacitor.

[0031] At the end of the discharge, the switching circuit is turned on and off according to the target working mode, and the soft start switch is turned on to precharge the first output capacitor and the second output capacitor.

[0032] When precharging is complete, the main circuit switch is turned on, and the first power circuit and the second power circuit are turned on.

[0033] A third aspect of the present invention provides a control method applied to the power conversion circuit described above, for realizing the operating mode switching process of the power conversion circuit, the control method comprising:

[0034] When the power conversion circuit is in the power-on state, the first power circuit and the second power circuit are controlled to enter the off state, and the main circuit switch and the soft start switch are controlled to enter the open state. The discharge circuit discharges the first output capacitor and the second output capacitor.

[0035] When the capacitor voltages of the first output capacitor and the second output capacitor are less than the capacitor voltage threshold, the switching circuit is turned on and off, triggering the switching of the connection mode between the first power circuit and the second power circuit; wherein, the connection mode includes series mode and parallel mode;

[0036] The soft start switch is controlled to enter the conducting state to charge the first output capacitor and the second output capacitor. Then, when the charging voltage reaches the charging voltage threshold, the main circuit switch is turned on, and the first power circuit and the second power circuit are controlled to enter the on state.

[0037] A fourth aspect of the present invention provides a control method applied to the power conversion circuit described above, for realizing the shutdown process of the power conversion circuit, the control method comprising:

[0038] The first and second power circuits are controlled to enter the off state, and the current in the power conversion circuit gradually decreases.

[0039] When the current through the main circuit switch and the soft start switch both decrease to the current threshold, the control discharge circuit discharges the first output capacitor and the second output capacitor, thus completing the shutdown of the power conversion circuit.

[0040] This invention provides a power conversion circuit and control method. Compared with the prior art, the advantages are as follows: The power conversion circuit includes a main circuit composed of a first power circuit, a second power circuit, a switching circuit, and a main circuit switch, as well as an auxiliary circuit composed of a sampling circuit, a discharge circuit, and a soft-start circuit. The soft-start circuit is equipped with a soft-start switch. Based on the control method adopted by this power conversion circuit, when the switching circuit controls the first power circuit and the second power circuit to switch between series / parallel modes, when the soft-start switch and the main circuit switch are disconnected, the third port can be completely disconnected from the internal circuit. Discharging the internal capacitor and switching between series and parallel will not affect the voltage of the second port and will not cause damage to the load of the second port. At the same time, the energy storage element of the second port will not charge the internal capacitor during discharge, and the internal battery voltage can be completely discharged. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a traditional power conversion circuit;

[0042] Figure 2 This is one embodiment of the power conversion circuit in the first embodiment of the present invention;

[0043] Figure 3This is a second embodiment of the power conversion circuit in the first embodiment of the present invention;

[0044] Figure 4 This is the third embodiment of the power conversion circuit in the first embodiment of the present invention;

[0045] Figure 5 This is the fourth embodiment of the power conversion circuit in the first embodiment of the present invention;

[0046] Figure 6 This is the fifth embodiment of the power conversion circuit in the first embodiment of the present invention;

[0047] Figure 7 This is a flowchart illustrating the control method in the second embodiment of the present invention;

[0048] Figure 8 This is a schematic diagram of the specific flow of the control method in the second embodiment of the present invention;

[0049] Figure 9 This is a flowchart illustrating the control method in the third embodiment of the present invention;

[0050] Figure 10 This is a schematic diagram of the specific flow of the control method in the third embodiment of the present invention;

[0051] Figure 11 This is a flowchart illustrating the control method in the fourth embodiment of the present invention;

[0052] Figure 12 This is a schematic diagram of the specific flow of the control method in the fourth embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] Example 1

[0055] A first embodiment of the present invention provides a power conversion circuit for realizing energy transfer between a first port and a second port. In some embodiments, the first port can be a BUS port, the second port can be a DC port, and the load connected to the DC port is an energy storage element. The power conversion circuit provided by the present invention is used to realize energy transfer between the BUS port and the DC port.

[0056] like Figure 2 The diagram shows the structure of a power conversion circuit; this power conversion circuit includes: a main circuit and an auxiliary circuit; wherein:

[0057] The main circuit includes a first power circuit 10, a second power circuit 20, and a switching circuit ( Figure 2 The diagram includes the first switch K1, the second switch K2, and the third switch K3, as well as the main circuit switch K4.

[0058] Specifically, the first power circuit 10 and the second power circuit 20 are disposed at the BUS port and connected to the power supply for power conversion. In some embodiments, the BUS port includes a first BUS port and a second BUS port, wherein the first power circuit 10 is connected to the first BUS port, the second power circuit 20 is connected to the second BUS port, and a first output capacitor C1 is connected in parallel at the output terminal of the first power circuit 10, and a second output capacitor C2 is connected in parallel at the output terminal of the second power circuit 20.

[0059] A switching circuit is used to switch between a series connection and a parallel connection between the first power circuit 10 and the second power circuit 20. In some embodiments, the switching circuit includes a first switch K1, a second switch K2, and a third switch K3, and satisfies the following conditions: when the output voltage is low, the first switch K1 is open, and the second switch K2 and the third switch K3 are closed, at which time the first power circuit 10 and the second power circuit 20 operate in parallel mode; when the output voltage is high, the first switch K1 is closed, and the second switch K2 and the third switch K3 are open, at which time the first power circuit 10 and the second power circuit 20 operate in series mode.

[0060] The main circuit switch K4 is installed in the main circuit to control the on / off state of the main circuit.

[0061] The auxiliary circuit includes a sampling circuit ( Figure 2 The circuit shown includes a first sampling circuit 30, a second sampling circuit 50, and a third sampling circuit 40, as well as a discharge circuit. Figure 2 The circuit shown includes a first discharge circuit 60, a soft start circuit 80, and a soft start switch K5.

[0062] Specifically, the sampling circuit is used to sample the capacitor voltage in the main circuit. In some embodiments, the sampling circuit includes a first sampling circuit 30, a second sampling circuit 50, and a third sampling circuit 40. The first sampling circuit 30 samples the voltage of the second output capacitor C2, the second sampling circuit 50 samples the positive voltage of the first output capacitor C1, and the third sampling circuit 40 samples the negative voltage of the first output capacitor C1. Through the voltage sampling of the first sampling circuit 30, the second sampling circuit 50, and the third sampling circuit 40, the voltage values ​​of the first output capacitor C1 and the second output capacitor C2 can be calculated, and based on these voltage values, a judgment can be made to control the on / off state of the switch in the switching circuit.

[0063] A discharge circuit is used to discharge the capacitance of the first output capacitor C1 and the second output capacitor C2. In some embodiments, only a first discharge circuit 60 is provided in the power circuit. This first discharge circuit 60 is connected between the positive and negative terminals of the DC terminal and can discharge the capacitance in either series or parallel mode of the power conversion circuit.

[0064] The soft start circuit 80 is used to perform soft start control on the main circuit when the main circuit switch K4 is closed.

[0065] The soft start switch K5, connected in series with the soft start circuit 80, is located between the first discharge circuit 60 and the DC port. The soft start switch K5 is used to control the on / off state of the soft start circuit.

[0066] In some embodiments, the power conversion circuit further includes a filter circuit 70 for filtering out ripple in the rectified output voltage during power transmission, wherein the filter circuit 70 is disposed between the first discharge circuit 60 and the soft-start circuit 80.

[0067] See Figure 3 , Figure 3 The diagram shows one embodiment of the power conversion circuit of the present invention. Figure 2 Based on the circuit structure shown, the connection method of the primary side of the first power circuit 10 and the second power circuit 20 is changed (the sampling circuit is not shown in the figure). In this embodiment, the primary side of the first power circuit 10 and the second power circuit 20 share a common bus. In other embodiments, the primary side of the first power circuit 10 and the second power circuit 20 are connected to two independent buses, which also achieves the purpose of energy transmission between the BUS end and the DC end.

[0068] See Figure 4 , Figure 4 The diagram shows one embodiment of the power conversion circuit of the present invention. Figure 2 An auxiliary power supply 90 is added to the circuit structure shown. The auxiliary power supply 90 is connected to the DC terminal, which is used to connect to the energy storage device. The auxiliary power supply 90 can draw power from the DC port, so discharging the first output capacitor C1 and the second output capacitor C2 does not affect the operation of the auxiliary power supply 90. In some other embodiments, the auxiliary power supply 90 can also be connected to other power sources, drawing power not only from the DC port but also from other power sources.

[0069] See Figure 5 , Figure 5 The diagram shows one embodiment of the power conversion circuit of the present invention. Figure 4Based on the circuit structure shown, a balancing circuit 100 is added, which is connected in parallel across the first output capacitor. The first sampling circuit 30, the second sampling circuit 50, and the third sampling circuit 40 are generally composed of voltage divider resistors. In series mode, both the first sampling circuit 30 and the third sampling circuit 40 are connected to the second output capacitor C2, causing the voltages on the first output capacitor C1 and the second output capacitor C2 to be inconsistent during soft-start pre-charging, with the voltage of the first output capacitor C1 being higher and the voltage of the second output capacitor C2 being lower. Therefore, a balancing circuit 100 is added across the first output capacitor C1 to make the impedances connected to the first output capacitor C1 and the second output capacitor C2 equal.

[0070] See Figure 6 , Figure 6 The diagram shows one embodiment of the power conversion circuit of the present invention. Figure 5 Based on the circuit structure shown, a second discharge circuit 200 and a third discharge circuit 300 are added. The second discharge circuit 200 is connected in parallel across the two ends of the first output capacitor C1, and the second discharge circuit 300 is connected in parallel across the two ends of the second output capacitor C2, so that the first switch K1, the second switch K2, and the third switch K3 can discharge the first output capacitor C1 and the second output capacitor C2 respectively when they are open.

[0071] In summary, the present invention provides a power conversion circuit, which enables the following: when the switching circuit controls the first power circuit and the second power circuit to switch between series mode and parallel mode, when the soft start switch and the main circuit switch are open, the second port can be completely disconnected from the internal circuit. Discharging the internal capacitor and switching between series and parallel will not affect the voltage of the second port and will not cause damage to the load of the second port. At the same time, the energy storage element of the second port will not charge the internal capacitor during discharge, and the internal battery voltage can be completely discharged.

[0072] Example 2

[0073] A second embodiment of the present invention provides a control method applied to the power conversion circuit as described in Embodiment 1, for realizing the power conversion circuit's power-on process. The circuit structure will not be described in detail here. See also... Figure 7 As shown, the power-on process includes:

[0074] Step 701: Control the main circuit switch K4 and soft start switch K5 to enter the open state, and the discharge circuit discharges the first output capacitor C1 and the second output capacitor C2.

[0075] Step 702: At the end of the discharge, control the switching circuit to open or close according to the target working mode, and control the soft start switch K5 to enter the conducting state to precharge the first output capacitor C1 and the second output capacitor C2.

[0076] Step 703: When pre-charging is complete, control the main circuit switch K4 to enter the conducting state, and control the first power circuit 10 and the second power circuit 20 to enter the open state.

[0077] During the discharge process in step 703, the first output capacitor C1, the second output capacitor C2, and the total voltage V can be used as a reference. AB The system determines whether the first output capacitor C1 or the second output capacitor C2 cannot discharge due to the disconnection of the first switch K1, the second switch K2, and the third switch K3. If so, the corresponding switch is turned on and the discharge continues.

[0078] After the first discharge, if the voltages of the first output capacitor C1 and the second output capacitor C2 decrease at similar rates, and the total voltage V... AB If the voltage difference is approximately equal to Vc1 + Vc2, it can be determined that the first switch K1 is on, the second switch K2, and the third switch K3 are off. If the voltage drop rate of the first output capacitor C1 is slow, it can be assumed that the first switch K1 and the second switch K2 are off, and the third switch K3 is on. If the voltage drop rate of the second output capacitor C2 is slow, it can be assumed that the first switch K1 and the third switch K3 are off, and the second switch K2 is on. If the voltage drop rates of the first output capacitor C1 and the second output capacitor C2 are both slow, it can be assumed that the first switch K1, the second switch K2, and the third switch K3 are all off. For the latter three cases, the voltage values ​​of the first output capacitor C1 and the second output capacitor C2 determine which switches are engaged for discharge. If the voltage difference between the first output capacitor C1 and the second output capacitor C2 is small, the second switch K2 and the third switch K3 can be turned on, and the first switch K1 can be turned off for discharge. If the voltage difference between the first output capacitor C1 and the second output capacitor C2 is large, only the first switch K1 can be turned on, and the second switch K2 and the third switch K3 can be turned off for discharge.

[0079] At the end of the discharge, the switch module is switched on and off according to the target working mode, and the soft start switch K5 is controlled to enter the conducting state to precharge the first output capacitor C1, the second output capacitor C2 and the capacitor in the filter circuit 70.

[0080] The activation process can be found in [reference needed]. Figure 8 The detailed flowchart shown is shown below.

[0081] Example 3

[0082] The third embodiment of the present invention provides a control method applied to the power conversion circuit as described in Embodiment 1, used to realize the switching process of the power conversion circuit's operating mode. The circuit structure will not be described in detail here. See also... Figure 9 As shown, the process of changing this working mode includes:

[0083] Step 801: When the power conversion circuit is in the power-on state, control the first power circuit 10 and the second power circuit 20 to enter the off state, and control the main circuit switch K4 and the soft start switch K5 to enter the open state. The discharge circuit 60 discharges the first output capacitor C1 and the second output capacitor C2.

[0084] Step 802: When the capacitor voltages of the first output capacitor C1 and the second output capacitor C2 are less than the capacitor voltage threshold, the switching circuit is turned on and off, triggering a switch between the connection modes of the first power circuit 10 and the second power circuit 20;

[0085] Step 803: Control the soft start switch to enter the conduction state to charge the first output capacitor C1 and the second output capacitor C2. Then, when the charging voltage reaches the charging voltage threshold, turn on the main circuit switch and control the first power circuit 10 and the second power circuit 20 to enter the on state.

[0086] This control method describes the switching process between the operating modes of the first power circuit 10 and the second power circuit 20 when the power conversion circuit is in the ON state; the operating modes include series mode and parallel mode. The switching process can be found in [reference needed]. Figure 10 The detailed flowchart is shown below. This switching process completely disconnects the DC port from the internal circuitry. Discharging the internal capacitors and switching between series and parallel connections will not affect the DC port voltage, nor will it damage the DC port load. At the same time, the DC port battery will not charge the internal capacitors during discharge, allowing the internal battery voltage to be completely discharged.

[0087] Example 4

[0088] The fourth embodiment of the present invention provides a control method applied to the power conversion circuit as described in Embodiment 1, for realizing the shutdown process of the power conversion circuit. The circuit structure will not be described in detail here. See also... Figure 11 As shown, the process of changing this working mode includes:

[0089] Step 901: Control the first power circuit 10 and the second power circuit 20 to enter the off state, and the current in the power conversion circuit gradually decreases;

[0090] Step 902: When the current through the main circuit switch K4 and the soft start switch K5 both decrease to the current threshold, the control discharge circuit 60 discharges the first output capacitor C1 and the second output capacitor C2 to complete the shutdown of the power conversion circuit.

[0091] It should be noted that this shutdown procedure applies to the shutdown process of power conversion circuits, and is not limited to shutdown after switching operating modes. The shutdown procedure can be found in [reference needed]. Figure 12 The detailed flowchart.

[0092] The above embodiments 2, 3, and 4 include the power-on process, mode switching process, and power-off process of the power conversion circuit. During the power-on process, the soft-start switch K5 can be disconnected after the main circuit switch K4 is turned on. During the power-off process, the soft-start switch K5 can be disconnected before the first and second power circuits are turned off, without affecting the reliability of the circuit. That is, the soft-start switch K5 only needs to be disconnected when the main circuit switch K4 is turned on, and it has little to do with whether the main power circuit is working or not.

[0093] In summary, the present invention provides a control method, which has the following advantages compared with the prior art:

[0094] The circuit is equipped with a sampling circuit that can sample the first and second output capacitors in this invention when all switches in the switching circuit are open. By adding a soft-start switch K5 in the auxiliary circuit, when the DC side of the module discharges, the main circuit switch and the soft-start switch K5 are open, which can completely disconnect the DC port from the internal circuit. Discharging the internal capacitor and switching between series and parallel will not affect the DC port voltage and will not cause damage to the DC port load. At the same time, the battery in the DC port will not charge the internal capacitor during discharge, and the internal battery voltage can be completely discharged.

[0095] The terms "first," "second," etc., used here only indicate the distinction in their names and do not imply any difference in their importance or position.

[0096] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power conversion circuit for realizing energy transfer between a first port and a second port, characterized in that, include: Main circuit and auxiliary circuit; wherein: The main circuit includes a first power circuit, a second power circuit, a switching circuit, and a main circuit switch; The first power circuit and the second power circuit are used to realize power conversion in the power conversion circuit, wherein the output terminal of the first power circuit is connected in parallel with a first output capacitor, and the output terminal of the second power circuit is connected in parallel with a second output capacitor. The switching circuit is used to switch between the series mode and the parallel mode between the first power circuit and the second power circuit. The main circuit switch is used to control the on / off state of the main circuit; The auxiliary circuit includes a sampling circuit, a discharge circuit, a soft start circuit, and a soft start switch; The sampling circuit is used to sample the capacitor voltages of the first output capacitor and the second output capacitor. The discharge circuit is used to discharge the capacitance of the first output capacitor and the second output capacitor. The soft-start circuit is used to perform soft-start control on the main circuit when the main circuit switch is closed. The soft start switch is used to control the on / off state of the soft start circuit; The sampling circuit includes: a first sampling circuit, a second sampling circuit, and a third sampling circuit; The first sampling circuit is used to sample and obtain the voltage of the second output capacitor. The second sampling circuit is used to sample and obtain the positive voltage of the first output capacitor. The third sampling circuit is used to sample and obtain the negative voltage of the first output capacitor, calculate and obtain the voltage values ​​of the first output capacitor and the second output capacitor, and make a judgment based on the voltage values ​​to control the on / off state of the switch in the switching circuit. The discharge circuit includes a first discharge circuit, a second discharge circuit, and a third discharge circuit; The first discharge circuit is connected in parallel in the main circuit and is used to discharge the first output capacitor and the second output capacitor when the switching circuit is connected. The second discharge circuit is connected in parallel across the two ends of the first output capacitor and is used to discharge the first output capacitor when the switching circuit is closed. The third discharge circuit is connected in parallel across the two ends of the second output capacitor and is used to discharge the second output capacitor when the switching circuit is closed.

2. The power conversion circuit according to claim 1, characterized in that, It also includes a filter circuit, which is disposed in the main circuit and is used to filter out ripple in the output voltage.

3. The power conversion circuit according to claim 1, characterized in that, The first power circuit and the second power circuit are located at the first port and are respectively connected to independent buses, or share the same bus.

4. The power conversion circuit according to claim 2, characterized in that, It also includes an auxiliary power supply, which is connected to the second port. The second port is used to connect to the energy storage device. The auxiliary power supply can also be connected to other power sources.

5. The power conversion circuit according to claim 3, characterized in that, It also includes a balancing circuit, which is connected in parallel across the two ends of the first output capacitor to balance the impedance of the first output capacitor and the second output capacitor.

6. A control method for implementing the power-on process of a power conversion circuit, characterized in that, The control method, applied to the power conversion circuit as described in any one of claims 1 to 5, includes: The main circuit switch and the soft start switch are controlled to enter the open state, and the discharge circuit discharges the first output capacitor and the second output capacitor. At the end of the discharge, the switching circuit is turned on and off according to the target working mode, and the soft start switch is turned on to precharge the first output capacitor and the second output capacitor. When precharging is complete, the main circuit switch is controlled to enter the conducting state, and the first power circuit and the second power circuit are controlled to enter the on state.

7. A control method for implementing the operating mode switching process of a power conversion circuit, characterized in that, The control method, applied to the power conversion circuit as described in any one of claims 1 to 5, includes: When the power conversion circuit is in the power-on state, the first power circuit and the second power circuit are controlled to enter the power-off state, and the main circuit switch and the soft start switch are controlled to enter the open state, and the discharge circuit discharges the first output capacitor and the second output capacitor. When the capacitor voltages of the first output capacitor and the second output capacitor are less than the capacitor voltage threshold, the switching circuit is controlled to switch the connection mode of the first power circuit and the second power circuit; wherein, the connection mode includes series mode and parallel mode; The soft-start switch is controlled to enter the conducting state to charge the first output capacitor and the second output capacitor. Then, when the charging voltage reaches the charging voltage threshold, the main circuit switch is turned on, and the first power circuit and the second power circuit are controlled to enter the on state.

8. A control method for implementing the shutdown process of a power conversion circuit, characterized in that, The control method, applied to the power conversion circuit as described in any one of claims 1 to 5, includes: The first power circuit and the second power circuit are controlled to enter the off state, and the current in the power conversion circuit gradually decreases; When the current through the main circuit switch and the soft start switch both decrease to the current threshold, the discharge circuit is controlled to discharge the first output capacitor and the second output capacitor, thereby shutting down the power conversion circuit.

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