Combined Boost Power Conversion Module, Device, System, and Method

Abstract

The present application discloses a combined boost power conversion module, device, system and method. The combined boost power conversion module includes a first boost circuit and a second boost circuit; the positive output terminal of the first boost circuit is connected to the positive output terminal of the second boost circuit, the neutral point output terminal of the first boost circuit is connected to the neutral point output terminal of the second boost circuit, and the negative output terminal of the first boost circuit is connected to the negative output terminal of the second boost circuit; the boost branch of the first boost circuit is located between the positive input terminal and the positive output terminal of the first boost circuit, and the boost branch of the second boost circuit is located between the negative input terminal and the negative output terminal of the second boost circuit. Compared with the existing symmetric BOOST boost circuit, the present application has fewer inductors, simpler product wiring, and can achieve positive and negative DC bus balance.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and particularly to a combined boost power conversion module, an inverter device, a photovoltaic power generation system, and a control method. Background Art

[0002] Boost circuits are widely used in fields such as photovoltaic and energy storage. As Figure 1 shown, currently, a symmetric BOOST boost circuit is generally adopted.

[0003] The symmetric BOOST boost circuit has the following deficiencies:

[0004] 1) Commonly used switching tubes are low-voltage devices and it is difficult to withstand higher voltages;

[0005] 2) There are many inductors and there is a problem of complex wiring;

[0006] 3) When multiple boost circuits are connected in parallel for output application, there are problems such as a large number of system input lightning protection devices, difficult PCB power wiring, and large common-mode interference.

[0007] Figure 2 is another existing boost circuit, Figure 3 is the wave generation timing diagram corresponding to this boost circuit. It can be seen from the figure that the voltage stress borne by the switching tube Q1 is 0.5(Uc1 + Uc2), and the voltage stress borne by the switching tube Q2 is Uc2. If Uc1 = Uc2 = 0.5Uout, then the voltage stresses borne by the switching tubes Q1 and Q2 are both 0.5Uout. It can be seen that this boost circuit can realize the application of low-voltage power tubes in a high-voltage system.

[0008] Compared with Figure 1 the symmetric BOOST boost circuit shown, Figure 2 the advantages of the boost circuit in

[0009] 1) There are few inductors and the product wiring is simple;

[0010] 2) When multiple boost circuits are connected in parallel for output application, they can share the negative electrode; there are few system input lightning protection devices, the PCB power wiring is simple, and the common-mode interference problem can be solved.

[0011] However, according to Figure 3 the wave generation timing of Figure 2 , if no voltage equalization measures are taken, the positive and negative DC busbars of this boost circuit will inevitably be unbalanced. In the worst case, the busbar voltage is all borne by the capacitor C2, resulting in excessive voltage stress on the switching tube Q2 and being broken down. Similar to Figure 5 shown, according to Figure 4The boost circuit in [it] also has this problem (the bus voltage is all borne by the capacitor C1, resulting in excessive voltage stress on the switching transistor Q1 and its breakdown). SUMMARY OF THE INVENTION

[0012] In view of this, the purpose of this application is to provide a combined boost power conversion module, an inverter device, a photovoltaic power generation system, and a control method to solve the problem of positive and negative DC bus imbalance existing in the existing boost circuit.

[0013] The technical solutions adopted by this application to solve the above technical problems are as follows:

[0014] According to one aspect of this application, a combined boost power conversion module is provided, including a first boost circuit and a second boost circuit;

[0015] The positive output terminal of the first boost circuit is connected to the positive output terminal of the second boost circuit, the neutral point output terminal of the first boost circuit is connected to the neutral point output terminal of the second boost circuit, and the negative output terminal of the first boost circuit is connected to the negative output terminal of the second boost circuit;

[0016] The boost branch of the first boost circuit is located between the positive input terminal and the positive output terminal of the first boost circuit, and the boost branch of the second boost circuit is located between the negative input terminal and the negative output terminal of the second boost circuit.

[0017] According to another aspect of this application, an inverter device is provided, including a post-stage inverter circuit and a pre-stage circuit; the pre-stage circuit uses the combined boost power conversion module described above; the combined boost power conversion module is used to boost the voltage input from its input terminal and output it from the output terminal; the input terminal of the inverter circuit is coupled to the output terminal of the combined boost power conversion module to invert the direct current output by it into alternating current.

[0018] According to another aspect of this application, a photovoltaic power generation system is provided, including a photovoltaic module, a pre-stage circuit, and a post-stage circuit; the pre-stage circuit uses the combined boost power conversion module described above; the photovoltaic module corresponds to the combined boost power conversion module one by one and is coupled to its input terminal; the combined boost power conversion module is used to boost the output voltage of the photovoltaic module and output it from its output terminal to the post-stage circuit.

[0019] According to another aspect of this application, a control method for a combined boost power conversion module is provided, and the method includes:

[0020] When the voltage of the first positive output terminal or the second positive output terminal is greater than a first preset value, control the dead time between the first switching transistor Q1 and the second switching transistor Q2 to increase, and / or control the dead time between the third switching transistor Q3 and the fourth switching transistor Q4 to decrease;

[0021] When the voltage of the first negative output terminal or the second negative output terminal is greater than a second preset value, control the dead time between the first switching transistor Q1 and the second switching transistor Q2 to decrease, and / or control the dead time between the third switching transistor Q3 and the fourth switching transistor Q4 to increase.

[0022] According to another aspect of the present application, there is provided a control method for a combined boost power conversion module, the method comprising:

[0023] When the voltage of the first positive output terminal or the second positive output terminal is greater than a third preset value, control the sum of the dead times between the first switching transistor Q1 and the second switching transistor Q2 and between the fifth switching transistor Q5 and the sixth switching transistor Q6 to increase, and / or control the sum of the dead times between the third switching transistor Q3 and the fourth switching transistor Q4 and between the seventh switching transistor Q7 and the eighth switching transistor Q8 to decrease;

[0024] When the voltage of the first negative output terminal or the second negative output terminal is greater than a fourth preset value, control the sum of the dead times between the first switching transistor Q1 and the second switching transistor Q2 and between the fifth switching transistor Q5 and the sixth switching transistor Q6 to decrease, and / or control the sum of the dead times between the third switching transistor Q3 and the fourth switching transistor Q4 and between the seventh switching transistor Q7 and the eighth switching transistor Q8 to increase.

[0025] The combined boost power conversion module, inverter device, photovoltaic power generation system and control method of the embodiments of the present application, compared with the existing symmetrical BOOST boost circuit, have fewer inductors, simpler product wiring, and can achieve bus balance. Description of the Drawings

[0026] Figure 1 Schematic diagram of an existing symmetrical BOOST boost circuit;

[0027] Figure 2 Schematic diagram of an existing boost circuit;

[0028] Figure 3 For Figure 2 The waveform generation timing schematic diagram of the boost circuit in

[0029] Figure 4Another schematic diagram of an existing boost circuit;

[0030] Figure 5 is Figure 4 The wave generation timing diagram of the boost circuit in

[0031] Figure 6 Schematic diagram of the combined boost power conversion module provided by the embodiment of the present application;

[0032] Figure 7 is Figure 6 The wave generation timing diagram of the boost circuit in

[0033] Figure 8 Another schematic diagram of the combined boost power conversion module provided by the embodiment of the present application;

[0034] Figure 9 is Figure 8 The wave generation timing diagram of the boost circuit in

[0035] The realization, functional characteristics and advantages of the purpose of the present application will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the present application 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 only used to explain the present application and are not used to limit the present application.

[0037] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0038] Embodiment 1

[0039] As Figure 6 shown, the embodiment of the present application provides a combined boost power conversion module, including a first boost circuit and a second boost circuit;

[0040] The positive output terminal of the first boost circuit is connected to the positive output terminal of the second boost circuit, the neutral point output terminal of the first boost circuit is connected to the neutral point output terminal of the second boost circuit, and the negative output terminal of the first boost circuit is connected to the negative output terminal of the second boost circuit;

[0041] The boost branch of the first boost circuit is located between the positive input terminal and the positive output terminal of the first boost circuit, and the boost branch of the second boost circuit is located between the negative input terminal and the negative output terminal of the second boost circuit.

[0042] Specifically, the first boost circuit includes a first positive input terminal, a first negative input terminal, a first boost inductor L1, a first diode D1, a second diode D2, a first switching transistor Q1, a second switching transistor Q2, a first capacitor C1, and a second capacitor C2; the first boost inductor L1 and the first diode D1 form the boost branch of the first boost circuit;

[0043] The first positive input terminal is connected to one end of the first boost inductor L1, and the other end of the first boost inductor L1 is connected to the anode terminal of the first diode D1 and the first electrode terminal of the first switching transistor Q1; the cathode terminal of the first diode D1 is connected to one end of the first capacitor C1 and forms the positive output terminal of the first boost circuit, and the other end of the first capacitor C1 is connected to one end of the second capacitor C2 and the cathode terminal of the second diode D2 and forms the neutral point output terminal of the first boost circuit; the anode terminal of the second diode D2 is connected to the second electrode terminal of the first switching transistor Q1 and the first electrode terminal of the second switching transistor Q2; the first negative input terminal is connected to the second electrode terminal of the second switching transistor Q2 and the other end of the second capacitor C2 and forms the negative output terminal of the first boost circuit;

[0044] The control terminals of the first switching transistor Q1 and the second switching transistor Q2 are both used to receive control signals to disconnect or conduct the electrical connection between their first electrode terminals and their second electrode terminals.

[0045] The second boost circuit includes a second positive input terminal, a second negative input terminal, a second boost inductor L2, a third diode D3, a fourth diode D4, a third switching transistor Q3, a fourth switching transistor Q4, a third capacitor C3, and a fourth capacitor C4; the second boost inductor L2 and the third diode D3 form the boost branch of the second boost circuit;

[0046] The second negative input terminal is connected to one end of the second boost inductor L2, and the other end of the second boost inductor L2 is connected to the cathode terminal of the third diode D3 and the second electrode terminal of the fourth switch Q4; the anode terminal of the third diode D3 is connected to one end of the fourth capacitor C4 to form the negative output terminal of the second boost circuit, and the other end of the fourth capacitor C4 is connected to one end of the third capacitor C3 and the anode terminal of the fourth diode D4 to form the neutral point output terminal of the second boost circuit; the cathode terminal of the fourth diode D4 is connected to the second electrode terminal of the third switch Q3 and the first electrode terminal of the fourth switch Q4; the second positive input terminal is connected to the first electrode terminal of the third switch Q3 and the other end of the third capacitor C3 to form the positive output terminal of the second boost circuit;

[0047] The control terminals of the third switch Q3 and the fourth switch Q4 are both used to receive control signals to disconnect or conduct the electrical connection between their first electrode terminals and their second electrode terminals.

[0048] In this embodiment, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 each include one of a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, and a triode.

[0049] Based on Figure 6 the shown combined boost power conversion module, an embodiment of the present application further provides a control method for the combined boost power conversion module, and the method includes:

[0050] When the voltage at the first positive output terminal or the second positive output terminal is greater than a first preset value, control the dead time between the first switch Q1 and the second switch Q2 to increase, and / or control the dead time between the third switch Q3 and the fourth switch Q4 to decrease;

[0051] When the voltage at the first negative output terminal or the second negative output terminal is greater than a second preset value, control the dead time between the first switch Q1 and the second switch Q2 to decrease, and / or control the dead time between the third switch Q3 and the fourth switch Q4 to increase.

[0052] Please combine Figure 7 to understand that in this embodiment, the first boost circuit is likely to cause the negative DC bus BUS- voltage to be too high, and the second boost circuit is likely to cause the positive DC bus BUS+ voltage to be too high. The DC bus balance can be achieved by controlling the dead times (t1 + t2) and (t3 + t4) of the wave generation timing. The specific adjustment process is as follows:

[0053] If the positive DC bus BUS+ voltage is too high, the bus balance can be achieved by any of the following methods: 1) Increase the time of t1 + t2; 2) Decrease the time of t3 + t4; 3) Increase the time of t1 + t2 and at the same time decrease the time of t3 + t4.

[0054] If the negative DC bus BUS- voltage is too high, the bus balance can be achieved by any of the following methods: 1) Increase the time of t3 + t4; 2) Decrease the time of t1 + t2; 3) Increase the time of t3 + t4 and at the same time decrease the time of t1 + t2.

[0055] Embodiment 2

[0056] As Figure 8 shown, the embodiment of the present application provides a combined boost power conversion module, including a first boost circuit and a second boost circuit; the first boost circuit and the second boost circuit can refer to the content described in Embodiment 1, which will not be elaborated here.

[0057] In this example, the combined boost power conversion module further includes a third boost circuit sharing the negative output terminal with the first boost circuit;

[0058] The positive output terminal of the first boost circuit is connected to the positive output terminal of the third boost circuit, and the neutral point output terminal of the first boost circuit is connected to the neutral point output terminal of the third boost circuit;

[0059] The boost branch of the third boost circuit is located between the positive input terminal and the positive output terminal of the third boost circuit.

[0060] Specifically, the third boost circuit includes a third positive input terminal, a third negative input terminal, a third boost inductor L3, a fifth diode D5, a sixth diode D6, a fifth switching tube Q5, and a sixth switching tube Q6; the third boost inductor L3 and the fifth diode D5 form the boost branch of the third boost circuit;

[0061] The third positive input terminal is connected to one end of the third boost inductor L3, the other end of the third boost inductor L3 is connected to the anode terminal of the fifth diode D5 and the first electrode terminal of the fifth switching tube Q5; the cathode terminal of the fifth diode D5 forms the positive output terminal of the third boost circuit; the anode terminal of the sixth switching tube Q6 is connected to the second electrode terminal of the fifth switching tube Q5 and the first electrode terminal of the sixth switching tube Q6, the cathode terminal of the sixth switching tube Q6 forms the neutral point output terminal of the third boost circuit; the third negative input terminal is connected to the second electrode terminal of the sixth switching tube Q6 and the negative output terminal of the first boost circuit;

[0062] The fifth switching transistor Q5 and the sixth switching transistor Q6 are both configured to receive a control signal to disconnect or connect the electrical connection between its first electrode terminal and its second electrode terminal.

[0063] Further, the combined boost power conversion module further includes a fourth boost circuit sharing the positive output terminal with the second boost circuit;

[0064] The negative output terminal of the second boost circuit is connected to the negative output terminal of the fourth boost circuit, and the neutral point output terminal of the second boost circuit is connected to the neutral point output terminal of the fourth boost circuit;

[0065] The boost branch of the fourth boost circuit is located between the negative input terminal and the negative output terminal of the fourth boost circuit.

[0066] Specifically, the fourth boost circuit includes a fourth positive input terminal, a fourth negative input terminal, a fourth boost inductor L4, a seventh diode D7, an eighth diode D8, a seventh switching transistor Q7, and an eighth switching transistor Q8;

[0067] The fourth negative input terminal is connected to one end of the fourth boost inductor L4, and the other end of the fourth boost inductor L4 is connected to the cathode terminal of the seventh diode D7 and the second electrode terminal of the eighth switching transistor Q8; the anode terminal of the seventh diode D7 forms the negative output terminal of the fourth boost circuit; the cathode terminal of the eighth diode D8 is connected to the second electrode terminal of the seventh switching transistor Q7 and the first electrode terminal of the eighth switching transistor Q8, and the anode terminal of the eighth diode D8 forms the neutral point output terminal of the fourth boost circuit; the fourth positive input terminal is connected to the first electrode terminal of the seventh switching transistor Q7 and the positive output terminal of the second boost circuit;

[0068] The control terminals of the seventh switching transistor Q7 and the eighth switching transistor Q8 are both configured to receive a control signal to disconnect or connect the electrical connection between its first electrode terminal and its second electrode terminal.

[0069] In this example, the control terminals of the fifth switching transistor Q5, the sixth switching transistor Q6, the seventh switching transistor Q7, and the eighth switching transistor Q8 are all configured to receive a control signal to disconnect or connect the electrical connection between its first electrode terminal and its second electrode terminal.

[0070] In this example, the fifth switching transistor Q5, the sixth switching transistor Q6, the seventh switching transistor Q7, and the eighth switching transistor Q8 each include one of a metal-oxide-semiconductor field effect transistor, an insulated gate bipolar transistor, and a triode.

[0071] Based on Figure 8For the combined boost power conversion module shown, an embodiment of the present application also provides a control method for the combined boost power conversion module, and the method includes:

[0072] When the voltage at the first positive output terminal or the second positive output terminal is greater than a third preset value, control the sum of the dead times between the first switch tube Q1 and the second switch tube Q2, and the sum of the dead times between the fifth switch tube Q5 and the sixth switch tube Q6 to increase, and / or control the sum of the dead times between the third switch tube Q3 and the fourth switch tube Q4, and the sum of the dead times between the seventh switch tube Q7 and the eighth switch tube Q8 to decrease;

[0073] When the voltage at the first negative output terminal or the second negative output terminal is greater than a fourth preset value, control the sum of the dead times between the first switch tube Q1 and the second switch tube Q2, and the sum of the dead times between the fifth switch tube Q5 and the sixth switch tube Q6 to decrease, and / or control the sum of the dead times between the third switch tube Q3 and the fourth switch tube Q4, and the sum of the dead times between the seventh switch tube Q7 and the eighth switch tube Q8 to increase.

[0074] Please understand in combination with Figure 9 and similar to Figure 7 :

[0075] If the positive DC bus BUS+ voltage is too high, the bus balance can be achieved by any of the following methods: 1) Increase the time of T1 (t1 + t2 + t5 + t6); 2) Decrease the time of T2 (T2 = t3 + t4 + t7 + t8); 3) Increase the time of T1 and at the same time decrease the time of T2.

[0076] If the negative DC bus BUS- voltage is too high, the bus balance can be achieved by any of the following methods: 1) Increase the time of T2; 2) Decrease the time of T1; 3) Increase the time of T2 and at the same time decrease the time of T1.

[0077] It should be noted that in this example, the combined boost power conversion module is not limited to a four-way boost circuit. When the number of boost circuit paths is greater than four, a similar Figures 8 - 9 combination method and voltage equalization strategy can also be used to optimize the system circuit design.

[0078] Embodiment 3

[0079] An embodiment of the present application provides an inverter device, which includes a post-stage inverter circuit and a pre-stage circuit; the pre-stage circuit adopts the combined boost power conversion module described in Embodiment 1 or Embodiment 2; the combined boost power conversion module is used to boost the voltage input from its input end and output it from the output end; the input end of the inverter circuit is coupled to the output end of the combined boost power conversion module for inverting the direct current output by the combined boost power conversion module into alternating current.

[0080] Embodiment 4

[0081] An embodiment of the present application provides a photovoltaic power generation system, which includes a photovoltaic module, a pre-stage circuit and a post-stage circuit; the pre-stage circuit adopts the combined boost power conversion module described in Embodiment 1 or Embodiment 2; the photovoltaic module corresponds to the combined boost power conversion module one by one and is coupled to its input end; the combined boost power conversion module is used to boost the output voltage of the photovoltaic module and output it from its output end to the post-stage circuit.

[0082] For the devices and systems of Embodiments 3-4, since the combined boost power conversion module of the foregoing embodiments is adopted, they inherit all the advantages of the combined boost power conversion module.

[0083] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, and the scope of the rights of the present application is not limited thereby. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the present application shall be within the scope of the rights of the present application.

Claims

1. A control method for a combined boost power conversion module, characterized in that: The combined boost power conversion module includes a first boost circuit and a second boost circuit; The positive output terminal of the first boost circuit is connected to the positive output terminal of the second boost circuit, the neutral point output terminal of the first boost circuit is connected to the neutral point output terminal of the second boost circuit, and the negative output terminal of the first boost circuit is connected to the negative output terminal of the second boost circuit; The boost branch of the first boost circuit is located between the positive input terminal and the positive output terminal of the first boost circuit, and the boost branch of the second boost circuit is located between the negative input terminal and the negative output terminal of the second boost circuit; The first boost circuit includes a first positive input terminal, a first negative input terminal, a first boost inductor L1, a first diode D1, a second diode D2, a first switch tube Q1, a second switch tube Q2, a first capacitor C1, and a second capacitor C2; the first boost inductor L1 and the first diode D1 form a boost branch of the first boost circuit; The first positive input terminal is connected to one end of the first boost inductor L1, and the other end of the first boost inductor L1 is connected to the anode terminal of the first diode D1 and the first electrode terminal of the first switch tube Q1; the cathode terminal of the first diode D1 is connected to one end of the first capacitor C1 and forms the positive output terminal of the first boost circuit, and the other end of the first capacitor C1 is connected to one end of the second capacitor C2 and the cathode terminal of the second diode D2 and forms the neutral point output terminal of the first boost circuit; the anode terminal of the second diode D2 is connected to the second electrode terminal of the first switch tube Q1 and the first electrode terminal of the second switch tube Q2; the first negative input terminal is connected to the second electrode terminal of the second switch tube Q2 and the other end of the second capacitor C2 and forms the negative output terminal of the first boost circuit; the second electrode terminal of the first switch tube Q1 is connected to the first electrode terminal of the second switch tube Q2; The second boost circuit includes a second positive input terminal, a second negative input terminal, a second boost inductor L2, a third diode D3, a fourth diode D4, a third switch tube Q3, a fourth switch tube Q4, a third capacitor C3, and a fourth capacitor C4; the second boost inductor L2 and the third diode D3 form a boost branch of the second boost circuit; The second negative input terminal is connected to one end of the second boost inductor L2, and the other end of the second boost inductor L2 is connected to the cathode terminal of the third diode D3 and the second electrode terminal of the fourth switch Q4; the anode terminal of the third diode D3 is connected to one end of the fourth capacitor C4 and forms the negative output terminal of the second boost circuit, and the other end of the fourth capacitor C4 is connected to one end of the third capacitor C3 and the anode terminal of the fourth diode D4 and forms the neutral point output terminal of the second boost circuit; the cathode terminal of the fourth diode D4 is connected to the second electrode terminal of the third switch Q3 and the first electrode terminal of the fourth switch Q4; the second positive input terminal is connected to the first electrode terminal of the third switch Q3 and the other end of the third capacitor C3 and forms the positive output terminal of the second boost circuit; the second electrode terminal of the third switch Q3 is connected to the first electrode terminal of the fourth switch Q4; The control ends of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are all used to receive control signals to disconnect or connect the electrical connection between the first electrode end and the second electrode end thereof; The method comprises: When the voltage at the positive output terminal of the first boost circuit or the positive output terminal of the second boost circuit is greater than a first preset value, controlling the dead time between the first switch tube Q1 and the second switch tube Q2 to increase, and / or controlling the dead time between the third switch tube Q3 and the fourth switch tube Q4 to decrease; When the voltage at the negative output terminal of the first boost circuit or the negative output terminal of the second boost circuit is greater than a second preset value, the dead time between the first switch tube Q1 and the second switch tube Q2 is controlled to decrease, and / or the dead time between the third switch tube Q3 and the fourth switch tube Q4 is controlled to increase.

2. The control method of the combined boost power conversion module according to claim 1, characterized in that: The first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 , and the fourth switch tube Q4 each include one of a metal-oxide semiconductor field-effect transistor, an insulated gate bipolar transistor, and a triode.

3. A control method for a combined boost power conversion module, characterized in that: The combined boost power conversion module includes a first boost circuit and a second boost circuit; The positive output terminal of the first boost circuit is connected to the positive output terminal of the second boost circuit, the neutral point output terminal of the first boost circuit is connected to the neutral point output terminal of the second boost circuit, and the negative output terminal of the first boost circuit is connected to the negative output terminal of the second boost circuit; The boost branch of the first boost circuit is located between the positive input terminal and the positive output terminal of the first boost circuit, and the boost branch of the second boost circuit is located between the negative input terminal and the negative output terminal of the second boost circuit; The first boost circuit includes a first positive input terminal, a first negative input terminal, a first boost inductor L1, a first diode D1, a second diode D2, a first switch tube Q1, a second switch tube Q2, a first capacitor C1, and a second capacitor C2; the first boost inductor L1 and the first diode D1 form a boost branch of the first boost circuit; The first positive input terminal is connected to one end of the first boost inductor L1, and the other end of the first boost inductor L1 is connected to the anode terminal of the first diode D1 and the first electrode terminal of the first switch tube Q1; the cathode terminal of the first diode D1 is connected to one end of the first capacitor C1 and forms the positive output terminal of the first boost circuit, and the other end of the first capacitor C1 is connected to one end of the second capacitor C2 and the cathode terminal of the second diode D2 and forms the neutral point output terminal of the first boost circuit; the anode terminal of the second diode D2 is connected to the second electrode terminal of the first switch tube Q1 and the first electrode terminal of the second switch tube Q2; the first negative input terminal is connected to the second electrode terminal of the second switch tube Q2 and the other end of the second capacitor C2 and forms the negative output terminal of the first boost circuit; the second electrode terminal of the first switch tube Q1 is connected to the first electrode terminal of the second switch tube Q2; The second boost circuit includes a second positive input terminal, a second negative input terminal, a second boost inductor L2, a third diode D3, a fourth diode D4, a third switch tube Q3, a fourth switch tube Q4, a third capacitor C3, and a fourth capacitor C4; the second boost inductor L2 and the third diode D3 form a boost branch of the second boost circuit; The second negative input terminal is connected to one end of the second boost inductor L2, and the other end of the second boost inductor L2 is connected to the cathode terminal of the third diode D3 and the second electrode terminal of the fourth switch Q4; the anode terminal of the third diode D3 is connected to one end of the fourth capacitor C4 and forms the negative output terminal of the second boost circuit, and the other end of the fourth capacitor C4 is connected to one end of the third capacitor C3 and the anode terminal of the fourth diode D4 and forms the neutral point output terminal of the second boost circuit; the cathode terminal of the fourth diode D4 is connected to the second electrode terminal of the third switch Q3 and the first electrode terminal of the fourth switch Q4; the second positive input terminal is connected to the first electrode terminal of the third switch Q3 and the other end of the third capacitor C3 and forms the positive output terminal of the second boost circuit; the second electrode terminal of the third switch Q3 is connected to the first electrode terminal of the fourth switch Q4; The control ends of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are all used to receive control signals to disconnect or connect the electrical connection between the first electrode end and the second electrode end thereof; The combined boost power conversion module further includes a third boost circuit sharing a negative output terminal with the first boost circuit, and a fourth boost circuit sharing a positive output terminal with the second boost circuit; The positive output terminal of the first boost circuit is connected to the positive output terminal of the third boost circuit, and the neutral point output terminal of the first boost circuit is connected to the neutral point output terminal of the third boost circuit; The boost branch of the third boost circuit is located between the positive input terminal and the positive output terminal of the third boost circuit; The negative output terminal of the second boost circuit is connected to the negative output terminal of the fourth boost circuit, and the neutral point output terminal of the second boost circuit is connected to the neutral point output terminal of the fourth boost circuit; The boost branch of the fourth boost circuit is located between the negative input terminal and the negative output terminal of the fourth boost circuit; The third boost circuit includes a third positive input terminal, a third negative input terminal, a third boost inductor L3, a fifth diode D5, a sixth diode D6, a fifth switch tube Q5, and a sixth switch tube Q6; the third boost inductor L3 and the fifth diode D5 form a boost branch of the third boost circuit; The third positive input terminal is connected to one end of the third boost inductor L3, and the other end of the third boost inductor L3 is connected to the anode terminal of the fifth diode D5 and the first electrode terminal of the fifth switch tube Q5; the cathode terminal of the fifth diode D5 forms the positive output terminal of the third boost circuit; the anode terminal of the sixth diode D6 is connected to the second electrode terminal of the fifth switch tube Q5 and the first electrode terminal of the sixth switch tube Q6, and the cathode terminal of the sixth diode D6 forms the neutral point output terminal of the third boost circuit; the third negative input terminal is connected to the second electrode terminal of the sixth switch tube Q6 and the negative output terminal of the first boost circuit; the second electrode terminal of the fifth switch tube Q5 is connected to the first electrode terminal of the sixth switch tube Q6; The fourth boost circuit includes a fourth positive input terminal, a fourth negative input terminal, a fourth boost inductor L4, a seventh diode D7, an eighth diode D8, a seventh switch tube Q7 and an eighth switch tube Q8; The fourth negative input terminal is connected to one end of the fourth boost inductor L4, and the other end of the fourth boost inductor L4 is connected to the cathode terminal of the seventh diode D7 and the second electrode terminal of the eighth switch tube Q8; the anode terminal of the seventh diode D7 forms the negative output terminal of the fourth boost circuit; the cathode terminal of the eighth diode D8 is connected to the second electrode terminal of the seventh switch tube Q7 and the first electrode terminal of the eighth switch tube Q8, and the anode terminal of the eighth diode D8 forms the neutral point output terminal of the fourth boost circuit; the fourth positive input terminal is connected to the first electrode terminal of the seventh switch tube Q7 and the positive output terminal of the second boost circuit; the first electrode terminal of the eighth switch tube Q8 is connected to the second electrode terminal of the seventh switch tube Q7; The control terminals of the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7, and the eighth switch tube Q8 are all used to receive control signals to disconnect or connect the electrical connection between the first electrode terminal and the second electrode terminal; The method comprises: When the voltage at the positive output terminal of the first boost circuit or the positive output terminal of the second boost circuit is greater than a third preset value, the sum of the dead time between the first switch tube Q1 and the second switch tube Q2 and the dead time between the fifth switch tube Q5 and the sixth switch tube Q6 is controlled to increase, and / or the sum of the dead time between the third switch tube Q3 and the fourth switch tube Q4 and the dead time between the seventh switch tube Q7 and the eighth switch tube Q8 is controlled to decrease; When the voltage at the negative output terminal of the first boost circuit or the negative output terminal of the second boost circuit is greater than a fourth preset value, the sum of the dead time between the first switch tube Q1 and the second switch tube Q2 and the dead time between the fifth switch tube Q5 and the sixth switch tube Q6 is controlled to decrease, and / or the sum of the dead time between the third switch tube Q3 and the fourth switch tube Q4 and the dead time between the seventh switch tube Q7 and the eighth switch tube Q8 is controlled to increase.

4. The control method of the combined boost power conversion module according to claim 3, characterized in that: The first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 each include one of a metal-oxide semiconductor field-effect transistor, an insulated gate bipolar transistor and a triode.

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