Boost circuit and photovoltaic inverter

By designing the switch module and voltage clamping module in the boost circuit of the photovoltaic inverter, the power switch tubes are divided into PV voltage evenly, which solves the problems of high withstand voltage, high damage rate and high cost of power switch tubes in the prior art. , achieving the effect of reducing costs and improving stability.

CN222531547UActive Publication Date: 2025-02-25NINGBO SUNWAYS TECH CO LTD
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Patent Information

Application Number
CN202420640381.9
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-03-30
Publication Date
2025-02-25
Estimated Expiration
2034-03-30

AI Technical Summary

Technical Problem

In existing photovoltaic inverters, the power switch tube of the boost circuit needs to withstand the entire PV voltage when it is turned off, resulting in high stress, high damage rate, and high voltage level power switch tubes are expensive, which increases the boost circuit. cost.

Method used

A boost circuit is designed, including a switching module and a voltage clamping module, and a first power switch tube and a second power switch tube are arranged in series, and the first resistor and TVS array diode are connected to both positive and negative ends of the DC bus. The first resistor and TVS array diode are arranged near the photovoltaic module. In this way, the first power switch tube and the second power switch tube are evenly divided into PV voltages, and each withstand 0.5 times the voltage.

Benefits of technology

It effectively reduces the voltage withstand demand of the power switch tube, reduces the conversion cost of the boost circuit, and ensures the stability of the switch module when it is turned on and off.

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Abstract

The utility model discloses a boost circuit and a photovoltaic inverter. The boost circuit comprises a switch module, a voltage clamping module and a PWM generator. The switch module comprises a first power switch tube and a second power switch tube which are connected to the positive end and the negative end of a direct current bus and are connected in series, and the voltage clamping module is connected to the positive end and the negative end of the direct current bus and is connected in series with a first resistor and a TVS array diode. The grid electrode of the first power switch tube is connected between the TVS array diode and the first resistor through a third resistor, a third transient suppression diode is connected in parallel between the collector electrode of the second power switch tube and the grid electrode of the first power switch tube, and a second resistor is connected in parallel between the collector electrode of the second power switch tube and the third resistor; the PWM generator is connected with the grid electrode of the second power switch tube and used for generating PWM pulses to drive the first power switch tube and / or the second power switch tube to be switched on and switched off, the voltage withstanding requirement of the power switch tubes can be effectively reduced through the booster circuit, and then the conversion cost of the booster circuit is reduced.
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Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic inverters, and in particular to a boost circuit and a photovoltaic inverter. Background Art

[0002] A photovoltaic inverter is a device that converts direct current (DC) power in a photovoltaic power generation system into alternating current (AC) power, and is an indispensable component of a photovoltaic power generation system. In a photovoltaic power generation system, solar panels convert sunlight into direct current, and the role of a photovoltaic inverter is to convert this DC power into an AC power suitable for the power supply network or directly supplying power to a home or office.

[0003] However, the PV voltage level of photovoltaic inverters is getting higher and higher, and the voltage resistance level of the power switch tube of the boost circuit is also getting higher and higher. Figure 1 ( Figure 1 As shown in the boost circuit diagram of the inverter in the prior art, when the power switch tube is turned off, the power switch tube needs to withstand the entire PV voltage, which makes the stress on the power switch tube high and easily causes damage to the power switch tube. At the same time, the power switch tube of high voltage level is expensive, which increases the cost of the boost circuit. Utility Model Content

[0004] In order to overcome the above shortcomings, the purpose of the present application is to provide a boost circuit and an inverter, wherein the boost circuit can effectively reduce the withstand voltage requirement of the power switch tube, thereby reducing the conversion cost of the boost circuit.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] A boost circuit for a photovoltaic inverter, the boost circuit comprising:

[0007] The switch module comprises a first power switch tube and a second power switch tube, wherein the first power switch tube and the second power switch tube are connected in series and connected to the positive and negative ends of the DC bus;

[0008] A voltage clamping module, comprising a first resistor and a TVS array diode, wherein the first resistor and the TVS array diode are connected in series and connected to the positive and negative ends of the DC bus, wherein the first resistor and the TVS array diode are arranged closer to the photovoltaic assembly than the switch module;

[0009] The gate of the first power switch tube is connected between the TVS array diode and the first resistor through a third resistor, a third transient suppression diode is connected in parallel between the collector of the second power switch tube and the gate of the first power switch tube, and a second resistor is connected in parallel between the collector of the second power switch tube and the third resistor;

[0010] The PWM generator is connected to the gate of the second power switch tube and is used to generate PWM pulses to drive the first power switch tube and / or the second power switch tube to be turned on and off.

[0011] In one implementation, when the second power switch tube is turned off, the impedance of the first resistor and the second resistor is smaller than the collector-emitter voltage of the second power switch tube.

[0012] In one implementation, when the second power switch tube is turned off, the collector-emitter voltage of the first power switch tube is equal to the collector-emitter voltage of the second power switch tube.

[0013] In one embodiment, the TVS array diode includes a first transient suppression diode and a second transient suppression diode, wherein the first transient suppression diode and the second transient suppression diode are arranged in series.

[0014] The first TVS diode, the second TVS diode and the third TVS diode are all bipolar TVS diodes.

[0015] In one embodiment, an inductor is further included, one end of the inductor is connected to the positive electrode interface of the photovoltaic component, and the other end of the inductor is connected to the positive end of the DC bus through a diode.

[0016] In one embodiment, a load module is further included, and the load module includes a first capacitor and a fifth resistor. The first capacitor is connected to the positive and negative ends of the DC bus, and the fifth resistor is connected to the positive and negative ends of the DC bus.

[0017] In one implementation, the first capacitor is disposed closer to the switch module than the fifth resistor.

[0018] In one embodiment, a gate resistor is further included, one end of which is connected to the output end of the PWM generator, and the other end of which is connected to the gate of the second power switch tube.

[0019] In one implementation, both the first power switch tube and the second power switch tube are IGBT tubes.

[0020] The embodiment of the present application further provides a photovoltaic inverter, the photovoltaic inverter comprising:

[0021] As the boost circuit mentioned above, the boost circuit is used to boost the direct current output by the photovoltaic module;

[0022] An inverter circuit converts the boosted direct current into alternating current.

[0023] Beneficial Effects

[0024] The boost circuit can not only ensure that the two first power switch tubes and the second power switch tubes arranged in series are turned on or off at the same time, but also enable the first power switch tube and the second power switch tube to evenly share the PV voltage by designing the TVS array diode, that is, the first power switch tube / the second power switch tube respectively withstands 0.5 times the voltage, thereby effectively reducing the withstand voltage requirement of the power switch tube, thereby reducing the cost of the boost circuit conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide an understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation on the technical solution of the present disclosure. The shapes and sizes of the components in the accompanying drawings do not reflect the actual proportions and are only intended to illustrate the content of the present application.

[0026] Figure 1 is a boost circuit diagram of an inverter in the prior art;

[0027] Figure 2 A boost circuit diagram provided in an embodiment of the present application;

[0028] Figure 3 This is a working principle diagram of the photovoltaic inverter provided in the embodiment of the present application. DETAILED DESCRIPTION

[0029] The above scheme is further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the present application and are not limited to the scope of the present application. The implementation conditions adopted in the examples can be further adjusted as the conditions of the specific manufacturer, and the unspecified implementation conditions are usually the conditions in conventional experiments.

[0030] Unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure should be understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connecting" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In this article, "electrical connection" includes the situation where the constituent elements are connected together through an element with some electrical function. "Elements with some electrical function" are not particularly limited as long as they can transfer electrical signals between the connected constituent elements. "Elements with some electrical function" can be, for example, electrodes or wiring, or switching elements such as transistors, or other functional elements such as resistors, inductors or capacitors. "Up", "down", "left", "right", etc. are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0031] In this application, the directions or positional relationships indicated by the terms "upper", "lower", "inner", "middle", etc. are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0032] The present application discloses a boost circuit, which is applied to a photovoltaic inverter and is used to boost a received DC voltage. Specifically, the boost circuit includes a switch module, a voltage clamp module and a PWM generator; the switch module includes a first power switch tube and a second power switch tube connected to the positive and negative ends of a DC bus and arranged in series, the voltage clamp module is connected to the positive and negative ends of the DC bus and is connected to a first resistor and a TVS array diode in series, wherein the first resistor and the TVS array diode are arranged on a side closer to a photovoltaic component than the switch module, the gate of the first power switch tube is connected between the TVS array diode and the first resistor through a third resistor, a third transient suppression diode is connected in parallel between the collector of the second power switch tube and the gate of the first power switch tube, and a second resistor is connected in parallel between the collector of the second power switch tube and the third resistor; the PWM generator is connected to the gate of the second power switch tube and is used to generate a PWM pulse to drive the first power switch tube and / or the second power switch tube to be turned on and off, and the boost circuit can effectively reduce the withstand voltage requirement of the power switch tube, thereby reducing the conversion cost of the boost circuit.

[0033] The present application also discloses a photovoltaic inverter 100, such as Figure 3 As shown, Figure 3 The working principle diagram of the photovoltaic inverter provided in the embodiment of the present application, the photovoltaic inverter 100 includes a boost circuit 110 and an inverter circuit 120, the boost circuit 110 is used to boost the direct current output by the photovoltaic module 200, and the inverter circuit 120 is used to convert the boosted direct current into alternating current. Specifically, the photovoltaic module 200 transmits direct current to the boost circuit through the photovoltaic interface (the photovoltaic interface includes a positive photovoltaic interface PV+ and a negative photovoltaic interface PV-), the boost circuit 110 boosts the received direct current voltage to the direct current voltage required by the photovoltaic inverter output control, and transmits the boosted direct current to the inverter circuit 120 through the positive terminal BUS+ of the direct current bus and the negative terminal BUS- of the direct current bus, the inverter circuit converts the boosted direct current into alternating current, and the alternating current is filtered by the filter circuit and then incorporated into the power grid 300.

[0034] Next join Figure 2 A boost circuit 110 provided in an embodiment of the present application is described. The boost circuit 110 can effectively reduce the withstand voltage requirement of the power switch tube, thereby reducing the conversion cost of the boost circuit.

[0035] The boost circuit 110 includes a switch module 10, a voltage clamp module 20 and a PWM generator 30;

[0036] The switch module 10 includes a first power switch tube Q1 and a second power switch tube Q2, which are connected in series to the positive and negative ends of the DC bus. Specifically, the first switch tube Q1 and the second power switch tube Q2 in the present application are both IGBT tubes.

[0037] The voltage clamping module 20 includes a first resistor R1 and a TVS array diode, which are connected in series and connected to the positive and negative ends of the DC bus, wherein the first resistor R1 and the TVS array diode are arranged closer to the photovoltaic assembly 200 than the switch module 10;

[0038] The gate (G) of the first power switch tube Q1 is connected between the TVS array diode and the first resistor R1 through a third resistor, a third transient suppression diode D3 is connected in parallel between the collector (C) of the second power switch tube Q2 and the gate (G) of the first power switch tube Q1, and a second resistor R2 is connected in parallel between the collector (C) of the second power switch tube Q2 and the third resistor R3;

[0039] The PWM generator 30 is connected to the gate (C) of the second power switch tube Q2 and is used to generate PWM pulses to drive the first power switch tube Q1 and / or the second power switch tube Q2 to turn on and off.

[0040] It can be understood that the output end of the PWM generator 30 generates a PWM pulse to drive the second power switch tube Q2 to turn on, and the first power switch tube Q1 is turned on at the same time under the action of the bootstrap effect. Correspondingly, when the output end of the PWM generator does not generate a PWM pulse, the second power switch tube Q2 is turned off, and the first power switch tube Q1 is also turned off at the same time. The boost circuit can not only ensure that the two first power switch tubes Q1 and the second power switch tubes Q2 arranged in series are turned on or off at the same time, but also through the design of the TVS array diode, the first power switch and the second power switch can evenly share the PV voltage, so that the first power switch tube Q1 / the second power switch tube Q2 can withstand 0.5 times the voltage respectively, thereby effectively reducing the withstand voltage requirement of the power switch tube, thereby reducing the conversion cost of the boost circuit.

[0041] In this embodiment, when the second power switch tube Q2 is turned off, the impedance of the first resistor R1 and the second resistor R2 is less than Vec2 of the second power switch tube Q2 (Vec2 represents the collector-emitter voltage of the Q2 tube). This design ensures that when the TVS array diode in the boost circuit is short-circuited, when the second power switch tube is turned off, Vec2 of the second power switch tube is greater than Vec1 of the first power switch tube Q1 (Vec1 represents the collector-emitter voltage of the Q1 tube). At the same time, when the TVS array diode in the boost circuit operates normally, when the second power switch tube is turned off, Vec2 of the second power switch tube is equal to Vec1 of the first power switch tube Q1. Specifically, Vec1 of the first power switch tube is clamped at 0.5 times the PV voltage, and Vec2 of the second power switch tube is clamped at 0.5 times the PV voltage.

[0042] In this embodiment, the TVS array diode includes a first transient suppression diode D1 and a second transient suppression diode D2, the first transient suppression diode D1 and the second transient suppression diode D2 are arranged in series, and further, the first transient suppression diode D1, the second transient suppression diode D2 and the third transient suppression diode D3 are all bipolar transient suppression diodes.

[0043] In this embodiment, the boost circuit 110 also includes a load module 40, which includes a first capacitor C1 and a fifth resistor R5, wherein the first capacitor C1 is connected to the positive and negative ends of the DC bus, and the fifth resistor R5 is connected to the positive and negative ends of the DC bus. Specifically, the first capacitor C1 is arranged in parallel between the emitter (E) of the second power switch tube Q2 and the collector (C) of the first power switch tube Q1, and the fifth resistor R5 is arranged in parallel between the emitter (E) of the second power switch tube Q2 and the collector (C) of the first power switch tube Q1. Furthermore, the first capacitor C1 is arranged on a side closer to the switch module 10 than the fifth resistor R5.

[0044] In this embodiment, an inductor L1 is also included, one end of the inductor L1 is connected to the positive terminal of the photovoltaic module 200, and the other end is connected to the positive terminal BUS+ of the DC bus through the diode D5, and the negative photovoltaic terminal PV- is connected to the negative terminal BUS- of the DC bus.

[0045] In this embodiment, a gate resistor R4 is further included, one end of the gate resistor R4 is connected to the output end of the PWM generator 30, and the other end is connected to the gate (G) of the second power switch tube Q2.

[0046] The above embodiments are only for illustrating the technical concept and features of the present application, and their purpose is to enable people familiar with the technology to understand the content of the present application and implement it accordingly, and they cannot be used to limit the protection scope of the present application. Any equivalent transformation or modification made according to the spirit of the present application shall be included in the protection scope of the present application.

Claims

1. A boost circuit for a photovoltaic inverter, characterized in that: include: The switch module comprises a first power switch tube and a second power switch tube, wherein the first power switch tube and the second power switch tube are connected in series and connected to the positive and negative ends of the DC bus; A voltage clamping module, comprising a first resistor and a TVS array diode, wherein the first resistor and the TVS array diode are connected in series and connected to the positive and negative ends of the DC bus, wherein the first resistor and the TVS array diode are arranged closer to the photovoltaic assembly than the switch module; The gate of the first power switch tube is connected between the TVS array diode and the first resistor through a third resistor, a third transient suppression diode is connected in parallel between the collector of the second power switch tube and the gate of the first power switch tube, and a second resistor is connected in parallel between the collector of the second power switch tube and the third resistor; The PWM generator is connected to the gate of the second power switch tube and is used to generate PWM pulses to drive the first power switch tube and / or the second power switch tube to be turned on and off.

2. The boost circuit according to claim 1, characterized in that: When the second power switch tube is turned off, the impedance of the first resistor and the second resistor is smaller than the collector-emitter voltage of the second power switch tube.

3. The boost circuit according to claim 1, characterized in that: When the second power switch tube is turned off, the collector-emitter voltage of the first power switch tube is equal to the collector-emitter voltage of the second power switch tube.

4. The boost circuit according to claim 1, characterized in that: The TVS array diode comprises a first transient suppression diode and a second transient suppression diode, wherein the first transient suppression diode and the second transient suppression diode are arranged in series, The first TVS diode, the second TVS diode and the third TVS diode are all bipolar TVS diodes.

5. The boost circuit according to claim 1, characterized in that: It also includes an inductor, one end of which is connected to the positive electrode interface of the photovoltaic component, and the other end of which is connected to the positive end of the DC bus through a diode.

6. The boost circuit according to claim 1, characterized in that: It also includes a load module, wherein the load module includes a first capacitor and a fifth resistor, The first capacitor is connected to the positive and negative ends of the DC bus, and the fifth resistor is connected to the positive and negative ends of the DC bus.

7. The boost circuit according to claim 6, characterized in that: The first capacitor is arranged closer to the switch module than the fifth resistor.

8. The voltage boost circuit according to claim 1, characterized in that: It also includes a gate resistor, one end of which is connected to the output end of the PWM generator, and the other end of which is connected to the gate of the second power switch tube.

9. The boost circuit according to claim 1, characterized in that: The first power switch tube and the second power switch tube are both IGBT tubes.

10. A photovoltaic inverter, characterized in that: include: The boost circuit as described in any one of claims 1 to 9 above, wherein the boost circuit is used to boost the direct current output by the photovoltaic module; An inverter circuit converts the boosted direct current into alternating current.