阅读说明：本技术 一种钳位型三电平升压功率变换电路 (Clamp type three-level boost power conversion circuit ) 是由 王文波 屈恺 鲁锦锋 周洪伟 梁欢迎 于 2019-09-26 设计创作，主要内容包括：一种钳位型三电平升压功率变换电路,包括电源、电感、第一开关模块、第二开关模块、第一单向导通器件、第二单向导通器件、第三单向导通器件、第四单向导通器件、第五单向导通器件、输出上母线电、输出下母线电容及负载单元；本发明中第四单向导通器件和第五单向导通器件组成钳位模块,用于对第一单向导通器件D1和第二单向导通器件D2的均压,对第一开关模块T1和第二开关模块T2的均压,从而避免半导体器件过压击穿的问题。由于输入和输出为共地系统,解决了传统三电平Boost拓扑中共模干扰的问题。(A clamp type three-level boost power conversion circuit comprises a power supply, an inductor, a first switch module, a second switch module, a first one-way conduction device, a second one-way conduction device, a third one-way conduction device, a fourth one-way conduction device, a fifth one-way conduction device, an upper bus output capacitor, a lower bus output capacitor and a load unit; in the invention, the fourth one-way conduction device and the fifth one-way conduction device form a clamping module which is used for equalizing the voltage of the first one-way conduction device D1 and the voltage of the second one-way conduction device D2 and equalizing the voltage of the first switch module T1 and the voltage of the second switch module T2, thereby avoiding the problem of overvoltage breakdown of semiconductor devices. Because the input and the output are common ground systems, the problem of common mode interference in the traditional three-level Boost topology is solved.)

1. A clamp type three-level boost power conversion circuit comprises a power supply, an inductor L, a first switch module T1, a second switch module T2, a first one-way conduction device D1, a second one-way conduction device D2, a third one-way conduction device D3, an output upper bus capacitor Cbus +, an output lower bus capacitor Cbus and a load unit, wherein the output upper bus capacitor Cbus + is connected with the output lower bus capacitor Cbus; the positive electrode of the power supply is connected with an inductor L, a first switch module T1 and a second switch module T2 in series in sequence to form a loop, the anode of a first unidirectional conducting device D1 is connected with the series node of the inductor L and the first switch module T1, the anode of a second unidirectional conducting device D2 is connected with the cathode of a first unidirectional conducting device D1, an output upper bus capacitor Cbus + and a lower bus capacitor Cbus-are connected in series in sequence, the other end of the output upper bus capacitor Cbus + is connected with the cathode of a second unidirectional conducting device D2, the other end of the lower bus capacitor Cbus-is connected with the negative electrode of the power supply, the anode of a third unidirectional conducting device D3 is connected with the positive electrode of the power supply, and the cathode of a third unidirectional conducting device D3 is connected with the cathode of a second unidirectional conducting device D2. The method is characterized in that: the boost power conversion circuit further comprises a clamping module.

2. The boost power conversion circuit according to claim 1, wherein: the clamping module comprises a fourth one-way conduction device D4, the anode of the fourth one-way conduction device D4 is connected with the series node of the first switch module T1 and the second switch module T2, and the cathode of the fourth one-way conduction device D4 is connected with the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-.

3. The boost power conversion circuit according to claim 1, wherein: the clamping module comprises a fourth one-way conduction device D4 and a first resistance-capacitance unit Z1, the anode of the fourth one-way conduction device D4 is connected with the series node of a first switch module T1 and a second switch module T2, and the cathode of the fourth one-way conduction device D4 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-; the first resistance-capacitance unit Z1 is connected in parallel with the first switch module T1.

4. The boost power conversion circuit according to claim 1, wherein: the clamping module comprises a fifth one-way conduction device D5, the anode of the fifth one-way conduction device D5 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-, and the cathode of the fifth one-way conduction device D5 is connected with the series node of the first one-way conduction device D1 and the second one-way conduction device D2.

5. the boost power conversion circuit according to claim 1, wherein: the clamping module comprises a fifth one-way conduction device D5 and a second resistance-capacitance unit Z2, wherein the anode of the fifth one-way conduction device D5 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-, and the cathode of the fifth one-way conduction device D5 is connected with the series node of a first one-way conduction device D1 and a second one-way conduction device D2; the second resistance-capacitance unit Z2 is connected in parallel with the first unidirectional conducting device D1.

6. The boost power conversion circuit according to claim 1, wherein: the clamping module comprises a fourth one-way conduction device D4 and a fifth one-way conduction device D5, the anode of the fourth one-way conduction device D4 is connected with the series node of the first switch module T1 and the second switch module T2, and the cathode of the fourth one-way conduction device D4 is connected with the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-; the anode of the fifth unidirectional conducting device D5 is connected to the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the cathode of the fifth unidirectional conducting device D5 is connected to the series node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2.

7. The boost power conversion circuit according to claim 1, wherein: the clamping module comprises a fourth unidirectional conducting device D4, a fifth unidirectional conducting device D5, a first resistance-capacitance unit Z1 and a second resistance-capacitance unit Z2, the anode of the fourth unidirectional conducting device D4 is connected with the series node of a first switch module T1 and a second switch module T2, and the cathode of the fourth unidirectional conducting device D4 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-; the anode of the fifth unidirectional conducting device D5 is connected with the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the cathode of the fifth unidirectional conducting device D5 is connected with the series node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2; the first resistance-capacitance unit Z1 is connected in parallel with the first switch module T1; the second resistance-capacitance unit Z2 is connected in parallel with the first unidirectional conducting device D1.

8. A boost power conversion circuit according to claim 2, 3, 6 or 7, characterized in that: when the clamping module starts the boost power conversion circuit, the boost power conversion circuit does not establish an output voltage, and the voltage stress of the second switch module T2 is smaller than the power supply voltage Vin, the fourth unidirectional conducting device D4 is conducted in the forward direction to clamp the potential of the second switch module T2 to the lower bus voltage; when the boost power conversion circuit works normally, when the first switch module T1 is turned on first and then turned off, and the second switch module T2 is turned on second and then turned off first, the fourth unidirectional conducting device D4 is turned on in the forward direction to clamp the voltage at the two ends of the second switch module T2 to the lower bus voltage.

9. A boost power conversion circuit according to claim 4 or 5, characterized in that: when the bus voltage of the boost power conversion circuit is established, the power supply is not powered on, and the voltage stress of the second unidirectional conducting device D2 is smaller than the sum of the voltages of the upper bus and the lower bus, the fifth unidirectional conducting device D5 is conducted in the forward direction, and the voltage of the second unidirectional conducting device D2 is clamped to the voltage of the upper bus; when the boost power conversion circuit works normally, when the first switch module T1 and the second switch module T2 are both turned on, the fifth unidirectional conducting device D5 is turned on in the forward direction to clamp the voltage across the second unidirectional conducting device D2 to the upper bus voltage.

10. The boost power conversion circuit according to claim 3, 5 or 7, wherein the first rc unit Z1 and the second rc unit Z2 in the clamping module are pure resistors or series-parallel structures of resistors and capacitors.

Technical Field

The application relates to the technical field of three-level boost power conversion circuits, in particular to a clamp type three-level boost power conversion circuit.

Background

The Boost circuit is generally referred to as a Boost power conversion circuit, namely, the Boost power conversion circuit is used for inputting a voltage and outputting a higher voltage to further realize power conversion, and generally, the Boost power conversion circuit can realize a multi-level Boost circuit which can input more than or equal to three levels. Under the same input condition, the multi-level Boost circuit can realize higher-level voltage output by using devices with smaller voltage withstanding levels by reducing the voltage stress of power devices. Compared with the traditional two-level Boost circuit, the multi-level Boost circuit can realize medium-voltage high-power output.

As shown in fig. 1, when the two-level Boost circuit is applied to a medium-voltage high-power condition, both T and D in fig. 1 need a high-voltage device, which is difficult to select and expensive. It is a common practice to achieve a higher level of voltage output by using a series connection of smaller voltage class devices as shown in fig. 2. However, the simple series connection of the devices is easy to generate non-uniform voltage in the use process, so that individual devices bear higher voltage stress, and further generate overvoltage breakdown.

Fig. 3 is a diagram of a conventional three-level Boost circuit, which is used as an MPPT circuit in photovoltaic, and when the positive and negative of a power supply and the positive and negative of a bus are not equal in potential, a large common-mode voltage is generated, which affects normal operation of the circuit and a system.

Disclosure of Invention

The invention provides a clamping type three-level boosting power conversion circuit which can solve the problems of non-voltage-sharing of devices in series connection and common-mode interference caused by the fact that positive and negative of a power supply and positive and negative of a bus are not equal in voltage in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

a clamp type three-level boost power conversion circuit comprises a power supply, an inductor L, a first switch module T1, a second switch module T2, a first one-way conduction device D1, a second one-way conduction device D2, a third one-way conduction device D3, an output upper bus capacitor Cbus +, an output lower bus capacitor Cbus and a load unit, wherein the output upper bus capacitor Cbus + is connected with the output lower bus capacitor Cbus; the positive electrode of the power supply is connected with an inductor L, a first switch module T1 and a second switch module T2 in series in sequence to form a loop, the anode of a first unidirectional conducting device D1 is connected with the series node of the inductor L and the first switch module T1, the anode of a second unidirectional conducting device D2 is connected with the cathode of a first unidirectional conducting device D1, an output upper bus capacitor Cbus + and a lower bus capacitor Cbus-are connected in series in sequence, the other end of the output upper bus capacitor Cbus + is connected with the cathode of a second unidirectional conducting device D2, the other end of the lower bus capacitor Cbus-is connected with the negative electrode of the power supply, the anode of a third unidirectional conducting device D3 is connected with the positive electrode of the power supply, and the cathode of a third unidirectional conducting device D3 is connected with the cathode of a second unidirectional conducting device D2. The boost power conversion circuit is characterized by further comprising a clamping module.

The clamping module preferably comprises a circuit: the direct current type direct current power supply comprises a fourth one-way conduction device D4, wherein the anode of the fourth one-way conduction device D4 is connected with the series node of a first switch module T1 and a second switch module T2, and the cathode of the fourth one-way conduction device D4 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-.

The clamping module preferably comprises a circuit: the circuit comprises a fourth one-way conducting device D4 and a first resistance-capacitance unit Z1, wherein the anode of the fourth one-way conducting device D4 is connected with the series node of a first switch module T1 and a second switch module T2, and the cathode of the fourth one-way conducting device D4 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-; the first resistance-capacitance unit Z1 is connected in parallel with the first switch module T1.

The clamping module preferably comprises a circuit: the direct current protection circuit comprises a fifth one-way conduction device D5, wherein the anode of the fifth one-way conduction device D5 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-, and the cathode of the fifth one-way conduction device D5 is connected with the series node of the first one-way conduction device D1 and the second one-way conduction device D2.

The clamping module preferably comprises a circuit: the three-phase inverter comprises a fifth one-way conducting device D5 and a second resistance-capacitance unit Z2, wherein the anode of the fifth one-way conducting device D5 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-, and the cathode of the fifth one-way conducting device D5 is connected with the series node of a first one-way conducting device D1 and a second one-way conducting device D2; the second resistance-capacitance unit Z2 is connected in parallel with the first unidirectional conducting device D1.

The clamping module preferably comprises a circuit: the three-phase inverter comprises a fourth unidirectional conducting device D4 and a fifth unidirectional conducting device D5, wherein the anode of the fourth unidirectional conducting device D4 is connected with the series node of a first switch module T1 and a second switch module T2, and the cathode of the fourth unidirectional conducting device D4 is connected with the series node of an upper bus capacitor Cbus + and a lower bus capacitor Cbus-; the anode of the fifth unidirectional conducting device D5 is connected to the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the cathode of the fifth unidirectional conducting device D5 is connected to the series node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2.

The clamping module preferably comprises a circuit: the three-phase single-direction-conduction three-phase inverter comprises a fourth one-direction-conduction device D4, a fifth one-direction-conduction device D5, a first resistance-capacitance unit Z1 and a second resistance-capacitance unit Z2. The anode of the fourth unidirectional conducting device D4 is connected with the series node of the first switch module T1 and the second switch module T2, and the cathode of the fourth unidirectional conducting device D4 is connected with the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-; the anode of the fifth unidirectional conducting device D5 is connected with the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the cathode of the fifth unidirectional conducting device D5 is connected with the series node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2; the first resistance-capacitance unit Z1 is connected in parallel with the first switch module T1, and the second resistance-capacitance unit Z2 is connected in parallel with the first unidirectional turn-on device D1.

When the clamping module starts the boost power conversion circuit, the boost power conversion circuit does not establish an output voltage, and the voltage stress of the second switch module T2 is smaller than the power supply voltage Vin, the fourth unidirectional conducting device D4 is conducted in the forward direction to clamp the potential of the second switch module T2 to the lower bus voltage; when the boost power conversion circuit works normally, when the first switch module T1 is turned on first and then turned off, and the second switch module T2 is turned on second and then turned off first, the fourth unidirectional conducting device D4 is turned on in the forward direction to clamp the voltage at the two ends of the second switch module T2 to the lower bus voltage.

When the bus voltage of the boost power conversion circuit is established, the power supply is not powered on, and the voltage stress of the second unidirectional conducting device D2 is smaller than the sum of the upper bus voltage and the lower bus voltage, the fifth unidirectional conducting device D5 is conducted in the forward direction, and the voltage of the second unidirectional conducting device D2 is clamped to the upper bus voltage; when the boost power conversion circuit works normally, when the first switch module T1 and the second switch module T2 are both turned on, the fifth unidirectional conducting device D5 is turned on in the forward direction to clamp the voltage across the second unidirectional conducting device D2 to the upper bus voltage.

The first resistance-capacitance unit Z1 and the second resistance-capacitance unit Z2 in the clamping module are pure resistors or series-parallel structures of resistors and capacitors.

Compared with the prior art, in the embodiment of the application, because the clamping module is added in the boost power conversion circuit, and the fourth unidirectional conducting device D4 in the module can clamp the voltage of the second switch module to the lower bus voltage, the stress of the second switch module can be limited, and therefore, when the power supply is powered on and the bus voltage is not established, the stress of the second switch module can be effectively clamped to the lower bus voltage. In the normal working process, the time sequence of the two switching tubes is that the first switching tube is firstly switched on and then switched off, the second switching tube is then switched on and then switched off, and according to the working time sequence, in the switching tube switching-on and switching-off processes, the fourth one-way conduction device can clamp the stress of the second switching module to the lower bus voltage, so that the second switching module is effectively protected, and overvoltage breakdown is avoided.

In some embodiments, the clamping module further includes a first rc unit Z1, and the first rc unit Z1 is connected in parallel to two ends of the first switch module. The first resistance-capacitance unit is composed of a resistor and a capacitor, and can be a resistor and a capacitor connected in series-parallel or a simple resistor or a capacitor. The first resistance-capacitance unit Z1 is configured to, when the first switch module T1 and the second switch module T2 are both off and voltage sharing is required naturally, increase voltage stress across the second switch module T2 by reducing impedance of the first switch module T1, and when the voltage stress of the second switch module T2 is greater than the lower bus voltage, the fourth unidirectional conducting device D4 is turned on in the forward direction to clamp the voltage stress of the second switch module T2 to the lower bus voltage.

In the embodiment of the present application, since the clamping module is added in the boost power conversion circuit, and the fifth unidirectional conducting switch D5 in the module can clamp the voltage of the second unidirectional conducting device D2 to the upper bus voltage, the stress of the second unidirectional conducting device D2 can be limited, and therefore, when the power supply is not powered on and the bus voltage is established, the stress of the second unidirectional conducting device D2 can be effectively clamped to the upper bus voltage. In the normal working process, when the two switch modules are both switched on, the fifth one-way conduction device D5 can clamp the stress of the second one-way conduction device D2 to the upper bus voltage, so that the second one-way conduction device is effectively protected, and overvoltage breakdown is avoided.

In some embodiments, the boost power conversion circuit further includes a second rc unit Z2, and the second rc unit Z2 is connected in parallel across the first unidirectional conducting device D1. The second resistance-capacitance unit is composed of a resistor and a capacitor, and can be a resistor and a capacitor connected in series-parallel or a simple resistor or a capacitor. The second resistance-capacitance unit Z2 is configured to, when the first switch module T1 and the second switch module T2 are both turned on and voltage sharing is required naturally, increase voltage stress at two ends of the second unidirectional conducting device D2 by reducing impedance of the first unidirectional conducting device D1, and when voltage stress of the second unidirectional conducting device D2 is greater than upper bus voltage, forward conduction of the fifth unidirectional conducting device clamps voltage stress of the second unidirectional conducting device D2 to the upper bus voltage.

The forward voltage drop of the third unidirectional conducting device D3 is smaller than the series voltage drop of the first unidirectional conducting device D1 and the second unidirectional conducting device D2. The withstand voltage of the fifth unidirectional device D5 is greater than the lower bus voltage. In the normal operation stage, when the first switch module T1 and the second switch module T2 are both turned off, the power current flows directly to the bus through the third unidirectional conducting device D3, which can significantly reduce the system loss.

Drawings

in order to more clearly illustrate the technical solutions in the implementation of the present application or the prior art, a brief description will be given below of the drawings used in the description of the embodiments of the present application or the prior art. It is clear that the following figures are some embodiments of the present application, from which other figures can be derived by a person skilled in the art without inventive effort.

Fig. 1 is a schematic diagram of a topology of a two-level Boost voltage Boost circuit.

Fig. 2 is a basic circuit diagram of the boost power conversion circuit of the present invention.

Fig. 3 is a schematic diagram of a topology of a conventional symmetric Boost circuit.

fig. 4a is a circuit diagram of a boost power conversion circuit of the present invention.

Fig. 4b is a circuit diagram of the boost power conversion circuit of the present invention.

Fig. 5a is a circuit diagram of a boost power conversion circuit of the present invention.

Fig. 5b is a circuit diagram of the boost power conversion circuit of the present invention.

Fig. 6a is a circuit diagram of a boost power conversion circuit of the present invention.

Fig. 6b is a circuit diagram of the boost power conversion circuit of the present invention.

Fig. 7a is a schematic diagram of current flow paths corresponding to 4 switching modes of the present invention, in which fig. 7a (1) is a switching mode a, fig. 7a (2) is a switching mode b, fig. 7a (3) is a switching mode c, and fig. 7a (4) is a switching mode d.

FIG. 7b is a diagram of the driving signals of T1 and T2 according to the present invention.

Fig. 8a is a circuit diagram of the boost power conversion circuit of the invention mirrored in fig. 6 a.

Fig. 8b is a circuit diagram of the boost power conversion circuit of the invention mirrored in fig. 6 b.

Detailed Description

In order to make the technical solution better understood by those skilled in the art, a three-level boost power conversion circuit is described in further detail below with reference to the accompanying drawings and the detailed description.

The boost power conversion circuit in the embodiment of the application mainly comprises:

Fig. 2 is a basic circuit diagram of the boost power conversion circuit of the present invention, which is a clamping type three-level boost power conversion circuit shown in fig. 2, and includes a power supply, an inductor L, a first switch module T1, a second switch module T2, a first one-way conduction device D1, a second one-way conduction device D2, a third one-way conduction device D3, an output upper bus capacitor Cbus +, an output lower bus capacitor Cbus-, and a load unit. The positive electrode of the power supply is connected with an inductor L, a first switch module T1 and a second switch module T2 in series in sequence to form a loop, the anode of a first unidirectional conducting device D1 is connected with the series node of the inductor L and the first switch module T1, the anode of a second unidirectional conducting device D2 is connected with the cathode of a first unidirectional conducting device D1, an output upper bus capacitor Cbus + and a lower bus capacitor Cbus-are connected in series in sequence, the other end of the output upper bus capacitor Cbus + is connected with the cathode of a second unidirectional conducting device D2, the other end of the lower bus capacitor Cbus-is connected with the negative electrode of the power supply, the anode of a third unidirectional conducting device D3 is connected with the positive electrode of the power supply, and the cathode of a third unidirectional conducting device D3 is connected with the cathode of a second unidirectional conducting device D2.

Fig. 4a is a circuit diagram of the boost power conversion circuit of the present invention, which is shown by adding a clamping circuit to the basic circuit of fig. 2, wherein the clamping circuit includes a fourth unidirectional conducting device D4. The anode of the fourth unidirectional conducting device D4 is connected to the series node of the first switch module T1 and the second switch module T2, and the cathode of the fourth unidirectional conducting device D4 is connected to the upper bus capacitor Cbus + and the lower bus capacitor Cbus-series node.

Fig. 4b is a circuit diagram of a boost power converter circuit according to the present invention, which is added with a clamping circuit based on the basic circuit of fig. 2, wherein the clamping circuit includes a fourth unidirectional conducting device D4 and a first rc unit Z1. The anode of the fourth unidirectional conducting device D4 is connected to the series node of the first switch module T1 and the second switch module T2, and the cathode of the fourth unidirectional conducting device D4 is connected to the upper bus capacitor Cbus + and the lower bus capacitor Cbus-series node. The first resistance-capacitance unit Z1 is connected in parallel with the first switch module T1.

Fig. 5a is a circuit diagram of the boost power conversion circuit of the present invention, which is shown by adding a clamping circuit to the basic circuit of fig. 3, wherein the clamping circuit includes a fifth unidirectional conducting device D5. The anode of the fifth unidirectional conducting device D5 is connected with the serial node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the cathode of the fifth unidirectional conducting device D5 is connected with the serial node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2

Fig. 5b is a circuit diagram of a boost power converter circuit according to the present invention, which is added with a clamping circuit based on the basic circuit of fig. 3, wherein the clamping circuit includes a fifth unidirectional conducting device D5 and a second rc unit Z2. The anode of the fifth unidirectional conducting device D5 is connected to the serial node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the cathode of the fifth unidirectional conducting device D5 is connected to the serial node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2. The second resistance-capacitance unit Z2 is connected in parallel with the first unidirectional conducting device D1.

Fig. 6a is a circuit diagram of a boost power converter circuit according to the present invention, which is added with a clamping circuit based on the basic circuit of fig. 3, wherein the clamping circuit includes a fourth unidirectional conducting device D4 and a fifth unidirectional conducting device D5. The anode of the fourth unidirectional conducting device D4 is connected to the series node of the first switch module T1 and the second switch module T2, the cathode of the fourth unidirectional conducting device D4 is connected to the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, the anode of the fifth unidirectional conducting device D5 is connected to the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the cathode of the fifth unidirectional conducting device D5 is connected to the series node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2.

Fig. 6b is a circuit diagram of a boost power conversion circuit according to the present invention, wherein a clamping circuit is added to the basic circuit of fig. 3, and the clamping circuit includes a fourth unidirectional conducting device D4, a fifth unidirectional conducting device D5, a first rc unit Z1, and a second rc unit Z2. The anode of the fourth unidirectional conducting device D4 is connected to a series node between the first switch module T1 and the second switch module T2, the cathode of the fourth unidirectional conducting device D4 is connected to a series node between the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, the anode of the fifth unidirectional conducting device D5 is connected to a series node between the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, the cathode of the fifth unidirectional conducting device D5 is connected to a series node between the first unidirectional conducting device D1 and the second unidirectional conducting device D2, the first resistance-capacitance unit Z1 is connected in parallel to the first switch module T1, and the second resistance-capacitance unit Z2 is connected in parallel to the first unidirectional conducting device D1.

The clamping working principle of the clamping circuit in the circuit is as follows:

When the clamping module starts the boost power conversion circuit, the boost power conversion circuit does not establish an output voltage, and the voltage stress of the second switch module T2 is smaller than the power supply voltage Vin, the fourth unidirectional conducting device D4 is conducted in the forward direction to clamp the potential of the second switch module T2 to the lower bus voltage; when the boost power conversion circuit works normally, when the first switch module T1 is turned on first and then turned off, and the second switch module T2 is turned on second and then turned off first, the fourth unidirectional conducting device D4 is turned on in the forward direction to clamp the voltage at the two ends of the second switch module T2 to the lower bus voltage.

In the embodiment of the present application, since the fourth unidirectional device D4 is added to the boost power conversion circuit, and the second switch module T2 is clamped to the lower bus voltage by the device, the voltage stress of the second switch module T2 can be limited, and the voltage stress of the second switch module T2 is protected from exceeding the lower bus voltage. Therefore, when the input power of the boost power conversion circuit is powered on and the first switch module T1 and the second switch module T2 are both in the off state, it can be ensured that the voltage of the second switch module T2 is clamped to the lower bus voltage.

The first switch module T1 and the second switch module T2 in fig. 4a will form a natural voltage sharing, but the voltage stress of the second switch module T2 will not exceed the lower bus voltage due to the presence of the fourth unidirectional device D4.

In fig. 4b, a first rc unit Z1 is added on the basis of fig. 4a, and due to the function of the first rc unit Z1, it can be ensured that the voltage stress of the second switch module T2 is greater than that of the first switch module T1 and is also greater than the lower bus voltage in the natural voltage equalizing process. Under the action of the fourth unidirectional device D4, the voltage stress of the second switch module T2 is clamped to the lower bus voltage, so as to ensure voltage sharing between the first switch module T1 and the second switch module T2, and to ensure that each switch module has no risk of overvoltage breakdown.

In the embodiment of the application, since the fifth unidirectional device is added in the boost power conversion circuit, and the second unidirectional device D2 is clamped to the upper bus voltage through the fifth unidirectional device, the voltage stress of the second unidirectional device D2 can be limited, and the voltage stress of the second unidirectional device D2 is protected from exceeding the upper bus voltage. Therefore, when the bus voltage of the boost power conversion circuit is established, the input is not powered on or the bus voltage is established, and the first switch module T1 and the second switch module T2 are in an on state, it can be ensured that the voltage of the second unidirectional conductive device D2 is clamped to the upper bus voltage.

The first unidirectional conducting device D1 and the second unidirectional conducting device D2 in fig. 5a will form a natural voltage grading, but due to the presence of the fifth unidirectional conducting device D5, the voltage stress of the second unidirectional conducting device D2 will not exceed the upper bus voltage.

In fig. 5b, a second rc unit Z2 is added on the basis of fig. 5a, and due to the action of the second rc unit Z2, it can be ensured that the voltage stress of the second unidirectional conducting device D2 is greater than the voltage stress of the first unidirectional conducting device D1 and is also greater than the upper bus voltage in the natural voltage equalizing process. Under the action of the fifth one-way conduction device D5, the voltage stress of the second one-way conduction device D2 is clamped to the upper bus voltage, so that voltage sharing of the first one-way conduction device D1 and the second one-way conduction device D2 is ensured, and the risk of overvoltage breakdown of each switch module is avoided.

Fig. 7 is a schematic diagram of current flow paths corresponding to 4 switching modes and driving signals of the first switch module T1 and the second switch module T2 according to the present invention. As shown in the figure, the waveforms of the driving signal and the inductor current of the first switch module T1 and the second switch module T2 during normal operation are shown in fig. 7b, where T is the switching period and D is the duty cycle. On the basis of fig. 7b, the boost converter circuit shown in fig. 6a comprises the switching modes a, 7a (2), b, 7a (3), c and 7a (4) d of fig. 7a (1). Fig. 7a shows schematic current flow paths of the switching modes a, b, c and d, respectively. The following are respectively detailed:

a) Switching modes a, c

These two modes are identical. The first switch module T1 is turned on and the second switch module T2 is turned off. The current flows into the negative end of the power supply through the positive end of the power supply, the inductor L, the first switch module T1, the fourth one-way conducting device D4 and the lower bus capacitor Cbus-.

b) Switching mode b

The first switch module T1 and the second switch module T2 are both turned on, and current flows to the negative side of the power supply through the positive side of the power supply, the inductor L, the first switch module T1 and the second switch module T2. In this mode, the power supply charges the inductor, which stores energy.

c) Switching mode d

The first switch module T1 and the second switch module T2 are both off, and current flows to the negative side of the power supply through the positive side of the power supply, the inductor L, the first one-way conducting device D1, the second one-way conducting device D2, the upper and lower bus capacitors Cbus + and Cbus-. In this mode, the power supply and the inductor are discharged simultaneously, delivering energy to the bus.

From the above analysis, it can be seen that in the mode a and the mode c, the power supply charges the lower bus through the inductor L, the first switch module T1 and the fourth unidirectional device D4, so that the energy of the lower bus is greater than the energy of the upper bus. The load unit needs to transfer part of the lower bus energy to the full bus through real-time adjustment.

Fig. 8 is a mirror circuit diagram of the clamp type boost converter circuit according to the present invention.

As shown in fig. 8a, a power Vin, a first switch module T1, a second switch module T2, and an inductor are sequentially connected in series to form a loop, an upper bus capacitor Cbus +, a lower bus capacitor Cbus-, a second unidirectional conducting device D2, and a first unidirectional conducting device D1 are sequentially connected in series, an anode of the upper bus capacitor Cbus + is connected to an anode of the power Vin, a cathode of the first unidirectional conducting device D1 is connected to a series node of the second switch module T2 and the inductor L, an anode of the third unidirectional conducting device D3 is connected to a series node of the lower bus capacitor Cbus-and the second unidirectional conducting device D2, a cathode of the third unidirectional conducting device D3 is connected to a cathode of the power Vin, and the clamping circuit includes a fourth unidirectional conducting device D4 and a fifth unidirectional conducting device D5. The cathode of the fourth unidirectional conducting device D4 is connected to the series node of the first switch module T1 and the second switch module T2, the anode of the fourth unidirectional conducting device D4 is connected to the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, the cathode of the fifth unidirectional conducting device D5 is connected to the series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, and the anode of the fifth unidirectional conducting device D5 is connected to the series node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2.

As shown in fig. 8b, the power Vin, the first switch module T1, the second switch module T2, and the inductor are sequentially connected in series to form a loop, the upper bus capacitor Cbus +, the lower bus capacitor Cbus-, the second unidirectional conducting device D2, and the first unidirectional conducting device D1 are sequentially connected in series, the anode of the upper bus capacitor Cbus + is connected to the anode of the power Vin, the cathode of the first unidirectional conducting device D1 is connected to the series node of the second switch module T2 and the inductor L, the anode of the third unidirectional conducting device D3 is connected to the series node of the lower bus capacitor Cbus-and the second unidirectional conducting device D2, the cathode of the third unidirectional conducting device D3 is connected to the cathode of the power Vin, and the clamping circuit includes a fourth unidirectional conducting device D4, a fifth unidirectional conducting device D5, a first resistive-capacitive unit Z1, and a second resistive-capacitive unit Z2. The cathode of the fourth unidirectional conducting device D4 is connected to a series node of the first switch module T1 and the second switch module T2, the anode of the fourth unidirectional conducting device D4 is connected to a series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, the cathode of the fifth unidirectional conducting device D5 is connected to a series node of the upper bus capacitor Cbus + and the lower bus capacitor Cbus-, the anode of the fifth unidirectional conducting device D5 is connected to a series node of the first unidirectional conducting device D1 and the second unidirectional conducting device D2, the first resistance-capacitance unit Z1 is connected in parallel to the first switch module T1, and the second resistance-capacitance unit Z2 is connected in parallel to the first unidirectional conducting device D1.

The operation principle of the circuits in fig. 8a and 8b is completely the same as that in fig. 6a and 6b, and the specific circuit analysis can refer to fig. 6a and 6b, which is not repeated herein.