WO2022237449A1

WO2022237449A1 - Series coupling converter

Info

Publication number: WO2022237449A1
Application number: PCT/CN2022/087037
Authority: WO
Inventors: 李任贤; 申志鹏; 王小亮
Original assignee: 广州金升阳科技有限公司
Priority date: 2021-05-10
Filing date: 2022-04-15
Publication date: 2022-11-17
Also published as: CN113381612A; CN113381612B

Abstract

Disclosed in the present invention is a series coupling converter. The series coupling converter at least comprises two switch converters, wherein there is a series connection relationship between the switch converters, and there is a mutual coupling relationship between main power inductive devices in the switch converters. The series coupling converter further comprises at least one current sharing unit, wherein the current sharing unit is added to a branch outside a main power switch tube clamping network, and is used for shaping, when main power switch tubes in the switch converters are turned on, a pulse coupling current flowing through the main power switch tubes into a low-amplitude direct current. By means of the present invention, it can be ensured that the current in switch tubes is consistent without changing voltage sharing performance, thereby reducing the switch loss of a power switch tube, and enhancing the reliability of a circuit.

Description

A series coupled converter

technical field

The invention relates to the technical field of converters, in particular to the current equalization technology of series coupled converters.

Background technique

In recent years, technologies such as solar power generation, wind power generation, and hydropower generation have become increasingly mature. In the power generation control system and power transmission, the input voltage of the system is getting higher and higher, which can reach thousands of volts. Limited by the process technology of existing power switching semiconductor devices, the withstand voltage of commonly used switching semiconductor devices is far from meeting the application requirements of the system input voltage. If the high-voltage IGBT is used, it will bring problems of high cost and large volume (low frequency). Moreover, the existing IGBT cannot meet the withstand voltage requirement when the input voltage is greater than 2KV. In order to solve the problem of excessive stress of switching semiconductors, the industry more often adopts the topological structure of converters connected in series.

FIG. 1 is a schematic diagram of a known series-coupled boost switching converter, and FIG. 2 is a schematic diagram of a known series-coupled flyback switching converter. The two windings of the main transformer in Fig. 1 and Fig. 2 are in a coupling relationship. When the switching tubes are driven inconsistently or the input capacitors have deviations, it will cause uneven voltage on the input capacitors of each switching converter, and the switching converters will be coupled due to the effect of transformer coupling. Current, the coupling current flows out or flows into the two input capacitors through the switch tube, so as to ensure the voltage equalization of the input capacitors of the two switching converters. However, the coupling current is a pulse current waveform and its direction is opposite, which will cause the current waveforms of the two switching tubes to be inconsistent, resulting in greater switching loss.

In order to solve the above problems, taking the series-coupled flyback switching converter shown in Figure 2 as an example, an existing improvement in the industry is: connect a resistor in series on the common line, as shown in Figure 3, the series resistor can suppress Coupling pulse current, but it will weaken the energy of the coupling current, and part of the coupling current is released in the form of "heat", which affects the voltage equalization performance of the input side, and the current waveform of the two switch tubes still has the problem of inconsistency. In practical applications, there is a contradiction that the value of the series resistance should be both large and small, and it is difficult to compromise. Specifically, the larger the resistance value of the series resistance, the closer the current waveform of the two switch tubes is to the same, but it will reduce the input side of this topology. Voltage equalization performance: the smaller the resistance value of the series resistor, the better the voltage equalization performance on the input side, but the more inconsistent the current waveforms of the two switch tubes are, and the resistance loss is serious and easy to be damaged.

The solution that is easier for those skilled in the art is to replace the series resistor with a series inductor, as shown in Figure 4, which can effectively solve the problem in Figure 2, but an external drain will be formed when the switch tube is turned off. Inductively increases the switch tube voltage stress.

Therefore existing solutions are not perfect, have obvious shortcoming, be necessary to improve.

Contents of the invention

In view of this, the technical problem to be solved by the present invention is to provide a series coupled converter, which can effectively solve the problem of inconsistent coupling currents of the main power inductive devices of each series coupled converter, and is beneficial to reduce the loss of the main power switch tube and enhance the circuit reliability.

The present invention is realized through the following technical solutions:

A series coupled converter, comprising at least two switching converters and at least one current sharing unit, the switching converters are connected in series, the main power inductive devices in the switching converters are in a coupling relationship with each other, and the current sharing unit is arranged on the main The branch circuit other than the clamping network of the power switch tube is used to shape the pulse coupling current flowing in the main power switch tube into a low-amplitude direct current when the main power switch tube in the switching converter is turned on.

Further, the current sharing unit is arranged on the coupling current branch of the main power inductive device.

Further, the current sharing unit includes an inductive device.

As a first specific implementation of the series coupled converter of the present invention, the two switching converters are a first flyback converter and a second flyback converter, and the current sharing unit includes a first current sharing unit and a second current sharing unit unit;

The first flyback converter includes a first input capacitor C1, a first transformer winding L1A, a first power switch tube Q1, and a second diode D2, and the second flyback converter includes a second input capacitor C2, a second transformer winding L1B, the second power switch tube Q2, the fourth diode D4, the first current sharing unit includes the first diode D1, the first inductor L1, the second current sharing unit includes the third diode D3, the second inductor L2;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, the source pole of the first power switch tube Q1, the opposite end of the second transformer winding L1B, and one end of the first inductor L1 are connected, and the first inductor L1 The other end is connected to the anode of the first diode D1, the cathode of the first diode D1, the anode of the second diode D2, and the end of the same name of the first transformer winding L1A are connected, and the end of the second diode D2 The cathode is connected to the drain of the first power switch tube Q1, the opposite terminal of the first transformer winding L1A is connected to the positive pole of the first input capacitor C1, the same terminal of the second transformer winding L1B, the cathode of the third diode D3, The anodes of the fourth diode D4 are connected, the anode of the third diode D3 is connected to one end of the second inductor L2, the other end of the second inductor L2, the source of the second power switch tube Q2, and the second input capacitor The cathodes of C2 are connected to each other, and the cathode of the fourth diode D4 is connected to the drain of the second power switch tube Q2.

As a second specific implementation of the series coupled converter of the present invention, the two switching converters are a first boost switching converter and a second boost switching converter, and the current sharing unit is a first current sharing inductor L2;

The first boost switching converter includes a first input capacitor C1, a first output capacitor C3, a first coupling inductor winding L1A, a first power switching tube Q1, and a first diode D1. The first boost switching converter includes a second input Capacitor C2, second output capacitor C4, second coupled inductor winding L1B, second power switch tube Q2, and second diode D2;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, and one end of the first current sharing inductor L2 are connected, the other end of the first current sharing inductor L2, the negative pole of the first output capacitor C3, and the second output capacitor C4 The anode of the first power switch tube Q1, the drain of the second power switch tube Q2 are connected, the cathode of the first diode D1 is connected to the anode of the first output capacitor C3, and the second diode D2 The anode of the first coupled inductor winding L1A is connected to the negative pole of the second output capacitor C4, the same-named end of the first coupled inductor winding L1A is connected to the positive electrode of the first input capacitor C1, the opposite-named end of the first coupled inductor winding L1A, the first power switch tube Q1 The drain and the anode of the first diode D1 are connected, the opposite end of the second coupling inductor winding L1B is connected to the negative electrode of the second input capacitor C2, the same end of the second coupling inductor winding L1B, the second power switch The source of the transistor Q2 is connected to the cathode of the second diode D2.

As a third specific embodiment of the series coupled converter of the present invention, the two switching converters are a first buck switching converter and a second buck switching converter, and the current sharing unit is a first current sharing inductor L2;

The first buck switching converter includes a first input capacitor C1, a first output capacitor C3, a first coupling inductor winding L1A, a first power switching tube Q1, and a first diode D1, and the second buck switching converter includes a second input Capacitor C2, second output capacitor C4, second coupled inductor winding L1B, second power switch tube Q2, and second diode D2;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, the anode of the first diode D1, the cathode of the second diode D2, and one end of the first current sharing inductor L2 are connected, and the first current sharing inductor The other end of L2, the negative pole of the first output capacitor C3, and the positive pole of the second output capacitor C4 are connected, the source of the first power switch tube Q1, the cathode of the first diode D1, and the same name of the first coupling inductor winding L1A The drain of the second power switch tube Q2, the anode of the second diode D2, and the opposite end of the first coupling inductor winding L1B are connected, and the opposite end of the first coupling inductor winding L1A is connected to the first output The positive pole of the capacitor C3 is connected, the terminal of the same name of the first coupled inductor winding L1B is connected to the negative pole of the second output capacitor C4, the positive pole of the first input capacitor C1 is connected to the drain of the first power switch tube Q1, and the second input The negative pole of the capacitor C2 is connected to the source pole of the second power switch transistor Q2.

As the fourth specific implementation of the series coupled converter of the present invention, it also includes a first input capacitor C1, a first output capacitor C3, a second input capacitor C2 and a second output capacitor C4; the two switching converters It is the first buck-boost switching converter and the second buck-boost switching converter, and the current sharing unit is the first current sharing inductor L2;

The first buck-boost switching converter includes a first power switch tube Q1, a second power switch tube Q2, a first diode D1, a second diode D2, and a first coupled inductor winding L1A;

The second buck-boost switching converter includes a third power switch tube Q3, a fourth power switch tube Q4, a third diode D3, a fourth diode D4, and a second coupled inductor winding L1B;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, the anode of the first diode D1, the cathode of the third diode D3, and one end of the first current sharing inductor L2 are connected, and the first current sharing inductor The other end of L2, the source of the second power switch tube Q2, the drain of the third power switch tube Q3, the negative pole of the first output capacitor C3, and the positive pole of the second output capacitor C4 are connected, and the first power switch tube Q1 The source, the terminal with the same name of the first coupled inductor winding L1A, and the cathode of the first diode D1 are connected, and the anode of the second diode D2, the drain of the second power switch tube Q2, and the first coupled inductor winding L1A The opposite ends are connected, the anode of the third diode D3, the drain of the fourth power switch Q4, and the opposite end of the second coupling inductor winding L1B are connected, the source of the third power switch Q3, the fourth The cathode of the diode D4 is connected to the terminal of the same name of the second coupling inductor winding L1B, the anode of the first input capacitor C1 is connected to the drain of the first power switching tube Q1, and the cathode of the second input capacitor C2 is connected to the fourth power The source of the switch tube Q4 is connected, the cathode of the second diode D2 is connected to the anode of the first output capacitor C3, and the anode of the fourth diode D4 is connected to the cathode of the second output capacitor C4.

Explanation of term meaning:

Converter series connection: the input of the first stage converter is used to connect the input positive of the bus bar, the input negative of the first stage converter is connected to the input positive of the subsequent stage converter, and the input of the middle stage converter is connected to the front The input of the first stage converter is negative, the input negative of the middle stage converter is connected to the input positive of the subsequent stage converter, the input of the last stage converter is connected to the input negative of the previous stage converter, and the input of the last stage converter is Negative is used to connect the input negative of the busbar;

Mesh: Refers to a circuit that does not contain branch roads in the circuit, that is, a circuit that cannot be divided further;

Main power switching tube clamping network: refers to the mesh composed of only the main power switching tube and voltage source, or only the main power switching tube, diode and voltage source in each switching converter, and the main power switching tube in the mesh Its drain-source voltage is clamped by the voltage source when it is turned off;

Main power inductive device coupling current branch: each switching converter will generate coupling current due to the coupling relationship of the main power inductive device, and the path through which the coupling current flows is the main power inductive device coupling current branch.

The inventive idea of the present invention is to use the current sharing unit to shape the coupling current of the transformer, that is, to shape the pulse current into a low-amplitude DC current, and the current flowing through the switch tube when the main power switch tube is turned on includes the excitation current of the transformer and the coupling current, because the coupling current is a low-amplitude DC current and the amplitude is much smaller than the excitation current, so the shape of the original excitation current is hardly changed after the above two currents are combined, and finally the current of each main power switch tube is consistent. Because the current sharing unit only shapes the coupled current and does not reduce the average value of the coupled current, the voltage sharing characteristic is still maintained.

Compared with the prior art, the present invention has the following beneficial effects:

(1) When the input capacitor voltage is uneven, the known series coupled converter main power switch will flow a pulse coupling current when it is turned on, and the current equalizing unit of the present invention shapes the pulse current into a low-amplitude DC current, thus reducing the The turn-on loss of the main power switch tube enhances the reliability of the circuit.

(2) Since the currents of the main power switch tubes are consistent, it is only necessary to sample the current of the main power switch tubes of the low-voltage side converter, which is convenient for current detection.

Description of drawings

Fig. 1 is a schematic diagram of a known series coupled boost switching converter;

FIG. 2 is a schematic diagram of a known series coupled flyback switching converter;

Figure 3 is a schematic diagram of a series coupled flyback switching converter with a common line series resistor;

Fig. 4 is a schematic diagram of a series coupled flyback switching converter with a common line series inductor;

5 is a schematic diagram of the first embodiment of the present invention: a schematic diagram of an embodiment of a series coupled flyback switching converter;

6 is a schematic diagram of the second embodiment of the present invention: a schematic diagram of a series coupled boost switching converter embodiment;

7 is a schematic diagram of a third embodiment of the present invention: a schematic diagram of a series coupled buck switching converter embodiment;

FIG. 8 is a schematic diagram of a fourth embodiment of the present invention: a schematic diagram of an embodiment of a series coupled buck-boost switching converter.

Detailed ways

In order to make the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the invention, not to limit the invention.

first embodiment

Fig. 5 is a schematic diagram of an embodiment of a series coupled flyback switching converter of the present invention. The schematic diagram of a series coupled flyback embodiment of the present invention includes a first flyback converter, a second flyback converter, a first current sharing unit, and a second current sharing unit Unit, the first flyback converter includes the first input capacitor C1, the first transformer winding L1A, the first power switch tube Q1, the second diode D2, the second flyback converter includes the second input capacitor C2, the second The transformer winding L1B, the second power switch tube Q2, the fourth diode D4, the first current sharing unit includes the first diode D1, the first inductor L1, the second current sharing unit includes the third diode D3, the first Second inductor L2.

The function of the current sharing unit of the present invention is to shape the coupling current flowing through the main power inductive device when the main power switching tube in the switching converter is turned on. In the specific embodiment, the connection relationship of the current sharing unit needs to meet two conditions : One is added to the branch outside the clamping network of the main power switch tube; the other is added to the coupling current branch of the main power inductive device.

In this embodiment, there are two main power switch tube clamping networks, the first main power switch tube clamping network is formed by the first transformer winding L1A, the second diode D2, the first power switch tube Q1 and the first input capacitor C1 Surrounding mesh; the second main power switching tube clamping network is a mesh surrounded by the second transformer winding L1B, the fourth diode D4, the second power switching tube Q2 and the second input capacitor C2. The first input capacitor C1 and the second input capacitor C2 can be regarded as voltage sources, and the driving signals of the first power switch tube Q1 and the second power switch tube Q2 are the same, when the first power switch tube Q1 and the second power switch tube Q2 When it is turned off, the first transformer winding L1A and the second transformer winding L1B can be regarded as a voltage source, and the voltage at the drain-source of the first power switch tube Q1 is regarded as the first input capacitor C1 of the voltage source and the clamp of the first transformer winding L1A The voltage at the drain and source of the second power switch tube Q2 is clamped by the second input capacitor C2 and the second transformer winding L1B as a voltage source.

From the above analysis, it can be seen that the two current sharing units of this embodiment meet the above position requirements, and are added on the branches other than the clamping network of the main power switch tube. It can also be seen from Figure 5 that this embodiment and Figure 2 The difference between the known series-coupled flyback switching converters is that: the current sharing unit is added on the coupling current branch of the two converters, and the working principle when the first power switch tube Q1 and the second power switch tube Q2 are turned on is analyzed as follows:

When the voltages of the first input capacitor C1 and the second input capacitor C2 are the same, only the excitation current flows through the first power switch tube Q1 and the second power switch tube Q2, and at this time, the first current sharing unit and the second current sharing unit do not Participate in the work, the current of the first power switch tube Q1 and the second power switch tube Q2 are consistent;

When the voltage of the first input capacitor C1 is higher than that of the second input capacitor C2, the first transformer winding L1A generates a coupling current in the direction of flowing into the opposite end of the first transformer winding L1A, and the second transformer winding L1B generates a coupling current in the direction of Flowing out of the opposite end of the second transformer winding L1B, due to the existence of the fourth diode D4, the coupling current cannot flow into the second input capacitor C2 through the second power switch tube Q2, but can only pass through the second inductor L2 and the third diode The tube D3 flows into the second input capacitor C2;

When the voltage of the first input capacitor C1 is lower than that of the second input capacitor C2, the direction of the coupling current generated by the first transformer winding L1A is to flow out of the opposite terminal of the first transformer winding L1A, and the direction of the coupling current generated by the second transformer winding L1B is to flow into the second transformer winding L1B. The opposite end of the second transformer winding L1B, due to the existence of the second diode D2, the coupling current cannot flow into the first input capacitor C1 through the first power switch tube Q1, but can only pass through the first inductor L1 and the first diode D1 into the first input capacitor C1.

The main components of the current sharing unit of the present invention are the first inductance L1 and the second inductance L2, which shape the coupling current of the transformer and shape the pulse current into a low-amplitude direct current. When the voltages of the first input capacitor C1 and the second input capacitor C2 are not equal and the switch tube is turned on, the current flowing through the switch tube includes the excitation current and the coupling current of the transformer, because the coupling current is a low-amplitude DC current and the amplitude It is much smaller than the excitation current, so the shape of the original excitation current is hardly changed after the above two currents are synthesized, and finally the current of the two switch tubes is consistent.

It should be noted that there must be two current sharing units in this embodiment to better achieve the purpose of the invention under two abnormal conditions, that is, the first current sharing unit has a higher ratio of the first input capacitor C1 to the second input capacitor C2. It works when the voltage of the first input capacitor C1 is low, and injects charges into the first input capacitor C1; the second current sharing unit works when the voltage of the first input capacitor C1 is higher than that of the second input capacitor C2, and injects charges into the second input capacitor C2.

second embodiment

Fig. 6 is a schematic diagram of an embodiment of a series coupling boost switching converter of the present invention, a schematic diagram of an embodiment of a series coupling boost switching converter of the present invention, the switching converter includes a first boost switching converter and a second boost switching converter, and a current sharing unit is the first current sharing inductor L2.

The clamping network of the first main power switching tube in Fig. 6 is a mesh surrounded by the first power switching tube Q1, the first diode D1 and the first output capacitor C3, and the clamping network of the second main power switching tube is the second The mesh surrounded by the power switch tube Q2, the second diode D2 and the second output capacitor C4 is added to a branch outside the clamping network of the main power switch tube for current sharing. The driving signals of the first power switch tube Q1 and the second power switch tube Q2 are the same.

The difference between this embodiment and the known series-coupled boost switching converter in Fig. 1 is that a current sharing unit is added on the coupling current branch of the two converters, that is, a first current sharing inductor L2 is added, and the working principle is the same as that of the first implementation Similar to the example, the brief analysis is as follows:

When the voltages of the first input capacitor C1 and the second input capacitor C2 are different, the inductive coupling current I flows out or flows into the input capacitor through the first current sharing inductor L2. The first current sharing inductor L2 inhibits the inductive coupling current and shapes the pulse current into a low-amplitude direct current. When the switch tube is turned on, the current flowing through the switch tube includes the excitation current of the inductor and the coupling current. Because the coupling current is a low-amplitude DC current at this time and the amplitude is much smaller than the excitation current, the above two currents are combined and the original excitation is hardly changed. The current shape finally plays a role in the consistency of the currents of the two switch tubes.

The difference between this embodiment and the first embodiment is that the two switching converters share a current sharing unit. The reason is that the two switching converters of the present invention are boost switching converters. In addition, there are other meshes that share some lines, and the current sharing unit is arranged on the shared line, so that the sharing of the current sharing unit is realized.

third embodiment

Figure 7 is a schematic diagram of an embodiment of the series coupled buck switching converter of the present invention, a schematic diagram of an embodiment of the series coupled buck switching converter of the present invention, the switching converter includes a first buck switching converter and a second buck switching converter, and a current sharing unit is the first current sharing inductor L2.

The first buck switching converter includes a first input capacitor C1, a first output capacitor C3, a first coupling inductor winding L1A, a first power switching tube Q1, and a first diode D1, and the second buck switching converter includes a second input The capacitor C2, the second output capacitor C4, the second coupled inductor winding L1B, the second power switch tube Q2, and the second diode D2.

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, the anode of the first diode D1, the cathode of the second diode D2, and one end of the first current sharing inductor L2 are connected, and the first current sharing inductor The other end of L2, the negative pole of the first output capacitor C3, and the positive pole of the second output capacitor C4 are connected, the source of the first power switch tube Q1, the cathode of the first diode D1, and the same name of the first coupling inductor winding L1A The drain of the second power switch tube Q2, the anode of the second diode D2, and the opposite end of the second coupling inductor winding L1B are connected, and the opposite end of the first coupling inductor winding L1A is connected to the first output The positive pole of the capacitor C3 is connected, the same-named end of the second coupling inductor winding L1B is connected to the negative pole of the second output capacitor C4, the positive pole of the first input capacitor C1 is connected to the drain of the first power switch tube Q1, and the second input The negative pole of the capacitor C2 is connected to the source pole of the second power switch transistor Q2.

Figure 7 has two main power switch tube clamping networks, the first main power switch tube clamping network is a mesh surrounded by the first input capacitor C1, the first diode D1 and the first power switch tube Q1, the second The clamping network of the main power switch tube is a mesh surrounded by the second power switch tube Q2, the second diode D2 and the second input capacitor C2, and the current sharing is only added to a branch outside the clamping network of the main power switch tube. The driving signals of the first power switch tube Q1 and the second power switch tube Q2 are the same.

The principles of this embodiment are similar to those of the second embodiment, and will not be elaborated here.

Fourth embodiment

Fig. 8 is a schematic diagram of an embodiment of a series coupled BUCK-BOOST switching converter of the present invention, a schematic diagram of an embodiment of a series coupled BUCK-BOOST switching converter of the present invention, including a first input capacitor C1, a first output capacitor C3, and a second input capacitor C2 and the second output capacitor C4, the switching converter includes a first buck-boost switching converter and a second buck-boost switching converter, the current sharing unit is the first current sharing inductor L2; the first buck-boost switching converter includes The first power switch tube Q1, the second power switch tube Q2, the first diode D1, the second diode D2 and the first coupling inductor winding L1A; the second buck-boost switching converter includes a third power switch tube Q3 , the fourth power switch tube Q4, the third diode D3, the fourth diode D4 and the second coupled inductor winding L1B.

Figure 8 has four main power switch tube clamping networks, the first main power switch tube clamping network is a mesh surrounded by the first input capacitor C1, the first diode D1, and the first power switch tube Q1, and the second The clamping network of the main power switching tube is a mesh surrounded by the second power switching tube Q2, the second diode D2, and the first output capacitor C3, and the third main power switching tube clamping network is the second input capacitor C2, the second The mesh surrounded by the three diodes D3 and the fourth power switch tube Q4, the clamping network of the fourth main power switch tube is surrounded by the third power switch tube Q3, the fourth diode D4, and the second output capacitor C4 The mesh and current sharing are added to the branch outside the clamping network of the main power switch tube. The driving signals of the first power switch tube Q1 , the second power switch tube Q2 , the third power switch tube Q3 , and the fourth power switch tube Q4 are the same.

It should be noted that the above-mentioned embodiments are all aimed at the situation where there are two converters and one or two current sharing units. The present invention can also be extended to more than two converters and the current sharing units are less than or equal to Other situations of numbers can be deduced and realized by those skilled in the art, and will not be repeated here. It should be understood that although the above-mentioned specific embodiments are described to help better understanding and understanding of the present invention, there are other embodiments equivalent to the above-mentioned embodiments. The above embodiments are only for the purpose of giving examples in the way of illustration, and should not be regarded as limiting the protection scope of the present invention. Modifications or replacements of technical characteristics shall be deemed to be within the scope of the claims.

Claims

A series coupled converter, comprising at least two switching converters and at least one current sharing unit, the switching converters are connected in series, and the main power inductive devices in the switching converters are coupled to each other, characterized in that: current sharing The unit is arranged in a branch outside the clamping network of the main power switch tube, and is used for shaping the pulse coupling current flowing in the main power switch tube into a low-amplitude direct current when the main power switch tube in the switching converter is turned on.
The series coupled converter according to claim 1, characterized in that the current sharing unit is arranged on the coupling current branch of the main power inductive device.
The series coupled converter according to claim 1, characterized in that: the current sharing unit includes an inductive device.
The series coupled converter according to claim 1, wherein the two switching converters are a first flyback converter and a second flyback converter, and the current sharing unit includes a first current sharing unit and a second current sharing unit unit;

The first flyback converter includes a first input capacitor C1, a first transformer winding L1A, a first power switch tube Q1, and a second diode D2, and the second flyback converter includes a second input capacitor C2, a second transformer winding L1B, the second power switch tube Q2, the fourth diode D4, the first current sharing unit includes the first diode D1, the first inductor L1, the second current sharing unit includes the third diode D3, the second inductor L2;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, the source pole of the first power switch tube Q1, the opposite end of the second transformer winding L1B, and one end of the first inductor L1 are connected, and the first inductor L1 The other end is connected to the anode of the first diode D1, the cathode of the first diode D1, the anode of the second diode D2, and the end of the same name of the first transformer winding L1A are connected, and the end of the second diode D2 The cathode is connected to the drain of the first power switch tube Q1, the opposite terminal of the first transformer winding L1A is connected to the positive pole of the first input capacitor C1, the same terminal of the second transformer winding L1B, the cathode of the third diode D3, The anodes of the fourth diode D4 are connected, the anode of the third diode D3 is connected to one end of the second inductor L2, the other end of the second inductor L2, the source of the second power switch tube Q2, and the second input capacitor The cathodes of C2 are connected to each other, and the cathode of the fourth diode D4 is connected to the drain of the second power switch tube Q2.
The series coupled converter according to claim 1, wherein the two switching converters are a first boost switching converter and a second boost switching converter, and the current sharing unit is a first current sharing inductor L2;

The first boost switching converter includes a first input capacitor C1, a first output capacitor C3, a first coupling inductor winding L1A, a first power switching tube Q1, and a first diode D1. The first boost switching converter includes a second input Capacitor C2, second output capacitor C4, second coupled inductor winding L1B, second power switch tube Q2, and second diode D2;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, and one end of the first current sharing inductor L2 are connected, the other end of the first current sharing inductor L2, the negative pole of the first output capacitor C3, and the second output capacitor C4 The anode of the first power switch tube Q1, the drain of the second power switch tube Q2 are connected, the cathode of the first diode D1 is connected to the anode of the first output capacitor C3, and the second diode D2 The anode of the first coupled inductor winding L1A is connected to the negative pole of the second output capacitor C4, the same-named end of the first coupled inductor winding L1A is connected to the positive electrode of the first input capacitor C1, the opposite-named end of the first coupled inductor winding L1A, the first power switch tube Q1 The drain and the anode of the first diode D1 are connected, the opposite end of the second coupling inductor winding L1B is connected to the negative electrode of the second input capacitor C2, the same end of the second coupling inductor winding L1B, the second power switch The source of the transistor Q2 is connected to the cathode of the second diode D2.
The series coupled converter according to claim 1, wherein the two switching converters are a first buck switching converter and a second buck switching converter, and the current sharing unit is a first current sharing inductor L2;

The first buck switching converter includes a first input capacitor C1, a first output capacitor C3, a first coupling inductor winding L1A, a first power switching tube Q1, and a first diode D1, and the second buck switching converter includes a second input Capacitor C2, second output capacitor C4, second coupling inductor winding L1B, second power switch tube Q2, and second diode D2;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, the anode of the first diode D1, the cathode of the second diode D2, and one end of the first current sharing inductor L2 are connected, and the first current sharing inductor The other end of L2, the negative pole of the first output capacitor C3, and the positive pole of the second output capacitor C4 are connected, the source of the first power switch tube Q1, the cathode of the first diode D1, and the same name of the first coupling inductor winding L1A The drain of the second power switch tube Q2, the anode of the second diode D2, and the opposite end of the first coupling inductor winding L1B are connected, and the opposite end of the first coupling inductor winding L1A is connected to the first output The positive pole of the capacitor C3 is connected, the terminal of the same name of the first coupled inductor winding L1B is connected to the negative pole of the second output capacitor C4, the positive pole of the first input capacitor C1 is connected to the drain of the first power switch tube Q1, and the second input The negative electrode of the capacitor C2 is connected to the source electrode of the second power switch transistor Q2.
The series coupled converter according to claim 1, further comprising a first input capacitor C1, a first output capacitor C3, a second input capacitor C2 and a second output capacitor C4; the two switching converters It is the first buck-boost switching converter and the second buck-boost switching converter, and the current sharing unit is the first current sharing inductor L2;

The first buck-boost switching converter includes a first power switch tube Q1, a second power switch tube Q2, a first diode D1, a second diode D2, and a first coupled inductor winding L1A;

The second buck-boost switching converter includes a third power switch tube Q3, a fourth power switch tube Q4, a third diode D3, a fourth diode D4, and a second coupled inductor winding L1B;

The negative pole of the first input capacitor C1, the positive pole of the second input capacitor C2, the anode of the first diode D1, the cathode of the third diode D3, and one end of the first current sharing inductor L2 are connected, and the first current sharing inductor The other end of L2, the source of the second power switch tube Q2, the drain of the third power switch tube Q3, the negative pole of the first output capacitor C3, and the positive pole of the second output capacitor C4 are connected, and the first power switch tube Q1 The source, the end of the same name of the first coupled inductor winding L1A, and the cathode of the first diode D1 are connected, and the anode of the second diode D2, the drain of the second power switch tube Q2, and the first coupled inductor winding L1A The opposite ends are connected, the anode of the third diode D3, the drain of the fourth power switch Q4, and the opposite end of the second coupling inductor winding L1B are connected, the source of the third power switch Q3, the fourth The cathode of the diode D4 is connected to the terminal of the same name of the second coupling inductor winding L1B, the anode of the first input capacitor C1 is connected to the drain of the first power switching tube Q1, and the cathode of the second input capacitor C2 is connected to the fourth power The source of the switching tube Q4 is connected, the cathode of the second diode D2 is connected to the anode of the first output capacitor C3, and the anode of the fourth diode D4 is connected to the cathode of the second output capacitor C4.