Bidirectional active bridge converter based on capacitance isolation

Abstract

The utility model discloses a bidirectional active bridge converter based on capacitance isolation. The converter comprises two full bridges, two DC bus capacitors, two isolation capacitors and an inductor. And the direct current bus capacitor and the full bridge are connected in parallel to form an input or output port. According to the converter, a traditional transformer of a bidirectional active bridge based on transformer isolation is replaced by two isolation capacitors. And the isolation and bidirectional power flow functions of the converter are reserved. Compared with a transformer, the isolation capacitor only has conduction loss. Therefore, the efficiency of the bidirectional active bridge converter based on capacitor isolation is higher than that of a conventional bidirectional active bridge converter based on transformer isolation. And the energy density of the capacitor is far higher than that of the transformer. Therefore, the power density of the bidirectional active bridge converter based on capacitance isolation is far higher than that of a conventional bidirectional active bridge transformer based on transformer isolation.

Description

Technical Field

[0001] The utility model belongs to the field of power electronic converters, in particular to a bidirectional active bridge converter based on capacitor isolation. Background Art

[0002] The traditional bidirectional active bridge converter (DAB) based on transformer isolation is often used in the on-board charger of electric vehicles. Because its high-frequency transformer has the function of isolating the power grid and the electric vehicle, and it has a wide output voltage range. As a result, it is often used as a second-order DC-DC converter connected behind the PFC converter of the on-board charger to meet the wide range of charging voltage requirements of the electric vehicle battery. However, its high-frequency transformer is prone to increase transformer loss due to DC bias and other reasons, resulting in a decrease in overall efficiency. In order to solve this problem, the present invention uses two capacitors instead of the transformer. Transforming transformer isolation into capacitor isolation retains the ability of the converter to flow bidirectional power. And the capacitor has no magnetic core, so the capacitor has no DC bias problem and magnetic core loss. Compared with the traditional bidirectional active bridge converter based on transformer isolation, the bidirectional active bridge converter based on capacitor isolation has higher efficiency. Because the energy density of the capacitor is higher than that of the magnetic core, the bidirectional active bridge converter based on capacitor isolation has higher efficiency and higher power density. Summary of the invention

[0003] In order to solve the above problems, the purpose of the utility model is to provide a bidirectional active bridge converter based on capacitor isolation, which replaces the transformer of the traditional bidirectional active bridge converter based on transformer isolation with two capacitors. Thus, the transformer isolation is transformed into capacitor isolation. Capacitor isolation can achieve the same function as transformer isolation, while retaining the basic function of the converter.

[0004] To achieve the above purpose, the utility model provides a bidirectional active bridge converter based on capacitor isolation, which is implemented as follows:

[0005] A bidirectional active bridge converter based on capacitor isolation includes a left full bridge, a right full bridge, two isolation capacitors, two DC bus capacitors and an inductor. When power is transmitted from left to right, the left full bridge works as an inverter and the right full bridge works as a rectifier. By controlling the AC voltage on the left side of the inductor to lead the voltage on the right side by a certain phase, power can be transmitted from the left input side to the right output side. When power is transmitted from right to left, the right full bridge works as an inverter and the left full bridge works as a rectifier. By controlling the AC voltage on the right side of the inductor to lead the voltage on the left side by a certain phase, power can be transmitted from the right input side to the left output side. During the operation of the converter, high-frequency AC can flow through the isolation capacitor without hindrance. When the switch tube on the left or right side of the converter fails, high-frequency AC is no longer formed, and non-high-frequency AC cannot be transmitted through the isolation capacitor. At this time, the isolation capacitor takes the same isolation effect as the transformer. The positions of the inductor and the isolation capacitor can be interchanged at will without affecting the basic function of the converter.

[0006] The bidirectional active bridge converter based on capacitor isolation of the utility model has eight different circuit structures, including type I circuit, type II circuit, type III circuit, type IV circuit, type V circuit, type VI circuit, type VII circuit and type VIII circuit, and these circuits are composed of a left full bridge, a right full bridge, two isolation capacitors, two DC bus capacitors and an inductor.

[0007] The utility model has the following beneficial effects:

[0008] By adopting a capacitor isolation structure, high-frequency AC signals can be freely transmitted between isolation capacitors, effectively improving the efficiency of energy conversion and reducing energy loss. This bidirectional active bridge converter is suitable for a variety of power conversion scenarios, has a wide range of application prospects, and can meet the energy transmission needs of different fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is the I-type circuit schematic diagram of the utility model;

[0010] Figure 2 This is a schematic diagram of the type II circuit of the utility model;

[0011] Figure 3 This is the schematic diagram of the type III circuit of the utility model;

[0012] Figure 4 This is a schematic diagram of a type IV circuit of the utility model;

[0013] Figure 5 This is the V-shaped circuit schematic diagram of the utility model;

[0014] Figure 6This is a schematic diagram of a VI type circuit of the utility model;

[0015] Figure 7 This is a schematic diagram of the type VII circuit of the utility model;

[0016] Figure 8 This is the schematic diagram of the type VIII circuit of the utility model.

[0017] Description of main component symbols.

[0018] Left full bridge 1 Right full bridge 2 First half bridge 3 The second half bridge 4 The third half bridge 5 Fourth Half Bridge 6 DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below in conjunction with the embodiments and with reference to the accompanying drawings.

[0020] See also Figures 1 to 8 The figure shows a bidirectional active bridge converter based on capacitor isolation in the utility model, including a left full bridge 1, a right full bridge 2, a first isolation capacitor C3, a second isolation capacitor C4, a first DC bus capacitor C1, a second DC bus capacitor C1, and an inductor L.

[0021] In the bidirectional active bridge converter based on capacitor isolation of the utility model, when power is transmitted from left to right, the left full bridge 1 works as an inverter, and the right full bridge 2 works as a rectifier. By controlling the AC voltage on the left side of the inductor to lead the voltage on the right side by a certain phase, power can be transmitted from the left input side to the right output side. When power is transmitted from right to left, the right full bridge 2 works as an inverter, and the left full bridge 1 works as a rectifier. By controlling the AC voltage on the right side of the inductor to lead the voltage on the left side by a certain phase, power can be transmitted from the right input side to the left output side. During the operation of the converter, high-frequency AC can flow through the isolation capacitor without hindrance. When the switch tube on the left or right side of the converter fails, high-frequency AC is no longer formed, and non-high-frequency AC cannot be transmitted through the isolation capacitor. At this time, the isolation capacitor takes the same isolation effect as the transformer. The positions of the inductor and the isolation capacitor can be interchanged at will without affecting the basic function of the converter.

[0022] like Figures 1 to 8 As shown, the bidirectional active bridge converter based on capacitor isolation has eight different circuit structures, including type I circuit, type II circuit, type III circuit, type IV circuit, type V circuit, type VI circuit, type VII circuit, and type VIII circuit. These circuits are composed of a left full bridge 1, a right full bridge 2, a first isolation capacitor C3, a second isolation capacitor C4, a first DC bus capacitor C1, a second DC bus capacitor C1, and an inductor L.

[0023] like Figures 1 to 8As shown, the left full bridge 1 includes a first half bridge 3 and a second half bridge 4, and the right full bridge 2 includes a third half bridge 5 and a fourth half bridge 6; the first half bridge 3 is composed of a first switch tube Q1 and a second switch tube Q2 connected in series, the second half bridge 4 is composed of a third switch tube Q3 and a fourth switch tube Q4 connected in series, the third half bridge 5 is composed of a fifth switch tube Q5 and a sixth switch tube Q6 connected in series, and the fourth half bridge 6 is composed of a seventh switch tube Q7 and an eighth switch tube Q8 connected in series. The first DC bus capacitor C1 is connected in parallel with the first half bridge 3 to form a first port, the second DC bus capacitor C2 is connected in parallel with the second half bridge 4 to form a second port, and the first port and the second port can both be used as input or output ports.

[0024] like Figure 1 As shown, in the I-type circuit, the inductor L and the first isolation capacitor C3 are connected in series and then connected to the midpoint of the first half bridge 3 and the third half bridge 5, and the second isolation capacitor C4 is connected to the midpoint of the second half bridge 4 and the fourth half bridge 6.

[0025] like Figure 2 As shown, in the type II circuit, the first isolation capacitor C3 and the inductor L are connected in series and then connected to the midpoint of the first half bridge 3 and the third half bridge 5. The second isolation capacitor C4 is connected to the midpoint of the second half bridge 4 and the fourth half bridge 6.

[0026] like Figure 3 As shown, in the type III circuit, the inductor L and the first isolation capacitor C3 are connected in series and then connected to the midpoint of the second half bridge 4 and the fourth half bridge 6, and the first isolation capacitor C3 is connected to the midpoint of the first half bridge 3 and the third half bridge 5.

[0027] like Figure 4 As shown, in the IV type circuit, the inductor L and the second isolation capacitor C4 are connected in series and then connected to the midpoint of the second half bridge 4 and the fourth half bridge 6, and the first isolation capacitor C3 is connected to the midpoint of the first half bridge 3 and the third half bridge 5.

[0028] like Figure 5 As shown, in the V-type circuit, the inductor L and the first isolation capacitor C3 are connected in series and then connected to the midpoint of the first half bridge 3 and the fourth half bridge 6, and the second isolation capacitor C4 is connected to the midpoint of the second half bridge 4 and the third half bridge 5.

[0029] like Figure 6 As shown, in the VI type circuit, the first isolation capacitor C3 and the inductor L are connected in series and then connected to the midpoint of the first half bridge 3 and the fourth half bridge 6, and the second isolation capacitor C4 is connected to the midpoint of the second half bridge 4 and the third half bridge 5.

[0030] like Figure 7As shown, in the type VII circuit, the inductor L and the second isolation capacitor C4 are connected in series and then connected to the midpoint of the first half bridge 3 and the fourth half bridge 6, and the first isolation capacitor C3 is connected to the midpoint of the second half bridge 4 and the third half bridge 5.

[0031] like Figure 8 As shown, in the type VIII circuit, the second isolation capacitor C4 and the inductor L are connected in series and then connected to the midpoint of the first half bridge 3 and the fourth half bridge 6, and the first isolation capacitor C3 is connected to the midpoint of the second half bridge 4 and the third half bridge 5.

[0032] The working principle and working process of the utility model are as follows:

[0033] When power is transmitted from left to right, the left full bridge 1 works as an inverter, and the right full bridge 2 works as a rectifier. By controlling the AC voltage on the left side of the inductor L to lead the voltage on the right side by a certain phase, power can be transmitted from the left input side to the right output side. When power is transmitted from right to left, the right full bridge 2 works as an inverter, and the left full bridge 1 works as a rectifier. By controlling the AC voltage on the right side of the inductor L to lead the voltage on the left side by a certain phase, power can be transmitted from the right input side to the left output side. During the operation of the converter, high-frequency AC can flow through the first isolation capacitor C3 and the second isolation capacitor C4 without hindrance. When the switch tube on the left or right side of the converter fails, high-frequency AC is no longer formed, and non-high-frequency AC cannot be transmitted through the first isolation capacitor C3 and the second isolation capacitor C4. At this time, the first isolation capacitor C3 and the second isolation capacitor C4 play the same isolation role as the transformer, wherein the transmission positions of the inductor L and the first isolation capacitor C3 and the second isolation capacitor C4 can be interchanged at will without affecting the basic function of the converter.

Claims

1. A bidirectional active bridge converter based on capacitive isolation, Features: It includes a left full bridge, a right full bridge, a first isolation capacitor C3, a second isolation capacitor C4, a first DC bus capacitor C1, a second DC bus capacitor C1, and an inductor L. The left full bridge includes a first half bridge and a second half bridge, and the right full bridge includes a third half bridge and a fourth half bridge; the first half bridge is composed of a first switch tube Q1 and a second switch tube Q2 connected in series, the second half bridge is composed of a third switch tube Q3 and a fourth switch tube Q4 connected in series, the third half bridge is composed of a fifth switch tube Q5 and a sixth switch tube Q6 connected in series, and the fourth half bridge is composed of a seventh switch tube Q7 and an eighth switch tube Q8 connected in series. The first DC bus capacitor C1 is connected in parallel with the first half bridge to form a first port, the second DC bus capacitor C2 is connected in parallel with the second half bridge to form a second port, and the first port and the second port can both be used as input or output ports.

2. The bidirectional active bridge converter based on capacitive isolation according to claim 1, Features: The bidirectional active bridge converter based on capacitor isolation has eight different circuit structures, including type I circuit, type II circuit, type III circuit, type IV circuit, type V circuit, type VI circuit, type VII circuit, and type VIII circuit. These circuits are composed of a left full bridge, a right full bridge, a first isolation capacitor C3, a second isolation capacitor C4, a first DC bus capacitor C1, a second DC bus capacitor C1, and an inductor L. In the type I circuit, the inductor L and the first isolation capacitor C3 are connected in series and then connected to the midpoint of the first half bridge and the third half bridge, and the second isolation capacitor C4 is connected to the midpoint of the second half bridge and the fourth half bridge; in the type II circuit, the first isolation capacitor C3 and the inductor L are connected in series and then connected to the midpoint of the first half bridge and the third half bridge; the second isolation capacitor C4 is connected to the midpoint of the second half bridge and the fourth half bridge; in the type III circuit, the inductor L and the first isolation capacitor C3 are connected in series and then connected to the midpoint of the second half bridge and the fourth half bridge, and the first isolation capacitor C3 is connected to the midpoint of the first half bridge and The midpoint of the third half bridge; in the IV type circuit, the inductor L and the second isolation capacitor C4 are connected in series and then connected to the midpoint of the second half bridge and the fourth half bridge, and the first isolation capacitor C3 is connected to the midpoint of the first half bridge and the third half bridge. In the V type circuit, the inductor L and the first isolation capacitor C3 are connected in series and then connected to the midpoint of the first half bridge and the fourth half bridge, and the second isolation capacitor C4 is connected to the midpoint of the second half bridge and the third half bridge; in the VI type circuit, the first isolation capacitor C3 and the inductor L are connected in series and then connected to the midpoint of the first half bridge and the fourth half bridge, and the second isolation capacitor C4 is connected to the midpoint of the second half bridge and the third half bridge; in the VII type circuit, the inductor L and the second isolation capacitor C4 are connected in series and then connected to the midpoint of the first half bridge and the fourth half bridge, and the first isolation capacitor C3 is connected to the midpoint of the second half bridge and the third half bridge; in the VIII type circuit, the second isolation capacitor C4 and the inductor L are connected in series and then connected to the midpoint of the first half bridge and the fourth half bridge, and the first isolation capacitor C3 is connected to the midpoint of the second half bridge and the third half bridge.

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