DAB converter adopting bidirectional switch tap inductor
By employing a DAB converter with a bidirectional switching tap inductor, the equivalent magnetizing current is increased to achieve zero-voltage switching operation. This solves the efficiency and dynamic response issues of the DAB converter over a wide load and large battery voltage variation range, reduces switching losses, and maintains high efficiency and good dynamic response.
Patent Information
- Application Number
- CN202423298599.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2034-12-31
AI Technical Summary
The zero-voltage switching operation range of DAB converters is limited over a wide load range and a large range of battery voltage variations.
The DAB converter employing bidirectional switching tap inductors achieves zero-voltage switching operation under light and medium loads by increasing the equivalent magnetizing current, reduces the equivalent magnetizing current under heavy loads to maintain high efficiency, and reduces switching losses by switching the bidirectional switching tap inductors, adapting to changes in input voltage and output load.
It achieves extended zero-voltage switching operation over a wide load range and battery voltage variation range, reduces switching losses, maintains high converter efficiency and good dynamic response, and avoids current bias and surge voltage.
Smart Images
Figure CN223771945U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of converter technology, and in particular to a DAB converter using a bidirectional switch tap inductor. Background Technology
[0002] With the continuous development of society and the economy, energy issues are becoming increasingly prominent, making the development of new power electronic devices with high efficiency, high power density, and stable performance of great significance. Among them, DAB converters, due to their advantages such as high power density, current isolation, bidirectional energy transfer, and ease of achieving zero-voltage switching, are well-suited to the needs of AC grid-connected energy storage systems and are an ideal choice for DC / DC converters. Because of the zero-voltage switching operation, DAB converters can achieve high efficiency. Zero-voltage switching not only reduces switching losses but also eliminates voltage surges caused by hard switching operations due to reserve recovery. However, because energy storage systems require DAB converters to operate over a wide load range and a large battery voltage variation range, the zero-voltage switching operation range is limited. Utility Model Content
[0003] The purpose of this invention is to provide a DAB converter with a bidirectional switching tap inductor, which aims to solve the problem that the zero-voltage switching operation range is limited when the DAB converter operates over a wide load range and a large battery voltage variation range.
[0004] To achieve the above objectives, this utility model provides a DAB converter employing a bidirectional switched tap inductor, comprising a primary-side structure and a secondary-side structure, wherein the primary-side structure includes a DC power supply U. in Input capacitor C in The system comprises a first power switch S1, a second power switch S2, a third power switch S3, a fourth power switch S4, a high-frequency inductor L, a magnetizing inductor Lm, a bidirectional switch tap inductor Lt, and a transformer T; the first power switch S1, the second power switch S2, the third power switch S3, and the fourth power switch S4 are respectively connected to the DC power supply U. in The first power switch S1 is connected to the second power switch S2, the third power switch S3 is connected to the fourth power switch S4, the high-frequency inductor L is connected to the first power switch S1, the transformer T, and the fourth power switch S4, the magnetizing inductor Lm and the bidirectional switch tap inductor Lt are connected in parallel with the transformer T, and the input capacitor C... in The secondary structure is connected to the first power switch S1 and the second power switch S2 respectively; the secondary structure includes a load resistor R. L Output capacitor C outThe fifth power switch S5, the sixth power switch S6, the seventh power switch S7, and the eighth power switch S8; the fifth power switch S5, the sixth power switch S6, the seventh power switch S7, and the eighth power switch S8 are respectively connected to the load resistor R. L The fifth power switch S5 is connected to the sixth power switch S6, and the seventh power switch S7 is connected to the eighth power switch S8. The output capacitor C... out The fifth power switch S5 and the eighth power switch S8 are respectively connected to the seventh power switch S7 and the eighth power switch S8, and the fifth power switch S5 and the eighth power switch S8 are respectively connected to the transformer T.
[0005] The bidirectional switch tap inductor Lt includes a bidirectional switch and a dual-tap inductor, and the bidirectional switch and the dual-tap inductor are connected.
[0006] The bidirectional switch includes a first switch Q0, a second switch Q1, a third switch Q2, and a fourth switch Q3, wherein the first switch Q0 is connected to the second switch Q1, the third switch Q2, and the fourth switch Q3, respectively.
[0007] The dual-tap inductor includes a primary winding L1, a secondary winding L2, and a tertiary winding L3, a first tap H1, and a second tap H2. The primary winding L1 is connected to the second switch Q1, the first tap H1 is connected to the third switch Q2, and the second tap H2 is connected to the fourth switch Q3.
[0008] The bidirectional switch tap inductor is selected by turning on any one of the first switch Q0, the second switch Q1, the third switch Q2, and the fourth switch Q3 to select the inductance value connected to the circuit. The first switch Q0 is the main switch, and the second switch Q1, the third switch Q2, and the fourth switch Q3 are all branch switches.
[0009] This invention relates to a DAB converter employing a bidirectional switching tap inductor, wherein the drains of the first power switch S1 and the third power switch S3 are connected to the DC power supply U. in The positive terminal of the second power switch S2 and the source of the fourth power switch S4 are connected to the DC power supply U. inThe negative terminal of the first power switch S1 is connected to the drain of the second power switch S2, and the source of the third power switch S3 is connected to the drain of the fourth power switch S4. One end of the high-frequency inductor L is connected to the source of the first power switch S1 and the drain of the second power switch S2, and the other end of the high-frequency inductor L is connected to the same-name terminal of the primary side of the transformer T. The source of the third power switch S3 and the drain of the fourth power switch S4 are connected to the opposite-name terminals of the primary side of the transformer T. The magnetizing inductor Lm and the bidirectional switch tap inductor Lt are connected in parallel with the primary side of the transformer T. The input capacitor C... in Connected in parallel across the primary-side H-bridge. The drains of the fifth power switch S5 and the seventh power switch S7 are connected to the load resistor R. L One end is connected to the source of the sixth power switch S6 and the eighth power switch S8, and the load resistor R. L The other end is connected; the source of the fifth power switch S5 is connected to the drain of the sixth power switch S6, and the source of the seventh power switch S7 is connected to the drain of the eighth power switch S8; the source of the fifth power switch S5 and the drain of the sixth power switch S6 are connected to the same-named terminals of the secondary side of the transformer T, and the source of the seventh power switch S7 and the drain of the eighth power switch S8 are connected to the opposite-named terminals of the secondary side of the transformer T; the output capacitor C out Connected in parallel across the secondary H-bridge, this converter increases the equivalent magnetizing current through the bidirectional tap inductor Lt, achieving zero-voltage switching operation under light and medium loads. Under heavy loads, since zero-voltage switching operation is achieved without increasing the equivalent magnetizing current, the equivalent magnetizing current can be reduced without connecting the bidirectional tap inductor Lt, maintaining the converter's high efficiency under heavy loads. The bidirectional tap inductor Lt can reduce switching losses over a wider range as needed, improving converter efficiency. It also maintains good dynamic response when the system experiences sudden changes in input voltage and output load. There are no switching losses when the bidirectional tap inductor Lt is switched, and there is no DC bias or surge voltage generated in the bidirectional tap inductor current, thus no additional energy loss. This solves the problem that the zero-voltage switching operation range is limited when the DAB converter operates over a wide load range and a large battery voltage variation range. Attached Figure Description
[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0011] Figure 1This is a schematic diagram of a DAB converter structure using a bidirectional switch tap inductor according to the present invention.
[0012] Figure 2 This is a schematic diagram of the current loop when Q0 and Q1 are turned off during the operation of the bidirectional switch in the first working state of this utility model.
[0013] Figure 3 This is a schematic diagram of the current loop when Q0 is off and Q1 is on during the second working state of this utility model, when the bidirectional switch is turned on.
[0014] Figure 4 This is a schematic diagram of the current loop when Q0 is off and Q1 is on during the operation of the bidirectional switch in the third working state of this utility model.
[0015] Figure 5 This is a schematic diagram of the current loop when Q0 and Q1 are conducting during the operation of the bidirectional switch in the fourth working state of this utility model.
[0016] Figure 6 This is a schematic diagram of the current loop when Q0 and Q1 are conducting during the operation of the bidirectional switch in the fifth working state of this utility model.
[0017] Figure 7 This is a schematic diagram of the current loop when Q0 is on and Q1 is off during the operation of the bidirectional switch in the sixth working state of this utility model.
[0018] Figure 8 This is a schematic diagram of the current loop when Q0 is conducting and Q1 is turning off during the operation of the bidirectional switch in the seventh working state of this utility model.
[0019] Figure 9 This is a schematic diagram of the current loop when Q0 and Q1 are turned off during the operation of the bidirectional switch in the eighth working state of this utility model.
[0020] Figure 10 This is a schematic diagram of the control structure of this utility model. Detailed Implementation
[0021] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.
[0022] Please see Figures 1 to 10 This utility model provides a DAB converter using a bidirectional switched tap inductor, comprising a primary-side structure and a secondary-side structure, wherein the primary-side structure includes a DC power supply U. in Input capacitor Cin The system comprises a first power switch S1, a second power switch S2, a third power switch S3, a fourth power switch S4, a high-frequency inductor L, a magnetizing inductor Lm, a bidirectional switch tap inductor Lt, and a transformer T; the first power switch S1, the second power switch S2, the third power switch S3, and the fourth power switch S4 are respectively connected to the DC power supply U. in The first power switch S1 and the second power switch S2 are connected, the third power switch S3 and the fourth power switch S4 are connected, the high-frequency inductor L is connected to the first power switch S1, the transformer T and the fourth power switch S4, the magnetizing inductor Lm and the bidirectional switch tap inductor Lt are respectively connected in parallel with the transformer T, and the input capacitor C... in The secondary structure is connected to the first power switch S1 and the second power switch S2 respectively; the secondary structure includes a load resistor R. L Output capacitor C out The fifth power switch S5, the sixth power switch S6, the seventh power switch S7, and the eighth power switch S8; the fifth power switch S5, the sixth power switch S6, the seventh power switch S7, and the eighth power switch S8 are respectively connected to the load resistor R. L The fifth power switch S5 is connected to the sixth power switch S6, and the seventh power switch S7 is connected to the eighth power switch S8. The output capacitor C... out The fifth power switch S5 and the eighth power switch S8 are respectively connected to the seventh power switch S7 and the eighth power switch S8, and the fifth power switch S5 and the eighth power switch S8 are respectively connected to the transformer T.
[0023] In this embodiment, the drains of the first power switch S1 and the third power switch S3 are connected to the DC power supply U. in The positive terminal of the second power switch S2 and the source of the fourth power switch S4 are connected to the DC power supply U. in The negative terminal of the first power switch S1 is connected to the drain of the second power switch S2, and the source of the third power switch S3 is connected to the drain of the fourth power switch S4. One end of the high-frequency inductor L is connected to the source of the first power switch S1 and the drain of the second power switch S2, and the other end of the high-frequency inductor L is connected to the same-name terminal of the primary side of the transformer T. The source of the third power switch S3 and the drain of the fourth power switch S4 are connected to the opposite-name terminals of the primary side of the transformer T. The magnetizing inductor Lm and the bidirectional switch tap inductor Lt are connected in parallel and in parallel with the primary side of the transformer T. The input capacitor C... inConnected in parallel across the primary-side H-bridge. The drains of the fifth power switch S5 and the seventh power switch S7 are connected to the load resistor R. L One end is connected to the source of the sixth power switch S6 and the eighth power switch S8, and the load resistor R. L The other end is connected; the source of the fifth power switch S5 is connected to the drain of the sixth power switch S6, and the source of the seventh power switch S7 is connected to the drain of the eighth power switch S8; the source of the fifth power switch S5 and the drain of the sixth power switch S6 are connected to the same-named terminals of the secondary side of the transformer T, and the source of the seventh power switch S7 and the drain of the eighth power switch S8 are connected to the opposite-named terminals of the secondary side of the transformer T; the output capacitor C out Connected in parallel across the secondary H-bridge, this converter increases the equivalent magnetizing current through the bidirectional tap inductor Lt, achieving zero-voltage switching operation under light and medium loads. Under heavy loads, since zero-voltage switching operation is achieved without increasing the equivalent magnetizing current, the equivalent magnetizing current can be reduced without connecting the bidirectional tap inductor Lt, maintaining the converter's high efficiency under heavy loads. The bidirectional tap inductor Lt can reduce switching losses over a wider range as needed, improving converter efficiency. It also maintains good dynamic response when the system experiences sudden changes in input voltage and output load. There are no switching losses when the bidirectional tap inductor Lt is switched, and there is no DC bias or surge voltage generated in the bidirectional tap inductor current, thus no additional energy loss. This solves the problem that the zero-voltage switching operation range is limited when the DAB converter operates over a wide load range and a large battery voltage variation range.
[0024] Furthermore, the bidirectional switch tap inductor Lt includes a bidirectional switch and a dual-tap inductor, which are connected together. The bidirectional switch includes a first switch Q0, a second switch Q1, a third switch Q2, and a fourth switch Q3. The first switch Q0 is connected to the second switch Q1, the third switch Q2, and the fourth switch Q3, respectively. The dual-tap inductor includes a primary winding L1, a secondary winding L2, and a tertiary winding L3, a first tap H1, and a second tap H2. The primary winding L1 is connected to the second switch Q1, the first tap H1 is connected to the third switch Q2, and the second tap H2 is connected to the fourth switch Q3.
[0025] In this embodiment, the bidirectional switch tap inductor's inductance is selected by controlling the conduction of any one of the first switch transistor Q0, the second switch transistor Q1, the third switch transistor Q2, and the fourth switch transistor Q3. The first switch transistor Q0 is the main switch, while the second, third, and fourth switches Q1 and Q2 are all branch switches. The drain of the first switch transistor Q0 is connected to the same-name terminal of the primary winding of the transformer T, one end of the high-frequency inductor L, and one end of the magnetizing inductor Lm. The source of the first switch transistor Q0 is connected to the sources of the second, third, and fourth switches Q1 and Q3. The drain of the second switch transistor Q1 is connected to the same-name terminal of the primary winding L1 of the bidirectional switch inductor Lt. The drain of the third switch transistor Q2 is connected to the first tap H1, and the drain of the fourth switch transistor Q3 is connected to the second tap H2. The bidirectional switch tap inductor is connected in parallel to the primary side of the transformer T through the first port P1 and the second port P2. Specifically, when the first switch Q0 and the second switch Q1 are on, and the third switch Q2 and the fourth switch Q3 are off, the primary winding L1, the secondary winding L2, and the tertiary winding L3 are all connected to the circuit; when the first switch Q0 and the third switch Q2 are on, and the second switch Q1 and the fourth switch Q3 are off, the primary winding L1 and the tertiary winding L3 are all connected to the circuit; when the first switch Q0 and the fourth switch Q3 are on, and the second switch Q1 and the third switch Q2 are off, the tertiary winding L3 is connected to the circuit alone.
[0026] To better understand this technical solution, the following embodiments are provided for further explanation:
[0027] In the described embodiment, the primary winding L1, the secondary winding L2, and the tertiary winding L3 need to be connected to the circuit together. Therefore, the combination of the first switch Q0 and the second switch Q1 needs to be considered. Only the current direction in the first switch Q0, the second switch Q1, the bidirectional switch tap inductor Lt, the high-frequency inductor L, the magnetizing inductor Lm, and the transformer T is specified. Figure 1 The current i on the excitation inductor Lm mentioned in the text Lm and the current i on the bidirectional switch tap inductor Lt t The positive direction.
[0028] For details, please refer to Figures 2 to 9 , Figure 3 For magnetizing current i Lm The stage before it turns negative. Figure 5 For magnetizing current i LmThe stage before it turns into a positive direction.
[0029] There are eight operating states during the opening and closing of the bidirectional switch.
[0030] Operating state one, the current i on the magnetizing inductor Lm Lm To define the positive direction as from top to bottom, i.e. Lm >0, at this time Q0 and Q1 are turned off, and the current i flowing through the inductor of the bidirectional switch tap is... t =0;
[0031] In operating state two, Q1 is on, and Q0 is still off. The current i flowing through the inductor of the bidirectional switch tap is... t =0, so the conduction of Q1 is a zero-current switching operation with no switching losses;
[0032] Operating state three, the current i on the magnetizing inductor Lm To define the negative direction from bottom to top, i.e. Lm When the current is less than 0, the body diode in Q0 naturally conducts, and the current flowing through the inductor of the bidirectional switch tap is in the specified negative direction from bottom to top, i.e., i t <0. Furthermore, due to the instantaneous conduction of the body diode in Q0, i t =0, so no DC bias occurs in the inductor current of the bidirectional switch tap;
[0033] Operating state four, Q0 is turned on. Since the body diode in Q0 was turned on before this, the conduction of Q0 at this time is a zero-voltage switching operation with no switching loss.
[0034] Operating state five, the current i on the magnetizing inductor Lm To define the positive direction as from top to bottom, i.e. Lm When the current is greater than 0, Q0 and Q1 are conducting, and the current i flowing through the inductor of the bidirectional switch tap is... t >0;
[0035] In operating state six, the body diode in Q1 is always conducting, so the turn-off of Q1 is a zero-voltage switching operation with no switching losses. Q0 remains conducting, and the current i flowing through the bidirectional switch tap inductor... t >0;
[0036] Operating state seven, current i on the magnetizing inductor Lm To define the negative direction from bottom to top, i.e. Lm When the current i is less than 0, the body diode in Q1 naturally turns off, and the current i flowing through the inductor of the bidirectional switch tap increases. t =0;
[0037] Operating state eight, the current i flowing through the inductor of the bidirectional switch tap. t=0, Q0 is off, so the turn-off of Q0 at this time is a zero-current switching operation with no switching losses.
[0038] In summary, in the aforementioned operating state: because the body diode in Q0 or Q1 is turned on before Q0 is turned on or Q1 is turned off, the turning on of Q0 or the turning off of Q1 is a zero-voltage switching operation; because the current i flowing through the bidirectional switch tap inductor when Q1 is turned on or Q0 is turned off... t =0, so the conduction of Q1 or the turn-off of Q0 is a zero-current switching operation; and in all operating states, no DC bias or surge voltage will occur.
[0039] It is known that the transmitted power is controlled by the phase difference D between the high-side and low-side converters. In lightly loaded and medium-load DAB converters, the inductor current i of the high-side switch... L Too low to meet the zero-voltage condition. f is the converter's operating frequency, C is a constant, and T... d Dead time. Power transfer limiting the zero-voltage switching operation range:
[0040]
[0041] Therefore, it can be seen that the transmission power P, which limits the zero-voltage switching operation range, can be changed by controlling D, thereby achieving zero-voltage switching operation under light and medium loads. Furthermore, because...
[0042]
[0043] Therefore, it can be seen that D is affected by the excitation inductance Lm. By connecting bidirectional switch tap inductances of different sizes in parallel, the equivalent magnetizing inductance is changed, thereby increasing the equivalent magnetizing current and extending the zero-voltage switching operating range.
[0044] It is known that inductors can exhibit electromagnetic coupling, especially for air-core inductors, where the magnetic field exists within a large space around the inductor. If two inductors are very close together and in the same direction, electromagnetic coupling is easily achieved, resulting in mutual inductance M.
[0045] When the inductance value needs to be switched in the circuit, mutual inductance may occur between the windings of the tapped inductor. Specifically, Q0 and Q1 are turned on, and Q2 and Q3 are turned off. At this time, the primary winding L1, primary winding L2, and tertiary winding L3 are all connected to the circuit. Let the inductance value at this time be L. 123 The main switch Q0 and the second branch switch Q2 are turned on, while the first branch switch Q1 and the third branch switch Q3 are turned off. At this time, the secondary winding L2 and the tertiary winding L3 are connected to the circuit together. Let the inductance at this time be L. 23When the main switch Q0 and the third branch switch Q3 are turned on, and the first branch switch Q1 and the second branch switch Q2 are turned off, the third winding L3 is connected to the circuit alone, and the inductance is equal to L3.
[0046] Furthermore, the inductors of the bidirectional switch have the same direction at the same terminals, and the inductance of each winding is equal to L0. Assuming that the coupling coefficient k between each winding is taken as the ideal value of 1, that is, the fully coupled state.
[0047] so:
[0048] L 123 =L1+L2+L3+2×(M) 12 +M 23 +M 31 Mutual induction
[0049] Therefore L 123 =9L0.
[0050] L 23 =L2+L3+2×M 23 Mutual induction Therefore L 23 =4L0.
[0051] like Figure 10 As shown, the first step is to connect the load resistor R. L Voltage V on o with i o Multiply to obtain the current output power P o Then, the current output power P o With light-load reference output power P oref1 Medium-load reference output power P oref2 The difference is calculated. This difference is fed into the output power comparator. If the current output power P... o With light-load reference output power P oref1 The difference is positive or equal, indicating a light load; if the current output power P o With light-load reference output power P oref1 The difference is negative and is related to the light-load reference output power P. oref2 If the difference is positive or equal, it indicates a medium load; if the current output power P o With light-load reference output power P oref1 The difference is negative and is related to the light-load reference output power P. oref2A negative difference indicates a heavy load. Depending on the load conditions, determine the size of the tap inductor in the connected circuit and the combination of switches that the switch controller needs to control. For heavy loads, no switch control is required; for medium or light loads, the corresponding switch of the connected tap inductor needs to be controlled. The tap inductor should ideally be larger for light loads than for medium loads. Simultaneously, the current i flowing through the bidirectional switch tap inductor... Lt and magnetizing current i Lm Relative to the zero current reference point I ref The difference is calculated to determine the current state, thereby providing specific switching transistor drive signals through the switching controller.
[0052] The above-disclosed embodiments are merely preferred embodiments of a DAB converter employing a bidirectional switch tap inductor, and should not be construed as limiting the scope of this application. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments, and equivalent variations made in accordance with the claims of this application, still fall within the scope of this application.
Claims
1. A DAB converter employing a bidirectional switch-tapped inductor, characterized by ； The primary side structure includes a direct current power supply U in , an input capacitor C in , a first power switch S1, a second power switch S2, a third power switch S3, a fourth power switch S4, a high-frequency inductor L, an excitation inductor Lm, a bidirectional switch tap inductor Lt and a transformer T The first power switch tube S1, the second power switch tube S2, the third power switch tube S3 and the fourth power switch tube S4 are respectively connected with the direct current power supply U in The first power switch tube S1 and the second power switch tube S2 are connected, the third power switch tube S3 and the fourth power switch tube S4 are connected, the high-frequency inductor L is connected with the first power switch tube S1, the transformer T and the fourth power switch tube S4, the excitation inductor Lm and the bidirectional switch tap inductor Lt are respectively connected with the transformer T in parallel, the input capacitor C in are respectively connected with the first power switch tube S1 and the second power switch tube S2. The secondary side structure includes a load resistor R L , an output capacitor C out , a fifth power switch S5, a sixth power switch S6, a seventh power switch S7, and an eighth power switch S8. The fifth power switch S5, the sixth power switch S6, the seventh power switch S7 and the eighth power switch S8 are connected with the load resistor R L The fifth power switch S5 and the sixth power switch S6 are connected, the seventh power switch S7 and the eighth power switch S8 are connected, the output capacitor C out The seventh power switch S7 and the eighth power switch S8 are connected, the fifth power switch S5 and the eighth power switch S8 are connected with the transformer T respectively.
2. The DAB converter employing bidirectional switch-tapped inductors as recited in claim 1, wherein ； The bidirectional switch tap inductor Lt comprises a bidirectional switch and a double-tap inductor, and the bidirectional switch and the double-tap inductor are connected.
3. The DAB converter employing bidirectional switch-tapped inductors as recited in claim 2, wherein ； The bidirectional switch comprises a first switch Q0, a second switch Q1, a third switch Q2 and a fourth switch Q3, the first switch Q0 is connected with the second switch Q1, the third switch Q2 and the fourth switch Q3 respectively, and the bidirectional switch has a first port P1 and a second port P2.
4. The DAB converter employing the bidirectional switch tap inductor according to claim 3, characterized in that: The double-tap inductor comprises a primary winding L1, a secondary winding L2 and a tertiary winding L3, a first tap H1 and a second tap H2, the primary winding L1 is connected with the second switch Q1, the first tap H1 is connected with the third switch Q2, and the second tap H2 is connected with the fourth switch Q3.
5. The DAB converter employing bidirectional switch-tapped inductors as recited in claim 4, wherein ； The bidirectional switch tap inductor selects the inductance size of the access circuit by the conduction of the first switch Q0 and any one of the second switch Q1, the third switch Q2 and the fourth switch Q3, wherein the first switch Q0 is a total switch, and the second switch Q1, the third switch Q2 and the fourth switch Q3 are branch switches.