Power expander for use in three-phase LLC circuits

Abstract

The present invention relates to a power expansion device for use in a three-phase LLC circuit, the power expansion device including first and second full-bridge switch networks, first and second resonant networks, first and second transformer networks, and first and second rectifier networks. The primary side of the first transformer network is connected to an input voltage via the first resonant network and the first full-bridge switch network, and the secondary side is connected to a load via the first rectifier network. The primary side of the second transformer network is connected to an input voltage via the second resonant network and the second full-bridge switch network, and the secondary side is connected to a load via the second rectifier network. Each of the first and second transformer networks includes three transformer units. The secondary sides of any two transformer units in the first transformer network are star-connected to the secondary side of any one transformer unit in the second transformer network. The present invention is convenient for low-cost manufacturing implementation, can increase output power, achieve a wide output range, and solve the voltage balance and / or current balance problems.

Description

[Technical field]

[0001] The present invention relates to the field of new energy, and more particularly to a power expansion device used in a three-phase LLC circuit. [Background technology]

[0002] New energy vehicles, especially electric vehicles, have recently experienced unprecedented development. In order to meet the demand for charging electric vehicles, the requirements for power and reliability of charging modules at charging stations are increasing day by day. Existing charging modules usually adopt LLC topology circuits. However, under the condition of high power applications, it is necessary to interleave multiple LLC circuits, which can increase the output power and reduce the output ripple. However, due to the influence of the variation of resonance parameters, LLC circuits have a certain current unbalance or voltage unbalance problem between different LLC circuits.

[0003] Therefore, there is a need for a power expansion device for use in a three-phase LLC circuit that requires little modification to the LLC topology circuit, is convenient for low-cost manufacturing and implementation, and at the same time can increase output power, achieve a wide output range, and solve the problems of voltage balance and / or current balance. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem to be solved by the present invention is to provide a power expansion device for use in a three-phase LCC circuit, which requires little modification to an LLC topology circuit, is convenient for low-cost manufacturing and implementation, and at the same time, can increase output power, realize a wide range of output, and solve the problems of voltage balance and / or current balance, in view of the above-mentioned shortcomings of the existing technology. [Means for solving the problem]

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows: The configuration of the power expansion device used in the three-phase LLC circuit includes a first full-bridge switch network, a second full-bridge switch network, a first resonant network, a second resonant network, a first transformer network, a second transformer network, a first rectifier network and a second rectifier network. The primary side of the first transformer network is connected to the input voltage through the first resonant network and the first full-bridge switch network in turn, and the secondary side is connected to the load through the first rectifier network. The primary side of the second transformer network is connected to the input voltage through the second resonant network and the second full-bridge switch network in turn, and the secondary side is connected to the load through the second rectifier network.

[0006] The first transformer network includes a first transformer unit, a second transformer unit, and a third transformer unit, and the second transformer network includes a fourth transformer unit, a fifth transformer unit, and a sixth transformer unit. The secondary sides of any two transformer units in the first transformer network are star-connected with the secondary side of any one transformer unit in the second transformer network. The first full-bridge switch network includes a first full-bridge switch unit, a second full-bridge switch unit, and a third full-bridge switch unit, the first resonant network includes a first resonant unit, a second resonant unit, and a third resonant unit, and the first rectifier network includes a first rectifier unit, a second rectifier unit, and a third rectifier unit. The second full-bridge switch network includes a fourth full-bridge switch unit, a fifth full-bridge switch unit and a sixth full-bridge switch unit, the second resonant network includes a fourth resonant unit, a fifth resonant unit and a sixth resonant unit, the second rectifier network includes a fourth rectifier unit, a fifth rectifier unit and a sixth rectifier unit, the first transformer unit includes a first transformer and a second transformer, the second transformer unit includes a third transformer and a fourth transformer, the third transformer unit includes a fifth transformer and a sixth transformer, the fourth transformer unit includes a seventh transformer and an eighth transformer, the fifth transformer unit includes a ninth transformer and a tenth transformer, and the sixth transformer unit includes an eleventh transformer and a twelfth transformer.

[0007] A first end of a primary side of the first transformer is connected to a first end of the first full-bridge switch unit via the first resonant unit, a second end of the primary side is connected to a first end of the primary side of the second transformer, and a second end of the primary side of the second transformer is connected to a second end of the first full-bridge switch unit. A first end of a primary side of the third transformer is connected to a first end of the second full-bridge switch unit via the second resonant unit, a second end of the primary side is connected to a first end of the primary side of the fourth transformer, and a second end of the primary side of the fourth transformer is connected to a second end of the second full-bridge switch unit. A first end of the primary side of the fifth transformer is connected to a first end of the third full-bridge switch unit via the third resonant unit, a second end of the primary side is connected to a first end of the primary side of the sixth transformer, and a second end of the primary side of the sixth transformer is connected to a second end of the third full-bridge switch unit. A first end of the primary side of the seventh transformer is connected to a first end of the fourth full-bridge switch unit via the fourth resonant unit, a second end of the primary side is connected to a first end of the primary side of the eighth transformer, and a second end of the primary side of the eighth transformer is connected to a second end of the fourth full-bridge switch unit. A first end of the primary side of the ninth transformer is connected to a first end of the fifth full-bridge switch unit via the fifth resonant unit, a second end of the primary side is connected to a first end of the primary side of the tenth transformer, and a second end of the primary side of the tenth transformer is connected to a second end of the fifth full-bridge switch unit. A first end of the primary side of the eleventh transformer is connected to a first end of the sixth full-bridge switch unit via the sixth resonant unit, a second end of the primary side is connected to a first end of the primary side of the twelfth transformer, and a second end of the primary side of the twelfth transformer is connected to a second end of the sixth full-bridge switch unit.

[0008] A first end of the secondary side of the first transformer is connected to a first end of the first rectifier unit, and a first end of the secondary side of the second transformer is connected to a second end of the first rectifier unit. A first end of the secondary side of the third transformer is connected to a first end of the second rectifier unit, and a first end of the secondary side of the fourth transformer is connected to a second end of the second rectifier unit. A first end of the secondary side of the fifth transformer is connected to a first end of the fourth rectifier unit, and a first end of the secondary side of the sixth transformer is connected to a second end of the fourth rectifier unit. A first end of the secondary side of the seventh transformer is connected to a first end of the third rectifier unit, and a first end of the secondary side of the eighth transformer is connected to a second end of the third rectifier unit. A first end of the secondary side of the ninth transformer is connected to a first end of the fifth rectifier unit, a first end of the secondary side of the tenth transformer is connected to a second end of the fifth rectifier unit, a first end of the secondary side of the eleventh transformer is connected to a first end of the sixth rectifier unit, and a first end of the secondary side of the twelfth transformer is connected to a second end of the sixth rectifier unit.

[0009] The second end of the secondary side of the first transformer is connected to the second end of the secondary side of the third transformer and the second end of the secondary side of the seventh transformer, the second end of the secondary side of the second transformer is connected to the second end of the secondary side of the fourth transformer and the second end of the secondary side of the eighth transformer, the second end of the secondary side of the fifth transformer is connected to the second end of the secondary side of the ninth transformer and the second end of the secondary side of the eleventh transformer, and the second end of the secondary side of the sixth transformer is connected to the second end of the secondary side of the tenth transformer and the second end of the secondary side of the twelfth transformer.

[0010] Preferably, the first full-bridge switch network and the second full-bridge switch network are connected in series between a first input terminal and a second input terminal, and the first rectifier network and the second rectifier network are connected in parallel between a first output terminal and a second output terminal.

[0011] Preferably, the first full-bridge switch network and the second full-bridge switch network are connected in parallel between a first input terminal and a second input terminal, and the first rectifier network and the second rectifier network are connected in parallel between a first output terminal and a second output terminal.

[0012] Preferably, the first full-bridge switch network and the second full-bridge switch network are connected in parallel between a first input terminal and a second input terminal, and the first rectifier network and the second rectifier network are connected in series between a first output terminal and a second output terminal.

[0013] Preferably, the first full-bridge switch network and the second full-bridge switch network are connected in series between a first input terminal and a second input terminal, and the first rectifier network and the second rectifier network are connected in series between a first output terminal and a second output terminal. Effect of the Invention

[0014] The power expansion device of the three-phase LLC circuit, on the one hand, does not make excessive adjustments or modifications to the commonly used LLC half-bridge interleaved topology structure, so it is convenient for low-cost manufacturing and implementation, and at the same time, it can expand the output power, which is suitable for increasing the output power and realizing a wide range of output. On the other hand, it can achieve the effect of self-voltage balance when the six resonant tanks are connected in series, and self-current balance when they are connected in parallel, which improves reliability.

[0015] The present invention will be further described below in combination with figures and examples. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 shows a commonly used LLC half-bridge interleaved topology structure. [Diagram 2] FIG. 2 is a principle block diagram of a first preferred embodiment of a power expansion device used in a three-phase LLC circuit of the present invention. [Diagram 3] FIG. 3 is a circuit diagram of a second preferred embodiment of a power expansion device used in a three-phase LLC circuit of the present invention. [Figure 4]FIG. 4 is a circuit diagram of a third preferred embodiment of a power expansion device used in a three-phase LLC circuit of the present invention. [Diagram 5] FIG. 5 is a circuit diagram of a fourth preferred embodiment of a power expansion device used in a three-phase LLC circuit of the present invention. [Figure 6] FIG. 6 is a circuit diagram of a fifth preferred embodiment of a power expansion device used in a three-phase LLC circuit of the present invention. [Figure 7] FIG. 7 is a circuit diagram of the sixth preferred embodiment of the power expansion device used in the three-phase LLC circuit of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be described in more detail below in combination with figures and examples. It should be understood that the specific examples described herein are only used to explain the present invention, and do not limit the present invention.

[0018] Figure 1 shows a commonly used LLC half-bridge interleaved topology structure. As shown in Figure 1, in this topology structure, the primary and secondary windings of the transformer are respectively star-connected (also called Y-connected). This structure can achieve relatively good current balance and voltage balance effects, but when directly extending it to ultra-high power, the wiring of the transformer windings becomes very complicated and difficult to realize. Furthermore, the practical use of the half-bridge structure in a wide output voltage range brings about design difficulties.

[0019] Based on this, the present invention shows a power expansion device for use in a three-phase LLC circuit. Based on the LLC half-bridge interleaved topology structure shown in Figure 1, a three-phase full-bridge interleaved structure is shown, including a first full-bridge switch network, a second full-bridge switch network, a first resonant network, a second resonant network, a first transformer network, a second transformer network, a first rectifier network and a second rectifier network. The primary side of the first transformer network is connected to the input voltage through the first resonant network and the first full-bridge switch network in turn, and the secondary side is connected to the load through the first rectifier network. The primary side of the second transformer network is connected to the input voltage through the second resonant network and the second full-bridge switch network in turn, and the secondary side is connected to the load through the second rectifier network. The first transformer network includes a first transformer unit, a second transformer unit, and a third transformer unit, and the second transformer network includes a fourth transformer unit, a fifth transformer unit, and a sixth transformer unit, and the secondary sides of any two transformer units in the first transformer network are star-connected with the secondary side of any one transformer unit in the second transformer network.

[0020] The power expansion device of the three-phase LLC circuit does not make excessive adjustments or modifications to the commonly used LLC half-bridge interleaved topology structure, which is convenient for low-cost manufacturing and implementation, and can also expand the output power, which is suitable for increasing the output power and realizing a wide range of output. On the other hand, it can achieve the effect of self-voltage balance when the six resonant tanks are connected in series, and self-current balance when they are connected in parallel, which improves reliability.

[0021] Fig. 2 is a principle block diagram of a first preferred embodiment of a power expansion device used in a three-phase LLC circuit of the present invention. As shown in Fig. 2, the power expansion device used in a three-phase LLC circuit of the present invention includes a full-bridge switch network 101, a full-bridge switch network 201, a resonant network 102, a resonant network 202, a transformer network 103, a transformer network 203, a rectifier network 104 and a rectifier network 204. The primary side of the transformer network 103 is connected to the input voltage Uin through the resonant network 102 and the full-bridge switch network 101 in turn, and the secondary side is connected to the load 500 through the rectifier network 104. The primary side of the transformer network 203 is connected to the input voltage Uin through the resonant network 202 and the full-bridge switch network 201 in turn, and the secondary side is connected to the load 500 through the rectifier network 204. In a preferred embodiment shown in FIG. 2, the input voltage Uin may be the voltage across an input capacitor C1, across which are a first input terminal and a second input terminal, and across which are a first output terminal and a second output terminal, respectively.

[0022] The transformer network 103 includes a first transformer unit, a second transformer unit, and a third transformer unit, and the transformer network 203 includes a fourth transformer unit, a fifth transformer unit, and a sixth transformer unit. Each transformer unit may include one transformer, or two transformers with primary windings connected in series, or multiple transformers with primary windings connected in series. The secondary sides of any two transformer units in the transformer network 103 are star-connected with the secondary side of any one transformer unit in the transformer network 203. For example, the secondary sides of the first transformer unit and the second transformer unit are star-connected with the secondary side of the fourth transformer unit, and / or the secondary sides of the third transformer unit and the fifth transformer unit are star-connected with the secondary side of the sixth transformer unit. Of course, other suitable connection methods may also be adopted, as long as the secondary sides of any two transformer units in the transformer network 103 are star-connected with the secondary side of any one transformer unit in the transformer network 203.

[0023] In one preferred embodiment of the present invention, the full-bridge switch network 101 and the full-bridge switch network 201 can be connected in series between a first input terminal and a second input terminal; and the rectifier network 104 and the rectifier network 204 are connected in parallel between a first output terminal and a second output terminal. In another preferred embodiment of the present invention, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in parallel between a first input terminal and a second input terminal; and the rectifier network 104 and the rectifier network 204 are connected in parallel between a first output terminal and a second output terminal. In another preferred embodiment of the present invention, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in parallel between a first input terminal and a second input terminal; and the rectifier network 104 and the rectifier network 204 are connected in series between a first output terminal and a second output terminal. In another preferred embodiment of the present invention, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in series between a first input terminal and a second input terminal; the rectifier network 104 and the rectifier network 204 are connected in series between a first output terminal and a second output terminal.

[0024] In a preferred embodiment of the present invention, the first to sixth transformer units respectively include a first to sixth transformer. That is, the transformer networks 103 and 203 respectively include three transformers. Thus, correspondingly, the full-bridge switch networks 101 and 102 respectively include a three-phase full-bridge switch unit, i.e., three full-bridge switch units. The resonant networks 102 and 202 respectively include a three-phase resonant unit, i.e., three resonant units. The rectifier networks 104 and 204 respectively include a three-phase rectifier unit, i.e., three rectifier units, each of which includes two rectifier diodes. In another preferred embodiment of the present invention, the first to sixth transformer units respectively include two transformers whose primary sides are connected in series. That is, the transformer networks 103 and 203 respectively include six transformers. Therefore, correspondingly, the full-bridge switch networks 101 and 102 may each include a three-phase full-bridge switch unit, i.e., three full-bridge switch units. The resonant networks 102 and 202 may each include a three-phase resonant unit, i.e., three resonant units. The rectifier networks 104 and 204 each include a three-phase rectifier unit, i.e., three rectifier units, each of which includes four rectifier diodes.

[0025] The secondary sides of the existing transformer units are star-connected on the same resonant network, but the present invention creatively optimizes this so that the secondary sides of any two transformer units in one three-phase resonant network are star-connected with the secondary side of any one transformer in another three-phase resonant network. This forms an interconnection between the two resonant networks, and when the input and output are connected in series and parallel respectively in this way, the voltage balance and current balance of the hardware can be achieved. The star connection method mentioned here is a common name in the industry, also known as Y connection, which is a connection method between the windings of the secondary side of the transformer and the rectifier circuit, and is a shape that appears after the wire is extended. In addition, the concept provided by the present invention can be expanded based on the number of transformers, and when the transformers are expanded, the design of the transformer is easier, the layout is convenient, and the selection of the switch elements of the rectifier network is also easier.

[0026] FIG. 3 is a circuit diagram of a second preferred embodiment of the power expansion device used in the three-phase LLC circuit of the present invention. FIG. 3 shows an embodiment in which the inputs of two resonant networks are connected in series, and the outputs of two rectifier networks are connected in parallel. As shown in FIG. 3, the power expansion device used in the three-phase LLC circuit of the present invention includes a full-bridge switch network 101, a full-bridge switch network 201, a resonant network 102, a resonant network 202, a transformer network 103, a transformer network 203, a rectifier network 104, and a rectifier network 204. The primary side of the transformer network 103 is connected to the positive bus bar BUS+ and the neutral line through the resonant network 102 and the full-bridge switch network 101 in turn, and the secondary side is connected to the output positive pole Vo+ and the output negative pole Vo- through the rectifier network 104. The primary side of the transformer network 203 is connected to the neutral line and the negative bus bar BUS- through the resonant network 202 and the full-bridge switch network 201, and the secondary side is connected to the output positive pole Vo+ and the output negative pole Vo- through the rectifier network 204. That is, in this embodiment, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in series between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in parallel between the output positive pole Vo+ and the output negative pole Vo-. A load Ro is connected to the output positive pole Vo+ and the output negative pole Vo-.

[0027] In this preferred embodiment, the full-bridge switch network 101 includes a first full-bridge switch unit, a second full-bridge switch unit and a third full-bridge switch unit, i.e. the first full-bridge switch unit includes switch tubes S11, S21, S31 and S41, the second full-bridge switch unit includes switch tubes S51, S61, S71 and S81, and the third full-bridge switch unit includes switch tubes S91, S101, S111 and S121. The resonant network 102 includes a first resonant unit, a second resonant unit and a third resonant unit, i.e. each resonant unit includes a capacitor Cr1 and an inductor Lr1 connected in series. The resonant network 202 includes a fourth resonant unit, a fifth resonant unit and a sixth resonant unit, i.e. each resonant unit includes a capacitor Cr2 and an inductor Lr2 connected in series. The first to sixth transformer units respectively include the first to sixth transformers, i.e., transformers T11, T21, T31, T12, T22, and T32. The rectifier network 104 includes a first rectifier unit, a second rectifier unit, and a third rectifier unit, i.e., the first rectifier unit includes diodes D11 and D41, the second rectifier unit includes diodes D21 and D51, and the third rectifier unit includes diodes D31 and D61. The rectifier network 204 includes a fourth rectifier unit, a fifth rectifier unit, and a sixth rectifier unit, i.e., the fourth rectifier unit includes diodes D12 and D42, the second rectifier unit includes diodes D22 and D52, and the third rectifier unit includes diodes D32 and D62. In the preferred embodiment shown in FIG. 3, the rectifier network further includes input capacitors C1 and C2 and output capacitors Co1 and Co2. The main function of the resonant networks 102 and 202 is LLC series resonance, which realizes soft switching of the switch elements. The transformer networks 103 and 203 are responsible for insulation and voltage conversion regulation. The rectifier networks 104 and 204 are responsible for power rectification.

[0028] 3, the first end of the primary side of the transformer T11 is connected to the first end of the first full-bridge switch unit (i.e., the source terminal of the switch tube S11 and the drain terminal of the switch tube S31) through the first resonant unit, and the second end of the primary side is connected to the second end of the first full-bridge switch unit (i.e., the source terminal of the switch tube S21 and the drain terminal of the switch tube S21). The first end of the primary side of the transformer T21 is connected to the first end of the second full-bridge switch unit (i.e., the source terminal of the switch tube S51 and the drain terminal of the switch tube S71) through the second resonant unit, and the second end of the primary side is connected to the second end of the second full-bridge switch unit (i.e., the source terminal of the switch tube S61 and the drain terminal of the switch tube S81). The first end of the primary side of the transformer T31 is connected to the first end of the third full-bridge switch unit (i.e., the source terminal of the switch tube S91 and the drain terminal of the switch tube S111) through the third resonant unit, and the second end of the primary side is connected to the second end of the third full-bridge switch unit (i.e., the source terminal of the switch tube S101 and the drain terminal of the switch tube S121). The first end of the primary side of the transformer T12 is connected to the first end of the fourth full-bridge switch unit (i.e., the source terminal of the switch tube S12 and the drain terminal of the switch tube S32) through the fourth resonant unit, and the second end of the primary side is connected to the second end of the fourth full-bridge switch unit (i.e., the source terminal of the switch tube S22 and the drain terminal of the switch tube S42). A first end of the primary side of the transformer T22 is connected to a first end of the fifth full-bridge switch unit (i.e., the source terminal of the switch tube S52 and the drain terminal of the switch tube S72) via the fifth resonant unit, and a second end of the primary side is connected to a second end of the fifth full-bridge switch unit (i.e., the source terminal of the switch tube S62 and the drain terminal of the switch tube S82).A first end of the primary side of the transformer T32 is connected to a first end of the sixth full-bridge switch unit (i.e., the source terminal of the switch tube S92 and the drain terminal of the switch tube S112) via the sixth resonant unit, and a second end of the primary side is connected to a second end of the sixth full-bridge switch unit (i.e., the source terminal of the switch tube S102 and the drain terminal of the switch tube S122). The gate terminals of all the switch tubes are connected to the control signal, the drain terminals of the switch tubes S11, S21, S51, S61, S91, S101 are connected to the positive bus bar BUS+, the source terminals of the switch tubes S31, S41, S71, S81, S111 and S121 are connected to the neutral line, the drain terminals of the switch tubes S12, S22, S52, S62, S92, S102 are connected to the neutral line, and the source terminals of the switch tubes S32, S42, S72, S82, S112 and S222 are connected to the negative bus bar BUS-. The input capacitor C1 is connected between the positive bus bar BUS+ and the neutral line, and the input capacitor C2 is connected between the neutral line and the negative bus bar BUS-. In this application, the switch tubes used include, but are not limited to, Si MOS, IGBT, GaN MOS, SiC MOS, etc.

[0029] A first end of the secondary side of the transformer T11 is connected to a first end of the first rectifier unit (i.e., the anode of diode D11 and the cathode of diode D41), a first end of the secondary side of the transformer T21 is connected to a first end of the second rectifier unit (i.e., the anode of diode D21 and the cathode of diode D51), and a first end of the secondary side of the transformer T31 is connected to a first end of the fourth rectifier unit (i.e., the anode of diode D12 and the cathode of diode D42). The first end of the secondary side of the transformer T12 is connected to the first end of the third rectifier unit (i.e., the anode of the diode D31 and the cathode of the diode D61), the first end of the secondary side of the transformer T22 is connected to the first end of the fifth rectifier unit (i.e., the anode of the diode D22 and the cathode of the diode D52), and the first end of the secondary side of the transformer T32 is connected to the first end of the sixth rectifier unit (i.e., the anode of the diode D32 and the cathode of the diode D62). The second end of the secondary side of the transformer T11 is connected to the second end of the secondary side of the transformer T21 and the second end of the secondary side of the transformer T12, and the second end of the secondary side of the transformer T31 is connected to the second end of the secondary side of the transformer T22 and the second end of the secondary side of the transformer T32. The cathodes of the diodes D11, D21, and D31 and the cathodes of the diodes D12, D22, and D32 are connected to the output positive electrode Vo+, and the anodes of the diodes D41, D51, and D61 and the anodes of the diodes D42, D52, and D62 are connected to the output negative electrode Vo-. The output capacitors Co1 and Co2 are connected between the output positive electrode Vo+ and the output negative electrode Vo-, respectively.

[0030] In another preferred embodiment of the present invention, a switch tube rectifier network can be used instead of the diode rectifier network, where the rectifier networks 104 and 204 can adopt Si MOS, IGBT, GaN MOS, SiC MOS, Schottky diode, SIC diode, etc.

[0031] In the preferred embodiment, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in series between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in parallel between the output positive pole Vo+ and the output negative pole Vo-. In the transformer networks 103 and 203, the second end of the secondary side of the transformer T11 is connected to the second end of the secondary side of the transformer T21 and the second end of the secondary side of the transformer T12, and the second end of the secondary side of the transformer T31 is connected to the second end of the secondary side of the transformer T22 and the second end of the secondary side of the transformer T32. By star-connecting the secondary sides of any two transformers in the transformer network 103 with the secondary side of any one transformer in the transformer network 203, it is ensured that the series connection of the full-bridge switch network 101 and the full-bridge switch network 201 can achieve voltage balance, and the parallel connection of the rectifier network 104 and the rectifier network 204 can achieve current balance.

[0032] The present invention provides a power expansion device for use in a three-phase LLC circuit. Based on the existing three-phase half-bridge interleaved LLC, the concept of improving the topology of the three-phase full-bridge interleaved LLC is creatively presented, and the structure of the three-phase full-bridge interleaved LLC is presented. On the one hand, it expands the power and is more suitable for a wide range of output; on the other hand, by changing the star connection on the secondary side of the transformer, each phase of this topology has a relatively high ability of self-voltage balance and current balance, which can also simplify the hardware design and improve reliability. The six resonant tanks can achieve the effect of self-voltage balance when connected in series and self-current balance when connected in parallel, which improves reliability and makes the hardware design easier.

[0033] The power expansion device of the three-phase LLC circuit does not make excessive adjustments or modifications to the commonly used LLC half-bridge interleaved topology structure, which is convenient for low-cost manufacturing and implementation, and can also expand the output power at the same time, which is suitable for increasing the output power and realizing a wide range of output. On the other hand, the six resonant tanks can achieve the effect of self-pressure balance when connected in series and self-current balance when connected in parallel, which improves reliability.

[0034] Fig. 4 is a circuit diagram of a third preferred embodiment of the power expansion device used in the three-phase LLC circuit of the present invention. Fig. 4 shows an embodiment in which the inputs of two resonant networks are connected in parallel, and the outputs of two rectifier networks are connected in parallel. Therefore, in the preferred embodiment shown in Fig. 4, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in parallel between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in parallel between the output positive pole Vo+ and the output negative pole Vo-.

[0035] The connection relationship of the embodiment shown in Figure 4 is similar to that of Figure 3, with only the following differences: The drain terminals of switch tubes S11, S21, S51, S61, S91, and S101 are connected to the positive bus bar BUS+, and the source terminals of switch tubes S31, S41, S71, S81, S111, and S121 are connected to the negative bus bar BUS-. The drain terminals of switch tubes S12, S22, S52, S62, S92, and S102 are connected to the positive bus bar BUS+, and the source terminals of switch tubes S32, S42, S72, S82, S112, and S222 are connected to the negative bus bar BUS-. Input capacitors C1 and C2 are connected in series between the positive bus bar BUS+ and the negative bus bar BUS-.

[0036] In the preferred embodiment, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in parallel between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in parallel between the output positive pole Vo+ and the output negative pole Vo-. In the transformer networks 103 and 203, the second end of the secondary side of the transformer T11 is connected to the second end of the secondary side of the transformer T21 and the second end of the secondary side of the transformer T12, and the second end of the secondary side of the transformer T31 is connected to the second end of the secondary side of the transformer T22 and the second end of the secondary side of the transformer T32. By star-connecting the secondary sides of any two transformers in the transformer network 103 with the secondary side of any one transformer in the transformer network 203, it is ensured that the parallel connection of the full-bridge switch network 101 and the full-bridge switch network 201 can achieve current balance, and the parallel connection of the rectifier network 104 and the rectifier network 204 can achieve current balance.

[0037] FIG. 5 is a circuit diagram of a fourth preferred embodiment of the power expansion device for use in a three-phase LLC circuit of the present invention. FIG. 5 shows an embodiment in which the inputs of two resonant networks are connected in parallel, and the outputs of two rectifier networks are connected in series. Therefore, in the preferred embodiment shown in FIG. 5, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in parallel between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in series between the output positive pole Vo+ and the output negative pole Vo-. The specific connection relationship of the inputs can be referred to FIG. 4, and will not be repeated here. The connection relationship of the output part is similar to that of FIG. 3, except that the cathodes of the diodes D11, D21, and D31 are connected to the first end of the output capacitor Co1 of the output positive pole Vo+. The second end of the output capacitor Co1 is connected to the first end of the output capacitor Co2, the anodes of the diodes D41, D51 and D61, and the cathodes of the diodes D12, D22 and D32. The anodes of the diodes D42, D52 and D62 are connected to the output negative terminal Vo- and the second end of the output capacitor Co2.

[0038] In this preferred embodiment, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in parallel between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in series between the output positive pole Vo+ and the output negative pole Vo-. In the transformer networks 103 and 203, the second end of the secondary side of the transformer T11 is connected to the second end of the secondary side of the transformer T21 and the second end of the secondary side of the transformer T12, and the second end of the secondary side of the transformer T31 is connected to the second end of the secondary side of the transformer T22 and the second end of the secondary side of the transformer T32. By star-connecting the secondary sides of any two transformers in the transformer network 103 with the secondary side of any one transformer in the transformer network 203, it is ensured that the parallel connection of the full-bridge switch network 101 and the full-bridge switch network 201 can achieve current balance, and the series connection of the rectifier network 104 and the rectifier network 204 can achieve voltage balance.

[0039] FIG. 6 is a circuit diagram of a fifth preferred embodiment of the power expansion device for use in a three-phase LLC circuit of the present invention. FIG. 6 shows an embodiment in which the inputs of two resonant networks are connected in series, and the outputs of two rectifier networks are connected in series. Therefore, in the preferred embodiment shown in FIG. 6, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in series between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in series between the output positive pole Vo+ and the output negative pole Vo-. The specific connection relationship of the inputs and outputs can be referred to FIG. 3 and FIG. 5, respectively, and will not be repeated here.

[0040] In the preferred embodiment, the full-bridge switch network 101 and the full-bridge switch network 201 are connected in series between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in series between the output positive pole Vo+ and the output negative pole Vo-. In the transformer networks 103 and 203, the second end of the secondary side of the transformer T11 is connected to the second end of the secondary side of the transformer T21 and the second end of the secondary side of the transformer T12, and the second end of the secondary side of the transformer T31 is connected to the second end of the secondary side of the transformer T22 and the second end of the secondary side of the transformer T32. By star-connecting the secondary sides of any two transformers in the transformer network 103 with the secondary side of any one transformer in the transformer network 203, it is ensured that the series connection of the full-bridge switch network 101 and the full-bridge switch network 201 can achieve voltage balance, and the series connection of the rectifier network 104 and the rectifier network 204 can achieve voltage balance.

[0041] FIG. 7 is a circuit diagram of the sixth preferred embodiment of the power expansion device for use in a three-phase LLC circuit of the present invention. In the preferred embodiment shown in FIG. 7, the full-bridge switch network 101 and the full-bridge switch network 201 similar to FIG. 6 are connected in series between the positive busbar BUS+ and the negative busbar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in series between the output positive pole Vo+ and the output negative pole Vo-. This design is the same as the embodiment shown in FIG. 6, except that each transformer unit includes two transformers with their primaries connected in series, that is, the number of transformers is expanded from the original six to twelve. Therefore, the corresponding rectifier units each include four rectifier tubes, that is, the rectifier networks 104 and 204 are each formed by connecting two three-phase bridge rectifier circuits in parallel. That is, the first rectifier unit includes diodes D11, D41, D71, and D101, the second rectifier unit includes diodes D21, D51, D81, and D111, and the third rectifier unit includes diodes D31, D61, D91, and D121. The rectifier network 204 includes a fourth rectifier unit, a fifth rectifier unit, and a sixth rectifier unit, that is, the fourth rectifier unit includes diodes D12, D42, D72, and D102, the second rectifier unit includes diodes D22, D52, D82, and D112, and the third rectifier unit includes diodes D32, D62, D92, and D122.

[0042] As shown in Fig. 7, the transformer network 103 includes transformers T11, T21, T31, T41, T51, T61, T12, T22, T32, T42, T52, and T62. Similar to the embodiment shown in Fig. 6, a first end of a primary side of the transformer T11 is connected to a first end of the first full-bridge switch unit through the first resonant unit, a second end of the primary side is connected to a first end of the primary side of the transformer T21, and a second end of the primary side of the transformer T21 is connected to a second end of the first full-bridge switch unit. The first end of the primary side of the transformer T31 is connected to the first end of the second full-bridge switch unit via the second resonant unit, the second end of the primary side is connected to the first end of the primary side of the transformer T41, and the second end of the primary side of the transformer T41 is connected to the second end of the second full-bridge switch unit. The first end of the primary side of the transformer T51 is connected to the first end of the third full-bridge switch unit via the third resonant unit, the second end of the primary side is connected to the first end of the primary side of the transformer T61, and the second end of the primary side of the transformer T61 is connected to the second end of the third full-bridge switch unit. The first end of the primary side of the transformer T12 is connected to the first end of the fourth full-bridge switch unit via the fourth resonant unit, the second end of the primary side is connected to the first end of the primary side of the transformer T22, and the second end of the primary side of the transformer T22 is connected to the second end of the fourth full-bridge switch unit. The first end of the primary side of the transformer T32 is connected to the first end of the fifth full-bridge switch unit via the fifth resonant unit, the second end of the primary side is connected to the first end of the primary side of the transformer T42, and the second end of the primary side of the transformer T42 is connected to the second end of the fifth full-bridge switch unit. The first end of the primary side of the transformer T52 is connected to the first end of the sixth full-bridge switch unit via the sixth resonant unit, the second end of the primary side is connected to the first end of the primary side of the transformer T62, and the second end of the primary side of the transformer T62 is connected to the second end of the sixth full-bridge switch unit. The structures of the first to sixth full-bridge switch units may refer to the embodiment shown in FIG. 6 and will not be repeated here.

[0043] A first end of the secondary side of the transformer T11 is connected to a first end of the first rectifier unit (i.e., the anode of the diode D11 and the cathode of the diode D41), and a first end of the secondary side of the transformer T21 is connected to a second end of the first rectifier unit (i.e., the anode of the diode D71 and the cathode of the diode D101). A first end of the secondary side of the transformer T31 is connected to a first end of the second rectifier unit (i.e., the anode of the diode D21 and the cathode of the diode D51), and a first end of the secondary side of the transformer T41 is connected to a second end of the second rectifier unit (i.e., the anode of the diode D81 and the cathode of the diode D111). The first end of the secondary side of the transformer T51 is connected to the first end of the fourth rectifier unit (i.e., the anode of the diode D12 and the cathode of the diode D42), the first end of the secondary side of the transformer T61 is connected to the second end of the fourth rectifier unit (i.e., the anode of the diode D7 and the cathode of the diode D102), the first end of the secondary side of the transformer T12 is connected to the first end of the third rectifier unit (i.e., the anode of the diode D31 and the cathode of the diode D61), and the first end of the secondary side of the transformer T22 is connected to the second end of the third rectifier unit (i.e., the anode of the diode D91 and the cathode of the diode D121). A first end of the secondary side of the transformer T32 is connected to a first end of the fifth rectifier unit (i.e., the anode of the diode D22 and the cathode of the diode D52), and a first end of the secondary side of the transformer T42 is connected to a second end of the fifth rectifier unit (i.e., the anode of the diode D82 and the cathode of the diode D112). A first end of the secondary side of the transformer T52 is connected to a first end of the sixth rectifier unit (i.e., the anode of the diode D32 and the cathode of the diode D62), and a first end of the secondary side of the transformer T62 is connected to a second end of the sixth rectifier unit (i.e., the anode of the diode D92 and the cathode of the diode D122).

[0044] The second end of the secondary side of the transformer T11 is connected to the second end of the secondary side of the transformer T31 and the second end of the secondary side of the transformer T12, the second end of the secondary side of the transformer T21 is connected to the second end of the secondary side of the transformer T41 and the second end of the secondary side of the transformer T22, the second end of the secondary side of the transformer T51 is connected to the second end of the secondary side of the transformer T32 and the second end of the secondary side of the transformer T52, and the second end of the secondary side of the transformer T61 is connected to the second end of the secondary side of the transformer T42 and the second end of the secondary side of the transformer T62.

[0045] Similar to the preferred embodiment of FIG. 6, the secondary sides of any two sets of transformers whose primaries are connected in series in the transformer network 103 are star-connected with the secondary sides of any one set of transformers whose primaries are connected in series in the transformer network 203, ensuring that the series connection of the full-bridge switch network 101 and the full-bridge switch network 201 can realize voltage balance, and the series connection of the rectifier network 104 and the rectifier network 204 can achieve voltage balance.

[0046] In a further preferred embodiment of the present invention, as shown in FIG. 3, the circuit can also be designed such that the full-bridge switch network 101 and the full-bridge switch network 201 are connected in series between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in parallel between the output positive pole Vo+ and the output negative pole Vo-, ensuring that the series connection of the full-bridge switch network 101 and the full-bridge switch network 201 can realize voltage balance, and the parallel connection of the rectifier network 104 and the rectifier network 204 can achieve current balance. In a further preferred embodiment of the present invention, as shown in FIG. 4 , the circuit can also be designed such that the full bridge switch network 101 and the full bridge switch network 201 are connected in parallel between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in parallel between the output positive pole Vo+ and the output negative pole Vo-, ensuring that the parallel connection of the full bridge switch network 101 and the full bridge switch network 201 can realize current balance, and the parallel connection of the rectifier network 104 and the rectifier network 204 can achieve current balance. In a further preferred embodiment of the present invention, as shown in FIG. 5 , the circuit can also be designed such that the full bridge switch network 101 and the full bridge switch network 201 are connected in parallel between the positive bus bar BUS+ and the negative bus bar BUS-, and the rectifier network 104 and the rectifier network 204 are connected in series between the output positive pole Vo+ and the output negative pole Vo-; ensuring that the parallel connection of the full bridge switch network 101 and the full bridge switch network 201 can realize current balance, and the series connection of the rectifier network 104 and the rectifier network 204 can achieve voltage balance.

[0047] Based on the teachings of the present invention, those skilled in the art can implement these structures, and they will not be repeated here. Furthermore, this set of embodiments can expand the number of transformers, which is suitable for further expanding the output power, increasing the output power, and achieving a wider output range.

[0048] Although the present invention has been described with reference to specific embodiments, it should be understood by those skilled in the art that various changes and equivalent substitutions can be made to the present invention without departing from the scope of the present invention. In addition, various modifications can be made to the present invention to adapt to particular conditions or materials, without departing from the scope of the present invention. Therefore, it is not intended that the present invention be limited to the specific embodiments disclosed, but it is intended to include all embodiments within the scope of the appended claims.

[0049] The above description is only the preferred embodiment of the present invention, and does not limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. including a first full-bridge switch network, a second full-bridge switch network, a first resonant network, a second resonant network, a first transformer network, a second transformer network, a first rectifier network, and a second rectifier network; a primary side of the first transformer network is in turn connected to an input voltage via the first resonant network and the first full-bridge switch network, and a secondary side is connected to a load via the first rectifier network; a primary side of the second transformer network is in turn connected to the input voltage via the second resonant network and the second full-bridge switch network, and a secondary side is connected to the load via the second rectifier network; the first transformer network includes a first transformer unit, a second transformer unit, and a third transformer unit, and the second transformer network includes a fourth transformer unit, a fifth transformer unit, and a sixth transformer unit; the secondary sides of any two transformer units in the first transformer network are star-connected with the secondary side of any one transformer unit in the second transformer network; The first full-bridge switch network includes a first full-bridge switch unit, a second full-bridge switch unit and a third full-bridge switch unit, the first resonant network includes a first resonant unit, a second resonant unit and a third resonant unit, the first rectifier network includes a first rectifier unit, a second rectifier unit and a third rectifier unit; the second full-bridge switch network includes a fourth full-bridge switch unit, a fifth full-bridge switch unit and a sixth full-bridge switch unit, the second resonant network includes a fourth full-bridge switch unit, a fifth full-bridge switch unit and a sixth full-bridge switch unit, the second rectifier network includes a fourth resonant unit, a fifth resonant unit, and a sixth resonant unit, the second rectifier network includes a fourth rectifier unit, a fifth rectifier unit, and a sixth rectifier unit; the first transformer unit includes a first transformer and a second transformer, the second transformer unit includes a third transformer and a fourth transformer, the third transformer unit includes a fifth transformer and a sixth transformer, the fourth transformer unit includes a seventh transformer and an eighth transformer, the fifth transformer unit includes a ninth transformer and a tenth transformer, and the sixth transformer unit includes an eleventh transformer and a twelfth transformer; a first end of a primary side of the first transformer is connected to a first end of the first full-bridge switch unit through the first resonant unit, a second end of the primary side is connected to a first end of the primary side of the second transformer, a second end of the primary side of the second transformer is connected to a second end of the first full-bridge switch unit, a first end of a primary side of the third transformer is connected to a first end of the second full-bridge switch unit through the second resonant unit, a second end of the primary side is connected to a first end of the primary side of the fourth transformer, a second end of the primary side of the fourth transformer is connected to a second end of the second full-bridge switch unit, a first end of a primary side of the fifth transformer is connected to a first end of the third full-bridge switch unit through the third resonant unit, a second end of the primary side is connected to a first end of the primary side of the sixth transformer, and a second end of the primary side of the sixth transformer is connected to a second end of the third full-bridge switch unit; a first end of a primary side of a seventh transformer is connected to the first end of the fourth full-bridge switch unit through the fourth resonant unit, a second end of the primary side is connected to the first end of the primary side of the eighth transformer, a second end of the primary side of the eighth transformer is connected to the second end of the fourth full-bridge switch unit, a first end of a primary side of a ninth transformer is connected to the first end of the fifth full-bridge switch unit through the fifth resonant unit, a second end of the primary side is connected to the first end of the primary side of the tenth transformer, a second end of the primary side of the tenth transformer is connected to the second end of the fifth full-bridge switch unit, a first end of a primary side of a eleventh transformer is connected to the first end of the sixth full-bridge switch unit through the sixth resonant unit, a second end of the primary side is connected to the first end of the primary side of the twelfth transformer, and a second end of the primary side of the twelfth transformer is connected to the second end of the sixth full-bridge switch unit; A first end of the secondary side of the first transformer is connected to a first end of the first rectifier unit, a first end of the secondary side of the second transformer is connected to a second end of the first rectifier unit, a first end of the secondary side of the third transformer is connected to a first end of the second rectifier unit, a first end of the secondary side of the fourth transformer is connected to a second end of the second rectifier unit, a first end of the secondary side of the fifth transformer is connected to a first end of the fourth rectifier unit, and a first end of the secondary side of the sixth transformer is connected to a second end of the fourth rectifier unit. a first end of a secondary side of the seventh transformer is connected to a first end of the third rectifier unit, a first end of a secondary side of the eighth transformer is connected to a second end of the third rectifier unit, a first end of a secondary side of the ninth transformer is connected to a first end of the fifth rectifier unit, a first end of a secondary side of the tenth transformer is connected to a second end of the fifth rectifier unit, a first end of a secondary side of the eleventh transformer is connected to a first end of the sixth rectifier unit, and a first end of a secondary side of the twelfth transformer is connected to a second end of the sixth rectifier unit; a second end of the secondary side of the first transformer is connected to the second end of the secondary side of the third transformer and the second end of the secondary side of the seventh transformer, a second end of the secondary side of the second transformer is connected to the second end of the secondary side of the fourth transformer and the second end of the secondary side of the eighth transformer, a second end of the secondary side of the fifth transformer is connected to the second end of the secondary side of the ninth transformer and the second end of the secondary side of the eleventh transformer, and a second end of the secondary side of the sixth transformer is connected to the second end of the secondary side of the tenth transformer and the second end of the secondary side of the twelfth transformer.

2. 2. The power expansion device for a three-phase LLC circuit according to claim 1, wherein the first full-bridge switch network and the second full-bridge switch network are connected in series between a first input terminal and a second input terminal; and the first rectifier network and the second rectifier network are connected in parallel between a first output terminal and a second output terminal.

3. 2. The power expansion device for a three-phase LLC circuit according to claim 1, wherein the first full-bridge switch network and the second full-bridge switch network are connected in parallel between a first input terminal and a second input terminal; and the first rectifier network and the second rectifier network are connected in parallel between a first output terminal and a second output terminal.

4. 2. The power expansion device for a three-phase LLC circuit according to claim 1, wherein the first full-bridge switch network and the second full-bridge switch network are connected in parallel between a first input terminal and a second input terminal; and the first rectifier network and the second rectifier network are connected in series between a first output terminal and a second output terminal.

5. 2. The power expansion device for a three-phase LLC circuit according to claim 1, wherein the first full-bridge switch network and the second full-bridge switch network are connected in series between a first input terminal and a second input terminal; and the first rectifier network and the second rectifier network are connected in series between a first output terminal and a second output terminal.

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