Single stage ac / DC resonant converter

Abstract

To provide a single-stage AC / DC resonant converter.SOLUTION: The single-stage AC / DC resonant converter is used for converting a three phase AC power source into a DC power source, and includes a primary side circuit, a resonant circuit and a secondary side circuit. The primary-side circuit includes three sets of primary-side switch circuits, each primary-side switch circuit is connected to an AC power supply of one phase of the three phase AC power supply, and includes a rectifier circuit and a switch circuit. The rectifier circuit includes a rectifier bridge arm and a capacitor connected in parallel with the rectifier bridge arm, and the switch circuit is connected to the capacitor. The resonant circuit includes three sets of transformers, primary-side windings of the transformers are respectively connected to the switch circuits of each primary-side switch circuit, and secondary-side windings of the transformers form a secondary-side common winding. The secondary-side circuit includes a set of secondary-side switch circuits, and the secondary-side switch circuits are connected to the secondary-side common winding.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to AC / DC resonant converters, and more particularly to single-stage AC / DC resonant converters. [Background technology]

[0002] AC / DC converters are essential power conversion devices due to the need to power various electronic devices or charge batteries. Conventional AC / DC converters generally have a two-stage circuit structure, as shown in FIG. 1. Specifically, a conventional AC / DC converter 100A includes an AC / DC conversion circuit 100B, an intermediate capacitor CI, and a DC / DC conversion circuit 100C. The AC / DC conversion circuit 100B converts a single-phase or three-phase AC power source into an intermediate power source and stores the intermediate power source in the intermediate capacitor CI. The DC / DC conversion circuit 100C receives the intermediate power source stored in the intermediate capacitor CI as input power, converts it into output power of a specific voltage level, and supplies (or charges) a load 200 connected downstream.

[0003] On the other hand, when the input power source of the AC / DC converter 100A is a three-phase AC power source, a set of conversion circuits for power conversion is usually required for each phase. For this reason, most three-phase AC / DC converters 100A include three sets of AC / DC conversion circuits 100B, intermediate capacitors CI, and DC / DC conversion circuits 100C. The intermediate capacitors CI are usually used to store large amounts of power, which requires a large amount of installation space. As a result, the overall size of the AC / DC converter 100A becomes excessively large, making it unsuitable for a compact design. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, an important issue for the inventors is how to design a single-stage AC / DC resonant converter using a single-stage circuit structure instead of the conventional two-stage circuit structure. [Means for solving the problem]

[0005] To solve the above problems, the present invention provides a single-stage AC / DC resonant converter that overcomes the problems of the prior art. The single-stage AC / DC resonant converter according to the present invention is used to convert three-phase AC power into DC power, and includes a primary-side circuit, a resonant circuit, and a secondary-side circuit, wherein the primary-side circuit includes three sets of primary-side switch circuits, each of which is connected to one phase of the AC power of the three-phase AC power, and includes a rectifier circuit having a rectifier bridge arm and a capacitor connected in parallel to the rectifier bridge arm, and a switching circuit connected to the capacitor, and the resonant circuit includes three sets of transformers, the primary windings of the three sets of transformers are connected to the switching circuits of the three sets of primary-side switch circuits, respectively, the secondary windings of the three sets of transformers form a secondary-side common winding, and the secondary-side circuit includes one set of secondary-side switch circuits connected to the secondary-side common winding.

[0006] To solve the above problems, the present invention provides a single-stage AC / DC resonant converter that overcomes the problems of the prior art. The single-stage AC / DC resonant converter according to the present invention is used to convert three-phase AC power into DC power, and includes a primary-side circuit, a resonant circuit, and a secondary-side circuit, the primary-side circuit includes three sets of primary-side switch circuits, each of which includes a filter circuit connected to one phase of the AC power of the three-phase AC power and a switching circuit connected to the filter circuit, the resonant circuit includes three sets of transformers, the primary windings of the three sets of transformers are connected to the switching circuits of the three sets of primary-side switch circuits, respectively, the secondary windings of the three sets of transformers form a secondary-side common winding, and the secondary-side circuit includes one set of secondary-side switch circuits connected to the secondary-side common winding.

[0007] To solve the above problems, the present invention provides a single-stage AC / DC resonant converter that overcomes the problems of the prior art. The single-stage AC / DC resonant converter according to the present invention is used to convert three-phase AC power into DC power, and includes a primary-side circuit, a resonant circuit, and a secondary-side circuit, wherein the primary-side circuit includes three sets of primary-side switch circuits, each of which is connected to one phase of the AC power of the three-phase AC power and includes a switching circuit, the resonant circuit includes three sets of transformers, the primary windings of which are connected to the switching circuits of the three sets of primary-side switch circuits, respectively, and the secondary-side circuit includes three sets of secondary-side switch circuits, the input terminals of which are connected to the secondary windings of the three sets of transformers, and the output terminals of which are connected in parallel. [Effects of the Invention]

[0008] The main object and advantage of the present invention is to replace the conventional two-stage circuit with a single-stage circuit, and to use a multiple-switch configuration to convert a three-phase input to an output power supply. Therefore, the single-stage AC / DC resonant converter of the present invention does not require an intermediate energy storage element.

[0009] In order to better understand the techniques, means, and advantages of the present invention which are contemplated to achieve the objects of the present invention, the objects and features of the present invention will be better understood by referring to the detailed description of the invention and the accompanying drawings, which are provided for reference and explanation only and are not intended to limit the invention. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a conventional two-stage AC / DC converter. [Figure 2] 1 is a circuit diagram of a first embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 3] FIG. 4 is a circuit diagram of a second embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 4]FIG. 10 is a circuit diagram of a third embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 5] FIG. 10 is a circuit diagram of a fourth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 6] FIG. 10 is a circuit diagram of a fifth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 7] FIG. 10 is a circuit diagram of a sixth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 8] FIG. 10 is a circuit diagram of a seventh embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 9] FIG. 10 is a circuit diagram of an eighth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 10] FIG. 13 is a circuit diagram of a ninth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 11] FIG. 16 is a circuit diagram of a single-stage AC / DC resonant converter according to a tenth embodiment of the present invention. [Figure 12] FIG. 19 is a circuit diagram of an eleventh embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 13] FIG. 22 is a circuit diagram of a twelfth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 14] FIG. 22 is a circuit diagram of a thirteenth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 15] FIG. 22 is a circuit diagram of a fourteenth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 16] FIG. 22 is a circuit diagram of a fifteenth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 17] FIG. 22 is a circuit diagram of a sixteenth embodiment of a single-stage AC / DC resonant converter according to the present invention. [Figure 18] FIG. 22 is a circuit diagram of a seventeenth embodiment of a single-stage AC / DC resonant converter according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The technical contents and detailed description of the present invention will be explained below with reference to the drawings.

[0012] Unlike the conventional two-stage AC / DC converter shown in FIG. 1, the single-stage AC / DC resonant converter of the present invention does not require an intermediate energy storage element, nor does it require a DC power supply to be converted back to DC to produce an output power supply. Specifically, the single-stage AC / DC resonant converter of the present invention is applicable to a three-phase / single-phase unfolder topology, primarily a matrix converter topology. A matrix converter converts a three-phase input to an output power supply by switching between multiple switches. Similar to a voltage-source and current-source inverter, a matrix converter converts voltage and current in multiple stages. However, the DC link does not have an intermediate energy storage element, and the voltage and current conversion is completed in a single converter stage. Therefore, the capacitors between the three-phase AC power supplies R, Y, and B and the output capacitor Co are primarily used for filtering, not for energy storage. Therefore, the single-stage AC / DC resonant converter can operate in a manner that sequentially processes the three-phase AC power supplies R, Y, and B.

[0013] Please refer to FIG. 2, which shows a circuit diagram of a first embodiment of a single-stage AC / DC resonant converter according to the present invention. Also, please refer to FIG. 1. The single-stage AC / DC resonant converter 100 can employ a circuit configuration using a resonant tank circuit (e.g., but not limited to, LC, CLLC, etc.) consisting of inductors and capacitors, and is particularly suitable for dual active bridge (DAB) and series resonant dual active bridge (SR-DAB) circuit configurations. That is, the single-stage AC / DC resonant converter 100 according to the present invention can process three-phase AC power supplies R, Y, and B in a sequential manner and convert them into a DC power supply Pdc, and the voltage level of the converted DC power supply Pdc is controlled by a controller 6 to be stepped up or down. Note that to avoid excessive complexity of the circuit configuration, the present invention will mainly be described using an SR-DAB configuration as an example. However, other circuit configurations can be inferred based on the configuration disclosed in the present invention and will not be described in detail here.

[0014] Referring to FIG. 2, the single-stage AC / DC resonant converter (hereinafter referred to as resonant converter 100) converts three-phase AC power sources R, Y, and B into DC power source Pdc. The resonant converter 100 includes a primary circuit A, a resonant circuit B, and a secondary circuit C. The primary circuit A includes three sets of primary switch circuits 1, each of which includes a rectifier circuit 2 and a switching circuit 4. The rectifier circuit 2 includes a rectifier bridge arm 22 and a capacitor Cf connected in parallel with the rectifier bridge arm 22. The switching circuit 4 is connected to the capacitor Cf. As mentioned above, the capacitor Cf is not an intermediate energy storage element (i.e., it is not an element that can be used to store large amounts of power like an electrolytic capacitor), and is therefore primarily used for filtering rather than energy storage.

[0015] The resonant circuit B mainly includes three resonant tank circuits and three transformers T. The resonant tank circuits can vary depending on the circuit architecture of the resonant converter 100. Here, the present invention primarily focuses on the SR-DAB circuit architecture, i.e., the resonant tank circuits include a primary-side resonant tank circuit and a secondary-side resonant tank circuit. The primary-side resonant tank circuit includes a series-connected resonant inductor Lr1 and a resonant capacitor Cr1, and the secondary-side resonant tank circuit includes a series-connected resonant inductor Lr2 and a resonant capacitor Cr2. Each transformer T has a primary winding Wp and a secondary winding Ws. The primary winding Wp is connected to the switching circuit 4 of the primary switch circuit 1 via the primary-side resonant tank circuit. When the circuit architecture of the resonant converter 100 is SR-DAB, the secondary winding Ws forms a secondary common winding WCs together with the secondary resonant tank circuit. When the circuit architecture of the resonant converter 100 does not include a secondary resonant tank circuit, the secondary winding Ws forms the secondary common winding WCs. In one embodiment, the turns ratio between the primary winding Wp and the secondary winding Ws is shown as n:1, but this is not limited to this and may be any ratio that can be implemented in the resonant converter 100.

[0016] Unlike the primary side circuit A, the secondary side circuit C includes only one set of secondary side switch circuits 5, which are connected to the secondary side common winding WCs and a load 200. The load 200 may preferably be a battery, particularly, but not limited to, a battery for an electric vehicle. The resonant converter 100 further includes a controller 6, which outputs a control signal Sc to control the primary side circuit A and the secondary side circuit C, converting the voltage and current of the three-phase AC power supplies R, Y, and B into multiple stages and converting them into a DC power supply Pdc.

[0017] Further explanation will be given with reference to Fig. 2. The rectifier circuit 2 includes an inductor L in addition to a rectifier bridge arm 22 and a capacitor Cf connected in parallel to the rectifier bridge arm 22, and the inductor L is also used as a filter. The inductor L of each primary-side switch circuit 1 is connected to one end of an AC power supply Pac of one phase of the three-phase AC power supplies R, Y, and B, and the rectifier bridge arm 22 includes a first rectifier leg 222 and a second rectifier leg 224 connected in parallel to the capacitor Cf. One of the first rectifier leg 222 and the second rectifier leg 224 is connected to the inductor L, and the other of the first rectifier leg 222 and the second rectifier leg 224 is connected to the other end of the AC power supply Pac.

[0018] Specifically, an example will be described in which the first rectifier leg 222 is connected to an inductor L. The first rectifier leg 222 includes a first rectifier switch Qr1 and a second rectifier switch Qr2 connected in series, and a first rectifier node Pr1 is formed between the first rectifier switch Qr1 and the second rectifier switch Qr2. The second rectifier leg 224 also includes a third rectifier switch Qr3 and a fourth rectifier switch Qr4 connected in series, and a second rectifier node Pr2 is formed between the third rectifier switch Qr3 and the fourth rectifier switch Qr4. Therefore, the first rectifier node Pr1 is connected to the other end of the inductor L, and the second rectifier node Pr2 is connected to the neutral terminal N of the three-phase AC power supplies R, Y, and B.

[0019] The switching circuit 4 includes a first switching leg 42 and a second switching leg 44, which are connected in parallel to a capacitor Cf. The first switching leg 42 includes a first changeover switch Q1 and a second changeover switch Q2 connected in series, and a first primary-side node Pp1 is formed between the first changeover switch Q1 and the second changeover switch Q2. The second switching leg 44 includes a third changeover switch Q3 and a fourth changeover switch Q4 connected in series, and a second primary-side node Pp2 is formed between the third changeover switch Q3 and the fourth changeover switch Q4. One of the first primary side node Pp1 and the second primary side node Pp2 is connected to one of the primary side ground terminals Pgnd1, Pgnd2, and Pgnd3 (here, an example in which the first primary side node Pp1 is connected is shown), and the other of the first primary side node Pp1 and the second primary side node Pp2 is connected to the primary side winding Wp of the transformer T. Note that the primary side ground terminals Pgnd1, Pgnd2, and Pgnd3 connected in each primary side switch circuit 1 are different, and each first primary side node Pp1 is connected to a different primary side ground terminal Pgnd1, Pgnd2, and Pgnd3. The connection relationships in each embodiment of the present invention are similar, and detailed description thereof will be omitted hereinafter.

[0020] One end of the primary winding Wp is also connected to one of the primary ground terminals Pgnd1, Pgnd2, and Pgnd3, so that both ends of the primary winding Wp are connected to the first primary node Pp1 and the second primary node Pp2, respectively. The resonant inductor Lr1 and the resonant capacitor Cr1 of the primary resonant tank circuit may be connected between the first primary node Pp1 and one end of the primary winding Wp (FIG. 2 shows this configuration), or between the primary winding Wp and the primary ground terminals Pgnd1, Pgnd2, and Pgnd3. The primary resonant tank circuit may have various other configurations and connection methods (e.g., a configuration in which the resonant inductor Lr1 and the resonant capacitor Cr1 are disposed on both sides of the primary winding Wp), including, but not limited to, a configuration using a single resonant inductor, and detailed descriptions thereof will be omitted here.

[0021] In the secondary side shown in FIG. 2 , each secondary winding Ws is coupled to a primary winding Wp and commonly connected to the same node to form a secondary common winding WCs. Specifically, a first end of each secondary winding Ws is connected to a secondary ground terminal Sgnd, and a second end of each secondary winding Ws is connected to a common node P. The secondary switch circuit 5 includes a first secondary leg 52, a second secondary leg 54, and an output capacitor Co, with the first secondary leg 52 and the second secondary leg 54 connected in parallel to the output capacitor Co. The load 200 is connected to the output capacitor Co to receive power from the DC power source Pdc. The first secondary leg 52 includes a first secondary switch Qs1 and a second secondary switch Qs2 connected in series, with a first secondary node Ps1 being formed between the first secondary switch Qs1 and the second secondary switch Qs2. The second secondary leg 54 includes a third secondary switch Qs3 and a fourth secondary switch Qs4 connected in series, and a second secondary node Ps2 is formed between the third secondary switch Qs3 and the fourth secondary switch Qs4.

[0022] A node P of the secondary winding Ws is connected to one of a first secondary node Ps1 and a second secondary node Ps2 (the first secondary node Ps1 is illustrated here), and the other of the first secondary node Ps1 and the second secondary node Ps2 is connected to a secondary ground terminal Sgnd. Since one end of the secondary winding Ws is also connected to the secondary ground terminal Sgnd, both ends of the secondary winding Ws are connected to the first secondary node Ps1 and the second secondary node Ps2, respectively. The resonant inductor Lr2 and the resonant capacitor Cr2 of the secondary resonant tank circuit can also be arranged in a manner similar to that of the primary resonant tank circuit, and a detailed description thereof will be omitted here.

[0023] Overall, when the controller 6 outputs a control signal Sc, the rectifier bridge arm 22 of the resonant converter 100 can perform full-wave rectification. The rectified power is converted into a DC power supply Pdc at a predetermined voltage level through the switching circuit 4, the resonant circuit B, and the secondary-side circuit C. Furthermore, the resonant converter 100 can also provide a power factor correction (PFC) function by setting and operating the controller 6, thereby improving power conversion efficiency. In one embodiment, the rectifier bridge arm 22 mainly rectifies the AC power supply Pac, and therefore the switching speed (e.g., city power frequency) of its internal switches controlled by the controller 6 is slower than the switching speed (e.g., 400 kHz to 600 kHz) of the switching circuit 4. For this reason, the rectifier bridge arm 22 may be referred to as a "low-speed arm," while the switching legs 42, 44 in the switching circuit 4 may be referred to as "high-speed arms." These terms will be used in the following description, but detailed explanations will be omitted.

[0024] 2, the secondary windings Ws of the transformer T are connected in series in parallel and commonly connected to the same node P, and are connected to a set of secondary switch circuits 5 via this node P. This allows the number of secondary switches to be reduced (at least eight switches can be reduced compared to the case where three sets of conversion circuits are provided separately), thereby reducing power loss in the switches and the number of control signal outputs by the controller 6. Note that, although all of the switches in the present invention are exemplified as metal oxide semiconductor field effect transistors (MOSFETs), the present invention is not limited to this, and any electronic component that can be used as a switch (for example, an insulated gate bipolar transistor, a gallium nitride transistor, etc.) is also within the technical scope of this embodiment.

[0025] Fig. 3 is a circuit diagram of a second embodiment of a single-stage AC / DC resonant converter according to the present invention, and should be referred to in conjunction with Fig. 2. The primary circuit A in Fig. 3 is completely the same as that in Fig. 2, and the configuration and connection method of the primary winding Wp of the transformer T are also the same as those in Fig. 2. The difference between the two is that the configurations of the secondary common winding WCs and the secondary circuit C in Fig. 3 are different from those in Fig. 2. Specifically, the secondary winding Ws in Fig. 3 has a delta-connected structure, and forms a first node P1, a second node P2, and a third node P3 by being connected in this order.

[0026] The secondary switch circuit 5 includes a third secondary leg 56 in addition to the first secondary leg 52 and the second secondary leg 54 shown in FIG. 2. The third secondary leg 56 is connected in parallel to the first secondary leg 52 and includes a fifth secondary switch Qs5 and a sixth secondary switch Qs6 connected in series. A third secondary node Ps3 is formed between the fifth secondary switch Qs5 and the sixth secondary switch Qs6. The first node P1, the second node P2, and the third node P3 are connected to the first secondary node Ps1, the second secondary node Ps2, and the third secondary node Ps3, respectively. The delta-connection structure shown in FIG. 3 can also reduce the number of secondary switches. Furthermore, because the secondary winding Ws is wound as a three-phase winding and mounted on a single magnetic core, a three-phase transformer can be configured. This allows for a smaller three-phase transformer compared to conventional converters using three transformers.

[0027] FIG. 4 is a circuit diagram of a third embodiment of a single-stage AC / DC resonant converter according to the present invention, and should be referred to in conjunction with FIGS. 2 and 3. The primary-side circuit A in FIG. 4 is completely identical to that in FIG. 2, and the configuration and connection method of the primary-side winding Wp of the transformer T are also the same as those in FIG. 2. The configuration of the secondary-side circuit C is the same as that in FIG. 3. The difference between FIG. 4 and FIGS. 2 and 3 is that the configurations of the secondary-side common winding WCs and the secondary-side circuit C are different from those in FIGS. 2 and 3. Specifically, the secondary-side windings Ws in FIG. 4 adopt a Y-connection structure. In this configuration, first ends of the secondary-side windings Ws are connected to the first secondary-side node Ps1, the second secondary-side node Ps2, and the third secondary-side node Ps3 of the switch circuit 5, respectively, and second ends of the secondary-side windings Ws are connected to the common node P, as in FIG. 2. Therefore, the circuit configuration in FIG. 4 also has the effect of reducing the number of secondary-side switches and miniaturizing the three-phase transformer, as in FIG. 3.

[0028] Fig. 5 is a circuit diagram of a fourth embodiment of a single-stage AC / DC resonant converter according to the present invention, and should be referred to in conjunction with Figs. 2 to 4. The rectifier circuit 2 in Fig. 5 is completely the same as that in Fig. 2, except that the secondary-side circuit C includes three sets of secondary-side switch circuits 5, and the configuration of the switching circuit 4 is also different from that in Fig. 2. Specifically, the switching circuit 4 includes a first change-over switch Q1 and a second change-over switch Q2, and one end of the first change-over switch Q1 and the second change-over switch Q2 is connected to one end of a capacitor Cf, and the other end of the capacitor Cf is connected to any one of the primary-side ground terminals Pgnd1, Pgnd2, and Pgnd3.

[0029] Meanwhile, the configuration of resonant circuit B is also different from that shown in FIG. 2. Resonant circuit B in FIG. 5 does not include a resonant tank circuit on the primary side, but includes a secondary-side resonant tank circuit consisting of a resonant inductor Lr2 and a resonant capacitor Cr2 on the secondary side. Specifically, the primary winding Wp of each transformer T includes a first primary winding Wp1 and a second primary winding Wp2 connected in series, and a center tab terminal Pc is formed between the first primary winding Wp1 and the second primary winding Wp2. One end of the first primary winding Wp1 is connected to the other end of the first change-over switch Q1, and one end of the second primary winding Wp2 is connected to the other end of the second change-over switch Q2. Furthermore, the center tab terminal Pc of transformer T is connected to one of the primary ground terminals Pgnd1, Pgnd2, or Pgnd3.

[0030] 5, the configuration of each of the three secondary-side switch circuits 5 is the same as that of FIG. 2, and the input terminal of each secondary-side switch circuit 5 is connected to the secondary-side winding Ws of the transformer T. Specifically, in each secondary-side switch circuit 5, one of the first secondary-side node Ps1 and the second secondary-side node Ps2 (here, the first secondary-side node Ps1 is illustrated) is connected to one end of the corresponding secondary-side winding Ws, and the other of the first secondary-side node Ps1 and the second secondary-side node Ps2 is connected to the secondary-side ground terminal Sgnd. Since one end of the secondary-side winding Ws is also connected to the secondary-side ground terminal Sgnd, both ends of the secondary-side winding Ws are connected to the first secondary-side node Ps1 and the second secondary-side node Ps2, respectively. Furthermore, the resonant inductor Lr2 and the resonant capacitor Cr2 of the secondary-side resonant tank circuit can be arranged in the same manner as in the configuration of the secondary-side resonant tank circuit shown in FIG. 2, and therefore detailed description thereof will be omitted.

[0031] Referring again to FIG. 5, the three sets of secondary-side switch circuits 5 are independent of each other, and their output terminals are connected in parallel to commonly supply power to the load 200. Specifically, one terminal of the output capacitors Co of the three sets of secondary-side switch circuits 5 is commonly connected to form a positive output terminal, and the other terminal of the output capacitors Co is commonly connected to form a negative output terminal. Power is supplied to the load 200 by connecting the load 200 to the positive output terminal and the negative output terminal. As described above, in the configuration of FIG. 5, the switching circuit 4 of each phase is composed of only two switches (i.e., the first change-over switch Q1 and the second change-over switch Q2), so the number of switches in the primary-side switch circuit 1 can be reduced.

[0032] FIG. 6 is a circuit diagram of a fifth embodiment of a single-stage AC / DC resonant converter according to the present invention. Please refer to FIGS. 2 to 5, particularly to FIGS. 3 and 5. The circuit configuration of FIG. 6 is a combination of some of the configurations of FIGS. 2 and 5, and can achieve the effects of each of the configurations described above. Specifically, the primary circuit A of FIG. 6 is similar to the primary circuit A of FIG. 5, and the secondary circuit C is similar to the secondary circuit C of FIG. 2. Furthermore, the primary winding Wp of FIG. 6 also has a central tab structure, as in FIG. 5, and the secondary winding Ws is connected to the common node P, as in FIG. 2. Other detailed configurations and features can be understood by referring to FIGS. 3 and 5, so detailed description will be omitted here.

[0033] FIG. 7 is a circuit diagram of a sixth embodiment of a single-stage AC / DC resonant converter according to the present invention. Please refer to FIGS. 2 to 6, and particularly to FIGS. 3 and 5. FIG. 7 is similar to FIG. 6, and the circuit configuration is a combination of parts of FIGS. 3 and 5, and can similarly achieve the effects described above. The main difference is that the secondary winding Ws adopts a delta-connected structure, similar to FIG. 3. For other detailed configurations and features, please refer to FIGS. 3 and 5.

[0034] Figure 8 is a circuit diagram of a seventh embodiment of a single-stage AC / DC resonant converter according to the present invention; please refer to Figures 2 to 7, and particularly to Figures 4 and 5. Figure 8 is similar to Figure 6, and the circuit configuration is a combination of parts of Figures 4 and 5, and similarly achieves the effects described above. The main difference is that the secondary winding Ws employs a Y-connection structure, as in Figure 4. For other detailed configurations and features, please refer to Figures 4 and 5.

[0035] FIG. 9 is a circuit diagram of an eighth embodiment of a single-stage AC / DC resonant converter according to the present invention, and should be referred to in conjunction with FIGS. 2 to 8. The circuit shown in FIG. 9 is characterized in that the primary-side circuit A has a high-speed arm and a low-speed arm integrally configured, and three pairs of bridge arms (legs) connected in parallel. Specifically, in FIG. 9, the switching circuit 4 in FIG. 2 includes a first switching leg 42 and a second switching leg 44. A rectifier bridge arm 22 is further connected in parallel, forming a circuit in which three pairs of bridge arms are connected in parallel. More specifically, the rectifier bridge arm 22 is connected in parallel to a capacitor Cf, and the rectifier bridge arm 22 includes a first rectifier switch Qr1 and a second rectifier switch Qr2 connected in series. A third primary-side node Pp3 is formed between the first rectifier switch Qr1 and the second rectifier switch Qr2. One end of the first rectifier switch Qr1 is connected to one end of the capacitor Cf, one end of the second rectifier switch Qr2 is connected to the other end of the first rectifier switch Qr1 to form a third primary side node Pp3, and the other end of the second rectifier switch Qr2 is connected to the other end of the capacitor Cf.

[0036] In addition, the switching circuit 4 further includes a first inductor L1 and a second inductor L2. One end of the first inductor L1 is connected to one end of the AC power supply Pac, and the other end of the first inductor L1 is connected to a first primary-side node Pp1. One end of the second inductor L2 is similarly connected to one end of the AC power supply Pac, and the other end of the second inductor L2 is connected to a second primary-side node Pp2. As in FIG. 2, one of the first primary-side node Pp1 and the second primary-side node Pp2 is connected to the primary winding Wp, and the other is connected to primary ground terminals Pgnd1, Pgnd2, and Pgnd3. The third primary-side node Pp3 is connected to the other end of the AC power supply Pac. The circuit configuration in FIG. 9 is based on the configuration of a boost converter and is similar to a totem-pole power factor correction circuit (totem-pole PFC). That is, the primary-side circuit A mainly functions to boost the AC power supply Pac, and also eliminates one set of low-speed bridge arms. The other circuit configurations and effects are the same as those in FIG. 2, so detailed description will be omitted here.

[0037] Fig. 10 is a circuit diagram of a ninth embodiment of a single-stage AC / DC resonant converter according to the present invention. Please refer to Figs. 2 to 9, and particularly to Figs. 3 and 9. The circuit configuration of Fig. 10 is a combination of parts of the configurations of Figs. 3 and 9, and can achieve the effects described above. The main feature is that the secondary winding Ws has a delta-connected structure, similar to Fig. 3. Other detailed configurations and features can be understood by referring to Figs. 3 and 9, so detailed description will be omitted here.

[0038] Fig. 11 is a circuit diagram of a single-stage AC / DC resonant converter according to a tenth embodiment of the present invention. Please refer to Figs. 2 to 10, and particularly to Figs. 4 and 9. The circuit configuration of Fig. 11 is a combination of parts of the configurations of Figs. 4 and 9, and can similarly achieve the effects described above. The main feature is that the secondary winding Ws has a Y-connection structure, similar to Fig. 4. For other detailed configurations and features, please refer to Figs. 4 and 9.

[0039] FIG. 12 is a circuit diagram of an eleventh embodiment of a single-stage AC / DC resonant converter according to the present invention, and should be referred to in conjunction with FIGS. 2 to 11. A feature of FIG. 12 is that the primary-side circuit A does not include a low-speed arm, but instead employs a high-speed arm capable of bidirectional conduction and interruption. The resonant circuit B and secondary-side circuit C are the same as those in FIG. 2. Specifically, each of the three primary-side switch circuits 1 in FIG. 12 includes a filter circuit 3 and a switching circuit 4. The filter circuit 3 is connected to one-phase AC power supply Pac of three-phase AC power supplies R, Y, and B, and the switching circuit 4 is connected to the filter circuit 3 and the primary-side winding Wp. More specifically, the filter circuit 3 includes an inductor L and a capacitor Cf. Similar to FIG. 2, the inductor L and the capacitor Cf are not intermediate energy storage elements (e.g., electrolytic capacitors, etc.) but primarily function as filters.

[0040] More specifically, one end of the inductor L is connected to one end of the AC power supply Pac, and one end of the capacitor Cf is connected to the other end of the inductor L. The other end of the capacitor Cf is connected to the other end of the AC power supply Pac, and the switching circuit 4 is connected in parallel to the capacitor Cf. This switching circuit 4 is similar to that shown in FIG. 2 and includes a first switching leg 42 and a second switching leg 44, but the changeover switches Q1 to Q4 in the two switching legs 42 and 44 are all replaced with switch modules 422 to 444, and each of the switch modules 422 to 444 is configured as a bidirectional switch. Therefore, when both switches of a bidirectional switch are turned off, the current path is completely interrupted. Specifically, the first switching leg 42 includes a first switch module 422 and a second switch module 424 connected in series, and the first switch module 422 and the second switch module 424 each include switches connected in opposite directions (i.e., a configuration in which the polarities of the junction diodes are opposite to each other). Therefore, the first switching leg 42 includes four or more switches. One end of the first switch module 422 and the other end of the second switch module 424 are connected to the filter circuit 3 (more specifically, the first switching leg 42 is connected in parallel to the capacitor Cf), and a first primary-side node Pp1 is formed by the connection point between the other end of the first switch module 422 and one end of the second switch module 424.

[0041] Similarly, the second switching leg 44 includes a third switch module 442 and a fourth switch module 444 connected in series, with the third switch module 442 and the fourth switch module 444 each configured with switches connected in the opposite direction. Therefore, the second switching leg 44 also includes four or more switches. One end of the third switch module 442 and the other end of the fourth switch module 444 are connected to the filter circuit 3 (specifically, the second switching leg 44 is connected in parallel to the capacitor Cf). A second primary-side node Pp2 is formed at the connection point between the other end of the third switch module 442 and one end of the fourth switch module 444. The connection relationship between the first primary-side node Pp1 and the second primary-side node Pp2 is the same as in FIG. 2, with one end connected to one end of the primary-side winding Wp and the other end connected to the other end of the primary-side winding Wp and the primary-side ground terminals Pgnd1, Pgnd2, and Pgnd3. Other detailed connection configurations are also the same as in FIG. 2, and therefore will not be described here.

[0042] In one embodiment, the bidirectional switch may have various configurations with similar functions, in addition to a configuration in which two switch elements are connected in opposite directions in series. Therefore, the configuration of the switch modules 422 to 444 can be appropriately replaced depending on actual requirements. In other words, any type of bidirectional switch with bidirectional conduction / cutoff function should be included in the technical scope of this embodiment. Furthermore, other circuit configurations and connections not explicitly shown in FIG. 12 are the same as those in FIG. 2 and provide similar effects, so detailed description will be omitted here.

[0043] Fig. 13 is a circuit diagram of a twelfth embodiment of a single-stage AC / DC resonant converter according to the present invention. Please refer to Figs. 2 to 12, and particularly to Figs. 3 and 12. The circuit configuration of Fig. 13 is a combination of parts of the configurations of Figs. 3 and 12, and can similarly achieve the effects described above. The main feature is that the secondary winding Ws has a delta-connected structure, similar to Fig. 3. For other detailed configurations and features, please refer to Figs. 3 and 12.

[0044] Fig. 14 is a circuit diagram of a thirteenth embodiment of a single-stage AC / DC resonant converter according to the present invention. Please refer to Figs. 2 to 13, and particularly to Figs. 4 and 12. The circuit configuration of Fig. 14 is a combination of parts of the configurations of Figs. 4 and 12, and can similarly achieve the effects described above. The main feature is that the secondary winding Ws has a Y-connection structure, similar to Fig. 4. For other detailed configurations and features, please refer to Figs. 4 and 12.

[0045] FIG. 15 is a circuit diagram of a fourteenth embodiment of a single-stage AC / DC resonant converter according to the present invention, and should be referred to in conjunction with FIGS. 2 to 14. The secondary-side circuit C in FIG. 15 is completely identical to that in FIG. 5, and the filter circuit 3 is completely identical to that in FIG. 12. The difference lies in the configuration of the switching circuit 4. Specifically, the switching circuit 4 in FIG. 15 is similar to that in FIG. 5, but the first changeover switch Q1 and the second changeover switch Q2 are replaced with a first switch module 422 and a second switch module 424, respectively. Furthermore, the first switch module 422 and the second switch module 424 are both bidirectional switches, and have a configuration in which switch elements are connected in series with opposite polarities (i.e., a configuration in which the polarities of the connected diodes are opposite to each other). Note that the bidirectional switch is not limited to a configuration in which two switch elements are connected in series in opposite directions, and multiple other configurations having similar functions may exist, and therefore detailed description thereof will be omitted here.

[0046] More specifically, one end of the first switch module 422 and the second switch module 424 is connected to the filter circuit 3 (specifically, one end of the capacitor Cf is connected to one end of the capacitor Cf, and the other end of the capacitor Cf is connected to one end of the first primary winding Wp1 and the second primary winding Wp2, respectively). Note that other connection relationships and obtained effects are clear with reference to Figures 5 and 12, so detailed description will be omitted here.

[0047] Figures 16, 17, and 18 are circuit diagrams of fifteenth to seventeenth embodiments of the single-stage AC / DC resonant converter according to the present invention, and reference should be made to Figures 2 to 14, and particularly to Figures 2 to 4 and 15. The circuit configurations of Figures 16, 17, and 18 are combinations of partial configurations of Figures 2 and 15, Figures 3 and 15, and Figures 4 and 15, respectively, and can achieve the effects described above. Other detailed configurations and features can be understood by referring to Figures 2 to 4 and 15, so detailed description will be omitted here.

[0048] Although the preferred specific embodiments of the present invention have been described in detail and illustrated with drawings, the features of the present invention are not limited to these, and are not intended to limit the present invention. The technical scope of the present invention should be defined by the claims set forth below, and any changes or modifications that conform to the spirit of or similar to those set forth in the claims are also intended to be encompassed within the technical scope of the present invention. Various changes, modifications, variations, etc. that can be easily thought of by those skilled in the art based on the disclosure of the present invention are also included within the scope of the present invention. [Explanation of symbols]

[0049] 100A AC / DC converter 100B AC / DC conversion circuit CI Intermediate Capacitor 100C DC / DC conversion circuit 100 Resonant Converter A Primary circuit 1 Primary side switch circuit 2 Rectifier circuit L inductor Cf capacitor 22 Bridge Arm 222 First Rectification Leg Qr1 First rectifier switch Qr2 Second rectifier switch 224 Second Rectification Leg Qr3 Third rectifier switch Qr4 4th rectifier switch 3. Filter Circuit 4 Switching circuit L1 First inductor L2 Second inductor 42 First Switch Leg Q1 First changeover switch Q2 Second changeover switch 422 First Switch Module 424 Second Switch Module 44 Second Switch Leg Q3 Third switch Q4 4th changeover switch 442 Third Switch Module 444 4th Switch Module Pgnd1, Pgnd2, Pgnd3 Primary side ground terminal B resonant circuit Lr1, Lr2 resonant inductors Cr1, Cr2 resonant capacitors T transformer Wp primary winding Wp1 1st primary winding Wp2 Second primary winding PC center tab terminal Ws Secondary winding WCs Secondary common winding C Secondary circuit 5 Secondary side switch circuit 52 1st Secondary Leg Qs1 1st secondary switch Qs2 Secondary side switch 54 Secondary Leg Qs3 Third secondary switch Qs4 4th secondary switch 56 Third Secondary Leg Qs5 5th secondary switch Qs6 6th secondary switch Co Output Capacitor Sgnd Secondary ground terminal P-node P1 First node P2 Second node P3 Third node Pr1 First rectifier node Pr2 Second rectifier node Pp1 First primary node Pp2 Second primary node Pp3 Third primary node Ps1 First secondary node Ps2 Secondary node Ps3 Third secondary node 6 Controller 200 load R, Y, B three-phase AC power supply Pack AC power supply N Neutral terminal Pdc AC power supply Sc control signal

Claims

1. 1. A single-stage AC / DC resonant converter for converting three-phase AC power into DC power, comprising: The single-stage AC / DC resonant converter includes a primary side circuit, a resonant circuit, and a secondary side circuit; the primary side circuit includes three sets of primary side switch circuits; Each of the three sets of primary-side switch circuits is connected to one phase of the AC power supply of the three-phase AC power supply, and includes a rectifier circuit including a rectifier bridge arm and a capacitor connected in parallel to the rectifier bridge arm, and a switching circuit connected to the capacitor; The resonant circuit includes three transformers; the primary windings of the three transformers are respectively connected to the switching circuits of the three primary switch circuits, and the secondary windings of the three transformers form a secondary common winding; The single-stage AC / DC resonant converter, wherein the secondary circuit includes a set of secondary switch circuits connected to the secondary common winding.

2. the secondary-side switch circuit includes a first secondary-side leg and a second secondary-side leg; the first secondary leg includes a first secondary switch and a second secondary switch connected in series, and a first secondary node is formed between the first secondary switch and the second secondary switch; the second secondary leg is connected in parallel to the first secondary leg and includes a third secondary switch and a fourth secondary switch connected in series, and a second secondary node is formed between the third secondary switch and the fourth secondary switch; 2. The single-stage AC / DC resonant converter of claim 1, wherein first ends of secondary windings of the three sets of transformers are connected to a secondary ground terminal, and second ends of secondary windings of the three sets of transformers are commonly connected to a same node, the node being connected to one of the first secondary node and the second secondary node, and the other of the first secondary node and the second secondary node being connected to a secondary ground terminal.

3. the secondary-side switch circuit includes a first secondary-side leg, a second secondary-side leg, and a third secondary-side leg; the first secondary leg includes a first secondary switch and a second secondary switch connected in series, and a first secondary node between the first secondary switch and the second secondary switch; the second secondary leg is connected in parallel to the first secondary leg, includes a third secondary switch and a fourth secondary switch connected in series, and includes a second secondary node between the third secondary switch and the fourth secondary switch; the third secondary leg is connected in parallel with the first secondary leg, includes a fifth secondary switch and a sixth secondary switch connected in series, and includes a third secondary node between the fifth secondary switch and the sixth secondary switch; 2. The single-stage AC / DC resonant converter of claim 1, wherein first ends of secondary windings of the three sets of transformers are connected to the first secondary node, the second secondary node, and the third secondary node, respectively, and second ends of secondary windings of the three sets of transformers are commonly connected to the same node.

4. the secondary-side switch circuit includes a first secondary-side leg, a second secondary-side leg, and a third secondary-side leg; the first secondary leg includes a first secondary switch and a second secondary switch connected in series, and a first secondary node is formed between the first secondary switch and the second secondary switch; the second secondary leg is connected in parallel to the first secondary leg and includes a third secondary switch and a fourth secondary switch connected in series, and a second secondary node is formed between the third secondary switch and the fourth secondary switch; the third secondary leg is connected in parallel to the first secondary leg and includes a fifth secondary switch and a sixth secondary switch connected in series, and a third secondary node is formed between the fifth secondary switch and the sixth secondary switch; 2. The single-stage AC / DC resonant converter of claim 1, wherein secondary windings of the three sets of transformers are delta-connected to form first, second, and third nodes, and the first, second, and third nodes are connected to the first secondary node, the second secondary node, and the third secondary node, respectively.

5. the rectifier circuit further includes an inductor connected to one end of the AC power supply of one phase; 2. The single-stage AC / DC resonant converter according to claim 1, wherein the rectifier bridge arm includes a first rectifier leg and a second rectifier leg connected in parallel to the capacitor, the first rectifier leg being connected to the inductor, and the second rectifier leg being connected to the other end of the one phase of the AC power supply.

6. The switching circuit a first changeover switch having one end connected to one end of the capacitor and the other end connected to a primary-side ground terminal; a second changeover switch having one end connected to one end of the capacitor; 2. The single-stage AC / DC resonant converter of claim 1, wherein the primary winding of each transformer includes a first primary winding and a second primary winding connected in series, a center tab terminal is formed between the first primary winding and the second primary winding, one end of the first primary winding is connected to the other end of the first transfer switch, one end of the second primary winding is connected to the other end of the second transfer switch, and the center tab terminal is connected to the primary ground terminal.

7. the switching circuit includes a first switching leg and a second switching leg; the first switching leg is connected in parallel with the capacitor and includes a first changeover switch and a second changeover switch connected in series, and a first primary-side node is formed between the first changeover switch and the second changeover switch; the second switching leg is connected in parallel with the capacitor and includes a third changeover switch and a fourth changeover switch connected in series, a second primary side node is formed between the third changeover switch and the fourth changeover switch, 2. The single-stage AC / DC resonant converter of claim 1, wherein one of the first primary side node and the second primary side node is connected to a primary side ground terminal, and the other of the first primary side node and the second primary side node is connected to a primary side winding of one of the three sets of transformers.

8. the rectifying bridge arm is connected in parallel with the capacitor; a first rectifier switch having one end connected to one end of the capacitor; a second rectifier switch having one end connected to the other end of the first rectifier switch to form a third primary side node and the other end connected to the other end of the capacitor; The switching circuit a first inductor having one end connected to one end of the AC power supply of one phase and the other end connected to the first primary side node; a second inductor having one end connected to one end of the AC power supply of one phase and the other end connected to the second primary side node; 8. The single-stage AC / DC resonant converter of claim 7, wherein the third primary node is connected to the other end of the one phase of the AC power supply.

9. 1. A single-stage AC / DC resonant converter for converting three-phase AC power into DC power, comprising: The single-stage AC / DC resonant converter includes a primary side circuit, a resonant circuit, and a secondary side circuit; the primary side circuit includes three sets of primary side switch circuits; each of the three sets of primary-side switch circuits includes a filter circuit connected to one phase of the AC power supply of the three-phase AC power supply, and a switching circuit connected to the filter circuit; The resonant circuit includes three transformers; the primary windings of the three transformers are respectively connected to the switching circuits of the three primary switch circuits, and the secondary windings of the three transformers form a secondary common winding; The single-stage AC / DC resonant converter, wherein the secondary circuit includes a set of secondary switch circuits connected to the secondary common winding.

10. the secondary-side switch circuit includes a first secondary-side leg and a second secondary-side leg; the first secondary leg includes a first secondary switch and a second secondary switch connected in series, and a first secondary node is formed between the first secondary switch and the second secondary switch; the second secondary leg is connected in parallel to the first secondary leg and includes a third secondary switch and a fourth secondary switch connected in series, and a second secondary node is formed between the third secondary switch and the fourth secondary switch; 10. The single-stage AC / DC resonant converter of claim 9, wherein first ends of secondary windings of the three sets of transformers are connected to a secondary ground terminal, and second ends of secondary windings of the three sets of transformers are commonly connected to a same node, the node being connected to one of the first secondary node and the second secondary node, and the other of the first secondary node and the second secondary node being connected to a secondary ground terminal.

11. the secondary-side switch circuit includes a first secondary-side leg, a second secondary-side leg, and a third secondary-side leg; the first secondary leg includes a first secondary switch and a second secondary switch connected in series, and a first secondary node between the first secondary switch and the second secondary switch; the second secondary leg is connected in parallel to the first secondary leg, includes a third secondary switch and a fourth secondary switch connected in series, and includes a second secondary node between the third secondary switch and the fourth secondary switch; the third secondary leg is connected in parallel with the first secondary leg, includes a fifth secondary switch and a sixth secondary switch connected in series, and includes a third secondary node between the fifth secondary switch and the sixth secondary switch; 10. The single-stage AC / DC resonant converter of claim 9, wherein first ends of secondary windings of the three sets of transformers are connected to the first secondary node, the second secondary node, and the third secondary node, respectively, and second ends of secondary windings of the three sets of transformers are commonly connected to the same node.

12. the secondary-side switch circuit includes a first secondary-side leg, a second secondary-side leg, and a third secondary-side leg; the first secondary leg includes a first secondary switch and a second secondary switch connected in series, and a first secondary node is formed between the first secondary switch and the second secondary switch; the second secondary leg is connected in parallel to the first secondary leg and includes a third secondary switch and a fourth secondary switch connected in series, and a second secondary node is formed between the third secondary switch and the fourth secondary switch; the third secondary leg is connected in parallel to the first secondary leg and includes a fifth secondary switch and a sixth secondary switch connected in series, and a third secondary node is formed between the fifth secondary switch and the sixth secondary switch; 10. The single-stage AC / DC resonant converter of claim 9, wherein secondary windings of the three sets of transformers are delta-connected to form first, second, and third nodes, and the first, second, and third nodes are connected to the first secondary node, the second secondary node, and the third secondary node, respectively.

13. The filter circuit comprises: an inductor having one end connected to one end of the AC power supply of one phase; a capacitor having one end connected to the other end of the inductor and the other end connected to the other end of the AC power supply for one phase, 10. The single-stage AC / DC resonant converter of claim 9, wherein the switching circuit is connected in parallel with the capacitor.

14. the switching circuit includes a first switching leg and a second switching leg; the first switching leg includes a first switch module and a second switch module connected in series, one end of the first switch module and the other end of the second switch module are connected to the filter circuit, and the other end of the first switch module is connected to one end of the second switch module to form a first primary side node; the second switching leg is connected in parallel to the first switching leg and includes a third switch module and a fourth switch module connected in series, one end of the third switch module and the other end of the fourth switch module are connected to the filter circuit, and the other end of the third switch module is connected to one end of the fourth switch module to form a second primary side node; 10. The single-stage AC / DC resonant converter of claim 9, wherein one of the first primary side node and the second primary side node is connected to one end of a primary side winding, and the other of the first primary side node and the second primary side node is connected to the other end of the primary side winding and a primary side ground terminal.

15. The switching circuit a first switch module having one end connected to the filter circuit; a second switch module having one end connected to the filter circuit; 10. The single-stage AC / DC resonant converter of claim 9, wherein the primary winding of each transformer includes a first primary winding and a second primary winding connected in series, a center tab terminal is formed between the first primary winding and the second primary winding, one end of the first primary winding is connected to the other end of the first switch module, one end of the second primary winding is connected to the other end of the second switch module, and the center tab terminal is connected to a primary ground terminal.

16. 1. A single-stage AC / DC resonant converter for converting three-phase AC power into DC power, comprising: The single-stage AC / DC resonant converter includes a primary side circuit, a resonant circuit, and a secondary side circuit; the primary side circuit includes three sets of primary side switch circuits, each of which is connected to one phase of the AC power supply of the three-phase AC power supply and includes a switching circuit; the resonant circuit includes three transformers, primary windings of the three transformers are connected to switching circuits of the three primary switch circuits, respectively; the secondary-side circuit includes three sets of secondary-side switch circuits, input terminals of the three sets of secondary-side switch circuits are connected to secondary-side windings of the three sets of transformers, and output terminals of the three sets of secondary-side switch circuits are connected in parallel.

17. each of the three sets of secondary-side switch circuits includes a first secondary-side leg and a second secondary-side leg; the first secondary leg includes a first secondary switch and a second secondary switch connected in series, and a first secondary node is formed between the first secondary switch and the second secondary switch; the second secondary leg is connected in parallel to the first secondary leg and includes a third secondary switch and a fourth secondary switch connected in series, and a second secondary node is formed between the third secondary switch and the fourth secondary switch; 17. The single-stage AC / DC resonant converter of claim 16, wherein one of the first secondary node and the second secondary node is connected to a secondary winding of one of the three sets of transformers, and the other of the first secondary node and the second secondary node is connected to a secondary ground terminal.

18. Each of the three sets of primary side switch circuits comprises: a rectifier circuit including a rectifier bridge arm and a capacitor connected in parallel to the rectifier bridge arm; an inductor connected to one end of the AC power supply of one phase; a first switch module having one end connected to the capacitor; a second switch module having one end connected to the capacitor; 17. The single-stage AC / DC resonant converter of claim 16, wherein the primary winding of each transformer includes a first primary winding and a second primary winding connected in series, a center tab terminal is formed between the first primary winding and the second primary winding, one end of the first primary winding is connected to the other end of the first switch module, one end of the second primary winding is connected to the other end of the second switch module, and the center tab terminal is connected to a primary ground terminal.

19. each of the three sets of primary-side switch circuits further includes a filter circuit; the filter circuit includes an inductor and a capacitor, one end of the inductor and the other end of the capacitor are connected to both ends of the AC power supply of one phase, respectively, and the other end of the inductor is connected to one end of the capacitor; 17. The single-stage AC / DC resonant converter of claim 16, wherein one end of the capacitor is connected to the switching circuit and the other end of the capacitor is connected to a primary side ground terminal.

20. The switching circuit a first switch module having one end connected to the capacitor; a second switch module having one end connected to the capacitor; 20. The single-stage AC / DC resonant converter of claim 19, wherein the primary winding of each transformer includes a first primary winding and a second primary winding connected in series, a center tab terminal is formed between the first primary winding and the second primary winding, one end of the first primary winding is connected to the other end of the first switch module, one end of the second primary winding is connected to the other end of the second switch module, and the center tab terminal is connected to a primary ground terminal.

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