TWI913014B - Single-stage ac-dc resonant converter - Google Patents

Abstract

A single-stage AC-DC resonant converter is used to convert three-phase AC power into DC power, and 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 primary-side switch circuits, and the primary-side switch circuits are respectively coupled to one of the three-phase AC power. The resonant circuit includes three transformers. Primary-side windings of the transformers are respectively coupled to the primary-side switch circuits, and secondary-side windings of the transformers are coupled to the secondary-side circuit.

Description

Single-stage AC/DC resonant converter

This invention relates to an AC/DC resonant converter, and more particularly to a single-stage AC/DC resonant converter.

Due to the power supply and battery charging needs of various electronic devices, AC/DC converters have always been indispensable power conversion devices. Traditional AC/DC converters, as shown in Figure 1, are typically two-stage circuit structures. Specifically, a traditional 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 single-phase or three-phase AC power into an intermediate power source and stores the intermediate power in the intermediate capacitor CI. The DC/DC conversion circuit 100C uses the intermediate power stored in the intermediate capacitor CI as an input source and converts it into an output power source with a specific voltage level to power (or charge) the load 200 coupled to the downstream end.

On the other hand, if the input power of the AC/DC converter 100A is a three-phase AC power supply, each phase usually requires a complete set of conversion circuits for power conversion. Therefore, most three-phase AC/DC converters 100A include three sets of AC/DC conversion circuits 100B, an intermediate capacitor CI, and a DC/DC conversion circuit 100C. Since the intermediate capacitor CI is generally used to store a large amount of power and requires a large configuration space, the size of the AC/DC converter 100A will be too large, which is not conducive to miniaturization design.

Therefore, how to design a single-stage AC/DC resonant converter, using a single-stage circuit structure to replace the traditional two-stage circuit structure, is a major research topic that the creators of this project intend to undertake.

To address the aforementioned problems, this disclosure provides a single-stage AC/DC resonant converter to overcome the limitations of the prior art. Therefore, the single-stage AC/DC resonant converter disclosed herein is used to convert a three-phase AC power supply to a DC power supply, and 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 switching circuits, each of which is coupled to one phase of the three-phase AC power supply. Each primary-side switching circuit includes a rectifier circuit and a switching circuit. The rectifier circuit includes rectifier bridge arms and capacitors connected in parallel with the rectifier bridge arms, and the switching circuit is coupled with capacitors. The resonant circuit includes three transformers. The primary windings of the transformers are respectively coupled to the switching circuits of the primary-side switching circuit, and the secondary windings of the transformers form a common secondary winding. The secondary circuit includes a set of secondary-side switching circuits, and the secondary-side switching circuits are coupled to the common secondary winding.

To address the aforementioned problems, this disclosure provides a single-stage AC/DC resonant converter to overcome the limitations of the prior art. Therefore, the single-stage AC/DC resonant converter disclosed herein is used to convert a three-phase AC power supply to a DC power supply, and 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 switching circuits, and each primary-side switching circuit includes a filtering circuit and a switching circuit. The filtering circuit is coupled to one phase of the three-phase AC power supply, and the switching circuit is coupled to the filtering circuit. The resonant circuit includes three transformers. The primary windings of the transformers are respectively coupled to the switching circuits of the primary-side switching circuit, and the secondary windings of the transformers form a common secondary winding. The secondary circuit includes a set of secondary-side switching circuits, and the secondary-side switching circuits are coupled to the common secondary winding.

To address the aforementioned problems, this disclosure provides a single-stage AC/DC resonant converter to overcome the limitations of the prior art. Therefore, the single-stage AC/DC resonant converter disclosed herein is used to convert a three-phase AC power supply to a DC power supply, and 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 switching circuits, each of which is coupled to one phase of the three-phase AC power supply, and each primary-side switching circuit includes a switching circuit. The resonant circuit includes three transformers, the primary-side windings of which are respectively coupled to the switching circuits of the primary-side switching circuits. The secondary circuit includes three sets of secondary switching circuits. The input terminals of the secondary switching circuits are coupled to the secondary windings of the transformer, and the output terminals of the secondary switching circuits are coupled in parallel.

The main purpose and effect of this disclosure is that, since the single-stage AC/DC resonant converter disclosed herein uses a single-stage circuit structure to replace the traditional two-stage circuit structure, and the method of converting three-phase input to output power mainly uses multiple switches for switching, the single-stage AC/DC resonant converter disclosed herein does not require intermediate energy storage elements.

To gain a further understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in depth and in detail from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit this invention.

The technical content and detailed description of this invention are explained below with reference to the drawings:

The single-stage AC/DC resonant converter disclosed herein differs from the conventional two-stage AC/DC converter shown in Figure 1, which requires an intermediate energy storage element to store energy as DC power before converting the DC power into an output power. Specifically, the single-stage AC/DC resonant converter disclosed herein is suitable for three-phase/single-phase unfolder topology, primarily for matrix converter topology applications. Matrix converters for converting three-phase input to output power mainly use multiple switches for switching. In a DC-DC converter, similar to a voltage and current source inverter, the matrix converter handles voltage and current conversion in several stages. However, since there are no intermediate energy storage components, the voltage and current conversion can be completed in a single stage. Therefore, the capacitor between the three-phase AC power supply R, Y, B and the output capacitor Co is primarily used for filtering, not energy storage. Thus, a single-stage AC-DC resonant converter can process the three-phase AC power supply R, Y, B phase by phase.

Please refer to Figure 2, which is a circuit diagram of a first embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figure 1. The single-stage AC/DC resonant converter 100 can use a circuit architecture consisting of resonant slots composed of inductors and capacitors (e.g., but not limited to LC, CLLC, etc.), and is particularly suitable for using dual-active-bridge (DAB) and series resonant dual-active-bridge (SR DAB) circuit architectures. That is, the single-stage AC/DC resonant converter 100 disclosed herein can convert a three-phase AC power supply R, Y, B into a DC power supply Pdc in a phase-by-phase manner, and the voltage level of the converted DC power supply Pdc can be set and adjusted up or down by the controller 6. On the other hand, in order to avoid the circuit structure being too complicated, this disclosure mainly focuses on the circuit architecture of series resonant dual active bridge (SR DAB). Other circuit architectures can be deduced from the circuit structure shown in this disclosure and will not be described in detail.

Referring again to Figure 2, a single-stage AC/DC resonant converter (hereinafter referred to as resonant converter 100) is used to convert a three-phase AC power supply R, Y, B into a DC power supply Pdc. The resonant converter 100 includes a primary-side circuit A, a resonant circuit B, and a secondary-side circuit C. The primary-side circuit A includes three sets of primary-side switching circuits 1, and each set of primary-side switching circuits 1 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, and the switching circuit 4 is coupled to the capacitor Cf. As mentioned earlier, capacitor Cf is not an intermediate energy storage element (i.e., it is not an electrolytic capacitor or other element that can store large amounts of electrical energy), so it is mainly used for filtering rather than storing energy.

The resonant circuit B mainly includes three sets of resonant slots and three sets of transformers T, and the resonant slots may vary depending on the circuit architecture of the resonant converter 100. This disclosure primarily focuses on the circuit architecture of the SR DAB, where the resonant slots include primary-side resonant slots and secondary-side resonant slots. The primary-side resonant slots include a resonant inductor Lr1 and a resonant capacitor Cr1 connected in series, and the secondary-side resonant slots include a resonant inductor Lr2 and a resonant capacitor Cr2 connected in series. Each transformer T includes a primary winding Wp and a secondary winding Ws, and the primary winding Wp is coupled to the switching circuit 4 of the primary-side switching circuit 1 through the primary-side resonant slot. When the circuit architecture of the resonant converter 100 is an SR DAB circuit architecture, the secondary winding Ws and the secondary resonant slot form a secondary common winding WCs, and when the circuit architecture of the resonant converter 100 does not have a secondary resonant slot, the secondary winding Ws forms a secondary common winding WCs. It is worth mentioning that in one embodiment, the turns ratio of the primary winding Wp to the secondary winding Ws is indicated by n:1, but it is not limited to this and can be any ratio that can be implemented in the resonant converter 100.

The secondary circuit C differs from the primary circuit A, comprising only a secondary switching circuit 5, which is coupled to the secondary winding WCs and the load 200. The load 200 is preferably a battery, particularly for electric vehicles, but is not limited thereto. The resonant converter 100 also includes a controller 6, which provides a control signal Sc to control the primary circuit A and the secondary circuit C, converting the three-phase AC power supply R, Y, and B into a DC power supply Pdc by dividing it into several stages for voltage and current conversion.

Furthermore, referring to Figure 2, the rectifier circuit 2 includes not only the rectifier bridge arm 22 and the capacitor Cf connected in parallel with the rectifier bridge arm 22, but also an inductor L, which is also used for filtering. The inductor L of each primary-side switching circuit 1 is coupled to one end of one phase of the three-phase AC power supply Pac (R, Y, B), and the rectifier bridge arm 22 includes a first rectifier bridge arm 222 and a second rectifier bridge arm 224 connected in parallel with the capacitor Cf. One of the first rectifier bridge arm 222 and the second rectifier bridge arm 224 is coupled to the inductor L, and the other of the first rectifier bridge arm 222 and the second rectifier bridge arm 224 is coupled to the other end of the AC power supply Pac.

Specifically, taking the first rectifier bridge arm 222 coupled to the inductor L as an example, the first rectifier bridge arm 222 may include 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 bridge arm 224 may also include 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 coupled to the other end of the inductor L, and the second rectifier node Pr2 is coupled to the neutral terminal N of the three-phase AC power supply R, Y, B.

The switching circuit 4 includes a first switching bridge arm 42 and a second switching bridge arm 44, and a capacitor Cf is connected in parallel between the first switching bridge arm 42 and the second switching bridge arm 44. The first switching bridge arm 42 may include a first switching switch Q1 and a second switching switch Q2 connected in series, and a first primary-side node Pp1 is formed between the first switching switch Q1 and the second switching switch Q2. The second switching bridge arm 44 may include a third switching switch Q3 and a fourth switching switch Q4 connected in series, and a second primary-side node Pp2 is formed between the third switching switch Q3 and the fourth switching switch Q4. One of the first primary-side node Pp1 and the second primary-side node Pp2 is coupled to the primary-side grounding terminals Pgnd1, Pgnd2, and Pgnd3 (here, the first primary-side node Pp1 is used as an example), and the other of the first primary-side node Pp1 and the second primary-side node Pp2 is coupled to the primary-side winding Wp of the transformer T. The primary-side grounding terminals Pgnd1, Pgnd2, and Pgnd3 coupled to each set of primary-side switching circuits 1 are different; therefore, each first primary-side node Pp1 is coupled to a different primary-side grounding terminal Pgnd1, Pgnd2, and Pgnd3. The coupling relationships in the various embodiments described below are the same and will not be elaborated further here.

Since one end of the primary winding Wp is also coupled to the primary ground terminals Pgnd1, Pgnd2, and Pgnd3, the two ends of the primary winding Wp are respectively coupled to the first primary node Pp1 and the second primary node Pp2. Furthermore, the resonant inductance Lr1 and resonant capacitor Cr1 of the primary resonant slot can be coupled between the first primary node Pp1 and one end of the primary winding Wp (Figure 2 illustrates this structure), or coupled between the primary winding Wp and the primary ground terminals Pgnd1, Pgnd2, and Pgnd3. In addition, there are many other structures for the primary side resonant slot (such as, but not limited to, a single resonant inductor) and feasible coupling methods (such as, but not limited to, coupling methods where the resonant inductor Lr1 and the resonant capacitor Cr1 are respectively configured on both sides of the primary side winding Wp), which will not be described in detail here.

On the secondary side of Figure 2, the secondary-side windings Ws are respectively coupled to the primary-side windings Wp, and are connected to the same node to form a structure of shared secondary-side windings WCs. Specifically, the first end of each secondary-side winding Ws is coupled to the secondary-side ground terminal Sgnd, and the second end of each secondary-side winding Ws is commonly coupled to a node P. The secondary-side switching circuit 5 includes a primary-side bridge arm 52, a secondary-side bridge arm 54, and an output capacitor Co, with the primary-side bridge arm 52 and the secondary-side bridge arm 54 connected in parallel with the output capacitor Co. Furthermore, the load 200 can receive DC power Pdc through the coupling with the output capacitor Co. The first-stage side bridge arm 52 includes a first-stage side switch Qs1 and a second-stage side switch Qs2 connected in series, and a first-stage side node Ps1 is formed between the first-stage side switch Qs1 and the second-stage side switch Qs2. The second-stage side bridge arm 54 includes a third-stage side switch Qs3 and a fourth-stage side switch Qs4 connected in series, and a second-stage side node Ps2 is formed between the third-stage side switch Qs3 and the fourth-stage side switch Qs4.

Node P of the secondary winding Ws is coupled to one of the primary winding node Ps1 and the secondary winding node Ps2 (illustrated here as primary winding node Ps1), and the other of primary winding node Ps1 and secondary winding node Ps2 is coupled to the secondary ground terminal Sgnd. Since one end of the secondary winding Ws is also coupled to the secondary ground terminal Sgnd, the two ends of the secondary winding Ws are coupled to primary winding node Ps1 and secondary winding node Ps2 respectively. Furthermore, the resonant inductance Lr2 and resonant capacitor Cr2 of the secondary resonant slot can be configured similarly to those of the primary resonant slot, and will not be described in detail here.

In summary, the controller 6 provides a control signal Sc, enabling the rectifier arm 22 of the resonant converter 100 to perform full-wave rectification. The rectified power is then converted into a DC power supply Pdc of a specific level through the switching circuit 4, the resonant circuit B, and the secondary circuit C. Furthermore, the resonant converter 100 can also provide power factor correction (PFC) functionality through the settings and operation of the controller 6, thereby improving the power conversion efficiency of the resonant converter 100. It is worth noting that in one embodiment, the rectifier arm 22 primarily rectifies the AC power supply Pac; therefore, the switching speed of the switches within the controller 6 (e.g., but not limited to the mains frequency) is slower than the switching speed of the switches within the switching circuit 4 (e.g., but not limited to 400kHz~600kHz). Therefore, rectifier bridge arm 22 can also be called the slow arm, and the switching bridge arms 42 and 44 inside the switching circuit 4 can be called the fast arms. The subsequent disclosures are all the same, and will not be repeated here.

Furthermore, in the resonant converter 100 of Figure 2, since the secondary windings Ws of the transformer T are directly connected in parallel and uniformly coupled to the same node P, and a single set of secondary-side switching circuits 5 are coupled through this node P, the number of secondary-side switches can be reduced (at least 8 switches can be reduced if compared with a three-set separately converted architecture), thereby reducing the power loss of the switches and reducing the number of control signal outputs of the controller 6. On the other hand, the switches disclosed herein are all illustrated with metal-oxide-semiconductor field-effect transistors, but this is not a limitation. Any electronic component that can be used as a switch should be included in the scope of this embodiment (e.g., but not limited to, insulated-grid bipolar transistors, gallium nitride transistors, and other electronic components).

Please refer to Figure 3, which is a circuit diagram of the second embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figure 2. The primary circuit A in Figure 3 is exactly the same as that in Figure 2, and the structure and coupling method of the primary winding Wp of the transformer T are also the same as those in Figure 2. The difference lies in the structure of the common secondary winding WCs and the secondary circuit C in Figure 3, which are different from those in Figure 2. Specifically, the secondary winding Ws in Figure 3 has a delta connection structure. Therefore, the secondary winding Ws is coupled end-to-end in sequence to form the first node P1, the second node P2, and the third node P3.

In addition to the first-stage bridge arm 52 and the second-stage bridge arm 54 shown in Figure 2, the secondary-side switching circuit 5 also includes a third-stage bridge arm 56. The third-stage bridge arm 56 is connected in parallel to the first-stage bridge arm 52, and includes a fifth-stage switch Qs5 and a sixth-stage switch Qs6 connected in series. A third-stage node Ps3 is formed between the fifth-stage switch Qs5 and the sixth-stage switch Qs6, and the first node P1, the second node P2, and the third node P3 are respectively coupled to the first-stage node Ps1, the second-stage node Ps2, and the third-stage node Ps3. The number of secondary-side switches can also be reduced using the delta-connection structure shown in Figure 3. Furthermore, since the secondary winding Ws is wound as a three-phase winding and can be formed by a single iron core, the size of the three-phase transformer can be reduced (compared to the use of three transformers in traditional converters).

Please refer to Figure 4, which is a circuit diagram of the third embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2 and 3. The primary circuit A in Figure 4 is exactly the same as that in Figure 2. The structure and coupling method of the primary winding Wp of the transformer T are also the same as those in Figure 2, and the structure of the secondary circuit C is the same as that in Figure 3. The difference between Figure 4 and Figures 2 and 3 is that the structures of the common secondary winding WCs and the secondary circuit C are different from those in Figures 2 and 3. Specifically, the secondary winding Ws in Figure 4 has a Y-shaped connection structure. Therefore, the first end of each secondary winding is coupled to the first secondary node Ps1, the second secondary node Ps2, and the third secondary node Ps3 of the secondary switching circuit 5, respectively. The second end of each secondary winding Ws is similar to that in Figure 2, and is coupled to a single node P. Therefore, the circuit architecture in Figure 4 provides similar benefits to that in Figure 3, reducing the number of secondary switches and the size of the three-phase transformer.

Please refer to Figure 5, which is a circuit diagram of the fourth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-4. The rectifier circuit 2 in Figure 5 is exactly the same as that in Figure 2, except that the secondary-side circuit C includes three sets of secondary-side switching circuits 5, and the circuit architecture of the switching circuit 4 is also different from that in Figure 2. Specifically, the switching circuit 4 includes a first switching switch Q1 and a second switching switch Q2. One end of the first switching switch Q1 and the second switching switch Q2 are coupled to one end of the capacitor Cf, and the other end of the capacitor Cf is coupled to the primary-side ground terminals Pgnd1, Pgnd2, and Pgnd3.

On the other hand, the circuit architecture of resonant circuit B is also different from that in Figure 2. Furthermore, the resonant circuit B in Figure 5 is shown without a primary-side resonant slot, and the secondary side includes a secondary-side resonant slot formed by the resonant inductor Lr2 and the resonant capacitor Cr2. 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 tap Pc is formed between the first primary winding Wp1 and the second primary winding Wp2. One end of the first primary winding Wp1 is coupled to the other end of the first switching switch Q1, one end of the second primary winding Wp2 is coupled to the other end of the second switching switch Q2, and the center tap Pc of the transformer T is coupled to the primary side grounding terminals Pgnd1, Pgnd2, and Pgnd3.

In Figure 5, the circuit architecture of the three sets of secondary-side switching circuits 5 is the same as that in Figure 2, and the input terminal of the secondary-side switching circuit 5 is coupled to the secondary-side winding Ws of the transformer T. Specifically, one of the primary-side node Ps1 and the secondary-side node Ps2 of each set of secondary-side switching circuits 5 (here, the primary-side node Ps1 is used as an example) is coupled to one end of each set of secondary-side windings Ws, and the other of the primary-side node Ps1 and the secondary-side node Ps2 of each set of secondary-side switching circuits 5 is coupled to the secondary-side ground terminal Sgnd. Since one end of the secondary winding Ws is also coupled to the secondary ground terminal Sgnd, the two ends of the secondary winding Ws are coupled to the first secondary node Ps1 and the second secondary node Ps2, respectively. Furthermore, the resonant inductance Lr2 and resonant capacitor Cr2 of the secondary resonant slot can be configured similarly to the secondary resonant slot in Figure 2, and will not be elaborated further here.

Referring again to Figure 5, the three sets of secondary-side switching circuits 5 are independent of each other, and their output terminals are connected in parallel to supply power to the load 200. Specifically, one end of the output capacitor Co of the three sets of secondary-side switching circuits 5 is connected together to form the positive output terminal, and the other end of the output capacitor Co is connected together to form the negative output terminal. The positive and negative output terminals can be coupled to the load 200 to supply power. In summary, since each phase switching circuit 4 in Figure 5 uses only two switches (i.e., the first switching switch Q1 and the second switching switch Q2), the number of switches in the primary-side switching circuit 1 can be reduced.

Please refer to Figure 6, which is a circuit diagram of the fifth embodiment of the single-stage AC/DC resonant converter disclosed herein, and refer in conjunction with Figures 2-5, and repeatedly refer to Figures 3 and 5. The circuit architecture of Figure 6 is a combination of some circuit architectures of Figures 2 and 5, and can achieve the corresponding effects described above. Specifically, the primary circuit A in Figure 6 is the same as the primary circuit A in Figure 5, and the secondary circuit C in Figure 6 is the same as the secondary circuit C in Figure 2. Furthermore, the circuit structure of the primary winding Wp in Figure 6 is the same as that in Figure 5, and is also a center-tapped structure. The secondary winding Ws is the same as that in Figure 2, and is connected to the same node P. The remaining detailed circuit structure and features can be found in Figures 3 and 5, and will not be described in detail here.

Please refer to Figure 7, which is the circuit diagram of the sixth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-6, and repeatedly refer to Figures 3 and 5. Figure 7 is similar to Figure 6, and the circuit architecture is a combination of some circuit architectures of Figures 3 and 5, achieving the corresponding effects described above. The main difference is that the secondary winding Ws, as in Figure 3, is a delta-connected structure. Other detailed circuit structures and features can be referred to Figures 3 and 5, and will not be elaborated further here.

Please refer to Figure 8, which is the circuit diagram of the seventh embodiment of the single-stage AC/DC resonant converter disclosed herein, and then refer to Figures 2-7, and repeatedly refer to Figures 4-5. Figure 8 is also similar to Figure 6, and the circuit architecture is a combination of some circuit architectures of Figures 4 and 5, achieving the corresponding effects described above. The main difference is that the secondary winding Ws is the same as in Figure 4, with a Y-shaped connection structure. Other detailed circuit structures and features can be referred to Figures 4 and 5, and will not be elaborated further here.

Please refer to Figure 9, which is a circuit diagram of the eighth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-8. The main feature of Figure 9 is that the fast arm and slow arm in the primary-side circuit A are integrated to form a circuit with three sets of bridge arms connected in parallel. Specifically, Figure 9 is based on the switching circuit 4 in Figure 2, which includes a first switching bridge arm 42 and a second switching bridge arm 44, and further includes a rectifier bridge arm 22 connected in parallel to form a circuit with three sets of bridge arms connected in parallel. Furthermore, the rectifier bridge arm 22 is connected in parallel with a capacitor Cf, and the rectifier bridge arm 22 includes a first rectifier switch Qr1 and a second rectifier switch Qr2 connected in series, and 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 coupled to one end of the capacitor Cf, and one end of the second rectifier switch Qr2 is coupled to the other end of the first rectifier switch Qr1 to form the third primary-side node Pp3, and the other end of the second rectifier switch Qr2 is coupled to the other end of the capacitor Cf.

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 coupled to one end of the AC power supply Pac, and the other end of the first inductor L1 is coupled to the first primary-side node Pp1. One end of the second inductor L2 is coupled to one end of the AC power supply Pac, and the other end of the second inductor L2 is coupled to the second primary-side node Pp2. Similar to Figure 2, one of the first primary-side node Pp1 and the second primary-side node Pp2 is coupled to the primary-side winding Wp, and the other is coupled to the primary-side ground terminals Pgnd1, Pgnd2, and Pgnd3. Furthermore, the third primary-side node Pp3 is coupled to the other end of the AC power supply Pac. The circuit structure in Figure 9 is based on a boost converter circuit, which is similar to a totem pole power factor corrector. This means that the primary circuit A mainly boosts the AC power supply Pac, and it also eliminates one set of slow-speed bridge arms. Apart from that, the rest of the circuit structure and function are similar to those in Figure 2, and will not be described in detail here.

Please refer to Figure 10, which is the circuit diagram of the ninth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-9, and repeatedly refer to Figures 3 and 9. The circuit architecture of Figure 10 is mainly a combination of some circuit architectures of Figures 3 and 9, and can achieve the corresponding effects described above. The main difference is that the secondary winding Ws is the same as in Figure 3, which is a delta-connected structure. The remaining detailed circuit structure and features can be referred to Figures 3 and 9, and will not be described in detail here.

Please refer to Figure 11, which is the circuit diagram of the tenth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-10, and repeatedly refer to Figures 4 and 9. The circuit structure of Figure 11 is mainly a combination of some circuit structures of Figures 4 and 9, and can achieve the corresponding effects described above. The main difference is that the secondary winding Ws is the same as in Figure 4, with a Y-shaped connection structure. The remaining detailed circuit structure and features can be referred to Figures 4 and 9, and will not be described in detail here.

Please refer to Figure 12, which is a circuit diagram of the eleventh embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-11. The main feature of Figure 12 is that the primary-side circuit A does not have a slow-speed arm; instead, a fast-speed arm with bidirectional on/off is used. Furthermore, the resonant circuit B and the secondary-side circuit C are the same as in Figure 2. Specifically, the three sets of primary-side switching circuits 1 in Figure 12 each include a filter circuit 3 and a switching circuit 4. The filter circuit 3 is coupled to one phase of the three-phase AC power supply R, Y, and B, Pac, and the switching circuit 4 is coupled to the filter circuit 3 and the primary-side winding Wp. Specifically, the filter circuit 3 includes an inductor L and a capacitor Cf. Similar to the description in Figure 2, the main function of the inductor L and capacitor Cf is filtering, rather than acting as intermediate energy storage elements (i.e., not as elements that can store large amounts of electrical energy, such as electrolytic capacitors).

Furthermore, one end of inductor L is coupled to one end of AC power supply Pac, and one end of capacitor Cf is coupled to the other end of inductor L. The other end of capacitor Cf is coupled to the other end of AC power supply Pac, and capacitor Cf is connected in parallel with switching circuit 4. Switching circuit 4 is similar to that in Figure 2, and also includes a first switching bridge arm 42 and a second switching bridge arm 44, but the switching switches Q1~Q4 of switching bridge arms 42 and 44 are replaced with switching modules 422~444, and each switching module 422~444 is a bidirectional switch. Therefore, when both switches of the bidirectional switch are turned off, their paths can be completely disconnected. Specifically, the first switching arm 42 includes a first switching module 422 and a second switching module 424 connected in series, and the first switching module 422 and the second switching module 424 each include switches connected in reverse series (i.e., the directions of the junction diodes are exactly opposite). Therefore, the first switching arm 42 includes more than four switches. One end of the first switching module 422 and the other end of the second switching module 424 are coupled to the filter circuit 3 (specifically, a capacitor Cf connected in parallel to the first switching arm 42), and the other end of the first switching module 422 is coupled to one end of the second switching module 424 to form a first primary side node Pp1.

The second switching arm 44 includes a third switching module 442 and a fourth switching module 444 connected in series, and the third switching module 442 and the fourth switching module 444 also include switches connected in reverse series. Therefore, the second switching arm 44 also includes more than four switches. One end of the third switching module 442 and the other end of the fourth switching module 444 are coupled to the filter circuit 3 (specifically, a capacitor Cf connected in parallel in the second switching arm 44), and the other end of the third switching module 442 is coupled to one end of the fourth switching module 444 to form a second primary side node Pp2. The coupling relationship between the first primary side node Pp1 and the second primary side node Pp2 is similar to that in Figure 2. One of them is coupled to one end of the primary winding Wp, and the other is coupled to the other end of the primary winding Wp and the primary grounding terminals Pgnd1, Pgnd2, and Pgnd3. The remaining detailed coupling methods are similar to those in Figure 2, and will not be described in detail here.

It is worth mentioning that, in one embodiment, besides the embodiment of two switches connected in reverse series, there are several other embodiments of the bidirectional switch with different structures but the same function. Therefore, the structure of switch modules 422-444 can be selectively replaced according to actual needs. That is, any bidirectional switch with bidirectional on/off function should be included in the scope of this embodiment. In addition, the circuit structure and coupling relationship not mentioned in Figure 12 are similar to those in Figure 2 and can achieve similar effects, so they will not be described in detail here.

Please refer to Figure 13, which is the circuit diagram of the twelfth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-12, and repeatedly refer to Figures 3 and 12. The circuit structure of Figure 13 is mainly a combination of some circuit structures of Figures 3 and 12, and can achieve the corresponding effects described above. The main difference is that the secondary winding Ws is the same as in Figure 3, which is a delta-connected structure. The remaining detailed circuit structure and features can be referred to Figures 3 and 12, and will not be described in detail here.

Please refer to Figure 14, which is the circuit diagram of the thirteenth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-13, and repeatedly refer to Figures 4 and 12. The circuit structure of Figure 14 is mainly a combination of some circuit structures of Figures 4 and 12, and can achieve the corresponding effects described above. The main difference is that the secondary winding Ws is the same as in Figure 4, with a Y-shaped connection structure. The remaining detailed circuit structure and features can be referred to Figures 4 and 12, and will not be described in detail here.

Please refer to Figure 15, which is a circuit diagram of the fourteenth embodiment of the single-stage AC/DC resonant converter disclosed herein, and also refer to Figures 2-14. The secondary circuit C in Figure 15 is exactly the same as that in Figure 5, and the filter circuit 3 is exactly the same as that in Figure 12. The difference lies in the switching circuit 4. Specifically, the switching circuit 4 in Figure 15 is similar to that in Figure 5, but the first switching switch Q1 and the second switching switch Q2 are replaced by the first switching module 422 and the second switching module 424, respectively. Furthermore, the first switching module 422 and the second switching module 424 are also bidirectional switches, each including switches connected in reverse series (i.e., the directions of the junction diodes are exactly opposite). Similarly, besides the implementation of two switches connected in reverse series, there are many other implementations of bidirectional switches with different structures but the same function, which will not be elaborated here.

Furthermore, one end of the first switching module 422 and the second switching module 424 are coupled to the filter circuit 3 (specifically, one end of the capacitor Cf, and the other end of the capacitor Cf is coupled to the primary-side ground terminals Pgnd1, Pgnd2, and Pgnd3), and the other ends of the first switching module 422 and the second switching module 424 are respectively coupled to one end of the first primary-side winding Wp1 and the second primary-side winding Wp2. Other coupling relationships and their achievable effects can be referred to Figures 5 and 12, and will not be elaborated further here.

Please refer to Figures 16, 17, and 18, which are circuit diagrams of the fifteenth to seventeenth embodiments of the single-stage AC-DC resonant converter disclosed herein, and also refer to Figures 2-14, and repeatedly refer to Figures 2-4 and 15. The circuit architectures of Figures 16, 17, and 18 are mainly combinations of parts of the circuit architectures of Figures 2 and 15, 3 and 15, and 4 and 15, respectively, and can achieve the corresponding effects described above. The remaining detailed circuit structures and features can be referred to Figures 2-4 and 15, and will not be elaborated here.

However, the above description and drawings are merely detailed examples of preferred embodiments of the present invention. The features of the present invention are not limited thereto and are not intended to limit the present invention. The scope of the present invention shall be determined by the following patent application. All embodiments that conform to the spirit of the patent application and similar variations thereof shall be included in the scope of the present invention. Any variations or modifications that can be easily conceived by one skilled in the art within the field of the present invention shall be covered by the following patent application.

100A: AC/DC converter 100B: AC/DC conversion circuit CI: Intermediate capacitor 100C: DC/DC conversion circuit 100: Resonant converter A: Primary side circuit 1: Primary side switching circuit 2: Rectifier circuit L: Inductor Cf: Capacitor 22: Rectifier bridge arm 222: First rectifier bridge arm Qr1: First rectifier switch Qr2: Second rectifier switch 224: Second rectifier bridge arm Qr3: Third rectifier switch Qr4: Fourth rectifier switch 3: Filter circuit 4: Switching circuit L1: First Inductor L2: Second Inductor; 42: First Switching Arm; Q1: First Switch; Q2: Second Switch; 422: First Switching Module; 424: Second Switching Module; 44: Second Switching Arm; Q3: Third Switch; Q4: Fourth Switch; 442: Third Switching Module; 444: Fourth Switching Module; Pgnd1, Pgnd2, Pgnd3: Primary Side Grounding Terminal; B: Resonant Circuit; Lr1, Lr2: Resonant Inductors; Cr1, Cr2: Resonant Capacitors; T: Transformer; Wp: Primary Side Winding Wp1: First primary winding; Wp2: Second primary winding; Pc: Center tap terminal; Ws: Secondary winding; WCs: Secondary common winding; C: Secondary circuit; 5: Secondary switching circuit; 52: First primary bridge arm; Qs1: First primary switch; Qs2: Secondary switch; 54: Secondary bridge arm; Qs3: Third primary switch; Qs4: Fourth secondary switch; 56: Third secondary bridge arm; Qs5: Fifth secondary switch; Qs6: Sixth secondary switch; Co: Output capacitor; Sg nd: Secondary side ground terminal P: Node P1: First node P2: Second node P3: Third node Pr1: First rectifier node Pr2: Second rectifier node Pp1: First primary side node Pp2: Second primary side node Pp3: Third primary side node Ps1: First primary side node Ps2: Second primary side node Ps3: Third primary side node 6: Controller 200: Load R, Y, B: Three-phase AC power supply Pac: AC power supply N: Neutral terminal Pdc: DC power supply Sc: Control signal

Figure 1 shows a conventional two-stage AC/DC converter;

Figure 2 is a circuit diagram of a first embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 3 is a circuit diagram of a second embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 4 is a circuit diagram of the third embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 5 is a circuit diagram of the fourth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 6 is a circuit diagram of the fifth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 7 is a circuit diagram of the sixth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 8 is a circuit diagram of the seventh embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 9 is a circuit diagram of the eighth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 10 is a circuit diagram of the ninth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 11 is a circuit diagram of the tenth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 12 is a circuit diagram of the eleventh embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 13 is a circuit diagram of the twelfth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 14 is a circuit diagram of the thirteenth embodiment of the single-stage AC/DC resonant converter disclosed herein; and

Figure 15 is a circuit diagram of the fourteenth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 16 is a circuit diagram of the fifteenth embodiment of the single-stage AC/DC resonant converter disclosed herein;

Figure 17 is a circuit diagram of the sixteenth embodiment of the single-stage AC/DC resonant converter disclosed herein; and

Figure 18 is a circuit diagram of the seventeenth embodiment of the single-stage AC/DC resonant converter disclosed herein.

100: Resonance Converter

A: Primary circuit

1: Primary side switching circuit

2: Rectifier Circuit

L: Inductor

Cf: Capacitor

22: Rectifier Bridge Arm

222: First rectifier bridge arm

Qr1: First rectifier switch

Qr2: Second rectifier switch

224: Second rectifier bridge arm

Qr3: Third rectifier switch

Qr4: Fourth rectifier switch

4: Switching the circuit

42: First switching arm

Q1: First switching switch

Q2: Second switching switch

44: Second switching arm

Q3: Third switch

Q4: Fourth Switch

Pgnd1, Pgnd2, Pgnd3: Primary side grounding terminals

B: Resonant Circuit

Lr1, Lr2: Resonant inductors

Cr1, Cr2: Resonant capacitors

T: Transformer

Wp: Basic Side Winding Set

Ws: Secondary lateral winding

WCs: Secondary-side common windings

C: Secondary circuit

5: Secondary-side switching circuit

52: First-stage side bridge arm

Qs1: First-stage side switch

Qs2: Secondary stage side switch

54: Secondary side bridge arm

Qs3: Third stage side switch

Qs4: Fourth secondary side switch

Co: Output capacitor

Sgnd: Secondary side ground terminal

P: Node

Pr1: First rectifier node

Pr2: Second rectifier node

Pp1: First primary side node

Pp2: Second primary side node

Ps1: First-order side node

PS2: Secondary side node

6: Controller

200: Load

R, Y, B: Three-phase AC power supply

Pac: Alternating Current Power P ...

N: Neutral end

Pdc: DC power supply

Sc: Control Signal

Claims (19)

A single-stage AC/DC resonant converter for converting a three-phase AC power supply into a DC power supply, the single-stage AC/DC resonant converter comprising: a primary-side circuit including three sets of primary-side switching circuits, each of the primary-side switching circuits being coupled to one phase of the three-phase AC power supply, and each of the primary-side switching circuits comprising: a rectifier circuit including a rectifier bridge arm and a capacitor connected in parallel with the rectifier bridge arm; and a switching circuit coupled to the capacitor; A resonant circuit includes three sets of transformers and three sets of resonant slots. Each resonant slot includes a primary-side resonant slot and a secondary-side resonant slot. The primary-side resonant slot includes a first resonant inductor and a first resonant capacitor connected in series. The secondary-side resonant slot includes a second resonant inductor and a second resonant capacitor connected in series. The primary-side windings of the transformers are respectively coupled to the switching circuits of the primary-side switching circuits through the primary-side resonant slots of the resonant slots. The secondary-side windings of the transformers and the secondary-side resonant slots of the resonant slots form primary-side common windings. The primary-side circuit includes a set of secondary-side switching circuits, and the secondary-side switching circuits are coupled to the secondary-side common winding. The single-stage AC/DC resonant converter as described in claim 1, wherein the secondary-side switching circuit comprises: a primary-side bridge arm including a primary-side switch and a secondary-side switch connected in series, wherein a primary-side node is formed between the primary-side switch and the secondary-side switch; and a secondary-side bridge arm connected in parallel to the primary-side bridge arm, and including a tertiary-side switch and a fourth-side switch connected in series, wherein a secondary-side node is formed between the tertiary-side switch and the fourth-side switch; In this configuration, a first end of the secondary winding of the transformers is coupled to a primary-side ground terminal, and a second end of the secondary winding of the transformers is coupled to a node; the node is coupled to one of the primary-side node and the secondary-side node, and the other of the primary-side node and the secondary-side node is coupled to the primary-side ground terminal. As described in claim 1, the single-stage AC/DC resonant converter, wherein the secondary-side switching circuit comprises: a primary-side bridge arm including a primary-side switch and a secondary-side switch connected in series, wherein a primary-side node is included between the primary-side switch and the secondary-side switch; a secondary-side bridge arm, connected in parallel to the primary-side bridge arm, and including a tertiary-side switch and a fourth-side switch connected in series, wherein a secondary-side node is included between the tertiary-side switch and the fourth-side switch; and A third secondary side arm is connected in parallel to the first secondary side arm, and includes a fifth secondary side switch and a sixth secondary side switch connected in series, wherein a third secondary side node is included between the fifth secondary side switch and the sixth secondary side switch; wherein a first end of a secondary side winding of the transformers is respectively coupled to the first secondary side node, the second secondary side node and the third secondary side node, and a second end of a secondary side winding of the transformers is commonly coupled to a node. As described in claim 1, the single-stage AC/DC resonant converter, wherein the secondary-side switching circuit comprises: a primary-side bridge arm including a primary-side switch and a secondary-side switch connected in series, wherein a primary-side node is formed between the primary-side switch and the secondary-side switch; a secondary-side bridge arm connected in parallel to the primary-side bridge arm, and including a tertiary-side switch and a fourth-side switch connected in series, wherein a secondary-side node is formed between the tertiary-side switch and the fourth-side switch; and A third secondary side arm is connected in parallel to the first secondary side arm, and includes a fifth secondary side switch and a sixth secondary side switch connected in series, forming a third secondary side node between the fifth secondary side switch and the sixth secondary side switch; wherein, the secondary side windings of the transformers are sequentially coupled end-to-end to form a first node, a second node and a third node, and the first node, the second node and the third node are respectively coupled to the first secondary side node, the second secondary side node and the third secondary side node. As described in claim 1, the single-stage AC/DC resonant converter further includes: an inductor coupled to one end of one phase of the AC power supply; wherein the rectifier bridge arm includes a first rectifier bridge arm and a second rectifier bridge arm connected in parallel with the capacitor, and the first rectifier bridge arm and the second rectifier bridge arm are respectively coupled to the inductor and the other end of one phase of the AC power supply. As described in claim 1, the single-stage AC/DC resonant converter, wherein the switching circuit includes: a first switching switch, one end of which is coupled to one end of the capacitor, and the other end of the capacitor is coupled to a primary-side ground terminal; and a second switching switch, one end of which is coupled to one end of the capacitor; wherein each transformer's primary-side winding includes a first primary-side winding and a second primary-side winding connected in series, and a center tap is formed between the first primary-side winding and the second primary-side winding; one end of the first primary-side winding is coupled to the other end of the first switching switch, one end of the second primary-side winding is coupled to the other end of the second switching switch, and the center tap is coupled to the primary-side ground terminal. The single-stage AC/DC resonant converter as described in claim 1, wherein the switching circuit comprises: a first switching arm connected in parallel with the capacitor, and including a first switching switch and a second switching switch connected in series, forming a first primary-side node between the first switching switch and the second switching switch; and a second switching arm connected in parallel with the capacitor, and including a third switching switch and a fourth switching switch connected in series, forming a second primary-side node between the third switching switch and the fourth switching switch; wherein one of the first primary-side node and the second primary-side node is coupled to a primary-side ground terminal, and the other of the first primary-side node and the second primary-side node is coupled to the primary-side winding of one of the transformers. The single-stage AC/DC resonant converter as described in claim 7, wherein the rectifier bridge arm is connected in parallel with the capacitor, and includes: a first rectifier switch, one end of which is coupled to one end of the capacitor; and a second rectifier switch, one end of which is coupled to the other end of the first rectifier switch to form a third primary-side node, and the other end of which is coupled to the other end of the capacitor; the switching circuit further includes: a first inductor, one end of which is coupled to one end of one phase of the AC power supply, and the other end of which is coupled to the first primary-side node; and a second inductor, one end of which is coupled to one end of one phase of the AC power supply, and the other end of which is coupled to the second primary-side node; wherein the third primary-side node is coupled to the other end of one phase of the AC power supply. A single-stage AC/DC resonant converter for converting a three-phase AC power supply into a DC power supply, the single-stage AC/DC resonant converter comprising: a primary-side circuit including three sets of primary-side switching circuits, each of the primary-side switching circuits comprising: a filter circuit, respectively coupled to one phase of the three-phase AC power supply; and a switching circuit coupled to the filter circuit; A resonant circuit includes three sets of transformers and three sets of resonant slots. Each resonant slot includes a primary-side resonant slot and a secondary-side resonant slot. The primary-side resonant slot includes a first resonant inductor and a first resonant capacitor connected in series. The secondary-side resonant slot includes a second resonant inductor and a second resonant capacitor connected in series. The primary-side windings of the transformers are respectively coupled to the switching circuits of the primary-side switching circuits through the primary-side resonant slots of the resonant slots. The secondary-side windings of the transformers and the secondary-side resonant slots of the resonant slots form primary-side common windings. The primary-side circuit includes a set of secondary-side switching circuits, and the secondary-side switching circuits are coupled to the secondary-side common winding. The single-stage AC/DC resonant converter as described in claim 9, wherein the secondary-side switching circuit includes: a primary-side bridge arm including a primary-side switch and a secondary-side switch connected in series, wherein a primary-side node is formed between the primary-side switch and the secondary-side switch; and a secondary-side bridge arm connected in parallel to the primary-side bridge arm, including a tertiary-side switch and a fourth-side switch connected in series, wherein a secondary-side node is formed between the tertiary-side switch and the fourth-side switch; In this configuration, a first end of the secondary winding of the transformers is coupled to a primary-side ground terminal, and a second end of the secondary winding of the transformers is coupled to a node; the node is coupled to one of the primary-side node and the secondary-side node, and the other of the primary-side node and the secondary-side node is coupled to the primary-side ground terminal. As described in claim 9, the single-stage AC/DC resonant converter, wherein the secondary-side switching circuit comprises: a primary-side bridge arm including a primary-side switch and a secondary-side switch connected in series, wherein a primary-side node is included between the primary-side switch and the secondary-side switch; a secondary-side bridge arm, connected in parallel to the primary-side bridge arm, and including a tertiary-side switch and a fourth-side switch connected in series, wherein a secondary-side node is included between the tertiary-side switch and the fourth-side switch; and A third secondary side arm is connected in parallel to the first secondary side arm, and includes a fifth secondary side switch and a sixth secondary side switch connected in series, wherein a third secondary side node is included between the fifth secondary side switch and the sixth secondary side switch; wherein a first end of a secondary side winding of the transformers is respectively coupled to the first secondary side node, the second secondary side node and the third secondary side node, and a second end of a secondary side winding of the transformers is commonly coupled to a node. As described in claim 9, the single-stage AC/DC resonant converter, wherein the secondary-side switching circuit comprises: a primary-side bridge arm including a primary-side switch and a secondary-side switch connected in series, wherein a primary-side node is formed between the primary-side switch and the secondary-side switch; a secondary-side bridge arm connected in parallel to the primary-side bridge arm, and including a tertiary-side switch and a fourth-side switch connected in series, wherein a secondary-side node is formed between the tertiary-side switch and the fourth-side switch; and A third secondary side arm is connected in parallel to the first secondary side arm, and includes a fifth secondary side switch and a sixth secondary side switch connected in series, forming a third secondary side node between the fifth secondary side switch and the sixth secondary side switch; wherein, the secondary side windings of the transformers are sequentially coupled end-to-end to form a first node, a second node and a third node, and the first node, the second node and the third node are respectively coupled to the first secondary side node, the second secondary side node and the third secondary side node. As described in claim 9, the single-stage AC/DC resonant converter includes: an inductor, one end of which is coupled to one end of one phase of the AC power supply; and a capacitor, one end of which is coupled to the other end of the inductor, and the other end of which is coupled to the other end of one phase of the AC power supply; wherein the switching circuit is connected in parallel with the capacitor. The single-stage AC/DC resonant converter as described in claim 9, wherein the switching circuit comprises: a first switching arm, including a first switching module and a second switching module connected in series, wherein one end of the first switching module and the other end of the second switching module are coupled to the filter circuit, and the other end of the first switching module is coupled to one end of the second switching module to form a first primary-side node; a second switching arm, connected in parallel to the first switching arm, and including a third switching module and a fourth switching module connected in series, wherein one end of the third switching module and the other end of the fourth switching module are coupled to the filter circuit, and the other end of the third switching module is coupled to one end of the fourth switching module to form a second primary-side node; Wherein, one of the first primary-side node and the second primary-side node is coupled to one end of the primary-side winding, and the other of the first primary-side node and the second primary-side node is coupled to the other end of the primary-side winding and a primary-side ground terminal. As described in claim 9, the single-stage AC/DC resonant converter, wherein the switching circuit includes: a first switching module, one end of which is coupled to the filter circuit; and a second switching module, one end of which is coupled to the filter circuit; wherein each transformer's primary winding includes a first primary winding and a second primary winding connected in series, and a center tap is formed between the first primary winding and the second primary winding; one end of the first primary winding is coupled to the other end of the first switching module, one end of the second primary winding is coupled to the other end of the second switching module, and the center tap is coupled to a primary-side ground terminal. A single-stage AC/DC resonant converter for converting a three-phase AC power supply into a DC power supply, the single-stage AC/DC resonant converter comprising: a primary-side circuit including three sets of primary-side switching circuits, the primary-side switching circuits being respectively coupled to one phase of the three-phase AC power supply, and each of the primary-side switching circuits including a switching circuit, wherein the primary-side switching circuits further include: a rectifier circuit including a rectifier bridge arm and a capacitor connected in parallel with the rectifier bridge arm; an inductor coupled to one end of one phase of the AC power supply; a first switching module, one end of which is coupled to the capacitor; and a second switching module, one end of which is coupled to the capacitor; A resonant circuit includes three sets of transformers, the primary windings of which are respectively coupled to the switching circuits of the primary-side switching circuits; and a secondary-side circuit including three sets of secondary-side switching circuits, the input terminals of which are coupled to the secondary windings of the transformers, and the output terminals of which are coupled in parallel. Each transformer's primary winding includes a first primary winding and a second primary winding connected in series, with a center tap formed between the first primary winding and the second primary winding; one end of the first primary winding is coupled to the other end of the first switching module, one end of the second primary winding is coupled to the other end of the second switching module, and the center tap is coupled to a primary-side grounding terminal. As described in claim 16, the single-stage AC/DC resonant converter, wherein the secondary-side switching circuits respectively include: a primary-side bridge arm including a primary-side switch and a secondary-side switch connected in series, and a primary-side node is formed between the primary-side switch and the secondary-side switch; and a secondary-side bridge arm connected in parallel to the primary-side bridge arm, and including a tertiary-side switch and a fourth-side switch connected in series, and a secondary-side node is formed between the tertiary-side switch and the fourth-side switch; One of the primary-side nodes and the other of the secondary-side nodes is coupled to the secondary winding of one of the transformers, and the other of the primary-side nodes and the other of the secondary-side nodes is coupled to the primary-side grounding terminal. A single-stage AC/DC resonant converter for converting a three-phase AC power supply into a DC power supply, the single-stage AC/DC resonant converter comprising: a primary-side circuit including three sets of primary-side switching circuits, each primary-side switching circuit being coupled to one phase of the three-phase AC power supply, and each primary-side switching circuit including a switching circuit, wherein each switching circuit includes: a first switching module, one end coupled to the filter circuit; and a second switching module, one end coupled to the filter circuit; a resonant circuit including three sets of transformers, the primary-side windings of which are respectively coupled to the switching circuits of the primary-side switching circuits; and The primary-side circuit includes three sets of secondary-side switching circuits. The input terminals of these secondary-side switching circuits are coupled to the secondary-side windings of the transformers, and the output terminals of these secondary-side switching circuits are coupled in parallel. Each transformer's primary-side winding includes a first primary-side winding and a second primary-side winding connected in series, and a center tap is formed between the first primary-side winding and the second primary-side winding. One end of the first primary-side winding is coupled to the other end of the first switching module, one end of the second primary-side winding is coupled to the other end of the second switching module, and the center tap is coupled to a primary-side ground terminal. As described in claim 18, the single-stage AC/DC resonant converter further includes: a filter circuit comprising an inductor and a capacitor, one end of the inductor and the other end of the capacitor being respectively coupled to the two terminals of one phase AC power supply, and the other end of the inductor being coupled to one end of the capacitor; wherein one end of the capacitor is coupled to the first switching module and the second switching module, and the other end of the capacitor is coupled to a primary-side ground terminal.