Resonant converter

Abstract

This application provides a resonant converter, including an input circuit, a first switching circuit, a resonant circuit, a transformer circuit, a second switching circuit, and an output circuit. The input circuit provides an input voltage. The first switching circuit is coupled to the input circuit and includes a plurality of first switching units, each first switching unit including an output node. The resonant circuit includes a plurality of resonant slots, each resonant slot including a resonant capacitor and a resonant inductor connected in series, the plurality of resonant inductors being Y-connected to the plurality of output nodes. The transformer circuit has a plurality of connection nodes between its primary side and the plurality of resonant capacitors, the plurality of resonant capacitors being Y-connected to the primary side of the transformer circuit based on the plurality of connection nodes. The second switching circuit includes a plurality of second switching units, each second switching unit including an input node, the plurality of input nodes being delta-connected to the secondary side of the plurality of transformers. The output circuit is coupled to the second switching circuit and generates an output voltage.

Description

[Technical Field]

[0001] This application relates to the technical field of power converters, and in particular to a resonant converter. [Previous Technology]

[0002] With the spread of environmental awareness, electric vehicles have begun to rise and develop rapidly to replace automobiles and diesel vehicles. Because electric vehicles require more electrical energy, they usually need high-power power converters to assist in the distribution of electrical energy.

[0003] Currently, high-power power converters used in electric vehicles are usually full-bridge power converters. Although full-bridge power converters provide stable high output power, the switching of the switching elements in a full-bridge power converter is hard switching. Hard switching causes switching losses of the switching elements, thereby increasing the power loss of the full-bridge power converter and reducing its power conversion efficiency. [Summary of the Invention]

[0004] As described above, this application provides a resonant converter to solve the problem of high power loss in power converters.

[0005] Based on the foregoing, this application provides a resonant converter, including an input circuit, a first switching circuit, a resonant circuit, a transformer circuit, a second switching circuit, and an output circuit. The input circuit provides an input voltage. The first switching circuit is coupled to the input circuit and includes a plurality of first switching units; each first switching unit includes an output node. The resonant circuit includes a plurality of resonant slots, each resonant slot including a resonant capacitor and a resonant inductor connected in series. The plurality of resonant inductors are coupled to a plurality of output nodes in a Y-connection configuration. A plurality of connection nodes are present between the primary side of the transformer circuit and the plurality of resonant capacitors, and the plurality of resonant capacitors are coupled to the primary side of the transformer circuit in a Y-connection configuration based on the plurality of connection nodes. The second switching circuit includes a plurality of second switching units, each second switching unit including an input node. The plurality of input nodes are coupled to the secondary side of the transformer circuit in a delta connection configuration. The output circuit is coupled to the second switching circuit and generates an output voltage.

[0006] In summary, the resonant converter of this application achieves zero voltage switching (ZVS) or zero current switching (ZCS) through the configuration of the resonant circuit, thereby reducing the switching losses of the switching elements and the power loss of the power converter.

[0007] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the following describes the application in detail with reference to the preferred embodiments and accompanying drawings.

Implementation Method

[0009] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification.

[0010] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the accompanying drawings and embodiments. To enable those skilled in the art to better understand the solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without making innovative efforts should fall within the scope of protection of this application.

[0011] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0012] Please refer to Figure 1A, which is a circuit diagram of a resonant converter according to an embodiment of this application. As shown in Figure 1A, the resonant converter includes an input circuit 10, a first switching circuit 20, a resonant circuit 30, a transformer circuit 40, a second switching circuit 50, and an output circuit 60.

[0013] The input circuit 10 includes a voltage source VS1 and an input capacitor Cin. The voltage source VS1 provides the input voltage. The two ends of the input capacitor Cin are coupled to the voltage source VS1, that is, the input capacitor Cin and the voltage source VS1 are connected in parallel and coupled.

[0014] The first switching circuit 20 is coupled to the input circuit 10 and includes first switching units 21, 22, and 23. The first switching units 21, 22, and 23 are coupled in parallel to each other. The first switching unit 21 includes a first high-side switch S1, a first low-side switch S4, and a first output node A1; the first high-side switch S1 is coupled to one end of the input capacitor Cin, the first low-side switch S4 is coupled to the other end of the input capacitor Cin, the first high-side switch S1 and the first low-side switch S4 are coupled in series, and the first output node A1 is disposed between the first high-side switch S1 and the first low-side switch S4. The first switching unit 22 includes a second high-side switch S2, a second low-side switch S5, and a second output node B1; the second high-side switch S2 is coupled to the first high-side switch S1, the second low-side switch S5 is coupled to the first low-side switch S4, the second high-side switch S2 and the second low-side switch S5 are coupled in series, and the second output node B1 is disposed between the second high-side switch S2 and the second low-side switch S5. The first switching unit 23 includes a third high-side switch S3, a third low-side switch S6, and a third output node C1; the third high-side switch S3 is coupled to the second high-side switch S2, the third low-side switch S6 is coupled to the second low-side switch S5, the third high-side switch S3 and the third low-side switch S6 are connected in series, and the third output node C1 is located between the third high-side switch S3 and the third low-side switch S6.

[0015] The resonant circuit 30 includes a plurality of resonant slots, each of which includes a resonant capacitor and a resonant inductor connected in series. The plurality of resonant inductors are coupled to a plurality of output nodes in a Y-connection. Specifically, the resonant circuit 30 includes a first resonant slot 31, a second resonant slot 32, and a third resonant slot 33. The first resonant slot 31 includes a first resonant inductor Lr1 and a first resonant capacitor Cr1 connected in series. One end of the first resonant inductor Lr1 is coupled to a first output node A1, and the other end of the first resonant inductor Lr1 is coupled to the first resonant capacitor Cr1. The second resonant slot 32 includes a second resonant inductor Lr2 and a second resonant capacitor Cr2 connected in series. One end of the second resonant inductor Lr2 is coupled to a second output node B1, and the other end of the second resonant inductor Lr2 is coupled to the second resonant capacitor Cr2. The third resonant slot 33 includes a third resonant inductor Lr3 and a third resonant capacitor Cr3 connected in series. One end of the third resonant inductor Lr3 is coupled to a third output node C1, and the other end of the third resonant inductor Lr3 is coupled to the third resonant capacitor Cr3. The first resonant inductor Lr1, the second resonant inductor Lr2, and the third resonant inductor Lr3 are coupled to the first output node A1, the second output node B1, and the third output node C1 in a wye connection. Compared to the configuration where the first resonant inductor Lr1, the second resonant inductor Lr2, and the third resonant inductor Lr3 are coupled to the first output node A1, the second output node B1, and the third output node C1 in a delta connection, the configuration where the first resonant inductor Lr1, the second resonant inductor Lr2, and the third resonant inductor Lr3 are coupled to the first output node A1, the second output node B1, and the third output node C1 in a wye connection can reduce the value of the resonant inductance to 1 / 3 of the original value.

[0016] Due to the series coupling of the first resonant inductor Lr1 and the first resonant capacitor Cr1, the series coupling of the second resonant inductor Lr2 and the second resonant capacitor Cr2, and the series coupling of the third resonant inductor Lr3 and the third resonant capacitor Cr3, the first resonant frequency of the first resonant slot 31, the second resonant frequency of the second resonant slot 32, and the third resonant frequency of the third resonant slot 33 can be expressed as , and , and respectively, the first resonant frequency of the first resonant slot 31, the second resonant frequency of the second resonant slot 32, and the third resonant frequency of the third resonant slot 33. By adjusting the values ​​of the first resonant inductor Lr1 and the first resonant capacitor Cr1, the values ​​of the second resonant inductor Lr2 and the second resonant capacitor Cr2, and the values ​​of the third resonant inductor Lr3 and the third resonant capacitor Cr3, the first resonant frequency of the first resonant slot 31, the second resonant frequency of the second resonant slot 32, and the third resonant frequency of the third resonant slot 33 are determined.

[0017] When the switching frequency of the first switching unit 21 is greater than the first resonant frequency, the first resonant tank 31 is inductive and has ZVS characteristics; when the switching frequency of the first switching unit 21 is less than the first resonant frequency, the first resonant tank 31 is capacitive and has ZCS characteristics. When the switching frequency of the first switching unit 22 is greater than the second resonant frequency, the second resonant tank 32 is inductive and has ZVS characteristics; when the switching frequency of the first switching unit 22 is less than the second resonant frequency, the second resonant tank 32 is capacitive and has ZCS characteristics. When the switching frequency of the first switching unit 23 is greater than the third resonant frequency, the third resonant tank 33 is inductive and has ZVS characteristics; when the switching frequency of the first switching unit 23 is less than the third resonant frequency, the third resonant tank 33 is capacitive and has ZCS characteristics. By adjusting the switching frequency of the first switching unit 21 to the switching frequency of the first switching unit 23, the ZVS and ZCS characteristics of the first and third resonant tanks 31 and 33 are adjusted.

[0018] The primary side of the transformer circuit 40 has a plurality of connection nodes with a plurality of resonant capacitors, and the plurality of resonant capacitors are coupled to the primary side of the transformer circuit 40 in a wye connection based on the plurality of connection nodes. Specifically, the transformer circuit 40 includes a first transformer T1, a second transformer T2, and a third transformer T3. The primary side of the first transformer T1 has a first connection node CN1 with the first resonant capacitor Cr1, and the first connection node CN1 is coupled to the primary side of the third transformer T3. The primary side of the second transformer T2 has a second connection node CN2 with the second resonant capacitor Cr2, and the second connection node CN2 is coupled to the primary side of the first transformer T1. The primary side of the third transformer T3 has a third connection node CN3 with the third resonant capacitor Cr3, and the third connection node CN3 is coupled to the primary side of the second transformer T2. The first resonant capacitor Cr1 is Y-connected to the primary side of the transformer circuit 40 via the first connection node CN1; the second resonant capacitor Cr2 is Y-connected to the primary side of the transformer circuit 40 via the second connection node CN2; and the third resonant capacitor Cr3 is Y-connected to the primary side of the transformer circuit 40 via the third connection node CN3. Compared to the configuration where the first resonant capacitor Cr1, the second resonant capacitor Cr2, and the third resonant capacitor Cr3 are delta-connected to the primary side of the transformer circuit 40, the configuration where the first resonant capacitor Cr1, the second resonant capacitor Cr2, and the third resonant capacitor Cr3 are Y-connected to the primary side of the transformer circuit 40 will amplify the value of the resonant capacitors to three times the original value.

[0019] The first transformer T1 includes a primary winding 41A, a magnetizing inductor Lm1, and a secondary winding 42A. The primary winding 41A is located on the primary side of the first transformer T1 and is coupled in parallel with the magnetizing inductor Lm1, and is coupled to the first resonant capacitor Cr1 through the first connection node CN1. The secondary winding 42A is located on the secondary side of the first transformer T1. The second transformer T2 includes a primary winding 41B, a magnetizing inductor Lm2, and a secondary winding 42B. The primary winding 41B is located on the primary side of the second transformer T2 and is coupled in parallel with the magnetizing inductor Lm2, and is coupled to the second resonant capacitor Cr2 through the second connection node CN2. The secondary winding 42B is located on the secondary side of the second transformer T2. The third transformer T3 includes a primary winding 41C, a magnetizing inductor Lm3, and a secondary winding 42C. The primary winding 41C is located on the primary side of the third transformer T3 and is coupled in parallel with the magnetizing inductor Lm3, and is coupled to the third resonant capacitor Cr3 through the third connection node CN3. The secondary winding 42C is located on the secondary side of the third transformer T3.

[0020] The primary winding 41A of the first transformer T1, the primary winding 41B of the second transformer T2, and the primary winding 41C of the third transformer T3 are coupled to each other in a delta connection; in other words, the primary windings of the first transformer T1, the second transformer T2, and the third transformer T3 are coupled to each other in a delta connection. Similarly, the secondary windings 42A of the first transformer T1, the secondary windings 42B of the second transformer T2, and the secondary windings 42C of the third transformer T3 are coupled to each other in a delta connection; in other words, the secondary windings of the first transformer T1, the second transformer T2, and the third transformer T3 are coupled to each other in a delta connection. Through the above configuration, the current in the primary and secondary windings of the first transformer T1 to the third transformer T3 can be reduced, thereby reducing the copper wire loss of the coils.

[0021] The second switching circuit 50 includes second switching units 51, 52, and 53. The second switching units 51, 52, and 53 are connected in parallel and coupled to each other. The second switching unit 51 includes a first high-side rectifier switch SR1, a first low-side rectifier switch SR4, and a first input node D1; the first high-side rectifier switch SR1 and the first low-side rectifier switch SR4 are connected in series and coupled, and the first input node D1 is disposed between the first high-side rectifier switch SR1 and the first low-side rectifier switch SR4 and coupled to the secondary side coil winding 42A. The second switching unit 52 includes a second high-side rectifier switch SR2, a second low-side rectifier switch SR5, and a second input node E1. The second high-side rectifier switch SR2 and the second low-side rectifier switch SR5 are connected in series and coupled. The second high-side rectifier switch SR2 is coupled to the first high-side rectifier switch SR1, and the second low-side rectifier switch SR5 is coupled to the first low-side rectifier switch SR4. The second input node E1 is located between the second high-side rectifier switch SR2 and the second low-side rectifier switch SR5, and is coupled to the secondary coil winding 42A and the secondary coil winding 42B. The second switching unit 53 includes a third high-side rectifier switch SR3, a third low-side rectifier switch SR6, and a third input node F1. The third high-side rectifier switch SR3 and the third low-side rectifier switch SR6 are connected in series and coupled. One end of the third high-side rectifier switch SR3 is coupled to the second high-side rectifier switch SR2, and one end of the third low-side rectifier switch SR6 is coupled to the second low-side rectifier switch SR5. The third input node F1 is located between the third high-side rectifier switch SR3 and the third low-side rectifier switch SR6, and is coupled to the secondary winding 42B and the secondary winding 42C. The first input node D1, the second input node E1, and the third input node F1 are coupled to the secondary side of the first transformer T1, the secondary side of the second transformer T2, and the secondary side of the third transformer T3 in a delta connection.

[0022] The first high-side switch S1, the first low-side switch S4, the second high-side switch S2, the second low-side switch S5, the third high-side switch S3, the third low-side switch S6, the first high-side rectifier switch SR1, the first low-side rectifier switch SR4, the second high-side rectifier switch SR2, the second low-side rectifier switch SR5, the third high-side rectifier switch SR3, and the third low-side rectifier switch SR6 may be metal-oxide-semiconductor field-effect transistors (MOSFETs), trench MOSFETs, or insulated-gate bipolar transistors (IGBTs). The foregoing is merely an example and is not intended to limit this application.

[0023] The output circuit 60 is coupled to the second switching circuit 50. Specifically, the output circuit 60 includes an output capacitor Cout and a load resistor RL connected in parallel; one end of the output capacitor Cout is coupled to a third high-side rectifier switch SR3 and one end of the load resistor RL, and the other end of the output capacitor Cout is coupled to a third low-side rectifier switch SR6 and the other end of the load resistor RL. In other words, the output capacitor Cout is coupled in parallel with the third switching unit 53.

[0024] Please refer to Figure 1B, which is a block diagram illustrating a first switching circuit and a controller according to an embodiment of this application. As shown in Figure 1B, the resonant converter further includes a controller 70. The controller 70 is coupled to a first high-side switch S1, a first low-side switch S4, a second high-side switch S2, a second low-side switch S5, a third high-side switch S3, and a third low-side switch S6 to generate and transmit a plurality of control signals. The control signals of the first high-side switch S1, the second high-side switch S2, the third high-side switch S3, the first low-side switch S4, the second low-side switch S5, and the third low-side switch S6 are respectively labeled as Vgs1, Vgs2, Vgs3, Vgs4, Vgs5, and Vgs6.

[0025] The following analysis will focus on the control signal Vgs1 of the first high-side switch S1, the control signal Vgs2 of the second high-side switch S2, the control signal Vgs3 of the third high-side switch S3, the control signal Vgs4 of the first low-side switch S4, the control signal Vgs5 of the second low-side switch S5, and the control signal Vgs6 of the third low-side switch S6. Please refer further to FIG1C, which is a timing diagram illustrating the control signals of the first switch circuit according to an embodiment of this application. As shown in FIG1C and in conjunction with FIG1B, the phase difference between the control signal Vgs1 of the first high-side switch S1 and the control signal Vgs4 of the first low-side switch S4 is 180 degrees; in other words, the control signal Vgs1 of the first high-side switch S1 and the control signal Vgs4 of the first low-side switch S4 are complementary. The control signal Vgs2 of the second high-side switch S2 and the control signal Vgs5 of the second low-side switch S5 have a phase difference of 180 degrees; in other words, the control signals Vgs2 and Vgs5 of the second high-side switch S2 and the second low-side switch S5 are complementary. The control signal Vgs3 of the third high-side switch S3 and the control signal Vgs6 of the third low-side switch S6 have a phase difference of 180 degrees; in other words, the control signals Vgs3 and Vgs6 of the third high-side switch S3 and the third low-side switch S6 are complementary.

[0026] The phase difference between the control signal Vgs1 of the first high-side switch S1 and the control signal Vgs2 of the second high-side switch S1 is 120 degrees, and the phase difference between the control signal Vgs1 of the first high-side switch S1 and the control signal Vgs3 of the third high-side switch S3 is 240 degrees; in other words, the phase difference between the control signal Vgs2 of the second high-side switch S2 and the control signal Vgs3 of the third high-side switch S3 is 120 degrees. Due to the complementary relationships between the control signals Vgs1 and Vgs4 of the first high-side switch S1, the second high-side switch S2 and Vgs5 of the second low-side switch S5, and the third high-side switch S3 and Vgs6 of the third low-side switch S6, the phase difference between the control signals Vgs4 and Vgs5 of the first low-side switch S4 and the second low-side switch S5 is 120 degrees, and the phase difference between the control signals Vgs4 and Vgs6 of the first low-side switch S4 and the third low-side switch S6 is 240 degrees.

[0027] Given the phase difference between the control signals Vgs1 and Vgs2 of the first high-side switch S1, the phase difference between the control signals Vgs1 and Vgs3 of the first high-side switch S1 and the third high-side switch S3, the phase difference between the control signals Vgs4 and Vgs5 of the first low-side switch S4 and the second low-side switch S5, and the phase difference between the control signals Vgs4 and Vgs6 of the first low-side switch S4 and the third low-side switch S6, there is a phase difference between the current output by the first switching unit 21 and the current output by the first switching unit 22, and a phase difference between the current output by the first switching unit 21 and the current output by the first switching unit 23. In other words, the three currents output by the first switching units 21, 22, and 23 are the three-phase currents of the first switching circuit 20.

[0028] Since the conduction time of the first high-side switch S1, the conduction time of the second high-side switch S2 and the conduction time of the third high-side switch S3 are not the same, and the conduction time of the first low-side switch S4, the conduction time of the second low-side switch S5 and the third low-side switch S6 are not the same, and the first switch circuit 20 generates input current according to the input voltage, the input current of the first switch circuit 20 can be at least one of the three input currents output by the first switch units 21, 22 and 23.

[0029] Referring again to Figure 1A, the input current flows into at least one of the first resonant tank 31, the second resonant tank 32, and the third resonant tank 33. At least one of the first resonant tank 31, the second resonant tank 32, and the third resonant tank 33 generates a resonant current based on the input current. The resonant current output from the resonant circuit 30 to the transformer circuit 40 is at least one of the resonant currents of the first resonant tank 31, the second resonant tank 32, and the third resonant tank 33. Subsequently, the primary side of the transformer circuit 40 generates a first voltage and a first current based on the resonant current, where the value of the first current is less than the value of the resonant current; the secondary side of the transformer circuit 40 generates a second voltage and a second current based on the first voltage and the first current.

[0030] To prevent the first high-side switch S1 and the first low-side switch S4 from being simultaneously turned on, a first dead time td1 is established between the control signal Vgs1 of the first high-side switch S1 and the control signal Vgs4 of the first low-side switch S4. Specifically, a first dead time td1 is established between the rising edge of the control signal Vgs1 of the first high-side switch S1 and the falling edge of the control signal Vgs4 of the first low-side switch S4, and a first dead time td1 is established between the falling edge of the control signal Vgs1 of the first high-side switch S1 and the rising edge of the control signal Vgs4 of the first low-side switch S4. Correspondingly, a first dead time td1 is established between the control signal Vgs2 of the second high-side switch S2 and the control signal Vgs5 of the second low-side switch S5, and a first dead time td1 is also established between the control signal Vgs3 of the third high-side switch S3 and the control signal Vgs6 of the third low-side switch S6. By configuring the first dead time t d1, the switching losses of the switching elements are reduced.

[0031] Please refer to FIG1D, which is a block diagram illustrating a second switching circuit and a controller according to an embodiment of the present application. As shown in FIG1D, the controller 70 is coupled to a first high-side rectifier switch SR1, a first low-side rectifier switch SR4, a second high-side rectifier switch SR2, a second low-side rectifier switch SR5, a third high-side rectifier switch SR3, and a third low-side rectifier switch SR6 to generate and transmit a plurality of control signals. The control signals of the first high-side rectifier switch SR1, the second high-side rectifier switch SR2, the third high-side rectifier switch SR3, the first low-side rectifier switch SR4, the second low-side rectifier switch SR5, and the third low-side rectifier switch SR6 are respectively labeled as Vgs7, Vgs8, Vgs9, Vgs10, Vgs11, and Vgs12.

[0032] The following describes the control signals Vgs7 of the first high-side rectifier switch SR1, Vgs8 of the second high-side rectifier switch SR2, Vgs9 of the third high-side rectifier switch SR3, Vgs10 of the first low-side rectifier switch SR4, Vgs11 of the second low-side rectifier switch SR5, and Vgs12 of the third low-side rectifier switch SR6. Please further refer to FIG1E, which is a timing diagram illustrating the control signals of the second switching circuit according to an embodiment of this application. As shown in FIG1E and in conjunction with FIG1D, the phase difference between the control signal Vgs7 of the first high-side rectifier switch SR1 and the control signal Vgs10 of the first low-side rectifier switch SR4 is 180 degrees; in other words, the control signal Vgs7 of the first high-side rectifier switch SR1 and the control signal Vgs10 of the first low-side rectifier switch SR4 are complementary. The control signal Vgs8 of the second high-side rectifier switch SR2 and the control signal Vgs11 of the second low-side rectifier switch SR5 have a phase difference of 180 degrees; in other words, the control signals Vgs8 of the second high-side rectifier switch SR2 and Vgs11 of the second low-side rectifier switch SR5 are complementary. The control signal Vgs9 of the third high-side rectifier switch SR3 and the control signal Vgs12 of the third low-side rectifier switch SR6 have a phase difference of 180 degrees; in other words, the control signals Vgs9 of the third high-side rectifier switch SR3 and Vgs12 of the third low-side rectifier switch SR6 are complementary.

[0033] The phase difference between the control signal Vgs7 of the first high-side rectifier switch SR1 and the control signal Vgs8 of the second high-side rectifier switch SR2 is 120 degrees, and the phase difference between the control signal Vgs7 of the first high-side rectifier switch SR1 and the control signal Vgs9 of the third high-side rectifier switch SR3 is 240 degrees; in other words, the phase difference between the control signal Vgs8 of the second high-side rectifier switch SR2 and the control signal Vgs9 of the third high-side rectifier switch SR3 is 120 degrees. Due to the complementary relationships between the control signals Vgs7 and Vgs10 of the first high-side rectifier switch SR1, the second high-side rectifier switch SR2's control signal Vgs8 and the second low-side rectifier switch SR5's control signal Vgs11, and the third high-side rectifier switch SR3's control signal Vgs9 and the third low-side rectifier switch SR6's control signal Vgs12, the phase difference between the control signals Vgs10 and Vgs11 of the first low-side rectifier switch SR4 and the second low-side rectifier switch SR5 is 120 degrees, and the phase difference between the control signals Vgs10 and Vgs12 of the first low-side rectifier switch SR4 and the third low-side rectifier switch SR6 is 240 degrees.

[0034] To prevent the first high-side rectifier switch SR1 and the first low-side rectifier switch SR4 from being turned on simultaneously, there is a second dead time td2 between the control signal Vgs7 of the first high-side rectifier switch SR1 and the control signal Vgs10 of the first low-side rectifier switch SR4. Specifically, there is a second dead time td2 between the rising edge of the control signal Vgs7 of the first high-side rectifier switch SR1 and the falling edge of the control signal Vgs10 of the first low-side rectifier switch SR4, and a second dead time td2 between the falling edge of the control signal Vgs7 of the first high-side rectifier switch SR1 and the rising edge of the control signal Vgs10 of the first low-side rectifier switch SR4. Accordingly, a second dead time td2 exists between the control signal Vgs8 of the second high-side rectifier switch SR2 and the control signal Vgs11 of the second low-side rectifier switch SR5, and a second dead time td2 also exists between the control signal Vgs9 of the third high-side rectifier switch SR3 and the control signal Vgs12 of the third low-side rectifier switch SR6. The configuration of the second dead time td2 reduces switching losses of the switching elements.

[0035] According to the timing diagrams shown in Figures 1C and 1E, and in conjunction with Figures 1B and 1D, the timing of the first switching unit 21 is consistent with the timing of the second switching unit 51, the timing of the first switching unit 22 is consistent with the timing of the second switching unit 52, and the timing of the first switching unit 23 is consistent with the timing of the second switching unit 53. In other words, the timing of the control signal of the first switching circuit 20 located on the primary side of the transformer circuit 40 is consistent with the timing of the second switching circuit 50 located on the secondary side of the transformer circuit 40.

[0036] Referring again to Figure 1A, since the turn-on times of the first high-side rectifier switch SR1, the second high-side rectifier switch SR2, and the third high-side rectifier switch SR3 are not the same, and the turn-on times of the first low-side rectifier switch SR4, the second low-side rectifier switch SR5, and the third low-side rectifier switch SR6 are not the same, the second voltage generated on the secondary side of the transformer circuit 40 is input to at least one of the second switching units 51, 52, and 53. Subsequently, at least one of the second switching units 51, 52, and 53 generates an output current based on the second voltage, and the output current flows to the output capacitor Cout and the load resistor RL, respectively, to generate an output voltage.

[0037] The operating mechanism of the resonant converter will be described below with reference to Figures 1A, 1C, and 1E. During the period from time t0 to time t1, the first high-side switch S1 is off, and the first low-side switch S4 is on; the second high-side switch S2 is off, and the second low-side switch S5 is on; the third high-side switch S3 is on, and the third low-side switch S6 is off. The third high-side switch S3 generates and transmits an input current to the third resonant tank 33 based on the input voltage, and the third resonant tank 33 generates a resonant current based on the input current of the third high-side switch S3. Subsequently, the primary side of the third transformer T3 generates a first voltage and a first current based on the resonant current of the third resonant tank 33, and the secondary side of the third transformer T3 generates a second voltage and a second current based on the first voltage and the first current.

[0038] Accordingly, the first high-side rectifier switch SR1 is turned off, and the first low-side rectifier switch SR4 is turned on; the second high-side rectifier switch SR2 is turned off, and the second low-side rectifier switch SR5 is turned on; the third high-side rectifier switch SR3 is turned on, and the third low-side rectifier switch SR6 is turned off. The third high-side rectifier switch SR3 generates an output current based on the second voltage on the secondary side of the third transformer T3. The output current is input to the output capacitor Cout and the load resistor RL to generate an output voltage.

[0039] During the period from time point t1 to time point t2, the first high-side switch S1 is turned on, and the first low-side switch S4 is turned off; the second high-side switch S2 is turned off, and the second low-side switch S5 is turned on; the third high-side switch S3 is turned on, and the third low-side switch S6 is turned off. The first high-side switch S1 and the third high-side switch S3 generate and transmit input current to the first resonant tank 31 and the third resonant tank 33 respectively based on the input voltage. The first resonant tank 31 generates a resonant current based on the input current of the first high-side switch S1, and the third resonant tank 33 generates a resonant current based on the input current of the third high-side switch S3. Subsequently, the primary side of the first transformer T1 and the primary side of the second transformer T2 generate a first voltage and a first current based on the resonant current of the first resonant tank 31, and the primary side of the third transformer T3 generates a first voltage and a first current based on the resonant current of the third resonant tank 33. The secondary side of the first transformer T1 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the first transformer T1. The secondary side of the second transformer T2 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the second transformer T2. The secondary side of the third transformer T3 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the third transformer T3.

[0040] Accordingly, the first high-side rectifier switch SR1 is turned on, and the first low-side rectifier switch SR4 is turned off; the second high-side rectifier switch SR2 is turned off, and the second low-side rectifier switch SR5 is turned on; the third high-side rectifier switch SR3 is turned on, and the third low-side rectifier switch SR6 is turned off. The first high-side rectifier switch SR1 generates an output current based on the second voltage on the secondary side of the first transformer T1, and the third high-side rectifier switch SR3 generates an output current based on the second voltage on the secondary side of the third transformer T3. The output currents of the first high-side rectifier switch SR1 and the third high-side rectifier switch SR3 are input to the output capacitor Cout and the load resistor RL to generate an output voltage.

[0041] During the period from time point t2 to time point t3, the first high-side switch S1 is turned on, and the first low-side switch S4 is turned off; the second high-side switch S2 is turned off, and the second low-side switch S5 is turned on; the third high-side switch S3 is turned off, and the third low-side switch S6 is turned on. The first high-side switch S1 generates and transmits an input current to the first resonant tank 31 based on the input voltage, and the first resonant tank 31 generates a resonant current based on the input current of the first high-side switch S1. Subsequently, the primary side of the first transformer T1 generates a first voltage and a first current based on the resonant current of the first resonant tank 31; the secondary side of the first transformer T1 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the first transformer T1.

[0042] Accordingly, the first high-side rectifier switch SR1 is turned on, and the first low-side rectifier switch SR4 is turned off; the second high-side rectifier switch SR2 is turned off, and the second low-side rectifier switch SR5 is turned on; the third high-side rectifier switch SR3 is turned off, and the third low-side rectifier switch SR6 is turned on. The first high-side rectifier switch SR1 generates an output current based on the second voltage on the secondary side of the first transformer T1. The output current of the first high-side rectifier switch SR1 is input to the output capacitor Cout and the load resistor RL to generate an output voltage.

[0043] During the period from time point t3 to time point t4, the first high-side switch S1 is turned on and the first low-side switch S4 is turned off; the second high-side switch S2 is turned on and the second low-side switch S5 is turned off; the third high-side switch S3 is turned off and the third low-side switch S6 is turned on. The first high-side switch S1 generates and transmits an input current to the first resonant tank 31 based on the input voltage, and the second high-side switch S2 generates and transmits an input current to the second resonant tank 32 based on the input voltage; the first resonant tank 31 generates a resonant current based on the input current of the first high-side switch S1, and the second resonant tank 32 generates a resonant current based on the input current of the second high-side switch S2. Subsequently, the primary side of the first transformer T1 generates a first voltage and a first current based on the resonant current of the first resonant tank 31, and the primary sides of the second transformer T2 and the third transformer T3 generate a first voltage and a first current based on the resonant current of the first resonant tank 31 and the resonant current of the second resonant tank 32, respectively. The secondary side of the first transformer T1 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the first transformer T1. The secondary side of the second transformer T2 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the second transformer T2. The secondary side of the third transformer T3 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the third transformer T3.

[0044] Accordingly, the first high-side rectifier switch SR1 is turned on, and the first low-side rectifier switch SR4 is turned off; the second high-side rectifier switch SR2 is turned on, and the second low-side rectifier switch SR5 is turned off; the third high-side rectifier switch SR3 is turned off, and the third low-side rectifier switch SR6 is turned on. The first high-side rectifier switch SR1 generates an output current based on the second voltage on the secondary side of the first transformer T1, and the second high-side rectifier switch SR2 generates an output current based on the second voltage on the secondary side of the second transformer T2. The output currents of the first high-side rectifier switch SR1 and the second high-side rectifier switch SR2 are input to the output capacitor Cout and the load resistor RL to generate an output voltage.

[0045] During the period from time point t4 to time point t5, the first high-side switch S1 is turned off, and the first low-side switch S4 is turned on; the second high-side switch S2 is turned on, and the second low-side switch S5 is turned off; the third high-side switch S3 is turned off, and the third low-side switch S6 is turned on. The second high-side switch S2 generates and transmits an input current to the second resonant tank 32 based on the input voltage, and the second resonant tank 32 generates a resonant current based on the input current of the second high-side switch S2. Subsequently, the primary side of the second transformer T2 generates a first voltage and a first current based on the resonant current of the second resonant tank 32; the secondary side of the second transformer T2 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the second transformer T2.

[0046] Accordingly, the first high-side rectifier switch SR1 is turned off, and the first low-side rectifier switch SR4 is turned on; the second high-side rectifier switch SR2 is turned on, and the second low-side rectifier switch SR5 is turned off; the third high-side rectifier switch SR3 is turned off, and the third low-side rectifier switch SR6 is turned on. The second high-side rectifier switch SR2 generates an output current based on the second voltage on the secondary side of the second transformer T2. The output current of the second high-side rectifier switch SR2 is input to the output capacitor Cout and the load resistor RL to generate an output voltage.

[0047] During the period from time point t5 to time point t6, the first high-side switch S1 is turned off, and the first low-side switch S4 is turned on; the second high-side switch S2 is turned on, and the second low-side switch S5 is turned off; the third high-side switch S3 is turned on, and the third low-side switch S6 is turned off. The second high-side switch S2 generates and transmits an input current to the second resonant tank 32 based on the input voltage, and the third high-side switch S3 generates and transmits an input current to the third resonant tank 33 based on the input voltage; the second resonant tank 32 generates a resonant current based on the input current of the second high-side switch S2, and the third resonant tank 33 generates a resonant current based on the input current of the third high-side switch S3. Subsequently, the primary side of the second transformer T2 generates a first voltage and a first current based on the resonant current of the second resonant tank 32; the primary side of the third transformer T3 generates a first voltage and a first current based on the resonant current of the third resonant tank 33. The secondary side of the second transformer T2 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the second transformer T2. The secondary side of the third transformer T3 generates a second voltage and a second current based on the first voltage and the first current of the primary side of the third transformer T3.

[0048] Accordingly, the first high-side rectifier switch SR1 is turned off, and the first low-side rectifier switch SR4 is turned on; the second high-side rectifier switch SR2 is turned on, and the second low-side rectifier switch SR5 is turned off; the third high-side rectifier switch SR3 is turned on, and the third low-side rectifier switch SR6 is turned off. The second high-side rectifier switch SR2 generates an output current based on the second voltage on the secondary side of the second transformer T2, and the third high-side rectifier switch SR3 generates an output current based on the second voltage on the secondary side of the third transformer T3. The output currents of the second high-side rectifier switch SR2 and the third high-side rectifier switch SR3 are input to the output capacitor Cout and the load resistor RL to generate an output voltage.

[0049] Please refer to Figure 1F, which is a timing diagram illustrating the input current, resonant current, excitation current, and second current according to an embodiment of this application. As shown in Figure 1F and in conjunction with Figure 1A, the input current of the first switching unit 21 is labeled as i ph1, the input current of the first switching unit 22 is labeled as i ph2, the input current of the first switching unit 23 is labeled as i ph3, the current flowing into the primary side of the transformer circuit 40 is labeled as i pri, the excitation current flowing through the excitation inductor Lm1 is labeled as i Lm, and the second current generated on the secondary side of the transformer circuit 40 is labeled as i sec. The input current i ph1 of the first switching unit 21 and the input current i ph2 of the first switching unit 22 have a first phase difference of 120 degrees; the input current i ph1 of the first switching unit 21 and the input current i ph3 of the first switching unit 23 have a second phase difference of 240 degrees. The timing of the current ipri flowing into the primary side of transformer circuit 40 is consistent with the timing of the second current isec generated on the secondary side of transformer circuit 40. Since the primary side coil winding 41A and the magnetizing inductor Lm1 are connected in parallel, the peak value of the magnetizing current iLm of the magnetizing inductor Lm1 is less than the peak value of the current ipri flowing into the primary side of transformer circuit 40.

[0050] Please refer to Figure 1G, which is a timing diagram illustrating the control signals of the first high-side switch and the first high-side rectifier switch according to an embodiment of this application. As shown in Figure 1G, the conduction time of the control signal Vgs7 of the first high-side rectifier switch SR1 is less than the conduction time of the control signal Vgs1 of the first high-side switch S1. Specifically, the start time of the conduction time of the control signal Vgs7 of the first high-side rectifier switch SR1 is shortened by a predetermined time interval tp1 compared to the start time of the conduction time of the control signal Vgs1 of the first high-side switch S1, and the end time of the conduction time of the control signal Vgs7 of the first high-side rectifier switch SR1 is shortened by a predetermined time interval tp1 compared to the end time of the conduction time of the control signal Vgs1 of the first high-side switch S1. By adjusting the on-time of the control signal Vgs7 of the first high-side rectifier switch SR1 and the on-time of the control signal Vgs1 of the first high-side switch S1, malfunctions of the second switch circuit 50 can be avoided.

[0051] Similarly, the on-time of the control signal Vgs8 of the second high-side rectifier switch SR2 is less than the on-time of the control signal Vgs2 of the second high-side switch S2, and the on-time of the control signal Vgs9 of the third high-side rectifier switch SR3 is less than the on-time of the control signal Vgs3 of the third high-side switch S3. The on-time of the control signal Vgs10 of the first low-side rectifier switch SR4 is less than the on-time of the control signal Vgs4 of the first low-side switch S4, the on-time of the control signal Vgs11 of the second low-side rectifier switch SR5 is less than the on-time of the control signal Vgs5 of the second low-side switch S5, and the on-time of the control signal Vgs12 of the third low-side rectifier switch SR6 is less than the on-time of the control signal Vgs6 of the third low-side switch S6.

[0052] In the resonant converter of this embodiment, ZVS or ZCS is achieved through the configuration of the resonant circuit and the adjustment of the switching frequency of the first switching circuit, thereby improving the conversion efficiency of the power converter. By configuring the first dead time and the second dead time, the simultaneous conduction of the upper arm switch (i.e., high-side switch) and the lower arm switch (i.e., low-side switch) of the first switching unit, and the simultaneous conduction of the upper arm switch (i.e., high-side rectifier switch) and the lower arm switch (i.e., low-side rectifier switch) of the second switching unit, is prevented, thereby reducing the switching losses of the switching elements.

[0053] Please refer to Figure 2, which is a circuit diagram of a half-bridge to half-bridge resonant converter. As shown in Figure 2, the half-bridge to half-bridge resonant converter includes an input circuit 10, a first switching circuit 20, a resonant circuit 30, a transformer circuit 40, a second switching circuit 50, and an output circuit 60. The component configuration of the half-bridge to half-bridge resonant converter shown in Figure 2 is similar to that of the resonant converter shown in Figure 1A. Therefore, the similarities between the half-bridge to half-bridge resonant converter and the resonant converter will not be described again here. However, the half-bridge-half-bridge resonant converter shown in Figure 2 still differs from the resonant converter shown in Figure 1A: the first resonant inductor Lr1 is connected in series with the primary winding 41A of the first transformer T1, the second resonant inductor Lr2 is connected in series with the primary winding 41B of the second transformer T2, the third resonant inductor Lr3 is connected in series with the primary winding 41C of the third transformer T3, and the output circuit 60 further includes two capacitors C21 and C22 connected in series, and the secondary winding 42B of the second transformer T2 is coupled with two capacitors C21 and C22. In addition, in the half-bridge-half-bridge resonant converter, the neutral point of the primary side and the neutral point of the secondary side of the transformer circuit 40 are coupled to the ground terminal of the primary side and the ground terminal of the secondary side of the transformer circuit 40, respectively. In the resonant converter shown in Figure 1A, the neutral point of the primary side and the neutral point of the secondary side of the transformer circuit 40 are not coupled to the ground terminal of the primary side and the ground terminal of the secondary side of the transformer circuit 40.

[0054] Under the same ZVS current conditions, the specifications of the half-bridge-half-bridge resonant converter and the specifications of the resonant converter of this application can be set as shown in Table 1 and Table 2.

[0055] Table 1 Electrical specifications Half-bridge to half-bridge resonant converter The resonant converter of this application Input voltage 400V 400V Output voltage 49.58 V 49.54V Output Wattage 10 kW 10 kW Switching frequency 100 kHz 100 kHz Operating point (full load) At the resonant point At the resonant point Coss of the primary side switch capacitor (IMW65R050M2H) 190 pF 190 pF Dead Time 50 ns 50 ns Circle ratio 16:2 16:2 Magnetizing inductor 157.34 µH 420.32 µH Resonant capacitor 1.37 µF 597.41 nF Resonant inductor 1.2 µH 1.2 µH Leakage 0.65 µH 0.64 µH

[0056] It should be noted that the turns ratio of the first transformer T1, the turns ratio of the second transformer T2, and the turns ratio of the third transformer T3 are all set to the turns ratios shown in Table 1. The first dead time td1 shown in Figure 1C and the second dead time td2 shown in Figure 1E are all set to the dead times shown in Table 1. The magnetizing inductors Lm1, Lm2, and Lm3 are all set to the magnetizing inductors shown in Table 1. The first resonant capacitor Cr1, the second resonant capacitor Cr2, and the third resonant capacitor Cr3 are all set to the resonant capacitors shown in Table 1. The first resonant inductor Lr1, the second resonant inductor Lr2, and the third resonant inductor Lr3 are all set to the resonant inductors shown in Table 1.

[0057] Table 2 Core Specifications Half-bridge to half-bridge resonant converter The resonant converter of this application Cross-sectional area (Ae) of the central post of the magnetic core 174.04 mm 2 174.04 mm 2 Material KF9 KF9 Maximum magnetic flux density Bmax (hypothetical) 0.25T 0.25T Primary coil 0.1 * 500 shares 0.1 * 500 shares Secondary coil 0.6mm copper sheet 0.6mm copper sheet Circle ratio 16:2 16:2 air gap 0.38 mm 0.12 mm

[0058] It should be noted that the primary winding 41A of the first transformer T1, the primary winding 41B of the second transformer T2, and the primary winding 41C of the third transformer T3 are all set as the primary windings shown in Table 2. The secondary winding 42A of the first transformer T1, the secondary winding 42B of the second transformer T2, and the secondary winding 42C of the third transformer T3 are all set as the secondary windings shown in Table 2.

[0059] The performance of the half-bridge to half-bridge resonant converter and the resonant converter of this application are shown in Table 3.

[0060] Table 3 Performance parameters Half-bridge to half-bridge resonant converter The resonant converter of this application Peak primary-side switching current (A) 26.28 26.2 Effective value of primary side switching current (A) 13.15 13.08 Effective value of primary transformer current (A) 18.59 10.68 Number of components in a primary-side switch 6 6 Peak secondary-side switching current (A) 208.2 207.59 RMS value of secondary-side switching current (A) 103.97 103.76 RMS value of secondary transformer current (A) 147.02 84.67 Number of components in the secondary side switch 6 6 RMS value of resonant inductor current (A) 18.59 18.5

[0061] It should be noted that the primary-side switch in Table 3 is the first switching circuit 20, the primary-side transformer in Table 3 is the primary side of the transformer circuit 40, the secondary-side switch in Table 3 is the second switching circuit 50, the secondary-side transformer in Table 3 is the secondary side of the transformer circuit 40, and the effective value of the resonant inductor current in Table 3 can be the effective value of the resonant inductor current of the first resonant inductor Lr1, the effective value of the resonant inductor current of the second resonant inductor Lr2, or the effective value of the resonant inductor current of the third resonant inductor Lr3. According to Table 3, the resonant converter of this application has a smaller coil current stress in the transformer circuit 40 and a smaller air gap.

[0062] The losses of the resonant converter and the half-bridge-half-bridge resonant converter of this application will be further described below. In the half-bridge-half-bridge resonant converter, the core loss of the transformer circuit 40 is 2.71W, the copper loss on the primary side of the transformer circuit 40 is 3.96W, the copper loss on the secondary side of the transformer circuit 40 is 9.11W, and the total loss of the transformer circuit 40 is 15.75W; the magnetic field of the core of the transformer circuit 40 is 0.175T. In the resonant converter of this application, the core loss of the transformer circuit 40 is 8.43W, the copper loss on the primary side of the transformer circuit 40 is 1.31W, the copper loss on the secondary side of the transformer circuit 40 is 3W, and the total loss of the transformer circuit 40 is 12.74W; the magnetic field of the core of the transformer circuit 40 is 0.24T. According to the foregoing, when the resonant converter of this application is applied to a high-current, low-voltage circuit, the total loss of the transformer circuit 40 is relatively small.

[0063] Please refer to Figure 3, which is a circuit diagram of a full-bridge-full-bridge resonant converter. As shown in Figure 3, the full-bridge-full-bridge resonant converter includes an input circuit 10A, a first switching circuit 20A, a resonant circuit 30A, a transformer circuit 40A, a second switching circuit 50A, and an output circuit 60A.

[0064] The input circuit 10A includes a voltage source VS1. The configuration of the voltage source VS1 shown in Figure 3 is similar to that shown in Figure 1A, and will not be described again. The first switching circuit 20A includes three first switching units 21A, 22A, and 23A that are coupled in parallel to each other. The first switching unit 21A includes two first high-side switches S11 and S12, two first low-side switches S13 and S14, and first output nodes A11 and A12. The first high-side switch S11 and the first low-side switch S13 are coupled in series, and the first high-side switch S12 and the first low-side switch S14 are coupled in series. The first output node A11 is located between the first high-side switch S11 and the first low-side switch S13, and the first output node A12 is located between the first high-side switch S12 and the first low-side switch S14. The first switching unit 22A includes two second high-side switches S15 and S16, two second low-side switches S17 and S18, and second output nodes B11 and B12. The second high-side switch S15 and the second low-side switch S17 are connected in series, and the second high-side switch S16 and the second low-side switch S18 are connected in series. The second output node B11 is located between the second high-side switch S15 and the second low-side switch S17, and the second output node B12 is located between the second high-side switch S16 and the second low-side switch S18. The first switching unit 23A includes two third high-side switches S19 and S20, two third low-side switches S21 and S22, and third output nodes C11 and C12. The third high-side switch S19 and the third low-side switch S21 are connected in series and coupled together; the third high-side switch S20 and the third low-side switch S22 are connected in series and coupled together; the third output node C11 is located between the third high-side switch S19 and the third low-side switch S21, and the third output node C12 is located between the third high-side switch S20 and the third low-side switch S22.

[0065] The resonant circuit 30A includes a first resonant slot 31A, a second resonant slot 32A, and a third resonant slot 33A. The first resonant slot 31A includes a first resonant inductor Lr11 and a first resonant capacitor Cr11 connected in series; the first resonant capacitor Cr11 is coupled to the first output node A11, and the first resonant inductor Lr11 is coupled to the primary side of the transformer circuit 40A. The second resonant slot 32A includes a second resonant inductor Lr12 and a second resonant capacitor Cr12 connected in series; the second resonant capacitor Cr12 is coupled to the second output node B11, and the second resonant inductor Lr12 is coupled to the primary side of the transformer circuit 40A. The third resonant slot 33A includes a third resonant inductor Lr13 and a third resonant capacitor Cr13 connected in series; the third resonant capacitor Cr13 is coupled to the third output node C11, and the third resonant inductor Lr13 is coupled to the primary side of the transformer circuit 40A.

[0066] The transformer circuit 40A includes a first transformer T11, a second transformer T12, and a third transformer T13. The primary side of the first transformer T11 is coupled to a first resonant inductor Lr11 and a first output node A12, and the primary side of the first transformer T11 includes a magnetizing inductor Lm11. The primary side of the second transformer T12 is coupled to a second resonant inductor Lr12 and a second output node B12, and the primary side of the second transformer T12 includes a magnetizing inductor Lm12. The primary side of the third transformer T13 is coupled to a third resonant inductor Lr13 and a third output node C12, and the primary side of the third transformer T13 includes a magnetizing inductor Lm13.

[0067] The second switching circuit 50A includes three second switching units 51A, 52A, and 53A that are coupled in parallel to each other. The second switching unit 51A includes first high-side rectifier switches SR11 and SR12, first low-side rectifier switches SR13 and SR14, first input nodes D11 and D12, and capacitor C100; the first high-side rectifier switch SR11 and the first low-side rectifier switch SR13 are coupled in series, and the first high-side rectifier switch SR12 and the first low-side rectifier switch SR14 are coupled in series; the first input node D11 is disposed between the first high-side rectifier switch SR11 and the first low-side rectifier switch SR13, the first input node D12 is disposed between the first high-side rectifier switch SR12 and the first low-side rectifier switch SR14, and the first input nodes D11 and D12 are coupled to the secondary side of the first transformer T11. One end of capacitor C100 is coupled to the first high-side rectifier switch SR12, and the other end of capacitor C100 is coupled to the first low-side rectifier switch SR14.

[0068] The second switching unit 52A includes second high-side rectifier switches SR15 and SR16, second low-side rectifier switches SR17 and SR18, second input nodes E11 and E12, and capacitor C200. The second high-side rectifier switch SR15 and the second low-side rectifier switch SR17 are connected in series, and the second high-side rectifier switch SR16 and the second low-side rectifier switch SR18 are connected in series. The second input node E11 is located between the second high-side rectifier switch SR15 and the second low-side rectifier switch SR17, and the second input node E12 is located between the second high-side rectifier switch SR16 and the second low-side rectifier switch SR18. The second input nodes E11 and E12 are coupled to the secondary side of the second transformer T12. One end of capacitor C200 is coupled to the second high-side rectifier switch SR16, and the other end of capacitor C200 is coupled to the second low-side rectifier switch SR18. The third switching unit 53A includes third high-side rectifier switches SR19 and SR20, third low-side rectifier switches SR21 and SR22, third input nodes F11 and F12, and capacitor C300. The third high-side rectifier switch SR19 and the third low-side rectifier switch SR21 are connected in series, and the third high-side rectifier switch SR20 and the third low-side rectifier switch SR22 are connected in series. The third input node F11 is located between the third high-side rectifier switches SR19 and SR21, and the third input node F12 is located between the third high-side rectifier switches SR20 and SR22. The third input nodes F11 and F12 are coupled to the secondary side of the third transformer T13. One end of capacitor C300 is coupled to the third high-side rectifier switch SR20, and the other end of capacitor C300 is coupled to the third low-side rectifier switch SR22.

[0069] The output circuit 60A includes an output capacitor Cout connected in parallel with each other and a load resistor RL. The configuration of the output capacitor Cout and the load resistor RL shown in Figure 3 is similar to that shown in Figure 1A, and will not be described again.

[0070] Under the same ZVS current conditions, the specifications of the full-bridge-full-bridge resonant converter can be set as shown in Tables 4 and 5. The specifications of the resonant converter of this application are shown in Tables 1 and 2.

[0071] Table 4 Electrical specifications Full-bridge to full-bridge resonant converter Input voltage 400V Output voltage 49.58 V Output Wattage 10 kW Switching frequency 100 kHz Operating point (full load) At the resonant point Coss of the primary side switch capacitor (IMW65R050M2H) 190 pF Dead Time 50 ns Circle ratio 16:2 Magnetizing inductor 157.34 µH Resonant capacitor 1.37 µF Resonant inductor 1.2 µH Leakage 0.65 µH

[0072] It should be noted that the turns ratio of the first transformer T11, the turns ratio of the second transformer T12, and the turns ratio of the third transformer T13 are all set to the turns ratios shown in Table 4. The dead time of the switching element of the first switching circuit 20A and the dead time of the switching element of the second switching circuit 50A are all set to the dead time shown in Table 4. The magnetizing inductors Lm11, Lm12, and Lm13 are all set to the magnetizing inductors shown in Table 4. The first resonant capacitor Cr11, the second resonant capacitor Cr12, and the third resonant capacitor Cr13 are all set to the resonant capacitors shown in Table 1. The first resonant inductor Lr11, the second resonant inductor Lr12, and the third resonant inductor Lr13 are all set to the resonant inductors shown in Table 1.

[0073] Table 5 Core Specifications Half-bridge to half-bridge resonant converter Cross-sectional area (Ae) of the central post of the magnetic core 174.04 mm 2 Material KF9 Maximum magnetic flux density Bmax (hypothetical) 0.25T Primary coil 0.1 * 500 shares Secondary coil 0.6mm copper sheet Circle ratio 16:2 air gap 0.38 mm

[0074] It should be noted that the primary winding of the first transformer T11, the primary winding of the second transformer T12, and the primary winding of the third transformer T13 are all set as the primary windings shown in Table 5, and the secondary windings of the first transformer T11, the secondary windings of the second transformer T12, and the secondary windings of the third transformer T13 are all set as the secondary windings shown in Table 5.

[0075] The performance of the full-bridge-full-bridge resonant converter is shown in Table 6, and the performance of the resonant converter of this application is shown in Table 3.

[0076] Table 6 Performance parameters Full-bridge to full-bridge resonant converter Peak primary-side switching current (A) 14.13 Effective value of primary side switching current (A) 7.13 Effective value of primary transformer current (A) 10.09 Number of components in a primary-side switch 12 Peak secondary-side switching current (A) 105.71 RMS value of secondary-side switching current (A) 52.54 RMS value of secondary transformer current (A) 74.2 Number of components in the secondary side switch 12 RMS value of resonant inductor current (A) 10.09

[0077] It should be noted that the primary-side switch in Table 6 is the first switching circuit 20A, the primary-side transformer in Table 6 is the primary side of the transformer circuit 40A, the secondary-side switch in Table 6 is the second switching circuit 50A, the secondary-side transformer in Table 3 is the secondary side of the transformer circuit 40A, and the effective value of the resonant inductor current in Table 6 can be the effective value of the resonant inductor current of the first resonant inductor Lr11, the effective value of the resonant inductor current of the second resonant inductor Lr12, or the effective value of the resonant inductor current of the third resonant inductor Lr13. According to Table 6, although the current stress of the full-bridge-full-bridge resonant converter is less than that of the resonant converter of this application, the air gap of the full-bridge-full-bridge resonant converter is larger.

[0078] The losses of the full-bridge-full-bridge resonant converter will be further described below. In the full-bridge-full-bridge resonant converter, the core loss of transformer circuit 40A is 18.54W, the copper loss on the primary side of transformer circuit 40A is 2.05W, the copper loss on the secondary side of transformer circuit 40A is 3.9W, and the total loss of transformer circuit 40 is 24.49W; the magnetic field of the core of transformer circuit 40 is 0.35T. As mentioned above, the total loss of transformer circuit 40A in the full-bridge-full-bridge resonant converter is still greater than the total loss of transformer circuit 40 in the resonant converter of this application.

[0079] Please refer to Figure 4, which is an error comparison diagram of the resonant current of the resonant converter and the resonant current of the full-bridge-full-bridge resonant converter according to an embodiment of this application. Figure 4 analyzes the resonant current of the resonant converter and the resonant current of the full-bridge-full-bridge resonant converter under the conditions of errors in the resonant inductor, errors in the resonant capacitor, and errors in both the resonant capacitor and the resonant inductor. Here, the standard value of the resonant current of the first resonant slot 31, the second resonant slot 32, and the third resonant slot 33 of the resonant converter shown in Figure 1A is set to 26.18A, and the maximum standard value of the resonant current of the first resonant slot 31A, the second resonant slot 32A, and the third resonant slot 33A of the full-bridge-full-bridge resonant converter shown in Figure 3 is set to 14.12A.

[0080] As shown in the first part of Figure 4, and in conjunction with the resonant converter shown in Figure 1A, when the value of the second resonant inductor Lr2 is 1.1 times the value of the first resonant inductor Lr1 and the value of the third resonant inductor Lr3 is 0.9 times the value of the first resonant inductor Lr1, the maximum value of the resonant current iLr1 of the first resonant tank 31 is 25.58A, the maximum value of the resonant current iLr2 of the second resonant tank 32 is 25.95A, and the maximum value of the resonant current iLr3 of the third resonant tank 33 is 27.06A. As shown in the first part of Figure 4, and in conjunction with the full-bridge-full-bridge resonant converter shown in Figure 3, when the value of the second resonant inductor Lr12 is 1.1 times the value of the first resonant inductor Lr11 and the value of the third resonant inductor Lr13 is 0.9 times the value of the first resonant inductor Lr11, the maximum value of the resonant current iLr11 in the first resonant slot 31A is 14.74A, the maximum value of the resonant current iLr12 in the second resonant slot 32A is 12.61A, and the maximum value of the resonant current iLr13 in the third resonant slot 33A is 15.03A.

[0081] As shown in the second part of Figure 4, and in conjunction with the resonant converter shown in Figure 1A, when the value of the second resonant capacitor Cr2 is 1.1 times the value of the first resonant capacitor Cr1 and the value of the third resonant capacitor Cr3 is 0.9 times the value of the first resonant capacitor Cr1, the maximum value of the resonant current iLr1 of the first resonant tank 31 is 25.5A, the maximum value of the resonant current iLr2 of the second resonant tank 32 is 25.9A, and the maximum value of the resonant current iLr3 of the third resonant tank 33 is 27.18A. As shown in the second part of Figure 4, and in conjunction with the full-bridge-full-bridge resonant converter shown in Figure 3, when the value of the second resonant capacitor Cr12 is 1.1 times the value of the first resonant capacitor Cr11 and the value of the third resonant capacitor Cr13 is 0.9 times the value of the first resonant capacitor Cr11, the maximum value of the resonant current iLr11 of the first resonant slot 31A is 15.01A, the maximum value of the resonant current iLr12 of the second resonant slot 32A is 11.98A, and the maximum value of the resonant current iLr13 of the third resonant slot 33A is 15.45A.

[0082] As shown in the third part of Figure 4, and in conjunction with the resonant converter shown in Figure 1A, when the value of the second resonant inductor Lr2 is 1.1 times the value of the first resonant inductor Lr1 and the value of the third resonant inductor Lr3 is 0.9 times the value of the first resonant inductor Lr1, and the value of the second resonant capacitor Cr2 is 1.1 times the value of the first resonant capacitor Cr1 and the value of the third resonant capacitor Cr3 is 0.9 times the value of the first resonant capacitor Cr1, the maximum value of the resonant current iLr1 of the first resonant tank 31 is 24.93A, the maximum value of the resonant current iLr2 of the second resonant tank 32 is 25.75A, and the maximum value of the resonant current iLr3 of the third resonant tank 33 is 28.09A. As shown in the third part of Figure 4, and in conjunction with the full-bridge to full-bridge resonant converter shown in Figure 3, when the value of the second resonant inductor Lr12 is 1.1 times the value of the first resonant inductor Lr11, and the value of the third resonant inductor Lr13 is 0.9 times the value of the first resonant inductor Lr11, and the value of the second resonant capacitor Cr12 is 1.1 times the value of the first resonant capacitor Cr11, and the value of the third resonant capacitor Cr13 is 0.9 times the value of the first resonant capacitor Cr11, the maximum value of the resonant current iLr11 in the first resonant slot 31A is 15.72A, the maximum value of the resonant current iLr12 in the second resonant slot 32A is 10.54A, and the maximum value of the resonant current iLr13 in the third resonant slot 33A is 16.46A.

[0083] As described above, the current difference caused by component errors in the resonant converter of this application is smaller than that caused by component errors in the full-bridge-full-bridge resonant converter; in other words, the range of current variation in the resonant converter of this application is smaller than that in the full-bridge-full-bridge resonant converter. Therefore, the resonant converter of this application has a higher tolerance for current errors caused by component errors.

[0084] In this embodiment, the first transformer T1, the second transformer T2, and the third transformer T3 each include a magnetic core. The primary winding 41A and the secondary winding 42A of the first transformer T1 share the magnetic core of the first transformer T1, the primary winding 41B and the secondary winding 42B of the second transformer T2 share the magnetic core of the second transformer T2, and the primary winding 41C and the secondary winding 42C of the third transformer T3 share the magnetic core of the third transformer T3.

[0085] The configuration of the magnetic cores of the first transformer T1, the second transformer T2, and the third transformer T3 will be described in detail below. Please refer further to Figures 5A and 5B, which are perspective views and cross-sectional views of the magnetic cores according to an embodiment of this application. As shown in Figures 5A and 5B, taking the primary winding 41A and secondary winding 42A of the first transformer T1 as examples, the magnetic core 43 of the first transformer T1 includes an upper cover 431, a lower cover 432, a first side post 433, a second side post 434, and a core post 435. The first side post 433 and the second side post 434 are disposed between the upper cover 431 and the lower cover 432. The upper cover 431, the lower cover 432, the first side post 433, and the second side post 434 together define an accommodating space, and the core post 435 is disposed in the accommodating space. The core post 435 is disposed between the upper cover 431 and the lower cover 432, and the first side post 433 and the second side post 434 are located on opposite sides of the core post 435; in other words, the core post 435 is disposed between the first side post 433 and the second side post 434. The primary coil winding 41A and the secondary coil winding 42A surround the magnetic core 43 in a clockwise or counterclockwise direction; in other words, the primary coil winding 41A and the secondary coil winding 42A share the magnetic core 43. The magnetic core 43 of the first transformer T1, the magnetic core of the second transformer T2, and the magnetic core of the third transformer T3 are disposed independently of each other. The configuration of the magnetic cores of the second transformer T2 and the third transformer T3 is the same as that of the magnetic core 43 of the first transformer T1, and will not be described again.

[0086] Please refer to Figures 6A and 6B, which are perspective views and cross-sectional views of the magnetic core according to another embodiment of this application. As shown in Figures 6A and 6B, the primary winding 41A and secondary winding 42A of the first transformer T1, the primary winding 41B and secondary winding 42B of the second transformer T2, and the primary winding 41C and secondary winding 42C of the third transformer T3 share a magnetic core 43A; in other words, the first transformer T1, the second transformer T2, and the third transformer T3 share a magnetic core 43A. The magnetic core 43A includes an upper cover 431A, a lower cover 432A, a first side post 433A, a second side post 434A, and a plurality of core posts, which are separately arranged and include a first core post 435A1, a second core post 435A2, and a third core post 435A3. The first side post 433A and the second side post 434A are disposed between the upper cover 431A and the lower cover 432A. The upper cover 431A, the lower cover 432A, the first side post 433A and the second side post 434A together define the accommodating space. The first core post 435A1, the second core post 435A2 and the third core post 435A3 are disposed in the accommodating space. The first core post 435A1, the second core post 435A2, and the third core post 435A3 are disposed between the upper cover 431A and the lower cover 432A. The first core post 435A1 and the third core post 435A3 are located on opposite sides of the second core post 435A2. The first side post 433A and the second core post 435A2 are located on opposite sides of the first core post 435A1. The second core post 435A2 and the second side post 434A are located on opposite sides of the third core post 435A3. In other words, the first core post 435A1, the second core post 435A2, and the third core post 435A3 are disposed between the first side post 433A and the second side post 434A. The first core post 435A1, the second core post 435A2, and the third core post 435A3 are not coupled to each other, and each of the first core post 435A1 to the third core post 435A3 has an air gap.

[0087] The primary winding 41A and secondary winding 42A of the first transformer T1 are wound around the first core post 435A1 in a clockwise direction, the primary winding 41B and secondary winding 42B of the second transformer T2 are wound around the second core post 435A2 in a clockwise direction, and the primary winding 41C and secondary winding 42C of the third transformer T3 are wound around the third core post 435A3 in a clockwise direction; in other words, the primary winding 41A and secondary winding 42A of the first transformer T1 share the first core post 435A1, the primary winding 41B and secondary winding 42B of the second transformer T2 share the second core post 435A2, and the primary winding 41C and secondary winding 42C of the third transformer T3 share the third core post 435A3.

[0088] Please refer to Figures 7A and 7B, which are perspective views and cross-sectional views of the magnetic core according to another embodiment of the present application. As shown in Figures 7A and 7B, the third magnetic core 43B3 of the third transformer T3, the second magnetic core 43B2 of the second transformer T2, and the first magnetic core 43B1 of the first transformer T1 are stacked sequentially. The first magnetic core 43B1, the second magnetic core 43B2, and the third magnetic core 43B3 share an upper cover 431B and a lower cover 432B.

[0089] The first magnetic core 43B1 includes a first side post 433B1, a second side post 434B1, a first intermediate cover plate 436B1, and a first core post 435B1. The first side post 433B1 and the second side post 434B1 are disposed between the upper cover 431B and the first intermediate cover plate 436B1. The upper cover 431B, the first side post 433B1, the second side post 434B1, and the first intermediate cover plate 436B1 together define an accommodating space, and the first core post 435B1 is disposed in the accommodating space. The first side post 433B1 and the second side post 434B1 are disposed on opposite sides of the first core post 435B1; in other words, the first core post 435B1 is disposed between the first side post 433B1 and the second side post 434B1. The primary winding 41A and the secondary winding 42A of the first transformer T1 are wound around the first core post 435B1 in a clockwise or counterclockwise manner; in other words, the primary winding 41A and the secondary winding 42A of the first transformer T1 share the first core post 435B1.

[0090] The second magnetic core 43B2 is located below the first magnetic core 43B1 and includes a first side post 433B2, a second side post 434B2, a second intermediate cover plate 436B2, and a second core post 435B2. The first side post 433B2 and the second side post 434B2 are disposed between the first intermediate cover plate 436B1 and the second intermediate cover plate 436B2. The first side post 433B1, the second side post 434B1, the first intermediate cover plate 436B1, and the second intermediate cover plate 436B2 together define an accommodating space. The second core post 435B2 is disposed within the accommodating space. The first side post 433B2 and the second side post 434B2 are disposed on opposite sides of the second core post 435B2; in other words, the second core post 435B2 is disposed between the first side post 433B2 and the second side post 434B2. The primary winding 41B and the secondary winding 42B of the second transformer T2 are wound around the second core post 435B2 in a clockwise or counterclockwise direction; in other words, the primary winding 41B and the secondary winding 42B of the second transformer T2 share the second core post 435B2.

[0091] The third magnetic core 43B3 is located below the second magnetic core 43B3 and includes a first side post 433B3, a second side post 434B3, a third intermediate cover plate 436B3, and a third core post 435B3. The first side post 433B3 and the second side post 434B3 are disposed between the second intermediate cover plate 436B2 and the lower cover 432B. The first side post 433B3, the second side post 434B3, the I-plate 436B2, and the lower cover 432B together define an accommodating space, and the third core post 435B3 is disposed within the accommodating space. The first side post 433B3 and the second side post 434B3 are located on opposite sides of the third core post 435B3; in other words, the third core post 435B3 is disposed between the first side post 433B3 and the second side post 434B3. The third intermediate cover plate 436B3 serves as the lower cover 432B. The primary winding 41C and the secondary winding 42C of the third transformer T3 are wound around the third core post 435B3 in a clockwise or counterclockwise direction; in other words, the primary winding 41C and the secondary winding 42C of the third transformer T3 share the third core post 435B3.

[0092] The first core post 435B1, the second core post 435B2 and the third core post 435B3 are not coupled to each other, and the first core post 435B1 to the third core post 435B3 all have air gaps.

[0093] Please refer to Figures 8A and 8B, which are perspective views and cross-sectional views of the magnetic core according to another embodiment of this application. As shown in Figures 8A and 8B, the primary winding 41A and secondary winding 42A of the first transformer T1, the primary winding 41B and secondary winding 42B of the second transformer T2, and the primary winding 41C and secondary winding 42C of the third transformer T3 share the magnetic core 43C; in other words, the first transformer T1, the second transformer T2, and the third transformer T3 share the magnetic core 43C. The configuration of the magnetic core 43C shown in Figures 8A and 8B is similar to the configuration of the magnetic core 43A shown in Figures 6A and 6B, and the similarities will not be repeated. However, there are still differences between the magnetic core 43C shown in Figures 8A and 8B and the magnetic core 43A shown in Figures 6A and 6B: the first core post 435C1, the second core post 435C2, and the third core post 435C3 are interconnected and coupled.

[0094] Please refer to Figures 9A and 9B, which are perspective views illustrating the magnetic core according to another embodiment of this application. As shown in Figures 9A and 9B, the primary winding 41A and secondary winding 42A of the first transformer T1, the primary winding 41B and secondary winding 42B of the second transformer T2, and the primary winding 41C and secondary winding 42C of the third transformer T3 share a magnetic core 43D; in other words, the first transformer T1, the second transformer T2, and the third transformer T3 share a magnetic core 43D. The magnetic core 43D includes an upper cover 431D, a lower cover 432D, and a plurality of core posts, including a first core post 433D1, a second core post 433D2, a third core post 433D3, and a fourth core post 433D4. The first core post 433D1, the second core post 433D2, the third core post 433D3, and the fourth core post 433D4 are disposed between the upper cover 431D and the lower cover 432D. The first core post 433D1, the second core post 433D2, and the third core post 433D3 surround the fourth core post 433D4. The first core post 433D1, the second core post 433D2, and the third core post 433D3 are not coupled to each other. The first core post 433D1, the second core post 433D2, and the third core post 433D3 are coupled to the fourth core post 433D4 respectively. The first core post 433D1, the second core post 433D2, and the third core post 433D3 each have an air gap, while the fourth core post 433D4 has no air gap.

[0095] The primary winding 41A and the secondary winding 42A of the first transformer T1 are wound around the first core post 433D1 in a clockwise or counterclockwise direction; the primary winding 41B and the secondary winding 42B of the second transformer T2 are wound around the second core post 433D2 in a clockwise or counterclockwise direction; and the primary winding 41C and the secondary winding 42C of the third transformer T3 are wound around the third core post 433D3 in a clockwise or counterclockwise direction.

[0096] Please refer to Figures 10A and 10B, which are perspective views and cross-sectional views of the magnetic core according to another embodiment of this application. As shown in Figures 10A and 10B, the primary winding 41A and secondary winding 42A of the first transformer T1, the primary winding 41B and secondary winding 42B of the second transformer T2, and the primary winding 41C and secondary winding 42C of the third transformer T3 share a magnetic core 43D. The configuration of the magnetic core 43D shown in Figures 10A and 10B is similar to that shown in Figures 9A and 9B, and the similarities will not be described again. However, the magnetic core 43D shown in Figures 10A and 10B still differs from the magnetic core 43D shown in Figures 9A and 9B: there is no fourth core post 433D4, the first core post 433D1, the second core post 433D2, and the third core post 433D3 are coupled to each other, and the first core post 433D1, the second core post 433D2, and the third core post 433D3 each have an air gap.

[0097] In summary, the resonant converter of this application achieves zero voltage switching (ZVS) or zero current switching (ZCS) through the configuration of the resonant circuit, thereby reducing the switching losses of the switching elements and the power loss of the power converter. [Simplified Explanation of the Diagram]

[0008] Figure 1A is a circuit diagram of a resonant converter according to an embodiment of the present application. Figure 1B is a block diagram of a first switching circuit and a controller according to an embodiment of the present application. Figure 1C is a timing diagram of the control signals of the first switching circuit according to an embodiment of the present application. Figure 1D is a block diagram of a second switching circuit and a controller according to an embodiment of the present application. Figure 1E is a timing diagram of the control signals of the second switching circuit according to an embodiment of the present application. Figure 1F is a timing diagram of the input current, resonant current, excitation current, and second current according to an embodiment of the present application. Figure 1G is a timing diagram of the control signals of the first high-side switch and the first high-side rectifier switch according to an embodiment of the present application. Figure 2 is a circuit diagram of a half-bridge to half-bridge resonant converter. Figure 3 is a circuit diagram of a full-bridge to full-bridge resonant converter. Figure 4 is an error comparison diagram of the resonant current of the resonant converter and the resonant current of the full-bridge to full-bridge resonant converter according to an embodiment of the present application. Figure 5A is a perspective view of a magnetic core according to one embodiment of the present application. Figure 5B is a cross-sectional view of a magnetic core according to one embodiment of the present application. Figure 6A is a perspective view of a magnetic core according to another embodiment of the present application. Figure 6B is a cross-sectional view of a magnetic core according to another embodiment of the present application. Figure 7A is a perspective view of a magnetic core according to yet another embodiment of the present application. Figure 7B is a cross-sectional view of a magnetic core according to yet another embodiment of the present application. Figure 8A is a perspective view of a magnetic core according to yet another embodiment of the present application. Figure 8B is a cross-sectional view of a magnetic core according to yet another embodiment of the present application. Figure 9A is a perspective view of a magnetic core according to yet another embodiment of the present application. Figure 9B is a cross-sectional view of a magnetic core according to yet another embodiment of the present application. Figure 10A is a perspective view of a magnetic core according to yet another embodiment of the present application. Figure 10B is a cross-sectional view of a magnetic core according to yet another embodiment of the present application.

Claims

1. A resonant converter, comprising: An input circuit provides an input voltage; A first switching circuit coupled to the input circuit and including a plurality of first switching units, each of the plurality of first switching units including an output node; a resonant circuit including a plurality of resonant slots, each of the plurality of resonant slots including a resonant capacitor and a resonant inductor connected in series, the plurality of resonant inductors being Y-connected to the plurality of output nodes; a transformer circuit having a plurality of connection nodes between a primary side of the transformer circuit and the plurality of resonant capacitors, the plurality of resonant capacitors being Y-connected to the primary side of the transformer circuit based on the plurality of connection nodes; a second switching circuit including a plurality of second switching units, each of the plurality of second switching units including an input node, the plurality of input nodes being delta-connected to the primary and secondary sides of the transformer circuit; and an output circuit coupled to the second switching circuit and generating an output voltage; The plurality of first switching units include a first high-side switch, a first low-side switch, a second high-side switch, a second low-side switch, a third high-side switch, and a third low-side switch; the plurality of second switching units include a first high-side rectifier switch, a first low-side rectifier switch, a second high-side rectifier switch, a second low-side rectifier switch, a third high-side rectifier switch, and a third low-side rectifier switch. Specifically, when the first high-side switch is turned on, the first low-side switch is turned off, the second high-side switch is turned off, the second low-side switch is turned on, the third high-side switch is turned off, and the third low-side switch is turned on, the first high-side switch generates an input current based on the input voltage, one of the plurality of resonant slots generates a resonant current based on the input current, the primary side of the transformer circuit generates a first voltage based on the resonant current, and the secondary side of the transformer circuit generates a second voltage based on the first voltage; the first high-side rectifier switch is turned on, the first low-side rectifier switch is turned off, the second high-side rectifier switch is turned off, the second low-side rectifier switch is turned on, the third high-side rectifier switch is turned off, and the third low-side rectifier switch is turned on, the first high-side rectifier switch outputs an output current to the output circuit based on the second voltage.

2. The resonant converter as claimed in claim 1, wherein, The first switching circuit generates an input current based on the input voltage, the resonant circuit generates a resonant current based on the input current, the primary side of the transformer circuit generates a first voltage based on the resonant current, the secondary side of the transformer circuit generates a second voltage based on the first voltage, the second switching circuit generates an output current based on the second voltage, and the output circuit generates the output voltage based on the output current.

3. The resonant converter as described in claim 2, wherein, The current flowing through the primary side of the transformer circuit is a first current, and the value of the first current is less than the value of the resonant current.

4. The resonant converter as claimed in claim 1 further includes a controller electrically connected to a plurality of the first switching units and a plurality of the second switching units to provide a plurality of control signals.

5. The resonant converter as described in claim 4, wherein, Each of the plurality of the first switching units includes a high-side switch and a low-side switch, and the output node is located between the high-side switch and the low-side switch.

6. The resonant converter as claimed in claim 5, wherein, The phase difference between the control signal of the high-side switch and the control signal of the low-side switch is 180 degrees.

7. The resonant converter as claimed in claim 5, wherein, There is a first dead time between the control signal of the high-side switch and the control signal of the low-side switch.

8. The resonant converter as claimed in claim 5, wherein, The plurality of high-side switches include a first high-side switch, a second high-side switch, and a third high-side switch, wherein the phase difference between the control signal of the first high-side switch and the control signal of the second high-side switch is 120 degrees, and the phase difference between the control signal of the first high-side switch and the control signal of the third high-side switch is 240 degrees.

9. The resonant converter as claimed in claim 5, wherein, Each of the plurality of the second switching units includes a high-side rectifier switch and a low-side rectifier switch, and the input node is located between the high-side rectifier switch and the low-side rectifier switch.

10. The resonant converter as claimed in claim 9, wherein, The phase difference between the control signal of the high-side rectifier switch and the control signal of the low-side rectifier switch is 180 degrees.

11. The resonant converter as claimed in claim 9, wherein, There is a second dead time between the control signal of the high-side rectifier switch and the control signal of the low-side rectifier switch.

12. The resonant converter as claimed in claim 9, wherein, The plurality of high-side switches include a first high-side rectifier switch, a second high-side rectifier switch, and a third high-side rectifier switch. The phase difference between the control signal of the first high-side rectifier switch and the control signal of the second high-side rectifier switch is 120 degrees, and the phase difference between the control signal of the second high-side rectifier switch and the control signal of the third high-side rectifier switch is 240 degrees.

13. The resonant converter as claimed in claim 9, wherein, The on-time of the control signal of the high-side rectifier switch is shorter than the on-time of the control signal of the high-side switch, and the on-time of the control signal of the low-side rectifier switch is shorter than the on-time of the control signal of the low-side switch.

14. The resonant converter as claimed in claim 1, wherein, The transformer circuit includes a plurality of transformers, the primary sides of the plurality of transformers being coupled to each other in a delta connection, and the secondary sides of the plurality of transformers being coupled to each other in a delta connection.

15. The resonant converter as claimed in claim 14, wherein, Each of the plurality of transformers includes a primary winding, a magnetizing inductor, and a secondary winding. The primary winding is disposed on the primary side and coupled in parallel with the magnetizing inductor. The plurality of primary windings are coupled to the plurality of resonant capacitors through the plurality of connection nodes. The plurality of secondary windings are disposed on the secondary side to be coupled to the plurality of input nodes.

16. The resonant converter as claimed in claim 15, wherein, Each of the plurality of transformers includes a magnetic core, and the plurality of magnetic cores are independently arranged with respect to each other. The magnetic core includes an upper cover, a lower cover, a first side post, a second side post, and a core post. The first side post, the second side post, and the core post are disposed between the upper cover and the lower cover. The core post is disposed between the first side post and the second side post. The primary winding and the secondary winding surround the core post.

17. The resonant converter as claimed in claim 15, wherein, Each of the plurality of transformers includes a magnetic core, the plurality of magnetic cores are stacked sequentially, the plurality of magnetic cores share an upper cover and a lower cover, the magnetic core includes a first side post, a second side post, an intermediate cover plate and a core post, the first side post, the second side post and the core post are disposed between the upper cover and the lower cover, the core post is disposed between the first side post and the second side post, the primary side coil winding and the secondary side coil winding surround the core post, and the intermediate cover plate of one of the plurality of magnetic cores serves as the lower cover.

18. The resonant converter as claimed in claim 15, wherein, The plurality of transformers include a magnetic core, and the plurality of transformers share the magnetic core. The magnetic core includes an upper cover, a lower cover, a first side post, a second side post, and a plurality of core posts. The first side post, the second side post, and the plurality of core posts are disposed between the upper cover and the lower cover, and the plurality of core posts are disposed between the first side post and the second side post. A plurality of primary windings and a plurality of secondary windings surround the plurality of core posts.

19. The resonant converter as claimed in claim 18, wherein, Multiple core posts are set separately from each other.

20. The resonant converter as claimed in claim 18, wherein, Multiple core posts are coupled to each other.

21. The resonant converter as claimed in claim 15, wherein, The plurality of transformers include a magnetic core, the plurality of transformers share the magnetic core, the magnetic core includes an upper cover, a lower cover and a plurality of core posts, the plurality of core posts are disposed between the upper cover and the lower cover, and a plurality of primary windings and a plurality of secondary windings surround the plurality of core posts.

22. The resonant converter as claimed in claim 1, wherein, When the first high-side switch is off, the first low-side switch is on, the second high-side switch is off, the second low-side switch is on, the third high-side switch is on, and the third low-side switch is off, the third high-side switch generates the input current based on the input voltage, one of the plurality of resonant slots generates the resonant current based on the input current, the primary side of the transformer circuit generates the first voltage based on the resonant current, and the secondary side of the transformer circuit generates the second voltage based on the first voltage; the first high-side rectifier switch is off, the first low-side rectifier switch is on, the second high-side rectifier switch is off, the second low-side rectifier switch is on, the third high-side rectifier switch is on, and the third low-side rectifier switch is off, the third high-side rectifier switch outputs the output current to the output circuit based on the second voltage.

23. The resonant converter as claimed in claim 1, wherein, When the first high-side switch is turned on, the first low-side switch is turned off, the second high-side switch is turned off, the second low-side switch is turned on, the third high-side switch is turned on, and the third low-side switch is turned off, the first high-side switch and the third high-side switch generate two input currents based on the input voltage. Two of the plurality of resonant slots generate two resonant currents based on the two input currents. The primary side of the transformer circuit generates two first voltages based on the two resonant currents, and the secondary side of the transformer circuit generates two second voltages based on the two first voltages. When the first high-side rectifier switch is turned on, the first low-side rectifier switch is turned off, the second high-side rectifier switch is turned off, the second low-side rectifier switch is turned on, the third high-side rectifier switch is turned on, and the third low-side rectifier switch is turned off, the first high-side rectifier switch and the third high-side rectifier switch output the output current to the output circuit based on the two second voltages.

24. The resonant converter as claimed in claim 1, wherein, When the first high-side switch is turned on, the first low-side switch is turned off, the second high-side switch is turned on, the second low-side switch is turned off, the third high-side switch is turned off, and the third low-side switch is turned on, the first high-side switch and the second high-side switch generate two input currents based on the input voltage. Two of the plurality of resonant slots generate two resonant currents based on the two input currents. The primary side of the transformer circuit generates two first voltages based on the two resonant currents, and the secondary side of the transformer circuit generates two second voltages based on the two first voltages. When the first high-side rectifier switch is turned on, the first low-side rectifier switch is turned off, the second high-side rectifier switch is turned on, the second low-side rectifier switch is turned off, the third high-side rectifier switch is turned off, and the third low-side rectifier switch is turned on, the first high-side rectifier switch and the second high-side rectifier switch output the output current to the output circuit based on the two second voltages.

25. The resonant converter as claimed in claim 1, wherein, When the first high-side switch is off, the first low-side switch is on, the second high-side switch is on, the second low-side switch is off, the third high-side switch is off, and the third low-side switch is on, the second high-side switch generates the input current based on the input voltage, one of the plurality of resonant slots generates the resonant current based on the input current, the primary side of the transformer circuit generates the first voltage based on the resonant current, and the secondary side of the transformer circuit generates the second voltage based on the first voltage; the first high-side rectifier switch is off, the first low-side rectifier switch is on, the second high-side rectifier switch is on, the second low-side rectifier switch is off, the third high-side rectifier switch is off, and the third low-side rectifier switch is on, the second high-side rectifier switch outputs the output current to the output circuit based on the second voltage.

26. The resonant converter as claimed in claim 1, wherein, When the first high-side switch is off, the first low-side switch is on, the second high-side switch is on, the second low-side switch is off, the third high-side switch is on, and the third low-side switch is off, the second high-side switch and the third high-side switch generate two input currents based on the input voltage. Two of the plurality of resonant slots generate two resonant currents based on the two input currents. The primary side of the transformer circuit generates two first voltages based on the two resonant currents, and the secondary side of the transformer circuit generates two second voltages based on the two first voltages. The first high-side rectifier switch is off, the first low-side rectifier switch is on, the second high-side rectifier switch is on, the second low-side rectifier switch is off, the third high-side rectifier switch is on, and the third low-side rectifier switch is off. The second high-side rectifier switch and the third high-side rectifier switch output the output current to the output circuit based on the two second voltages.

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