Multiphase voltage converter current balance

Abstract

This relates to components for three-phase power systems. [Solution] The multiphase power supply circuit comprises a first voltage converter stage, a resonant choke stage, and a transformer assembly. The resonant choke stage comprises first and second resonant inductors electrically coupled to the first and second voltage outputs of the first voltage converter stage, and the transformer assembly comprises a primary coil assembly and a secondary coil assembly. Each primary coil assembly comprises first and second primary windings. The first primary winding comprises a first node and a second node electrically coupled to the resonant choke stage. The second primary winding comprises a first node and a second node electrically coupled to the resonant choke stage. The second nodes of the first primary winding are both electrically coupled, and the first nodes of the second primary winding are both electrically coupled. The first and second resonant inductors are wound around the first leg of a first magnetic core.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application is a partial continuation application of U.S. Application No. 18 / 893 / 472, filed on September 23, 2024, which is a continuation of U.S. Application No. 17 / 823,849, filed on August 31, 2022. The entire disclosure of the above applications is incorporated herein by reference.

[0002] Aspects of the present disclosure relate to electronic components, and more particularly, to components for three - phase power systems.

Background Art

[0003] Three - phase LLC power converters are commonly used in various systems, including telecommunications systems, high - speed chargers for electric vehicles, and other applications that require high power density and high efficiency.

[0004] These three - phase LLC power converters typically include an inductor / transformer pair for each of the three phases. Current imbalance circulating between the primary currents due to differences in the tolerance of component values can negatively affect converter efficiency and even cause the converter to fail.

Summary of the Invention

[0005] According to one aspect of the present disclosure, a polyphase power supply circuit comprises a first voltage converter stage, a resonant choke stage, and a transformer assembly electrically coupled to the resonant choke stage. The first voltage converter stage comprises a pair of voltage inputs and a pair of voltage outputs. The resonant choke stage comprises a first resonant inductor electrically coupled to a first voltage output of the pair of voltage outputs of the first voltage converter stage, and a second resonant inductor electrically coupled to a second voltage output of the pair of voltage outputs of the first voltage converter stage. The transformer assembly comprises a plurality of primary coil assemblies and a plurality of secondary coil assemblies. Each primary coil assembly of the plurality of primary coil assemblies comprises a first and a second primary winding. The first primary winding comprises a first node and a second node electrically coupled to the resonant choke stage. The second primary winding comprises a first node and a second node electrically coupled to the resonant choke stage. The second nodes of the first primary winding are electrically coupled together, and the first nodes of the second primary winding are electrically coupled together, and the first and second resonant inductors are wound around the first leg of the first magnetic core.

[0006] According to another aspect of the present disclosure, the method includes coupling a first voltage output of a first voltage converter stage to a first resonant inductor of a resonant choke stage, coupling a second voltage output of the first voltage converter stage to a second resonant inductor of a resonant choke stage, and coupling a transformer assembly to the resonant choke stage. The transformer assembly comprises a plurality of primary coil assemblies, each primary coil assembly comprising a first and a second primary winding. The first primary winding comprises a first node electrically coupled to the resonant choke stage and a second node. The second primary winding comprises a first node and a second node electrically coupled to the resonant choke stage. The method also includes coupling the second node of the first primary winding together, coupling the first node of the second primary winding together, and winding the first and second resonant inductors around a first leg of a first magnetic core.

[0007] Many aspects of this disclosure can be better understood by referring to the following drawings. While several implementations are described in relation to these drawings, this disclosure is not limited to the implementations disclosed herein. In contrast, the intent is to cover all alternative, modified, and equivalent forms. [Brief explanation of the drawing]

[0008] [Figure 1] This is an exemplary three-phase power supply circuit comprising three LLC resonant voltage converters according to one embodiment. [Figure 2] This figure shows an exemplary single-phase LLC resonant voltage converter for use in the three-phase power supply circuit of Figure 1, Figure 5, or Figure 8, according to one embodiment. [Figure 3] This is one embodiment of the three-phase power supply circuit shown in Figure 1, which is an example. [Figure 4] This figure shows the winding configuration of the transformer assembly shown in Figure 3 on an exemplary integrated core body according to one embodiment. [Figure 5] This is an isometric view of the core body portion according to one embodiment. [Figure 6] This figure shows one embodiment of the three-phase power supply circuit in Figure 1, according to another embodiment. [Figure 7] This figure shows the winding configuration of the transformer assembly shown in Figure 6 on an exemplary integrated core body according to one embodiment. [Figure 8] This is a partial isometric view of an exemplary integrated core body shown in Figure 7, according to one embodiment. [Figure 9] This figure shows an exemplary single-phase LLC resonant voltage converter for use in the three-phase power supply circuit shown in Figure 1, Figure 3, or Figure 6, according to one embodiment. [Figure 10] This figure shows an exemplary three-phase LLC resonant voltage converter for use in the three-phase power supply circuit of Figure 1, Figure 3, or Figure 6, according to one embodiment. [Figure 11] This figure shows an exemplary three-phase power supply circuit comprising three LLC resonant voltage converters according to one embodiment. [Figure 12]This figure shows an exemplary single-phase LLC resonant voltage converter stage according to one embodiment. [Figure 13] This figure shows an exemplary single-phase LLC resonant voltage converter stage according to one embodiment. [Figure 14] This figure shows an exemplary embodiment of an LLC resonant voltage converter resonant choke stage according to one embodiment. [Figure 15] This figure shows an exemplary embodiment of an LLC resonant voltage converter resonant choke stage according to another embodiment. [Figure 16] This figure shows a transformer and secondary circuit block according to one embodiment. [Figure 17] This figure shows the winding configuration of the transformer assembly shown in Figure 15 on an exemplary pair of core configurations according to one embodiment. [Figure 18] This figure shows the winding configuration of the transformer assembly shown in Figure 15 on an exemplary integrated core configuration according to one embodiment. [Modes for carrying out the invention]

[0009] While this disclosure is susceptible to various modifications and alternative forms, specific embodiments are shown in the drawings as examples and described in detail herein. However, it should be understood that the descriptions of specific embodiments herein are not intended to limit this disclosure to the specific forms disclosed, but rather to cover all modifications, equivalents, and alternatives that fall within the spirit and scope of this disclosure. Note that in some of the drawings, the corresponding reference numerals indicate the corresponding parts.

[0010] The embodiments of this disclosure are described here in more detail with reference to the accompanying drawings. The following description is essentially illustrative and is not intended to limit the disclosure, use, or application.

[0011] Exemplary embodiments are provided so that this disclosure is thorough and fully conveys the scope to those skilled in the art. To provide a complete understanding of the embodiments of this disclosure, numerous specific details are set forth such as examples of specific components, devices, and methods. It will be apparent to those skilled in the art that specific details need not be employed, that the exemplary embodiments can be embodied in many different forms, and that none of them should be construed as limiting the scope of this disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0012] The disclosure herein is detailed and accurate to enable those skilled in the art to implement the present invention, but the physical embodiments disclosed herein merely exemplify the present invention which can be embodied in other specific structures. Although the preferred embodiments have been described, details can be changed without departing from the present invention as defined by the claims.

[0013] FIG. 1 is a diagram showing an exemplary three-phase power circuit 100 including three LLC resonant voltage converters. This exemplary power circuit 100 includes three LLC resonant voltage converters 101, 102, and 103 such as the LLC resonant voltage converters in FIGS. 2 to 10 described later.

[0014] Each of the three LLC resonant voltage converters 101, 102, and 103 includes a pair of voltage inputs 104, 1,05 (DC+ and DC-). The DC+ and DC- inputs to the voltage converters 101, 102, 103 are applied with an input voltage VIN across capacitors C1 106 and C2 107, and when the values of capacitors C1 106 and C2 107 are the same, it acts to divide the input voltage VIN in half.

[0015] Each of the three LLC resonant voltage converters 101, 102, and 103 includes a pair of voltage outputs 108, 109 (OUT+ and OUT-). For example, the current generated by a voltage converter (e.g., 101) and supplied through its voltage output OUT+ 108 flows through transformer assembly T1 110, through the other two voltage converters (e.g., 102, 103), and returns through voltage output OUT- 109. When supplied through voltage output OUT- 109, the generated current returns to voltage output OUT+ 108 after flowing through voltage converters 102, 103 and transformer assembly 110. In embodiments of the voltage converters 101, 102, and 103 disclosed herein, a pair of voltage outputs 108, 109 are required to convert an input voltage VIN to an output current. An LLC voltage converter having only a single output electrically coupled to a transformer assembly is not contemplated herein.

[0016] FIG. 2 shows an exemplary single-phase LLC resonant voltage converter 200 having a pair of voltage outputs 201, 202 for use within a three-phase power circuit disclosed herein. In this exemplary embodiment, an input voltage is applied to inputs DC+ 203 and DC- 204 of voltage converter 200. In some exemplary embodiments, the input voltage may be provided by a power factor correction circuit.

[0017] Switch Q1 205 and diode D1 206 form a first half-bridge, and switch Q2 207 and diode D2 208 form a second half-bridge. Diodes D1 206 and D2 208 are blocking diodes that block current when switches Q1 205 and Q2 207 are both on. In one embodiment, resistor R10 209 is included between diode D1 206 and diode D2 208 to ground diodes D1 206 and D2 208. In another embodiment, diodes D1 206 and D2 208 may be directly grounded without resistor R10 209.

[0018] Switch Q1 205 is driven by an isolation driver E1 210 and resistors R1 211 and R2 212. Switch Q2 207 is driven by an isolation driver E2 213 and resistors R3 214 and R4 215. Both isolation drivers E1 213 and E2 213 are driven by a square wave AA 216 generated by a control circuit (not shown).

[0019] The maximum voltage stress on switches Q1 205 and Q2 207 is equal to half of the input voltage between DC+203 and DC-204, while switch Q3 217 is subjected to the full voltage stress of the input voltage between DC+203 and DC-204. In an exemplary embodiment, if the input voltage between DC+203 and DC-204 is 440 volts, switches Q1 205 and Q2 207 can be rated at 300-400 volts, and Q3 217 can be rated at 600-650 volts.

[0020] Switch Q3 217 is configured to short-circuit diodes D1 206 and D2 208 when activated by isolation driver E3 218 and resistors R5 219 and R6 220. Isolation driver E3 218 is driven by a square wave BB 221 generated by a control circuit (not shown).

[0021] Each half-bridge drives one primary node of the primary coil of the external transformer via a capacitor / inductor pair. A first half-bridge, comprising switch Q1 205 and diode D1 206, drives the primary coil of the external transformer via electrically series-coupled split resonant components capacitor C1 222 and inductor L1 223. A second half-bridge, comprising switch Q2 207 and diode D2 208, drives the primary coil of the external transformer via electrically series-coupled split resonant components capacitor C2 224 and inductor L2 225. Output voltages OUT+201 and OUT-202 are provided to the first and second nodes of the primary coil assembly of the external transformer assembly, as described herein. In the embodiment shown in Figure 2, the resonant tank section of the LLC resonant voltage converter 200 includes capacitors 222, 224 and inductors 223, 225.

[0022] Referring back to Figures 1 and 3, the voltage outputs 108 and 109 of each LLC resonant voltage converter 101-103 are electrically coupled to the respective primary winding assemblies 111, 112, and 113 of the transformer assembly 110. In a multiphase interleaved LLC resonant voltage converter power supply as shown in Figure 1, current imbalances circulating between primary currents due to differences in component tolerances can adversely affect converter efficiency. Therefore, embodiments of the transformer assembly 110 disclosed herein counteract current imbalances. As shown, primary winding assembly 111 is formed from a pair of primary windings P1 300 and P4 301, primary winding assembly 112 is formed from a pair of primary windings P2 302 and P5 303, and primary winding assembly 113 is formed from a pair of primary windings P3 304 and P6 305. Thus, each primary winding assembly coupled to an LLC voltage converter includes a pair of primary windings.

[0023] Primary winding P1 300 includes a first node 306 at its dot end, which is electrically coupled to the voltage output 108 of the LLC resonant voltage converter 101. Primary winding P2 302 includes a first node 307 at its dot end, which is electrically coupled to the voltage output 108 of the LLC resonant voltage converter 102. Primary winding P3 304 includes a first node 308 at its dot end, which is electrically coupled to the voltage output 108 of the LLC resonant voltage converter 103. The second nodes 309, 310, and 311 on the opposite side of the dot ends of primary windings P1 to P3 are all electrically coupled.

[0024] The first nodes 312, 313, and 314 at the dot ends of primary windings P4 to P6 are all electrically coupled. Primary winding P4 301 includes a second node 315 on the opposite side of its dot end, which is electrically coupled to the voltage output 109 of the LLC resonant voltage converter 101. Primary winding P5 303 includes a second node 316 on the opposite side of its dot end, which is electrically coupled to the voltage output 109 of the LLC resonant voltage converter 102. Primary winding P6 305 includes a second node 317 on the opposite side of its dot end, which is electrically coupled to the voltage output 109 of the LLC resonant voltage converter 103.

[0025] The total number of primary turns is P1+P4=P2+P5=P3+P6. Therefore, the primary winding for each phase is divided into equal halves. In one embodiment, primary windings P1-P6 have equal numbers of turns. The electrically coupled terminations of the first half of the windings (e.g., the second nodes 309-311 of windings P1-P3) are short-circuited together to form one floating star connection. Similarly, the starting ends of the second half of the windings (e.g., the first nodes 312-314 of windings P4-P6) are connected to form another floating star connection. When electrically coupled with an LLC voltage converter having divided resonant components (e.g., capacitors 222, 224 and inductors 223, 225 of the LLC resonant voltage converter 200 in Figure 2), the advantage associated with substantially equal voltages with opposite polarity at the transformer terminals is that common-mode (CM) noise is reduced.

[0026] The three secondary windings S1-S3 114, 115, and 116 of transformer assembly 110 are inductively coupled to primary winding assemblies 111, 112, and 113, and electrically coupled to their respective bridge rectifiers 117, 118, and 119. The current inductively generated in secondary winding 114 by primary winding assembly 111 drives diodes D1-D4 120-123 of bridge rectifier 117. The current inductively generated in secondary winding 115 by primary winding assembly 112 drives diodes D5-D8 124-127 of bridge rectifier 118. The current inductively generated in secondary winding 116 by primary winding assembly 113 drives diodes D9-D12 128-131 of bridge rectifier 119. The output of the bridge rectifier 119 generates an output voltage VOUT 132 across the output filter capacitor C3 133, which drives the load resistor RLOAD 134.

[0027] As shown in Figure 4, the winding relationships of the primary winding assemblies 111, 112, 113 and secondary windings 114, 115, 116 around the core 400 that together form a three-phase magnetic assembly are shown. The core 400 has an upper E portion 401 and a lower E portion 402. Each portion 401, 402 has a central leg or limb portion 403 and first and second outer leg or limb legs 404, 405. Also, the base portion 406 of each core portion 401, 402 is joined to the legs 403-405. The arrangement of the primary winding assemblies 111, 112, 113 and secondary windings 114, 115, 116 around the core legs 403-405 results in a sum of magnetic flux within the winding legs that is not zero. Therefore, a common core return leg portion 407 is provided for the windings on the core legs 403-405. The magnetic flux from the three phases (e.g., LLC resonant voltage converters 101, 102, and 103) within the core return leg 407 acts to provide a path for the third harmonic flux.

[0028] Figure 5 shows an isometric view of the core body 500 of the lower E portion 402 of the core 400 of Figure 4 according to one embodiment. Another core body (not shown) that mirrors the core body 500 can be used in the upper E portion 401. The two core bodies may each have primary windings 300-305 that are wound around them together with secondary windings 114-116 and joined together to form the completed core 400 shown in Figure 4.

[0029] Figure 6 shows an embodiment of the three-phase power supply circuit of Figure 1 according to another embodiment. Similar to the embodiment shown in Figure 3, the power supply circuit of Figure 6 includes star-connected primary windings 300-305. Furthermore, secondary winding assemblies 114-116 are also star-connected.

[0030] As shown in the figure, secondary winding assembly 114 is formed from a pair of secondary windings S1 600 and S4 601, secondary winding assembly 115 is formed from a pair of secondary windings S2 602 and S5 603, and secondary winding assembly 116 is formed from a pair of secondary windings S3 604 and S6 605. Therefore, each secondary winding assembly coupled to bridge rectifiers 117-119 includes a pair of secondary windings.

[0031] Secondary winding 600 includes a first node 606 at its dot end, electrically coupled to diode pair D1, D2 of bridge rectifier 117. Secondary winding 602 includes a first node 607 at its dot end, electrically coupled to diode pair D5, D6 of bridge rectifier 118. Secondary winding 604 includes a first node 608 at its dot end, electrically coupled to diode pair D9, D10 of bridge rectifier 119. The second nodes 609, 610, and 611 on the opposite side of the dot ends of secondary windings 600, 602, and 604 are all electrically coupled.

[0032] The first nodes 612, 613, and 614 at the dot ends of secondary windings 601, 603, and 605 are all electrically coupled. Secondary winding 601 includes a second node 615 on the opposite side of its dot end, which is electrically coupled to the diode pair D3 and D4 of bridge rectifier 117. Secondary winding P5 303 includes a second node 616 on the opposite side of its dot end, which is electrically coupled to the diode pair D7 and D8 of bridge rectifier 118. Secondary winding P6 305 includes a second node 617 on the opposite side of its dot end, which is electrically coupled to the diode pair D11 and D12 of bridge rectifier 119.

[0033] As shown in Figure 7, the winding relationships of the primary winding assemblies 111, 112, 113 and secondary winding assemblies 114, 115, 116 around the core 700, which together form a three-phase magnetic assembly, are shown. As explained with respect to Figures 4 and 5, the sum of the magnetic flux in the winding legs is not zero. In contrast, with respect to the circuit configurations shown in Figures 6 and 7, since both the primary windings 300-305 and the secondary windings 600-602 and 603-605 are star-connected, the sum of the magnetic flux in the winding legs is zero or negligible. Therefore, the core 700 can be implemented using the structure of the core 400 in Figure 4 without the core return legs 407. Accordingly, Figure 8 shows an isometric view of the core body 800 of an exemplary lower E portion 402 of the core 700, including legs 403-405 around which the primary and secondary winding assemblies 111-116 are wound. The core return legs 407 in Figure 5 are unnecessary.

[0034] Figure 9 shows an exemplary single-phase LLC resonant voltage converter 900 for use as an LLC resonant voltage converter (e.g., converters 101, 102, 103, etc.) according to one embodiment. The LLC voltage converter 900 is shown implemented as a resonant full-bridge LLC series converter and has a voltage input formed from a pair of voltage input terminals DC+901 and DC-902 that can be coupled to the input voltage VIN shown in Figure 1. The LLC voltage converter 900 includes a switching bridge 903 having a first pair of power switches 904, 905 coupled in series and parallel to the respective voltage inputs, and a second pair of power switches 906, 907 coupled in series and parallel to the respective voltage inputs. A first resonant inductor 908 is coupled in series between the first pair of power switches 904, 905 and a first resonant capacitor 909. A second resonant inductor 910 is coupled in series between the second pair of power switches 906, 907 and a second resonant capacitor 911.

[0035] Controller 912 is coupled to synchronously control power switches 904-907 using pulse-width modulation (PWM) signals, thereby ensuring that the power conversion in voltage converter 900 is not in phase with the power conversion in other voltage converters 102 and 103, such as having a 120° phase difference. For example, the PWM signal can control the on and off states of power switches 904 and 907, as well as the on and off states of power switches 905 and 906, together.

[0036] Figure 10 shows an exemplary three-phase LLC resonant voltage converter 1000 according to another embodiment. In this embodiment, each of the LLC resonant voltage converters 101 to 103 includes two pairs of power switches coupled to their respective resonant inductors and capacitors. LLC resonant voltage converter 101 includes a first pair of power switches 1001, 1002 coupled to a resonant inductor 1003 and a resonant capacitor 1004. LLC resonant voltage converter 101 also includes a second pair of power switches 1005, 1006 coupled to a resonant inductor 1007 and a resonant capacitor 1008. LLC resonant voltage converters 102, 103 are configured similarly. For example, LLC resonant voltage converter 102 includes power switches 1009, 1010, a resonant inductor 1011, and a resonant capacitor 1012 in a first configuration, and power switches 1013, 1014, a resonant inductor 1015, and a resonant capacitor 1016 in a second configuration. The LLC resonant voltage converter 103 includes power switches 1017, 1018, a resonant inductor 1019, and a resonant capacitor 1020 in a first configuration, and power switches 1021, 1022, a resonant inductor 1023, and a resonant capacitor 1024 in a second configuration. As shown in the figure, the first pair of power switches ((1001, 1002), (1009, 1010), (1017, 1018)) are coupled in parallel, and the second pair of power switches ((1005, 1006), (1013, 1014), (1021, 1022)) are coupled in parallel. The first pair of switches is further coupled in series with the second set of power switches. Furthermore, the first and second pairs of switches connected in series are coupled in parallel with the input voltage VIN.

[0037] Figure 11 shows an exemplary three-phase power supply circuit 1100 including three LLC resonant voltage converters. This exemplary power supply circuit 1100 comprises three LLC resonant voltage converter stages 1101, 1102, and 1103 and an LLC resonant voltage converter resonant choke stage 1104. The LLC resonant voltage converter stages 1101-1103 and the LLC resonant voltage converter resonant choke stage 1104 together form three LLC voltage converters.

[0038] Each of the three LLC resonant voltage converter stages 1101, 1102, and 1103 includes a pair of voltage inputs 1105 and 1106 (DC+ and DC-). The input voltage VIN is applied to the DC+ and DC- inputs 1105 and 1106 of the voltage converter stages 1101, 1102, and 1103 across capacitors C1 1107 and C2 1108, acting to divide the input voltage VIN in half when the values ​​of capacitors C1 1107 and C2 1108 are the same.

[0039] Each of the three LLC resonant voltage converter stages 1101, 1102, and 1103 includes a pair of voltage outputs 1109, 1110 (OUT+ and OUT-). The current generated by the voltage converter stage (e.g., 1101) and supplied through its voltage output OUT+1109 flows, for example, through the first resonant capacitor and resonant inductor pair 1111 of the LLC resonant voltage converter resonant choke stage 1104, through the transformer assembly T1 1112 of the transformer and secondary circuit block 1113, through other resonant capacitor and resonant inductor pairs 1114, 1115, 1116, 1117, through the other two voltage converter stages (e.g., 1102, 1103), through other resonant capacitor and resonant inductor pairs 1118, and returns through the voltage output OUT-1110. When supplied via voltage output OUT-1110, the generated current flows through the resonant capacitor and resonant inductor pair 1118, voltage converter stages 1102, 1103, resonant capacitor and resonant inductor pairs 1114-1117, transformer block 1112, and resonant capacitor and resonant inductor pair 1111, before returning to voltage output OUT+1109. In embodiments of the voltage converter stages 1101, 1102, and 1103 disclosed herein, a pair of voltage outputs 1109, 1110 are required to convert the input voltage VIN into an output current. LLC voltage converters having only a single output electrically coupled to a transformer assembly are not intended herein.

[0040] Figure 12 shows an exemplary single-phase LLC resonant voltage converter stage 1200 having a pair of voltage outputs 1201, 1202 for use in a three-phase power supply circuit disclosed herein. In this exemplary embodiment, input voltages are applied to the inputs DC+1203 and DC-1204 of the voltage converter 1200. In some exemplary embodiments, the input voltages may be provided by a power factor correction circuit.

[0041] Switch Q1 1205 and diode D1 1206 constitute a first half-bridge, and switch Q2 1207 and diode D2 1208 constitute a second half-bridge. Diodes D1 1206 and D2 1208 are blocking diodes and block current when switches Q1 1205 and Q2 1207 are turned on simultaneously. In one embodiment, resistor R10 1209 is included between diodes D1 1206 and D2 1208 to ground diodes D1 1206 and D2 1208. In another embodiment, diodes D1 1206 and D2 1208 may be directly grounded without resistor R10 1209.

[0042] Switch Q1 1205 is driven by isolation driver E1 1210 and resistors R1 1211 and R2 1212. Switch Q2 1207 is driven by isolation driver E2 1213 and resistors R3 1214 and R4 1215. Both isolation drivers E1 1213 and E2 1213 are driven by a square wave AA 1216 generated by a control circuit (not shown).

[0043] The maximum voltage stress on switches Q1 1205 and Q2 1207 is equal to half of the input voltage between DC+1203 and DC-1204, while switch Q3 1217 is subjected to the full voltage stress of the input voltage between DC+1203 and DC-1204. In an exemplary embodiment, if the input voltage between DC+1203 and DC-1204 is 440 volts, switches Q1 1205 and Q2 1207 can be rated at 300-400 volts, and Q3 1217 can be rated at 600-650 volts.

[0044] Switch Q3 1217 is configured to short-circuit diodes D1 1206 and D2 1208 when activated by isolation driver E3 1218 and resistors R5 1219 and R6 1220. Isolation driver E3 1218 is driven by a square wave BB 1221 generated by a control circuit (not shown).

[0045] Each half-bridge drives one primary node of the primary coil of an external transformer (e.g., transformer assembly 1112 in Figure 11) via a resonant capacitor / inductor pair (e.g., resonant capacitor / inductor pairs 1111, 1114, 1115 in Figure 11). A first half-bridge, comprising switch Q1 1205 and diode D1 1206, drives the primary coil of the external transformer via electrically series-coupled split resonant capacitor and inductor components. A second half-bridge, comprising switch Q2 1207 and diode D2 1208, drives the primary coil of the external transformer via different electrically series-coupled split resonant capacitor and inductor components. Output voltages OUT+1201 and OUT-1202 are provided to the first and second nodes of the primary coil assembly of the external transformer assembly, as described herein.

[0046] Figure 13 shows an exemplary single-phase LLC resonant voltage converter stage 1300 for use as an LLC resonant voltage converter stage (e.g., converter stages 1101, 1102, 1103, etc.) according to another embodiment. The LLC voltage converter stage 1300 is shown implemented as a resonant full-bridge LLC series converter and has voltage inputs formed from a pair of voltage input terminals DC+1301 and DC-1302 that can be coupled to the input voltage VIN shown in Figure 11. The LLC voltage converter stage 1300 includes a switching bridge 1303 having a first pair of power switches 1304, 1305 coupled in series and parallel to the respective voltage inputs, and a second pair of power switches 1306, 1307 coupled in series and parallel to the respective voltage inputs. The pair of voltage outputs 1308 and 1309 are coupled to resonant capacitor / inductor pairs similar to the voltage outputs 1201 and 1202 in Figure 12 (for example, resonant capacitor / inductor pairs 1111, 1114, and 1115 in Figure 11).

[0047] Controller 1310 is coupled to synchronously control power switches 1304-1307 using pulse-width modulation (PWM) signals, thereby ensuring that the power conversion in voltage converter stage 1300 is not in phase with the power conversion in other voltage converters 1102 and 1103, such as having a 120° phase difference. For example, the PWM signal can control the on and off states of power switches 1304 and 1307, as well as the on and off states of power switches 1305 and 1306, together.

[0048] Figure 14 shows an exemplary embodiment of an LLC resonant voltage converter resonant choke stage 1104 according to one embodiment. As shown, each of the resonant capacitor and resonant inductor pairs 1111, 1114, and 1116 includes a resonant capacitor C1 1119 and a resonant inductor L1 1120, and each of the resonant capacitor and resonant inductor pairs 1115, 1117, and 1117 includes a resonant capacitor C2 1121 and a resonant inductor L2 1122.

[0049] In the embodiment shown in Figure 14, the inductors 1120 and 1122 of the resonant capacitor / inductor pairs 1111 and 1118 are wound around a single core 1400. The inductors 1120 and 1122 of the resonant capacitor / inductor pairs 1114-1115 are wound around another single core 1401. The inductors 1120 and 1122 of the resonant capacitor / inductor pairs 1116-1117 are wound around another single core 1402. The cores 1400-1402 may be, for example, UU cores, UI cores, EE cores, EI cores, or any combination thereof. The resonant capacitor / inductor pairs are wound around the cores 1400-1402 as shown to ensure current balance between the star-connected primary windings of the transformer assembly 1112, and the star connection itself balances the current between the three phases of the LLC resonant voltage converter stages 1101, 1102, and 1103.

[0050] Figure 15 shows the arrangement of the LLC resonant voltage converter resonant choke stage 1104 shown in Figure 14 according to another embodiment. As shown, the inductors 1120 and 1122 of the resonant capacitor / inductor pairs 1111 and 1118 are wound around an outer core leg 1500, such as the core 400 shown in Figure 4; the inductors 1120 and 1122 of the resonant capacitor / inductor pairs 1114 to 1115 are wound around another outer core leg 1501; and the inductors 1120 and 1122 of the resonant capacitor / inductor pairs 1116 to 1117 are wound around a central core leg 1502. The first core base portion 1503 and the second core base portion 1504 join the core legs 1500 to 1502. The core in Figure 15 (formed by the leg and base portions 1500-1504) can represent a three-phase EE core or EI core, which offers the same current balancing advantages as described above for cores 1400, 1401, and 1402, but provides a smaller footprint and lower losses due to the smaller volume of the integrated core compared to three separate cores (e.g., cores 1400, 1401, and 1402).

[0051] Figure 16 shows one embodiment of the transformer and secondary circuit block 1113 of Figure 11 according to one embodiment. The transformer assembly 1112 includes three primary winding assemblies 1600, 1601, and 1602. In a multiphase interleaved LLC resonant voltage converter power supply as shown in Figure 11, current imbalance circulating between primary currents due to differences in component tolerances can adversely affect converter efficiency. Therefore, the embodiments of the transformer assembly 1112 disclosed herein counteract current imbalance. As shown, primary winding assembly 1600 is formed from a pair of primary windings P1 1603 and P4 1604, primary winding assembly 1601 is formed from a pair of primary windings P2 1605 and P5 1606, and primary winding assembly 1602 is formed from a pair of primary windings P3 1607 and P6 1608.

[0052] Primary winding P1 1603 includes a first node 1609 at its dot end, which is electrically coupled to the voltage output 1109 of the LLC resonant voltage converter 1101. Primary winding P2 1605 includes a first node 1610 at its dot end, which is electrically coupled to the voltage output 1109 of the LLC resonant voltage converter 1102. Primary winding P3 1607 includes a first node 1611 at its dot end, which is electrically coupled to the voltage output 1109 of the LLC resonant voltage converter 1103. The second nodes 1612, 1613, and 1614 on the opposite side of the dot ends of primary windings P1 to P3 are all electrically coupled.

[0053] The first nodes 1615, 1616, and 1617 at the dot ends of primary windings P4 to P6 are all electrically coupled. Primary winding P4 1604 includes a second node 1618 on the opposite side of its dot end, which is electrically coupled to the voltage output 1110 of the LLC resonant voltage converter 1101. Primary winding P5 1606 includes a second node 1619 on the opposite side of its dot end, which is electrically coupled to the voltage output 1110 of the LLC resonant voltage converter 1102. Primary winding P6 1608 includes a second node 1620 on the opposite side of its dot end, which is electrically coupled to the voltage output 1110 of the LLC resonant voltage converter 1103.

[0054] The total number of primary turns is P1+P4=P2+P5=P3+P6. Therefore, the primary winding for each phase is divided into equal halves. In one embodiment, primary windings P1-P6 have equal numbers of turns. The electrically coupled terminations of the first half of the windings (e.g., the second nodes 1612-1614 of windings P1-P3) are short-circuited together to form one floating star connection. Similarly, the starting ends of the second half of the windings (e.g., the first nodes 1615-1617 of windings P4-P6) are connected to form another floating star connection. When electrically coupled with an LLC voltage converter having split resonant components (e.g., capacitors 1119, 1121 and inductors 1120, 1122 of the LLC resonant voltage converter choke stage 1104), the advantage associated with substantially equal voltages with opposite polarity at the transformer terminals is that common-mode (CM) noise is reduced.

[0055] The three secondary winding assemblies S1-S3 1621, 1622, and 1623 of the transformer assembly 1112 are inductively coupled to the primary winding assemblies 1600-1602 and electrically coupled to their respective bridge rectifiers. Diodes D1-D4 1624-1627 form the first bridge rectifier (e.g., bridge rectifier 117 in Figure 1). Diodes D5-D8 1628-1631 form the second bridge rectifier (e.g., bridge rectifier 118 in Figure 1). Diodes D9-D12 1632-1635 form the third bridge rectifier (e.g., bridge rectifier 119 in Figure 1).

[0056] As shown in the figure, secondary winding assembly 1621 is formed from a pair of secondary windings S1 1636 and S4 1637, secondary winding assembly 1622 is formed from a pair of secondary windings S2 1638 and S5 1639, and secondary winding assembly 1623 is formed from a pair of secondary windings S3 1640 and S6 1641.

[0057] Secondary winding 1636 includes a first node 1642 at its dot end, electrically coupled to diode pair D1, D2 1624, 1625. Secondary winding 1638 includes a first node 1643 at its dot end, electrically coupled to diode pair D5, D6 1628, 1629. Secondary winding 1640 includes a first node 1644 at its dot end, electrically coupled to diode pair D9, D10 1632, 1633. Second nodes 1645, 1646, and 1647 on the opposite side of the dot ends of secondary windings 1636, 1638, and 1640 are all electrically coupled.

[0058] The first nodes 1648, 1649, and 1650 at the dot ends of secondary windings 1637, 1639, and 1641 are all electrically coupled. Secondary winding 1637 includes a second node 1651 on the opposite side of its dot end, which is electrically coupled to diode pair D3, D4 1626, 1627. Secondary winding P5 1606 includes a second node 1652 on the opposite side of its dot end, which is electrically coupled to diode pair D7, D8 1630, 1631. Secondary winding P6 1608 includes a second node 1653 on the opposite side of its dot end, which is electrically coupled to diode pair D11, D12 1634, 1635. As shown in Figures 11 and 16, the voltage outputs 1654 and 1655 of the transformer and secondary circuit block 1113 generate the output voltage VOUT 1123 across the output filter capacitor C3 1124 that drives the load resistor RLOAD 1125.

[0059] As shown in Figure 16, the winding relationships of the primary winding assemblies 1600-1602 and secondary winding assemblies 1621-1623 around a core that together forms a three-phase magnetic assembly are shown. The core has a central leg or limb 1656 and first and second outer legs or limbs 1657, 1658. Furthermore, base portions 1659, 1660 join the legs 1656-1658. In one embodiment, a common core return leg, such as the core return leg 407 in Figure 4, can be provided in the windings of the core legs 1656-1658. The magnetic flux from the three phases (e.g., LLC resonant voltage converters 1101, 1102, 1103) within the core return leg acts to provide a path for a third harmonic magnetic flux.

[0060] In one embodiment, the primary winding assemblies 1600-1602 and the secondary winding assemblies 1621-1623 are tightly wound around the core in a manner similar to that illustrated and described with respect to Figure 4. This maintains a balanced layout in the secondary circuit block 1113 and avoids impedance imbalances between the windings.

[0061] Figure 17 shows one embodiment of the transformer and secondary circuit block 1113 of Figure 16 according to one embodiment. As shown, the transformer and secondary circuit stage 1113 of Figure 16 is divided between two magnetic cores. In the first core configuration 1661, the first core (including legs 1656-1658 and base 1659-1660) continues to have primary windings 1604, 1606, 1608 and secondary windings 1637, 1639, 1641 wound on it. In the second core configuration 1662, the second core includes a central leg 1663 having primary windings 1605 and secondary windings 1638 wound on it. The first outer leg 1664 has primary windings 1603 and secondary windings 1636 wound on it. The second outer leg portion 1665 has a primary winding 1607 and a secondary winding 1640 wound over it. A pair of core base portions 1666, 1667 connect the legs 1663 to 1665. The first and second core configurations 1661, 1662 provide less restrictive tolerances for the layout of the rectifying components coupled to the secondary windings 1636 to 1641.

[0062] In another embodiment shown in Figure 18, a single core configuration 1800 is shown that combines the advantages of the first and second core configurations 1661, 1662. The single magnetic core includes a first central leg or limb 1801 and a first pair of outer legs or limbs 1802, 1803. The central leg and outer legs 1801-1803 extend between a first base portion 1804 and an intermediate portion 1805. A second central leg or limb 1806 and a second pair of outer legs or limbs 1807, 1808 extend between the intermediate portion 1805 and a second base portion 1809. The core formed by the legs and base portions 1801-1809 may be an EIE core in some examples.

[0063] Figure 18 also shows a number of transistors 1810-1821 (e.g., metal-oxide-semiconductor field-effect transistors (MOSFETs)) that replace the diodes 1624-1635 in Figure 17. The transistors 1810-1821 may be controlled by a controller, for example, as a synchronous rectifier. In addition to the diodes in Figure 17, the diodes 1624-1635 in Figure 16 may also be replaced by MOSFETs. Furthermore, the transistors 1810-1821 in Figure 18 may be replaced by diodes as shown in Figures 16 and 17. Diodes and transistors are sometimes referred to as rectifier switches in this specification.

[0064] Based on the disclosures shown in Figures 11 to 18 and described above, various three-phase LLC voltage converters having star-connected primary and secondary windings can be formed. In one embodiment, the voltage converter stage shown in Figure 12 can be combined with the choke stage 1104 of Figure 14 and the transformer and secondary circuit stage 1113 of Figure 16.

[0065] In another embodiment, the voltage converter stage shown in Figure 12 can be combined with the choke stage 1104 in Figure 14 and the transformer and secondary circuit stage 1113 in Figure 17.

[0066] In another embodiment, the voltage converter stage shown in Figure 12 can be combined with the choke stage 1104 in Figure 14 and the transformer and secondary circuit stage 1113 in Figure 18.

[0067] In another embodiment, the voltage converter stage shown in Figure 12 can be combined with the choke stage 1104 in Figure 15 and the transformer and secondary circuit stage 1113 in Figure 16.

[0068] In another embodiment, the voltage converter stage shown in Figure 12 can be combined with the choke stage 1104 in Figure 15 and the transformer and secondary circuit stage 1113 in Figure 17.

[0069] In another embodiment, the voltage converter stage shown in Figure 12 can be combined with the choke stage 1104 in Figure 15 and the transformer and secondary circuit stage 1113 in Figure 18.

[0070] In another embodiment, the voltage converter stage shown in Figure 13 can be combined with the choke stage 1104 in Figure 14 and the transformer and secondary circuit stage 1113 in Figure 16.

[0071] In another embodiment, the voltage converter stage shown in Figure 13 can be combined with the choke stage 1104 in Figure 14 and the transformer and secondary circuit stage 1113 in Figure 17.

[0072] In another embodiment, the voltage converter stage shown in Figure 13 can be combined with the choke stage 1104 in Figure 14 and the transformer and secondary circuit stage 1113 in Figure 18.

[0073] In another embodiment, the voltage converter stage shown in Figure 13 can be combined with the choke stage 1104 in Figure 15 and the transformer and secondary circuit stage 1113 in Figure 16.

[0074] In another embodiment, the voltage converter stage shown in Figure 13 can be combined with the choke stage 1104 in Figure 15 and the transformer and secondary circuit stage 1113 in Figure 17.

[0075] In another embodiment, the voltage converter stage shown in Figure 13 can be combined with the choke stage 1104 in Figure 15 and the transformer and secondary circuit stage 1113 in Figure 18.

[0076] Although the present invention has been described in detail in relation to only a limited number of embodiments, it should be readily understood that the present invention is not limited to such disclosed embodiments. Rather, the present invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent configurations that are not described herein but are in accordance with the spirit and scope of this disclosure. Furthermore, although various embodiments of this disclosure have been described, it should be understood that aspects of this disclosure may include only a subset of the embodiments described. Therefore, the present invention should not be considered limited by the foregoing description, but only by the appended claims.

Claims

1. A multiphase power supply circuit, The first voltage converter stage, A pair of voltage inputs, A pair of voltage outputs, A first voltage converter stage comprising, It is a resonant choke stage, A first resonant inductor is electrically coupled to the first voltage output of the pair of voltage outputs of the first voltage converter stage, A second resonant inductor is electrically coupled to the second voltage output of the pair of voltage outputs of the first voltage converter stage, A resonant choke stage equipped with, A transformer assembly electrically coupled to the aforementioned resonant choke stage, Multiple primary coil assemblies, Multiple secondary coil assemblies, A transformer assembly equipped with, Each of the above-mentioned multiple primary coil assemblies is The first primary winding, A first node electrically coupled to the resonant choke stage, The second node and A first primary winding comprising, The second primary winding, The first node and, A second node electrically coupled to the aforementioned resonant choke stage, A second primary winding comprising, The second nodes of the first primary winding are electrically coupled together. The first nodes of the second primary winding are electrically coupled together. A multiphase power supply circuit in which the first and second resonant inductors are wound around the first legs of the first magnetic core.

2. A second voltage converter stage having a pair of voltage outputs, The system further comprises a third voltage converter stage having a pair of voltage outputs, The aforementioned resonant choke stage, A third resonant inductor is electrically coupled to the first voltage output of the pair of voltage outputs of the second voltage converter stage, A fourth resonant inductor is electrically coupled to the second voltage output of the pair of voltage outputs of the second voltage converter stage, A fifth resonant inductor is electrically coupled to the first voltage output of the pair of voltage outputs of the third voltage converter stage, A sixth resonant inductor is electrically coupled to the second voltage output of the pair of voltage outputs of the third voltage converter stage, The multiphase power supply circuit according to claim 1, further comprising the following:

3. The third and fourth resonant inductors are wound around the second leg of the first magnetic core, The fifth and sixth resonant inductors are wound around the third leg of the magnetic core, The multiphase power supply circuit according to claim 2, wherein the first, second, and third legs of the first magnetic core are joined to each other via a pair of core bases.

4. The third and fourth resonant inductors are wound around the first leg of the second magnetic core, The multiphase power supply circuit according to claim 2, wherein the fifth and sixth resonant inductors are wound around the first leg of the third magnetic core.

5. Each of the aforementioned multiple secondary coil assemblies is A first secondary winding having a first node and a second node, A second secondary winding comprising a first node and a second node, The second nodes of the first secondary winding are electrically coupled together. The multiphase power supply circuit according to claim 1, wherein the first nodes of the second secondary winding are electrically coupled together.

6. The transformer assembly is further electrically coupled to a bridge rectifier assembly comprising three bridge rectifiers, Each bridge rectifier, A first pair of rectifier switches electrically coupled in series, A second pair of rectifier switches electrically coupled in series, Equipped with, The first pair of rectifier switches is electrically connected in parallel with the second pair of rectifier switches. The rectifier switch includes one of a diode and a transistor. The multiphase power supply circuit according to claim 5.

7. The first primary winding of the first primary coil assembly among the plurality of primary coil assemblies and the first secondary winding of the first secondary coil assembly among the plurality of secondary coil assemblies are wound around the first leg of the second magnetic core. The first primary winding of the second primary coil assembly among the plurality of primary coil assemblies and the first secondary winding of the second secondary coil assembly among the plurality of secondary coil assemblies are wound around the second leg of the second magnetic core. The first primary winding of the third primary coil assembly among the plurality of primary coil assemblies and the first secondary winding of the third secondary coil assembly among the plurality of secondary coil assemblies are wound around the third leg of the second magnetic core. The multiphase power supply circuit according to claim 5.

8. The second primary winding of the first primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the first secondary coil assembly among the plurality of secondary coil assemblies are wound around the first leg of the second magnetic core. The second primary winding of the second primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the second secondary coil assembly among the plurality of secondary coil assemblies are wound around the second leg of the second magnetic core. The second primary winding of the third primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the third secondary coil assembly among the plurality of secondary coil assemblies are wound around the third leg of the second magnetic core. The multiphase power supply circuit according to claim 7.

9. The second primary winding of the first primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the first secondary coil assembly among the plurality of secondary coil assemblies are wound around the first leg of the third magnetic core. The second primary winding of the second primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the second secondary coil assembly among the plurality of secondary coil assemblies are wound around the second leg of the third magnetic core. The second primary winding of the third primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the third secondary coil assembly among the plurality of secondary coil assemblies are wound around the third leg of the third magnetic core. The multiphase power supply circuit according to claim 7.

10. The first voltage converter stage, Two switches and two diodes coupled to a three-level LLC circuit configuration between the pair of voltage inputs and the pair of voltage outputs, wherein the two switches and two diodes are A first switch and a first diode configured as a first half-bridge, A second switch and a second diode configured as a second half-bridge, It is equipped with two switches and two diodes, A third switch, which is coupled across the first and second diodes to short-circuit the first and second diodes in response to the third switch being in conductive mode, A multiphase power supply circuit according to claim 1, comprising:

11. The first voltage converter stage is a switch assembly, A first pair of switches electrically coupled in series, A second pair of switches electrically coupled in series, The first pair of switches is electrically connected in parallel with the second pair of switches. The first pair of switches is electrically coupled in parallel with the pair of voltage inputs. The multiphase power supply circuit according to claim 1, comprising a switch assembly.

12. It is a method, The first voltage output of the first voltage converter stage is coupled to the first resonant inductor of the resonant choke stage, The second voltage output of the first voltage converter stage is coupled to the second resonant inductor of the resonant choke stage, The method involves coupling a transformer assembly to the resonant choke stage, wherein the transformer assembly includes a plurality of primary coil assemblies, and each of the plurality of primary coil assemblies is The first primary winding, A first node electrically coupled to the resonant choke stage, The second node and A first primary winding comprising, The second primary winding, The first node and, A second node electrically coupled to the aforementioned resonant choke stage, A second primary winding comprising, and a coupling, The second node of the first primary winding is connected to the first primary winding, The first node of the second primary winding is connected to the first node of the second primary winding, A method comprising winding the first and second resonant inductors around the first leg of the first magnetic core.

13. The coupling involves connecting a second voltage converter stage to the resonant choke stage, wherein the second voltage converter stage has a pair of voltage outputs. The coupling involves connecting a third voltage converter stage to the resonant choke stage, wherein the third voltage converter stage has a pair of voltage outputs. The third resonant inductor is coupled to the first voltage output of the pair of voltage outputs of the second voltage converter stage, The fourth resonant inductor is coupled to the second voltage output of the pair of voltage outputs of the second voltage converter stage, The fifth resonant inductor is coupled to the first voltage output of the pair of voltage outputs of the third voltage converter stage, The method according to claim 12, further comprising coupling a sixth resonant inductor to the second voltage output of the pair of voltage outputs of the third voltage converter stage.

14. The third and fourth resonant inductors are wound around the second leg of the magnetic core, The method according to claim 13, further comprising winding the fifth and sixth resonant inductors around the third leg of the magnetic core.

15. The transformer assembly further comprises a plurality of secondary coil assemblies, each secondary coil assembly is A first secondary winding having a first node and a second node, A second secondary winding comprising a first node and a second node, The method described above is The second node of the first secondary winding is connected to the first secondary winding, The first node of the second secondary winding is connected to the second node, The method according to claim 12, further comprising:

16. The first primary winding of the first primary coil assembly among the plurality of primary coil assemblies and the first secondary winding of the first secondary coil assembly among the plurality of secondary coil assemblies are wound around the first leg of the second magnetic core, The first primary winding of the second primary coil assembly among the plurality of primary coil assemblies and the first secondary winding of the second secondary coil assembly among the plurality of secondary coil assemblies are wound around the second leg of the second magnetic core, The method according to claim 15, further comprising winding the first primary winding of a third primary coil assembly among the plurality of primary coil assemblies and the first secondary winding of a third secondary coil assembly among the plurality of secondary coil assemblies around the third leg of the second magnetic core.

17. The second primary winding of the first primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the first secondary coil assembly among the plurality of secondary coil assemblies are wound around the first leg of the second magnetic core, The second primary winding of the second primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the second secondary coil assembly among the plurality of secondary coil assemblies are wound around the second leg of the second magnetic core, The method according to claim 16, further comprising winding the second primary winding of the third primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the third secondary coil assembly among the plurality of secondary coil assemblies around the third leg of the second magnetic core.

18. The second primary winding of the first primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the first secondary coil assembly among the plurality of secondary coil assemblies are wound around the first leg of the third magnetic core, The second primary winding of the second primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the second secondary coil assembly among the plurality of secondary coil assemblies are wound around the second leg of the third magnetic core, The method according to claim 16, further comprising winding the second primary winding of the third primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the third secondary coil assembly among the plurality of secondary coil assemblies around the third leg of the third magnetic core.

19. The second primary winding of the first primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the first secondary coil assembly among the plurality of secondary coil assemblies are wound around the fourth leg of the second magnetic core, The second primary winding of the second primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the second secondary coil assembly among the plurality of secondary coil assemblies are wound around the fifth leg of the second magnetic core, The method according to claim 16, further comprising winding the second primary winding of the third primary coil assembly among the plurality of primary coil assemblies and the second secondary winding of the third secondary coil assembly among the plurality of secondary coil assemblies around the sixth leg of the second magnetic core.

20. The first voltage converter stage, A first switch and a first diode configured as a first half-bridge, A second switch and a second diode configured as a second half-bridge, A third switch, which is coupled across the first and second diodes to short-circuit the first and second diodes in response to the third switch being in conductive mode, Equipped with, The method described above is The method according to claim 12, further comprising coupling the first, second, and third switches and the first and second diodes in a three-level LLC circuit configuration.

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