Layouts of multiple transformers and multiple rectifiers of interleaving converter

The present invention relates to multi-phase parallel-interleaved converter circuits with each phase having two or more transformers and two or more rectifiers electrically coupled to the two or more transformers, and layouts of the transformers and the rectifiers of the multi-phase parallel-interleaved converter circuits. In the layouts, the multiple transformers and the multiple rectifiers of the multi-phase converters are interleavingly arranged to be symmetrical to common output polarized capacitor(s) so as to ensure the rectifier outputs of each phase relative to the common output polarized capacitors is symmetrical, thereby reducing the output ripples of the current of the output capacitors.

FIELD OF THE INVENTION

The present invention generally relates to interleaving converter circuits having multiple transformers and multiple rectifiers, and more particularly, to a resonant converter, and layouts of the multiple transformers and the multiple rectifiers of the interleaving LLC-SRC circuits.

BACKGROUND OF THE INVENTION

An LLC series-resonant converter (LLC-SRC) has found widespread applications in power supply devices, because of its advantages over other types of converters. For example, its design is relatively simple, and can achieve the zero voltage switching (ZVS) operation of the primary MOS (metal-oxide semiconductor) and the zero current switching (ZCS) operation of the secondary MOS in a full load range, thereby enhancing the system efficiency.

However, the output current of the LLC-SRC has a “half-chord” waveform. Additionally, when the switching frequency is lower than the resonant frequency, the current of the secondary MOS is un-continued and its peaks are relatively high, which increase not only the predefined/specification values of component currents, but also the conduction losses of the converter.

The conventional LLC-SRC has drawbacks of which the output current has large ripples. In order to meet relatively same output voltage ripples of a conventional PWM converter and requirements of the current ripples of the capacitor, the outputs need to be parallel-coupled to a number of capacitors. To apply the LLC-SRC in strong current situations, it is necessary to adapt an interleaving mode, that is, two or N LLC-SRCs are parallel-connected/interleaved. Using a control circuit to make the switches of each LLC-SRC driven with a 90° or 180°/N shift may effectively reduce the output current ripples and increase the frequency of the output current ripples, thereby reducing the number of the output capacitors, lowering the specifications of the power switching elements, so as to achieve the goal of reducing costs and increasing the output power and the power density while still having the advantages of the LLC-SRC ZVS and ZCS.

The parallel-interleaved LLC-SRC is applicable to power supplies of high power and high current. The parallel-interleaved LLC-SRC mainly refers to a converter in which the outputs of two or more LLC-SRCs are parallel-connected and coupled to a common output filter capacitor. When two LLC-SRCs are interleaved, there are two types of input connections: one is that the inputs are parallel-connected, which is adapted for the low input voltages and used only for power amplification. The other is that the inputs are series-connected, where a three-phase PFC is generally coupled prior to the inputs. Accordingly, the use of switches with lower voltage stress meets the requirements of high input voltages. In the two-phase interleaved LLC-SRC, the distribution of the rectifier outputs at the secondary side is symmetrical relative to the common output capacitor, whereby the amplitudes of the output currents of the rectifiers in the two phases are equal, while and phases are shifted at 90°. After the output currents are superpositioned, an output current of the output capacitor with small ripples can be achieved.

However, in practice, the length difference of the conductive wires transmitting the rectifier outputs of the secondary sides of the two-phase interleaved LLC-SRC to the common output capacitor may result in different parasitic resistances and parasitic inductances therein, thereby inevitably causing the asymmetry of the output currents. Consequently, the amplitude and phase shifts are generated in the two-phase rectifier output currents, which result in the increase of the ripple current of the output capacitor, and deteriorating the parallel-interleaved effect.

In the low-voltage and strong-current applications, due to product specifications, each parallel-interleaved LLC-SRC may have two or more transformers. Considering the limitation of the current stress of the rectifier MOS and the cost, each LLC-SRC may have two or more corresponding rectifiers. If the layouts of the transformers and rectifiers are not appropriated, the interleaving effect will be greatly reduced.

SUMMARY OF THE INVENTION

The present invention, in one aspect, relates to a converter circuit. In one embodiment, the converter circuit has a first output and a second output, and comprises a first converter and a second converter.

Each converter includes a switch network circuit; a first transformer and a second transformer, each transformer having a primary winding and at least one secondary winding, wherein the switch network circuit and the primary windings of the first and second transformers are electrically connected to each other; and a first rectifier and a second rectifier electrically coupled to the secondary windings of the first transformer and the second transformer, respectively, each rectifier having a first output and a second output.

The first and second outputs of the first rectifiers of the first and second converters are electrically parallel-connected to a first output capacitor that is electrically connected between the first and second outputs of the converter circuit. The first and second outputs of the second rectifiers of the first and second converters are electrically parallel-connected to a second output capacitor that is electrically connected between the first and second outputs of the converter circuit.

In one embodiment, each converter has a first input and a second input. The second input of the first converter is electrically series-connected to the first input of the second converter. The first input of the first converter and the second input of the second converter are electrically coupled to a voltage source for receiving an input voltage.

In one embodiment, each resonant converter further comprises a switch network circuit, electrically coupled between the first and second inputs and the resonant tank. In one embodiment, the switch network circuit of each resonant converter comprises a half-bridge circuit or a full-bridge circuit.

In one embodiment, each of the first and second output capacitors comprises one or more high frequency filtering capacitors.

In one embodiment, each of the first and second rectifiers of each resonant converter comprises a half-bridge circuit or a full-bridge circuit.

In another aspect, the present invention relates to a layout of the resonant converter circuit as disclosed above.

In one embodiment, the layout includes a main board, a first sub-board and a second sub-board spaced-apart and vertically attached to the main board along a predetermined direction. The first rectifiers of the first and second resonant converters and the first output capacitor are spaced-apart disposed on one side of the first sub-board such that the first output capacitor is placed between the first rectifiers of the first and second resonant converters, and the first transformers of the first and second resonant converters are mounted on the other side of the first sub-board, spatially aligned with and electrically connected to the first rectifiers of the first and second resonant converters, respectively. The second rectifiers of the first and second resonant converters and the second output capacitor are spaced-apart disposed on one side of the second sub-board such that the second output capacitor is placed between the second rectifiers of the first and second resonant converters, and the second transformers of the first and second resonant converters are mounted on the other side of the second sub-board, spatially aligned with and electrically connected to the second rectifiers of the first and second resonant converters, respectively.

In one embodiment, the first rectifiers of the first and second resonant converters are placed symmetrically on two sides of the first output capacitor, and wherein the second rectifiers of the first and second resonant converters are placed symmetrically on two sides of the second output capacitor.

In one embodiment, the first transformers of the first and second resonant converters are mounted on the other side of the first sub-board by fixing pins of the secondary windings of the first transformers of the first and second resonant converters symmetrically on the first sub-board. The second transformers of the first and second resonant converters are mounted on the other side of the second sub-board by symmetrically fixing pins of the secondary windings of the second transformers of the first and second resonant converters symmetrically on the second sub-board.

In one embodiment, each sub-board has a positive output port and a negative output port electrically parallel-connected to a respective one of the first and second output capacitors. The positive and negative output ports of the first sub-board are electrically parallel-connected to the positive and negative output ports of the second sub-board, respectively, which are electrically parallel-connected to the first and second outputs of the resonant converter circuit.

The layout may further comprises one or more polarized capacitors disposed on the main board, and wherein the one or more polarized capacitors are electrically parallel-connected to the first and second outputs of the resonant converter circuit.

In yet another aspect, the present invention relates to a layout of the resonant converter circuit as disclosed above. In one embodiment, the layout includes a main board, and a sub-board vertically attached to the main board. The first rectifier of the first resonant converter, the first output capacitor, the first rectifier of the second resonant converter, the second rectifier of the first resonant converter, the second output capacitor and the second rectifier of the second resonant converter are spaced-apart and orderly disposed on one side of the sub-board along a predetermined direction such that the first output capacitor is placed between the first rectifier of the first resonant converter and the first rectifier of the second resonant converter, and the second output capacitor is placed between the second rectifier of the first resonant converter and the second rectifier of the second resonant converter. The first transformer of the first resonant converter, the first transformer of the second resonant converter, the second transformer of the first resonant converter and the second transformer of the second resonant converter are orderly mounted on the other side of the sub-board, spatially aligned with and electrically connected to the first rectifier of the first resonant converter, the first rectifier of the second resonant converter, the second rectifier of the first resonant converter and the second rectifier of the second resonant converter, respectively.

In one embodiment, the first transformer of the first resonant converter, the first transformer of the second resonant converter, the second transformer of the first resonant converter and the second transformer of the second resonant converter are orderly mounted on the other side of the first sub-board by fixing pins of the secondary windings of the corresponding transformers on the sub-board.

In one embodiment, the sub-board has a first positive output port and a first negative output port electrically parallel-connected to the first output capacitor, and a second positive output port and a second negative output port electrically parallel-connected to the second output capacitor. The first positive output port and the first negative output port electrically parallel-connected to the second positive output port and the second negative output port, which are electrically parallel-connected to the first and second outputs of the resonant converter circuit.

In one embodiment, the layout may also have one or more polarized capacitors disposed on the main board, and wherein the one or more polarized capacitors are electrically parallel-connected to the first and second outputs of the resonant converter circuit.

In a further aspect, the present invention relates to a resonant converter circuit. In one embodiment, the resonant converter circuit has a first output and a second output, and includes M resonant converters, {Gm}, m=1, 2, 3, . . . , M, M being an integer greater than one. Each resonant converter Gmincludes an resonant tank; N transformers {Tm,n}, and N rectifiers, {Rm,n}, n=1, 2, 3, . . . N, N being an integer greater than one. Each transformer Tm,nhas a primary winding and at least one secondary winding. The resonant tank and the primary windings of the N transformers are electrically connected to each other in series. Each rectifier Rm,nhaving a first output and a second output, and electrically coupled to the at least one secondary winding of a respective transformer Tm,n.

In one embodiment, the multiple transformers {Tm,n} and the multiple rectifiers {Rm,n} of the M resonant converters {Gm} are arranged in N groups such that each group includes the n-th transformers T1,n, T2,n, T3,n, . . . TM,nand the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm}. For each group, the first and second outputs of the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} are electrically parallel-connected to a n-th output capacitor, CFn, which is electrically connected between the first and second outputs of the resonant converter circuit.

In one embodiment, each resonant converter Gmhas a first input and a second input, wherein the second input of any one but the last resonant converter Gmis electrically series-connected to the first input of its immediate next resonant converter Gm+1, and wherein the first input of the first resonant converter G1and the second input of the last resonant converter GMare electrically coupled to a voltage source for receiving an input voltage.

In one embodiment, each resonant converter Gmfurther comprises a switch network circuit, NCm, electrically coupled between the first and second inputs and the resonant tank. In one embodiment, the switch network circuit NCmof each resonant converter Gmcomprises a half-bridge circuit or a full-bridge circuit.

In one embodiment, each output capacitor CFncomprises one or more high frequency filtering capacitors.

In one embodiment, each rectifier Rm,nof each resonant converter Gmcomprises a half-bridge circuit or a full-bridge circuit.

In yet a further aspect, the present invention relates to a layout of the resonant converter circuit as disclosed above. In one embodiment, the layout includes a main board, and N sub-boards spaced-apart and vertically attached to the main board along a predetermined direction, where for each group, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} and the n-th output capacitor CFnare spaced-apart disposed on one side of the n-th sub-board, and the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the n-th sub-board, spatially aligned with and electrically connected to the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm}, respectively.

In one embodiment, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} are placed symmetrically on two sides of the n-th output capacitor on the n-th sub-board.

In one embodiment, the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the first sub-board by fixing pins of the secondary windings of each of the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} symmetrically on the n-th sub-board.

In one embodiment, the n-th sub-board has a positive output port and a negative output port electrically parallel-connected to the respective n-th output capacitor. The positive and negative output ports of the N sub-boards are electrically parallel-connected to the first and second outputs of the resonant converter circuit, respectively.

The layout further has one or more polarized capacitors disposed on the main board, and wherein the one or more polarized capacitors are electrically parallel-connected to the first and second outputs of the resonant converter circuit.

In one aspect, the present invention relates to a layout of the resonant converter circuit as disclosed above. In one embodiment, the layout includes a main board, and a sub-board vertically attached to the main board, where for each group, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} and the n-th output capacitor CFnare spaced-apart and orderly disposed on one side of the sub-board along a predetermined direction, and the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the sub-board along the predetermined direction, spatially aligned with and electrically connected to the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm}, respectively, so as to define a respective sub-layout. Each sub-layout is arranged along the predetermined direction.

In one embodiment, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} are placed symmetrically on two sides of the n-th output capacitor on the sub-board.

In one embodiment, the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the first sub-board by fixing pins of the secondary windings of each of the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} symmetrically on the sub-board.

In one embodiment, the sub-board has M pairs of positive and negative output ports. Each pair of the positive and negative output ports electrically parallel-connected to the respective output capacitor. The M pairs of positive and negative output ports are electrically parallel-connected to the first and second outputs of the resonant converter circuit, respectively.

In one embodiment, the layout further has one or more polarized capacitors disposed on the main board, and wherein the one or more polarized capacitors are electrically parallel-connected to the first and second outputs of the resonant converter circuit.

DETAILED DESCRIPTION OF THE INVENTION

The description will be made as to the embodiments of the present invention in conjunction with the accompanying drawings inFIGS. 1-7. In accordance with the purposes of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to interleaving converter circuits having multiple transformers and multiple rectifiers, and layouts of the multiple transformers and the multiple rectifiers of the interleaving converter circuits.

Referring toFIGS. 1 and 2, a resonant converter circuit100is shown according to one embodiment of the present invention. The resonant converter circuit100has a first input101, a second input102, a first output103, a second output104, a first resonant converter G1and a second resonant converter G2.

In one embodiment, the first and second resonant converters G1and G2are structurally the same. As shown inFIG. 2, the first resonant converter G1includes a switch network circuit SNC1, an resonant tank LLC1electrically coupled to switch network circuit SNC1, a first transformer T1,1and a second transformer T1,2electrically coupled to the resonant tank LLC1, a first rectifier R1,1and a second rectifier R1,2electrically coupled to the first transformer T1,1and the second transformer T1,2, respectively.

Specifically, each transformer T1,1/T1,2has a primary winding and two secondary windings. The resonant tank LLC1and the primary windings of the first and second transformers T1,1and T1,2are electrically connected to each other in series. The first and second rectifiers R1,1and R1,2are electrically coupled to the secondary windings of the first and second transformers T1,1and T1,2, respectively.

Each rectifier R1,1/R1,2has a first output111/113and a second output112/114. As shown inFIG. 1, the first outputs111and121and the second outputs112and122of the first rectifiers R1,1and R2,1of the first and second resonant converters G1and G2are electrically parallel-connected to a first output capacitor CF1that is, in turn, electrically connected between the first and second outputs103and104of the resonant converter circuit100. The first outputs113and123and the second outputs114and124of the second rectifiers R1,2and R2,2of the first and second resonant converters G1and G2are electrically parallel-connected to a second output capacitor CF2that is, in turn, electrically connected between the first and second outputs103and104of the resonant converter circuit100.

Additionally, each resonant converter G1/G2has a first input115/125and a second input116/126. The second input116of the first resonant converter G1is electrically series-connected to the first input125of the second resonant converter G2. The first input115of the first resonant converter G1and the second input126of the second resonant converter G2are electrically coupled to the first input101and the second input102of the resonant converter circuit100, respectively, for receiving an input voltage V1n.

In this exemplary embodiment shown inFIGS. 1 and 2, the switch network circuit SNC1/SNC2of each resonant converter G1/G2comprises a full-bridge circuit. In another embodiment, the switch network circuit SNC1/SNC2of each resonant converter G1/G2comprises a half-bridge circuit (not shown).

In one embodiment, each of the first and second output capacitors CF1and CF2includes one or more high frequency filtering capacitors.

In the embodiment shown inFIGS. 1 and 2, each of the first and second rectifiers of each resonant converter comprises a half-bridge circuit. The half-bridge circuit is formed of, for example, two TDSON-8 packaged MOS transistors. In another embodiment, each rectifier includes a full-bridge circuit.

As such a configuration, the resonant converter circuit100operates in an interleaved mode. Ideally, the amplitudes of the output currents of the rectifiers in the two phases are equal, while and phases are shifted at 90°, and thus an output current of the common output capacitor C0has small ripples or no ripples. However, in practice, the conductive wires/leads transmitting the rectifier outputs to the common output capacitor in the two-phase interleaved converters may have different lengths and thus different parasitic resistances and parasitic inductances generated therein. The generated parasitic resistances and inductances may cause the asymmetry of the output currents, which results in the ripple increase of the output capacitor and deteriorates the parallel-interleaved effect.

According to embodiments of the present invention, different layouts of the multiple transformers and the multiple rectifiers of the resonant converter circuit are provided, in which the multiple transformers and the multiple rectifiers of the multi-phase converters are interleavingly arranged to be symmetrical to the common output polarized capacitor(s) so as to ensure the rectifier outputs of each phase relative to the common output polarized capacitor is symmetrical, thereby reducing the output ripples of the current of the output capacitors.

Referring now toFIG. 3, the layout300of the resonant converter circuit100shown inFIG. 1is illustrated according to one embodiment of the present invention. Specifically, the layout300includes a main board360, a first sub-board361and a second sub-board362spaced-apart and vertically attached to the main board360along a direction365that is determined based on a specific product design. In one embodiment, each of the main board360, the first sub-board361and the second sub-board362includes a printed circuit board (PCB).

In the layout300, the first rectifiers R1,1and R2,1of the first and second resonant converters G1and G2and the first output capacitor CF1are spaced-apart disposed on one side of the first sub-board361such that the first output capacitor CF1is placed between the first rectifiers R1,1and R2,1of the first and second resonant converters G1and G2. Preferably, the first rectifiers R1,1and R2,1of the first and second resonant converters G1and G2are placed symmetrically on two lateral sides of the first output capacitor CF1. The first rectifiers R1,1and R2,1are electrically connected to the first output capacitor CF1. Further, the first transformers T1,1and T2,1of the first and second resonant converters G1and G2are mounted on the other side of the first sub-board361, spatially aligned with and electrically connected to the first rectifiers R1,1and R2,1of the first and second resonant converters G1and G2, respectively. In the exemplary embodiment shown inFIG. 3, the conductive pins331A and331B of the secondary windings of the first transformer T1,1of the first resonant converter G1is fixed on the first sub-board361by welding or other mounting means. Similarly, the conductive pins341A and341B of the secondary windings of the first transformer T2,1of the second resonant converter G2is fixed on the first sub-board361by welding or other mounting means. Preferably, the conductive pins331A and331B, and341A and341B of the secondary windings of the first transformers T1,1and T2,1of the first and second resonant converters G1and G2, are symmetrically fixed on the first sub-board361. The first sub-board361has a positive output port311and a negative output port312electrically parallel-connected to the first output capacitor CF1.

Furthermore, the second rectifiers R1,2and R2,2of the first and second resonant converters G1and G2and the second output capacitor CF2are spaced-apart disposed on one side of the second sub-board362such that the second output capacitor CF2is placed between the second rectifiers R1,2and R2,2of the first and second resonant converters G1and G2. Preferably, the second rectifiers R1,2and R2,2of the first and second resonant converters G1and G2are placed symmetrically on two lateral sides of the second output capacitor CF2. The second rectifiers R1,2and R2,2are electrically connected to the second output capacitor CF1. In addition, the second transformers T1,2and T2,2of the first and second resonant converters G1and G2are mounted on the other side of the second sub-board362, spatially aligned with and electrically connected to the second rectifiers R1,2and R2,2of the first and second resonant converters G1and G2, respectively. In the exemplary embodiment shown inFIG. 3, the conductive pins332A and332B of the secondary windings of the second transformer T1,2of the first resonant converter G1is fixed on the second sub-board362by welding or other mounting means. Similarly, the conductive pins342A and342B of the secondary windings of the second transformer T2,2of the second resonant converter G2is fixed on the second sub-board362by welding or other mounting means. Preferably, the conductive pins332A and332B, and342A and342B of the secondary windings of the second transformers T1,2and T2,2of the first and second resonant converters G1and G2, are symmetrically fixed on the first sub-board361. The second sub-board362has a positive output port321and a negative output port322electrically parallel-connected to the second output capacitor CF2. The positive output port311and the negative output port312of the first sub-board361are eclectically connected to the positive output port321and the negative output port322of the second sub-board362, respectively, which in turn, are eclectically connected to the first and second outputs103and104of the resonant converter circuit.

By welding the positive output ports311and321and the negative output ports312and322of the first and second sub-boards361and362to the main board360, the first sub-board361and the second sub-board362are secured to the main board360.

Additionally, the layout300may further comprises one or more polarized capacitors, e.g., CO1, CO2, CO3, disposed on the main board360, and are electrically parallel-connected to the first and second outputs103and104of the resonant converter circuit. The placements of the rectifiers R1,1, R1,2, R2,1and R2,2and the corresponding transformers T1,1, T1,2, T2,1, and T2,2are preferably symmetrical to the one or more polarized capacitors.

FIG. 4shows another embodiment of the layout of the resonant converter circuit100shown inFIG. 1. In the embodiment, the layout400includes a main board460, and a sub-board461vertically attached to the main board460.

In this layout400, the first rectifier R1,1of the first resonant converter G1, the first output capacitor CF1, the first rectifier R2,1of the second resonant converter G2, the second rectifier R1,2of the first resonant converter G1, the second output capacitor CF2and the second rectifier R2,2of the second resonant converter G2are spaced-apart disposed in order on one side of the sub-board461along a desired direction465. Preferably, the first rectifier R1,1of the first resonant converter G1and the first rectifier R2,1of the second resonant converter G2are placed symmetrically to the first output capacitor CF1. The second rectifier R1,2of the first resonant converter G1and the second rectifier R2,2of the second resonant converter G2are placed symmetrically to the second output capacitor CF2.

Furthermore, the first transformer T1,1of the first resonant converter G1, the first transformer T2,1of the second resonant converter G2, the second transformer T1,2of the first resonant converter G1and the second transformer T2,2of the second resonant converter G2are mounted in order on the other side of the sub-board461, spatially aligned with and electrically connected to the first rectifier R1,1of the first resonant converter G1, the first rectifier R2,1of the second resonant converter G2, the second rectifier R1,2of the first resonant converter G1and the second rectifier R2,2of the second resonant converter G2, respectively. In one embodiment, as shown inFIG. 4, each of the first transformer T1,1of the first resonant converter G1, the first transformer T2,1of the second resonant converter G2, the second transformer T1,2of the first resonant converter G1and the second transformer T2,2of the second resonant converter G2is fixed on the first sub-board461by welding the conductive pins (431A,431B)/(441A,441B)/(432A,432B)/(442A,442B) of the secondary windings of the corresponding transformer T1,1/T2,1/T1,2/T2,2on the sub-board461.

In addition, the sub-board461has a first positive output port411and a first negative output port412electrically parallel-connected to the first output capacitor CF1, and a second positive output port421and a second negative output port422electrically parallel-connected to the second output capacitor CF2. The first positive output port412and the first negative output port412electrically parallel-connected to the second positive output port421and the second negative output port422, which are in turn, electrically parallel-connected to the first and second outputs103and104of the resonant converter circuit. Similarly, by welding the first and second positive output ports411and421and the first and second negative output ports412and422of the sub-boards461to the main board460, the sub-board461is secured to the main board460.

In this exemplary embodiment shown inFIG. 4, three polarized capacitors, CO1, CO2and CO3are electrically parallel-connected to the first and second outputs103and104of the resonant converter circuit. Similarly, the placements of the rectifiers R1,1, R1,2, R2,1and R2,2and the corresponding transformers T1,1, T1,2, T2,1, and T2,2are preferably symmetrical to the one or more polarized capacitors.

Referring toFIGS. 5 and 6, a resonant converter circuit500is shown according to another embodiment of the present invention. In the exemplary embodiment, the resonant converter circuit500includes M resonant converters, {Gm}, m=1, 2, 3, . . . , M, M being an integer greater than one.

As shown inFIG. 6, each resonant converter Gmhas an resonant tank, N transformers {Tm,n}, and N rectifiers, {Rm,n}, n=1, 2, 3, . . . N, N being an integer greater than one. Each transformer Tm,nincludes a primary winding and at least one secondary winding. The resonant tank and the primary windings of the N transformers are electrically connected to each other in series. Each rectifier Rm,nis electrically coupled to the at least one secondary winding of a respective transformer Tm,n. In the embodiment shown inFIG. 6, each rectifier Rm,nincludes a half-bridge circuit formed of for example, two MOS switches. Additionally, a full-bridge circuit can also be used as the rectifier Rm,n. Each rectifier Rm,nhas a first output and a second output.

As shown inFIG. 5, the multiple transformers {Tm,n} and the multiple rectifiers {Rm,n}, where m=1, 2, 3, . . . , M, and n=1, 2, 3, . . . N, are arranged in N groups, {Bn}. Each group Bnincludes all the n-th transformers T1,n, T2,n, T3,n, . . . TM,nand the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm}. For each group Bn, the first and second outputs of the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} are electrically parallel-connected to a n-th output capacitor, CFn, which is in turn, electrically connected between the first and second outputs103and104of the resonant converter circuit500. Each output capacitor CFncomprises one or more high frequency filtering capacitors. In addition, one or more polarized capacitor Co may electrically coupled between the first and second outputs103and104of the resonant converter circuit500.

Further, each resonant converter Gmmay also includes a switch network circuit, NCm, electrically coupled to the resonant tank. The switch network circuit NCmcan be a half-bridge circuit or a full-bridge circuit.

Additionally, each resonant converter Gmhas a first input and a second input electrically coupled to the switch network circuit NCm. In the exemplary embodiment shown inFIG. 5, the second input of any one but the last resonant converter Gmis electrically series-connected to the first input of its immediate next resonant converter Gm+1. The first input of the first resonant converter G1and the second input of the last resonant converter GMare electrically connected to the first input101and the second input102of the resonant converter circuit500, respectively, for receiving an input voltage Vin.

FIG. 7shows schematically a resonant converter circuit700according to yet another embodiment of the present invention. Similar to the resonant converter circuit500shown inFIGS. 5 and 6, the resonant converter circuit700includes M resonant converters, {Gm}, m=1, 2, 3, . . . M, M being an integer greater than one. Except that each resonant converter Gmincludes only N transformers {Tm,n}, and N rectifiers, {Rm,n}, n=1, 2, 3, . . . N, N being an integer greater than one. Each transformer Tm,nincludes a primary winding and a secondary winding. The primary windings of the N transformers of each resonant converter Gmare electrically connected to each other in series. Each rectifier Rm,nis electrically coupled to the secondary winding of a respective transformer Tm,n. Each rectifier Rm,nhas a first output and a second output.

As shown inFIG. 7, the multiple transformers {Tm,n} and the multiple rectifiers {Rm,n}, where m=1, 2, 3, . . . M, and n=1, 2, 3, . . . N, are arranged in N groups, {Bn}. Each group Bnincludes all the n-th transformers T1,n, T2,n, T3,n, . . . TM,nand the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm}. For each group Bn, the first and second outputs of the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} are electrically parallel-connected to a n-th output capacitor, CFn, which is in turn, electrically connected between the first and second outputs103and104of the resonant converter circuit700. Each output capacitor CFncomprises one or more high frequency filtering capacitors. In addition, one or more polarized capacitor Co may electrically coupled between the first and second outputs103and104of the resonant converter circuit700.

Further, each resonant converter Gmmay also includes a switch network circuit, NCm, electrically coupled to the N transformers {Tm,n}.

Additionally, each resonant converter Gmhas a first input and a second input electrically coupled to the switch network circuit NCm. In the exemplary embodiment shown inFIG. 7, the second input of any one but the last resonant converter Gmis electrically series-connected to the first input of its immediate next resonant converter Gm+1. The first input of the first resonant converter G1and the second input of the last resonant converter GMare electrically connected to the first input101and the second input102of the resonant converter circuit700, respectively, for receiving an input voltage Vin.

In one aspect of the present invention, a layout of the resonant converter circuit500/700is provided. The layout (not shown) includes a main board, and N sub-boards spaced-apart and vertically attached to the main board along a direction defined by a production design. In the layout, for each group Bn, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} and the n-th output capacitor CFnare spaced-apart disposed on one side of the n-th sub-board, while the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the n-th sub-board, spatially aligned with and electrically connected to the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm}, respectively. In one embodiment, the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the first sub-board by fixing pins of the secondary windings of each of the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} on the n-th sub-board. Preferably, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} are placed symmetrically on two sides of the n-th output capacitor on the n-th sub-board.

In one embodiment, the n-th sub-board has a positive output port and a negative output port electrically parallel-connected to the respective n-th output capacitor. The positive and negative output ports of the N sub-boards are electrically parallel-connected to the first and second outputs of the resonant converter circuit, respectively.

The layout further has one or more polarized capacitors disposed on the main board, and are electrically parallel-connected to the first and second outputs of the resonant converter circuit500/700.

According to the present invention, another embodiment of the layout of the resonant converter circuit500/700is also provided. The layout (not shown) includes a main board, and a sub-board vertically attached to the main board. In the layout, for each group Bn, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} and the n-th output capacitor CFnare spaced-apart and orderly disposed on one side of the sub-board along a predetermined direction, while the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the sub-board along the predetermined direction, spatially aligned with and electrically connected to the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm}, respectively, so as to define a respective sub-layout. Each sub-layout is arranged along the predetermined direction.

Preferably, the n-th rectifiers R1,n, R2,n, R3,n, . . . RM,nof the M resonant converters {Gm} are placed symmetrically on two sides of the n-th output capacitor on the sub-board.

In one embodiment, the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} are mounted on the other side of the first sub-board by fixing pins of the secondary windings of each of the n-th transformers T1,n, T2,n, T3,n, . . . TM,nof the M resonant converters {Gm} symmetrically on the sub-board.

In one embodiment, the sub-board has M pairs of positive and negative output ports. Each pair of the positive and negative output ports is electrically parallel-connected to the respective output capacitor. The M pairs of positive and negative output ports are electrically parallel-connected to the first and second outputs of the resonant converter circuit, respectively.

In sum, the present invention, among other things, recites multi-phase parallel-interleaved converter circuits with each phase having two or more transformers and two or more rectifiers electrically coupled to the two or more transformers, and layouts of the multiple transformers and the multiple rectifiers of the multi-phase parallel-interleaved converter circuits. In the layouts, the multiple transformers and the multiple rectifiers of the multi-phase converters are interleavingly arranged to be symmetrical to the common output polarized capacitor(s) so as to ensure the rectifier outputs of each phase relative to the common output polarized capacitor is symmetrical, thereby reducing the output ripples of the current of the output capacitors.