High efficiency zero-voltage switching (ZVS) assistance circuit for power converter

1. An apparatus comprising:

a power converter configured to convert input power into output power, the power converter comprising first and second converter bridges, each converter bridge comprising multiple transistors; and

a zero-voltage switching (ZVS) assistance circuit comprising first and second inverse controlled rectifiers (ICRs), each of the first and second ICRs configured to provide current to the transistors in the first and second converter bridges, each of the first and second ICRs comprising a rectifier connected to a regulator,

wherein the regulator in the first ICR is configured to regulate the current that is provided by the first ICR and the regulator in the second ICR is configured to regulate the current that is provided by the second ICR.

2. The apparatus of claim 1 , wherein the power converter comprises two primary converter bridges and two secondary converter bridges.

3. The apparatus of claim 2 , wherein the first and second converter bridges represent the primary converter bridges.

4. The apparatus of claim 2 , wherein the first and second converter bridges represent the secondary converter bridges.

5. The apparatus of claim 2 , wherein:

the first and second converter bridges represent the primary converter bridges; and

the ZVS assistance circuit further comprises third and fourth ICRs, each of the third and fourth ICRs configured to provide current to transistors in the secondary converter bridges.

6. The apparatus of claim 2 , wherein:

the first converter bridge further comprises first and second windings of a first main transformer;

the second converter bridge further comprises first and second windings of a second main transformer; and

each main transformer further comprises a third winding configured to electrically couple one of the primary converter bridges and one of the secondary converter bridges.

7. The apparatus of claim 6 , wherein:

the first and second windings of the first main transformer are coupled between two pairs of transistors in the first converter bridge; and

the first and second windings of the second main transformer are coupled between two pairs of transistors in the second converter bridge.

8. The apparatus of claim 1 , wherein:

the first converter bridge further comprises a first winding of a first auxiliary transformer and a first winding of a second auxiliary transformer;

the second converter bridge further comprises a second winding of the first auxiliary transformer and a second winding of the second auxiliary transformer; and

each auxiliary transformer further comprises a third winding configured to electrically couple the first and second converter bridges and one of the ICRs.

9. The apparatus of claim 1 , wherein the converter bridges comprise series resonant converter (SRC) bridges.

10. An apparatus comprising:

a power converter configured to convert input power into output power, the power converter comprising first and second converter bridges, each converter bridge comprising multiple transistors; and

a zero-voltage switching (ZVS) assistance circuit comprising first and second inverse controlled rectifiers (ICRs), each of the first and second ICRs configured to provide current to the transistors in the first and second converter bridges;

wherein the first converter bridge further comprises a first winding of a first auxiliary transformer and a first winding of a second auxiliary transformer;

wherein the second converter bridge further comprises a second winding of the first auxiliary transformer and a second winding of the second auxiliary transformer;

wherein each auxiliary transformer further comprises a third winding configured to electrically couple the first and second converter bridges and one of the ICRs;

wherein the first winding of the first auxiliary transformer is coupled across a first pair of transistors and a second pair of transistors in the first converter bridge;

wherein the second winding of the first auxiliary transformer is coupled across a first pair of transistors and a second pair of transistors in the second converter bridge;

wherein the first winding of the second auxiliary transformer is coupled between the first pair of transistors in the first converter bridge and the first pair of transistors in the second converter bridge; and

wherein the second winding of the second auxiliary transformer is coupled between the second pair of transistors in the first converter bridge and the second pair of transistors in the second converter bridge.

11. A system comprising:

a power converter configured to convert input power into output power, the power converter comprising first and second converter bridges, each converter bridge comprising multiple transistors;

a zero-voltage switching (ZVS) assistance circuit comprising first and second inverse controlled rectifiers (ICRs), each of the first and second ICRs configured to provide current to the transistors in the first and second converter bridges, each of the first and second ICRs comprising a rectifier connected to a regulator; and

a controller configured to control operation of the first and second converter bridges and the ZVS assistance circuit,

wherein the regulator in the first ICR is configured to regulate the current that is provided by the first ICR and the regulator in the second ICR is configured to regulate the current that is provided by the second ICR.

12. The system of claim 11 , wherein the controller comprises:

a phase-shift modulation (PSM) controller configured to control the converter bridges; and

a pulse width modulation (PWM) controller configured to control the ZVS assistance circuit.

13. The system of claim 12 , wherein:

the PSM controller is configured to generate control signals for the transistors in the converter bridges based on an input voltage, an input current, an output voltage, and an output current of the power converter; and

the PWM controller is configured to generate control signals for the regulators in the ZVS assistance circuit based on currents through the transistors in the converter bridges.

14. The system of claim 13 , wherein the PWM controller is configured to apply pre-shaped voltages to transistors in the regulators to enable substantially zero-loss turn-off commutation of the transistors in the regulators.

15. The system of claim 11 , wherein:

the first converter bridge further comprises first and second windings of a first main transformer;

the second converter bridge further comprises first and second windings of a second main transformer; and

each main transformer further comprises a third winding configured to electrically couple one of the first and second converter bridges to an additional converter bridge.

16. The system of claim 15 , wherein:

the first and second windings of the first main transformer are coupled between two pairs of transistors in the first converter bridge; and

the first and second windings of the second main transformer are coupled between two pairs of transistors in the second converter bridge.

17. The system of claim 11 , wherein:

the first converter bridge further comprises a first winding of a first auxiliary transformer and a first winding of a second auxiliary transformer;

the second converter bridge further comprises a second winding of the first auxiliary transformer and a second winding of the second auxiliary transformer; and

each auxiliary transformer further comprises a third winding configured to electrically couple the first and second converter bridges and one of the ICRs.

18. A system comprising:

a power converter configured to convert input power into output power, the power converter comprising first and second converter bridges, each converter bridge comprising multiple transistors;

a zero-voltage switching (ZVS) assistance circuit comprising first and second inverse controlled rectifiers (ICRs), each of the first and second ICRs configured to provide current to the transistors in the first and second converter bridges; and

a controller configured to control operation of the first and second converter bridges and the ZVS assistance circuit;

wherein the first converter bridge further comprises a first winding of a first auxiliary transformer and a first winding of a second auxiliary transformer;

wherein the second converter bridge further comprises a second winding of the first auxiliary transformer and a second winding of the second auxiliary transformer;

wherein each auxiliary transformer further comprises a third winding configured to electrically couple the first and second converter bridges and one of the ICRs;

wherein the first winding of the first auxiliary transformer is coupled across a first pair of transistors and a second pair of transistors in the first converter bridge;

wherein the second winding of the first auxiliary transformer is coupled across a first pair of transistors and a second pair of transistors in the second converter bridge;

wherein the first winding of the second auxiliary transformer is coupled between the first pair of transistors in the first converter bridge and the first pair of transistors in the second converter bridge; and

wherein the second winding of the second auxiliary transformer is coupled between the second pair of transistors in the first converter bridge and the second pair of transistors in the second converter bridge.

19. A method comprising:

converting input power into output power using first and second converter bridges of a power converter, each converter bridge comprising multiple transistors; and

providing current to the transistors in the first and second converter bridges using a zero-voltage switching (ZVS) assistance circuit, the ZVS assistance circuit comprising first and second inverse controlled rectifiers (ICRs) that provide the current, each of the first and second ICRs comprising a rectifier connected to a regulator,

wherein the regulator in the first ICR is configured to regulate the current that is provided by the first ICR and the regulator in the second ICR is configured to regulate the current that is provided by the second ICR.

20. The method of claim 19 , further comprising:

controlling the transistors in the power converter using pulse-shift modulation (PSM) control; and

controlling regulators in the ZVS assistance circuit using pulse width modulation (PWM) control;

wherein the PWM control comprises applying pre-shaped voltages to transistors in the regulators to enable substantially zero-loss turn-off commutation of the transistors in the regulators.