Zero-voltage-switching DC-DC converters with synchronous rectifiers
View Patent ↗A DC-DC converter includes an inductor, a synchronous rectifier (SR) connected to the inductor, and an active switch connected to the inductor and the SR. An active resonant tank (ART) cell is connected to the SR or a transformer in parallel such that a resonant capacitor of the ART cell is charged through the active switch and discharged through the synchronous rectifier so that during a switch transition period energy is pumped out of the resonant capacitor by activating the ART cell to eliminate reverse recovery switching loss and achieve Zero Voltage Switching (ZVS).
1. A DC-DC converter comprising:
a first inductor;
a synchronous rectifier connected to the inductor;
a first switch connected to the inductor and the synchronous rectifier; and
an active resonant tank cell including a second switch, a second inductor and a capacitor, the second inductor and the capacitor coupled in series with the second switch, the active resonant tank cell connected to the synchronous rectifier in parallel.
2. The converter of claim 1 , wherein the synchronous rectifier and first switch are MOSFET devices.
3. The converter of claim 1 , wherein the converter is one of a buck converter, a boost converter, and a buck-boost converter.
4. The converter of claim 1 , wherein the converter is an isolated converter.
5. The converter of claim 1 , wherein the active resonant tank cell further includes a diode connected in parallel to the capacitor.
6. The converter of claim 1 , wherein the active resonant tank cell further includes a diode connected in parallel to the capacitor and the second switch.
7. The converter of claim 4 , wherein the converter is one of a forward converter, a flyback converter, a flyback converter, a half-bridge converter, a push-pull converter, and a full-bridge converter.
8. A dc-dc converter comprising:
a transformer having a primary winding and a secondary winding;
a synchronous rectifier connected to the secondary winding; and
a first active resonant tank cell connected across the primary winding, the first active resonant tank cell including a switch, an inductor and a capacitor, the inductor and the capacitor connected in series with the switch.
9. The converter of claim 8 , wherein the synchronous rectifier is a MOSFET device.
10. The converter of claim 8 , wherein the first active resonant tank cell further includes a diode connected in parallel to the capacitor.
11. The converter of claim 8 , wherein the first active resonant tank cell further includes a diode connected in parallel to the capacitor and the switch.
12. The converter of claim 8 , wherein the switch is a MOSFET device.
13. The converter of claim 8 , wherein the converter is a forward converter.
14. The converter of claim 8 , wherein the converter is a flyback converter.
15. The converter of claim 8 , wherein the converter is a half-bridge converter.
16. The converter of claim 8 , wherein the converter is a push-pull converter.
17. The converter of claim 8 , wherein the converter is a full-bridge converter.
18. The converter of claim 8 , further including a second active resonant tank cell connected across the primary winding, the second active resonant tank cell including a second switch connected in series with a second capacitor.
19. The converter of claim 8 , further including a second synchronous rectifier connected to the secondary winding.
20. A dc-dc converter comprising:
a transformer having a primary winding and a secondary winding;
a synchronous rectifier connected to the secondary winding;
an external winding electromagnetically coupled to the primary winding and the secondary winding; and
a first active resonant tank cell connected across the external winding, the first active resonant tank cell including a switch, an inductor and a capacitor. the inductor and the capacitor connected in series with the switch.
21. The converter of claim 20 , wherein the synchronous rectifier is MOSFET device.
22. The converter of claim 20 , wherein the first active resonant tank cell further includes a diode connected in parallel to the capacitor.
23. The converter of claim 20 , wherein the first active resonant tank cell further includes a diode connected in parallel to the capacitor of and the switch.
24. The converter of claim 20 , wherein the switch is a MOSFET device.
25. The converter of claim 20 , wherein the converter is a forward converter.
26. The converter of claim 20 , wherein the converter is a flyback converter.
27. The converter of claim 20 , wherein the converter is a half-bridge converter.
28. The converter of claim 20 , wherein the converter is a push-pull converter.
29. The converter of claim 20 , wherein the converter is a full-bridge converter.
30. The converter of claim 20 , further including a second synchronous rectifier connected to the secondary winding.
31. The converter of claim 1 , wherein the converter is configured to reverse a current through the synchronous rectifier while the synchronous rectifier is on and the first switch is off.
32. The converter of claim 1 , wherein the converter is configured to prevent a body diode of the synchronous rectifier from conducting a body diode current when the synchronous rectifier turns off.
33. The converter of claim 1 , wherein the converter is configured to discharge a junction capacitance of the first switch while the first switch is off.
34. The converter of claim 1 , wherein the converter is configured to charge a junction capacitance of the synchronous rectifier after the synchronous rectifier is turned off.
35. The converter of claim 1 , wherein the active resonant tank cell is charged through the first switch when the second switch is off.
36. The converter of claim 18 , wherein the first and second active resonant tank cells share an inductor.
37. The converter of claim 20 , further comprising a second active resonant tank cell coupled to the first active resonant tank cell in parallel.
38. The converter of claim 35 , wherein the first and second active resonant tank cells share an inductor.