| 摘要 |
Systems and methods for operating improved flyback converters are disclosed, in which leakage energy is returned to the input power source rather than to the output load, while still achieving zero voltage switching (i.e., ZVS) operation. In some embodiments, the improved converters may transfer the energy stored in the leakage inductance to a snubber capacitor(s) at the instant of turning off of the control switch. Further, the improved converter embodiments may also retain the stored energy in the snubber capacitor(s) when the power is being delivered to the load by the secondary circuits. The improved converter embodiments may start the transfer of leakage energy stored in the snubber capacitor(s) to the primary winding once the energy stored in the transformer is delivered to the load. Finally, the improved converter embodiments may intelligently control their active clamp switches such that all leakage inductance energy is returned to the input source. |
| 主权项 |
1. A power conversion apparatus, comprising:
a transformer, wherein the transformer has a primary winding and a secondary winding; a first switch coupled to the primary winding so as to control the flow of current through the primary winding; a second switch coupled to the primary winding, so as to control the flow of current through an active resonant clamp circuit, wherein the active resonant clamp circuit is configured to absorb leakage energy from the primary winding, and comprises:
a first capacitor coupled to the primary winding;a second capacitor coupled to the primary winding; anda first diode connected in series between the first capacitor and the second capacitor; and a controller coupled to the first switch and the second switch, configured to:
switch the first switch on, so as to store energy in the primary winding of the transformer;switch the first switch off, so as to charge the first and second capacitors in series;disconnect the first and second capacitors from the primary winding of the transformer once all leakage inductance energy has been transferred from the transformer to the first and second capacitors, so as to begin to discharge the first and second capacitors in parallel;switch the second switch off at a predetermined time interval or when the voltage across the first and second capacitors each falls to a predetermined voltage level; andswitch the first switch on, so as to achieve zero voltage switching. |
