Simple zero current switch circuit
View Patent ↗A simple zero current switch circuit includes a first coil set and a second coil set that are wound at a selected coil ratio and bridge electrically an energy storing inductor, an output diode and a conduction switch of a power-factor corrector. The leaking inductance of the first coil set generates a back electromotive force to make the conduction switch in a zero current switching condition. An energy conversion circuit is provided to store reverse energy according to the coil ratio of the second coil set and the first coil set and reclaims the energy to an output capacitor of the power-factor corrector while the output diode generates a reverse recovery condition. Thereby reverse recovery time of the output diode can be shortened.
1. A simple zero current switch circuit to control a conduction switch of a power-factor corrector in a zero current condition during ON/OFF switching operations, the power-factor corrector including an energy storing inductor to receive a commutated electric power and store energy and perform discharging, an output diode and an output capacitor electrically bridging the energy storing inductor and a power output end, and a conduction switch and a controller electrically bridging the energy storing inductor and the output diode, the zero current switch circuit comprising:
a first coil set bridging the energy storing inductor and the output diode, the first coil set being connected to the conduction switch through a second coil set which is wound reversely according to a selected coil ratio relative to the first coil set, the first coil set having a leaking inductance to generate a back electromotive force to make the conduction switch in a zero current switching condition during ON/OFF operations; and
an energy conversion circuit which is coupled with the power-factor corrector, the first coil set and the second coil set to form a power circuit, the energy conversion circuit including a plurality of diodes, capacitors, and a resistor; while the output diode generating a reverse recovery condition, the energy conversion circuit stores reverse energy according to the coil ratio of the second coil set relative to the first coil set and reclaims the energy to the output capacitor, discharge of said reverse energy being determined by said coil ratio to increase a speed of output diode discharge, an amount of current of the discharge is determined by the coil ratio so that said inductor is maintained in a saturated condition, thereby reverse recovery time of the output diode is shortened.
2. The simple zero current switch circuit of claim 1 , wherein the first coil set and the second coil set are wound in reverse directions.
3. The simple zero current switch circuit of claim 1 , wherein said first coil set has a first end and a second end, said first end being connected jointly to said energy storing inductor and a first end of said second coil set, said second end of said first coil set being connected to said output diode.
4. The simple zero current switch circuit of claim 3 , wherein said second coil set has a second end connected directly to a terminal of said conduction switch.
5. The simple zero current switch circuit of claim 4 , wherein said energy conversion circuit includes a first capacitor and a first resistor, a first end of said first capacitor and said first resistor connected directly to said terminal of said conduction switch and said second end of said second coil, a second end of said first capacitor and said first resistor being connected together.
6. The simple zero current switch circuit of claim 5 , wherein said second end of said first capacitor and said first resistor are jointly connected to a first end of at least one of said plurality of diodes.