Low cost high efficiency power converter

DETAILED DESCRIPTION A new circuit for switch mode power converters achieves high efficiency and zero voltage switching by using an auxiliary switch, a capacitor, an auxiliary winding and an inductor.
This circuit can be applied in boost, buck-boost, buck, isolated forward or isolated flyback converters.
A control circuit causes the auxiliary switch to turn-on before the main power switch, and the capacitor provides voltage to energize the inductor and force current to flow into the auxiliary winding.
The current is transformed to the main winding and discharges capacitance across the main power switch to approximately zero volts before the main power switch turns on.
Hence ZVS is obtained and can greatly reduce the switching loss across the main power switch.