Isolated circuits Include: active clamp forward(ACF),push pull forward,half bridge(symmetrical half bridge SHB and duty cycle shifted half bridge DCSHB) etc.

Aimed at the feature that the locality of axis of the armature mmf is determined by the brush in dc motor, a new concept on clamp is proposed.

This converter uses a simple auxiliary circuit without the active switch and lossy components so that the voltage stress of secondary rectifier diode is reduced and the current to charge or discharge clamping capacitance is self-adjusted in accordance with the load.

In development of the power stage for a 2 kVA high frequency on line UPS,methods of anti parallel diode across the serial resistor and active clamps are adopted to reduce the gate voltage spikes over MOS gated inverter power switches during their turn off.