Full-bridge isolated Current Fed converter with active clamp

摘要

The present invention relates to a power converter which uses pulse width modulated (PWM) control to provide a galvanically isolated dc output. Topologically, the converter uses a full-bridge switching scheme with a boost converter, and can be referred to as an isolated boost converter. The converter includes an ancillary circuit comprised of a switch transistor and a series connected capacitor which act as an active clamp. The converter of the present invention allows for a number of significant advantages. The converter provides zero voltage transitions in all switches, thereby preventing losses due to leakage currents in the switching transistors during switching transitions. The converter further provides a path for transformer magnetizing current flow, and also clamps the leakage inductance related to voltage spikes across the switches. These advantages allow the converter to keep stress on the active components low which makes the circuit more efficient. The circuit of the present invention has a simple structure which gives it good power density and makes it inexpensive, and is also capable of high frequency operation.