Soft-switched boost converter with isolated active snubber

摘要

A boost converter employs an isolated active snubber to reduce the losses caused by the reverse-recovery characteristic of a boost rectifier and the turn-on discharge loss of the output capacitance of the boost switch. The losses are reduced by inserting the primary winding of a coupled-inductor in the series path of the boost switch and the rectifier, to control the rate of current change (i.e., the di/dt rate) of the rectifier during its turn-off, and to create the conditions for zero- voltage turn-on for the boost switch. The energy from the inductor, after the boost-switch is turned off, is delivered to the output via the secondary winding of the coupled-inductor which is connected in series with a clamping capacitor and an auxiliary switch to form an isolated active snubber. The same technique can be extended to any member of the PWM-converter family.