ZVS-PWM-controlled parallel-resonant converter applied to a constant-current power supply

A parallel-resonant converter featuring zero-voltage-switching and control by pulse-width-modulation is proposed. Similar to a previously proposed series-resonant counterpart, it has a simple structure and can be controlled at a constant switching frequency using an active-clamp technique. The nearly constant current output characteristic of the parallel-resonant converter lends itself beneficially to precisely controlled constant current power supply applications. An experimental breadboard featured an output-current accuracy of /spl plusmn/0.6% at 1 A over a range of input voltages from 34 to 46 V and output voltages from 2 to 20 V. A maximum efficiency of 80% was observed.