A very simple method to obtain one additional fully regulated output in zero-current-switched quasiresonant converters

A novel solution to the problem of obtaining an additional fully regulated output in zero current-switched quasi-resonant power converters (ZCS-QRCs) is presented. The solution consists of connecting low-power PWM (pulse width modulation) topology to the resonant switch and modulating the duty cycle (in addition to the switching frequency) in the power transistor. The PWM topology must have a transformer or a tapped-inductor to overcome a constraint between the output voltage gain in both outputs. The converter obtained has a nonzero-current-switching, but the increase in switching losses is very small if the power handled by the new output is much smaller than the one delivered by the main output.<>