A novel variable duty cycle half-forward converter having low current harmonics and high power factor

This paper introduces a new technique whereby the switching frequency and the duty cycle of the isolated half-forward buck converter are continually varied. The new method is based on relating the switching frequency of the power MOSFET and its duty cycle to the amplitude of the full wave rectified power frequency voltage waveform This technique is amicable to the network as its almost harmonic free unlike the normal buck converter. Hence the standard additional boost converter used with buck converter to subdue current harmonics is spared by this new method. The advent of very fast processors makes such a control strategy easily attainable. The obtained simulation results have shown excellent compatibility to the boost-buck design.