Synthesizing power electronic switching waveforms for reduced EMI generation

A method of analysing switching waveforms using their derivative terms shows that imposing an ‘S-shaped’ profile on the switching transitions offers significant improvements in the control of power loss and radiated EMI in power converters. Numerical modelling to investigate the effects of varying the timing parameters of the waveforms enables switching transients to be shaped to reduce high-frequency spectral content. The resulting synthesized waveforms are used to demonstrate experimentally that total high-frequency power content is reduced without any associated increase in switching time and therefore power loss.