Comparison of resonant link and hard switched inverter output spectra

Resonant link techniques allow high operating frequencies to be attained by providing instances of zero voltage or current at which the main power devices may change state. The switching losses are thus reduced and the devices may operate at higher frequencies. This is achieved by replacing the DC link of conventional hard switched inverters with a high frequency oscillatory link. A result of the resonant link technique is that the switching instants are fixed by the zero crossings of the link oscillation and the output waveform must be made up of integral pulses of the link waveform. This gives rise to an output spectrum that is significantly different from hard switched inverters where PWM techniques may be used