Integrating the digital time control algorithm with DC-bus “notching” circuit based soft-switched inverter

A single-phase full-bridge bi-level inverter using a DC-link quasi-resonant circuit (QRC) to introduce a zero-volts interval across the DC bus for soft switching is discussed. It is demonstrated that the digital time control (DTC) algorithm, a method that belongs to the family of zero average current error (ZACE) methods, is a suitable technique to be integrated with a typical QRC DC-link soft-switched inverter. Experimental results taken from a low power single-phase current-controlled inverter prototype are documented. These include quasi-resonant circuit waveforms, inverter waveforms and electromagnetic interference (EMI) spectral characteristics