Improving the Quasi Resonant DC Link in the Voltage Inverter; Studying the Losses and Designing the Control Circuits

One of the fundamental structures of inverters with soft switching is the use of quasi-resonant DC link (QRDCL) circuits, in which element switching occurs in the zero voltage (ZVS) and / or zero current (ZCS) conditions and also the use of pulse width modulation (PWM). One of the indices of distinction and superiority of these converters is losses in the QRDCL circuit, less losses, and the increase of converter’s frequency. This paper aims to calculate losses of the QRDCL and the design control circuits of improved QRDCL voltage inverter. In this regard, at first, the benefits of soft switching and general characteristics of various types of topologies used in inverters with soft switching is studied and then, the desired improved inverter with the capability of EDPWM (Enhanced Double PWM) which uses the single-phase soft switching technique (SPSS) is introduced. For proper functioning of the circuit, a particular type of the sinusoidal pulse width modulation (SPWM) is used, which its characteristics is studied and then the desired control circuit inverter is proposed. Finally, the full simulation of the inverter is conducted and the obtained results of analyzing the functionality of the circuit and mathematical equations governing the circuit are compared with the results come from computer simulation.