A three level full bridge DC-DC converter with ZVZCS PWM control scheme

In all the PWM DC to DC and DC to AC converter topologies, the controllable switches are operated in switch mode where they are required to turn ON and OFF the entire load current during each switching. Here the switches are subjected to high stress and high switching losses that increases linearly with the switching frequency of the PWM. Another major significant drawback of switch mode operation is the EMI produced due to large di/dt and dv/dt caused by a switch mode operation. Therefore, to realize high switching frequencies in converters, the aforementioned shortcomings are minimized if each switch in a converter changes its status (from ON to OFF or vice versa) when the voltage across it and/or the current through it is zero at the switching instant. This paper propose a simplified switching scheme for three level full bridge DC to DC converters that enables zero voltage and zero current switching of all the main power devices. This describes the main operational modes of the converter as well as simulated results through MATLAB/simulink.