Switching Assisting Circuit Improving the Efficiency of DC-DC Converters Based on Piezoelectric Resonators

A new type of converter based on piezoelectric resonators has been developed in recent years. One limitation of these converters is the parallel capacitance in the equivalent circuit of the resonator. This one needs to be charged and discharged, inducing a circulating current, which induces losses. To overcome that limitation, this paper presents an assisting circuit to reduce the piezoelectric voltage swing and then the circulating current. This one is applied to an isolated dual bridge dc-dc converter based on two piezoelectric resonators (PR). The principle is validated experimentally, showing improved efficiency of up to 11% and 5% on average.