A New Isolated Topology of DC–DC Converter Based on Piezoelectric Resonators

Abstract

This paper presents a new isolated topology of DC-DC converter based on piezoelectric resonators. Contrary to most existing topologies, the proposed one uses the natural isolation of piezoelectric resonators to isolate the converter's output from the input and vice-versa. Considering the resonators' constraints, our study focuses on the most efficient isolated conversion cycle with zero-voltage switching (ZVS) operations. The case studied is a highly efficient step-down isolated DC-DC converter with a gain ranging from 0 to 1 and an input voltage up to 360 V. The converter uses two piezoelectric resonators working in series. The conversion principle is validated thanks to a prototype operating at a frequency around 95 kHz. Experimental measurements are made on a wide range of input voltage from 12 V to 360 V with a conversion ratio of 0.0165 to 0.95. The output power reaches either 179.1 W with an 89% efficiency at 360 V input voltage and 346 V output voltage, or 4.5 W with a 97.2% peak efficiency for a 48 V to 45.8 V conversion, using a 25 mm piezoelectric disc with a thickness of 2 mm and 1 mm respectively. An efficiency higher than 80% is measured over a wide range of operating points.