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. 

A New Isolated Topology of DC-DC Converter based on Piezoelectric Resonators

This article 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 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 to 45.8 V conversion, using a 25 mm piezoelectric disc with a thickness of 2 and 1 mm, respectively. An efficiency higher than 80% is measured over a wide range of operating points.

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

The paper deals with arrays of numerous power conversion cells, associated in series and/or in parallel to build larger step up or step down direct current (DC)/DC isolated converters. The work focuses on the impact of the spread and distribution of the conversion cell characteristics on the characteristics and performance of the power converter array (PCA). Based on a characterization protocol, about 130 conversion standard cells (CSC) are characterized and classified from a statistical point of view. Three families are defined and representatives are chosen and implemented in various configurations, in open and closed loop control, to analyze the impact of their spread characteristic over the global converter, the PCA. The paper is based on an extended practical set up and protocols, all described in details. Guidelines on CSCs implementation with respect to their dispersion are provided at the end on the paper.

https://www.mdpi.com/2079-9292/8/9/917/pdf

Jean Christophe Podvin

Papers

Impact of Component Dispersion in DC to DC Low-Power Low-Voltage Power Converter Array