CEA-Leti improves DC-DC efficiency

The new design, known as the dual-bridge isolated piezoelectric resonator converter (DB-IPRC), achieves isolation through the use of two independent piezoelectric resonators. This enhanced DC-DC converter improves efficiency while preserving the core principle of converter isolation.

These findings were detailed in a paper titled 'Switching Assisting Circuit Improving the Efficiency of DC-DC Converters Based on Piezoelectric Resonators,' presented at PCIM Europe 2024. The paper reported that for a conversion from 200V to 120V, the converter achieved an efficiency of 96.2% when using an inductive assisting circuit, 94.3% with a piezoelectric assisting circuit, and 87.4% without any assisting circuit. The piezoelectric assisting circuit showed a more consistent efficiency over a narrower operational range than the inductive option, but produced a flatter converter response.

Building on breakthroughs from 2023

This latest development extends previous work by CEA-Leti, as published in IEEE Transactions on Power Electronics in August 2023. The article introduced a new isolated topology for DC-DC converters, leveraging the inherent isolation properties of piezoelectric resonators to separate the converter’s output from its input.

The use of piezoelectric resonators instead of inductors in power conversion, “will lead to a dramatic reduction in the size of power converters,” explained Ghislain Despesse, a co-author of the PCIM paper and the earlier article. “Our results make it possible to extend this type of compact conversion to isolated converters. So this type of converter is now compatible with a much wider range of applications, such as TVs, phones, tablets and electrical tools.”

Despesse also highlighted the misconceptions surrounding piezoelectricity: “For many people, piezoelectricity is associated with energy harvesting and the idea of low power,” Despesse said. “But in power conversion, piezoelectrics operate at high frequencies, greater than 100kHz, with no limits in terms of input power. That makes it possible to reach power levels of several hundred watts. The range of applications is therefore very broad, with most converters having a rated power of less than 100W.”