Investigation of using BSPT for ring-dot piezoelectric transformers for use in high-temperature resonant power supplies

SiC and GaN devices are gaining in popularity in both research and commercial applications. One of the many benefits of these devices is the possibility of power converter operation at temperatures in excess of that possible with Si-based devices (>200°C). A bismuth scandium lead titanate (BSPT) piezoelectric transformer is analysed for use in high temperature (up to 250°C), resonant converters using impedance spectroscopy and power converter measurements. The PT shows declining losses with temperatures during testing, translating into an improvement of 15% points in efficiency whilst more than doubling the output power across the temperature range. A peak performance of 0.7W output power and 53% efficiency at 225°C was achieved, giving comparable performance to previous work but at higher temperatures.