Fixed frequency controlled piezoelectric 10W DC/DC converter

Piezoelectric transformers (PT) have been widely adopted in AC/DC and DC/DC converters due to their many inherent advantages such as high insulation voltage and operate at high frequencies, with lower losses. However, their operating frequency has a strong dependence on load and also on other parameters, such as temperature or voltage level applied. This frequency drift not only causes an inconvenience that affects PT efficiency but also gives a problem to achieved zero voltage switching (ZVS) condition in the power stage. In this paper, we use a new design procedure to determine the optimal size of a staked disk-type piezoelectric transformer with radial-mode vibration that operates at fixed frequency in step-down 10W DC/DC converter for spatial application, which is small in size but has high efficiency and which gives us an optimal range for regulating voltage under a wide load variation.