New control method of piezoelectric transformer converter by PWM and PFM for wide range of input voltage

摘要

A new control method of a piezoelectric transformer (PT) converter by PWM and PFM is presented. The combination of an active-clamp circuit and a resonant circuit makes it possible to control the output voltage of the PT converter by PWM at a fixed switching frequency and PFM at a fixed duty ratio. The PT converter implemented on a printed circuit board was experimentally evaluated and a good controllability was successfully achieved.