Adaptive Frequency Control Strategy for Piezoelectric Transformer in AC/DC Adapter Applications using Phase-Detector

摘要

An adaptive frequency control method for AC/DC adapters using a piezoelectric transformer (PT) is proposed. It combined the conventional frequency method and frequency tracking for the PT such that the main frequency control loop to regulate the output voltage is compensated by the phase loop in order to adaptively change the operating frequency range. This method provides PT gain peak tracking to tackle the resonant frequency drift problems common in the PT according to the temperature changes and sample variations, and consequently makes more efficient and stable driving of the PT possible, thus improving the overall productivity. The validity of the proposed algorithm is verified by a constructed 40W AC/DC adapter hardware using a PT.