Design of a High-Performance Half-Bridge Resonant Inverter Using Piezoelectric Transformer for Driving LED

摘要

This paper presents the design of a high-performance half-bridge resonant inverter (HBRI) using piezoelectric transformers (PT) for driving a light emitting diode (LED) based backlight module. The target of the proposed inverter using a PT, with a physical size of 5-mm thickness and 50-mm length operating at frequency of 60-70 kHz, is designed to work with a resonant circuit to maintain a constant output current for the LED module. Also, the Zero-Voltage-Switching (ZVS) condition is to be achieved over the full operation range. The key resonant inductance and capacitance of the HBRI are optimally designed according to a given set of specifications, i.e. the desired switching frequency, the load current, the load resistance and the PT parameters. The equivalent circuits of PT are firstly investigated with basic two-port network theories. Then, a number of key parameters are developed and mathematically verified. The performance of various control functions and efficiency of the designed HBRI are verified with a practical design example. Both the simulation results using PSIMsoftware and the measured results from simple experimental setups are presented to show the effectiveness of the theoretical analyses and design methods.