Optimal frequency tracking method for phase‐shift PWM inverter

Abstract

AbstractThis paper proposes a new resonant frequency tracking control method for full‐bridge‐type high‐frequency inverters. Whereas the ordinary phase‐locked loop (PLL) based frequency control method uses a current sensor and a voltage sensor, the proposed technique can achieve the same purpose with a single current sensor. In high‐frequency power supply systems using a PLL, it is impossible to perform power control with an inverter. Therefore, an active converter must be used for power control, and the system grows larger. On the other hand, high‐frequency inverters using the proposed control system simultaneously enable power control and achieve the same resonant frequency tracking as a PLL, and thus high‐frequency power supply systems become extremely simple. This paper explains in detail the principle underlying the control method, and presents an example of a circuit to realize it. The theory is backed up by using a prototype high‐frequency power supply system which actually employs the proposed control system, thereby demonstrating its practical utility in industry. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.