Ultra-audio Frequency Induction Heating Power Phase-locked Control Strategy

This paper has researched on ultra-sound frequency induction heating power supply. Adopting parallel resonant topology, a 50kHz/160kW supply's phase lock control circuit has been designed which uses power IGBT as its switching devices.This paper mainly discusses the design and the application of the IGBT phase lock control circuit controlled by the induction heating power supply. Firstly, this paper has introduced the history and the basic knowledge of induction heating technology, and the development of power devices and the induction heating technology are introduced as well. Secondly, this paper compares the two basic resonant topologies. It also discusses the power regulation, the frequency auto-tracking strategy, and the basic way of inverter control. Based on the phase-locked loops theory and the basic structure of the phase-locked loops, this paper also analyzes the startup and control way of the inverter, brings forward the way of phase-locked control. At last, it gives the power supply design which includes rectifier and inverter control, and protection circuit as well. Based on the experimental waveforms, it specially analyzes the reason of inverter's startup failure. While improved the detecting circuit of voltage single, the limitation of the power's bandwidth has been broken.