Analysis of LLC Dual-frequency Induction Heating Power Supply with Time-sharing Control

The traditional single-frequency induction heating power supply is difficult to realize heat treatment of non-uniform workpiece, such as gear and track. And the high frequency transformer, which is required by the electromagnetic coupling load matching method, is large in volume, high in cost and difficult to realize. To solve the above problems, this paper presents a dual-frequency induction heating power supply topology based on LLC load resonance technology, which can realize the dual-frequency induction heating and the electrostatic coupling load matching. This paper adopts the time-sharing control strategy, then the dual-frequency current output is realized by controlling on-off of switching tube to carry on the autonomous switch in medium-high frequency. Using the method of electrostatic coupling load matching based on the LLC resonant circuit can replace the high-frequency transformer in the traditional electromagnetic coupling load matching mode. The circuit design scheme and parameter design principles are presented in this paper. On the basis of theoretical analysis, an experimental prototype has been set up to realize the function of two current frequency output and time adjustable. It also realizes the low cost and miniaturization of induction heating power supply.