Research On Induction Heating Power Supply Based On Sliding Mode Variable Structure Control

This paper realizes the current control system for series resonant converter of Induction heating based on sliding mode variable structure control. At first, in this paper, the advantage and limitation of control methods recently used in Induction heating system are analyzed. On this base, sliding mode variable structure controller is used. After the load circuit is analyzed, the mathematic model of series resonant converter for Induction heating are established, including the selection of the integrator switch surface and the control law of sliding mode. In the control circuit, the processor is TMS320LF2407 DSP, and the control algorithms are fully implemented by software; Detecting the load coil currents by Hall Components, DSP produces PWM signals with programmable pulse wide to drive the load coil by IGBT, and signals enter the A/D input pins of DSP before sliding mode variable structure control algorithms implemented by software; A method of implementing digital phase-locked loop based on DSP according to the mathematics model of analog phase-locked loop is analyzed. The system can operate with high robustness and has good dynamic performance. The results of simulation and experiment show that the integrator switch surface and the control law of sliding mode which is design in the paper not only hold the high robustness, but also highly reduce the chattering which is bad to the control system. The experimental results are perfect and show that this method not only preserves the merit of SMVSC, but also possesses adaptation to system.