Independent Power Control in Dual Coil Induction Heating System for Liquid Foods

The temperature distribution inside the workpiece is not uniform in a single coil induction heating systems. Using multiple coils for a workpiece can be solution to the problem, but in this case, independent power control of the each coil is a big challenge. In this paper, a novel method is proposed for this problem in which the resonant frequency of individual coils are separated each other in frequency domain. The optimum distance between coil resonance frequencies are investigated in detail. By using the proposed method, the each coil can be controlled independently by adjusting both the PWM frequency and duty cycle. The simulation results verify that the proposed method is very effective to control the individual coil power.