Abstract
This paper proposes a coil current control method for zone-control induction heating (ZCIH) systems based on the transformation to rectangular coordinates. A ZCIH system comprises two or more sets of a high-frequency inverter and a work coil, and it controls the amplitude of the coil current to adjust the heat/temperature distribution on a workpiece. For proper operation, the coil currents should be controlled in phase with each other. The proposed method controls the real and the imaginary parts of each coil current instead of its amplitude and phase angle. As a result, the proposed method makes it possible to achieve stable control in a wide amplitude range of heating power. Experimental results obtained from a 3-kW three-zone ZCIH laboratory setup are shown to verify the validity of the proposed method and to demonstrate a quick response in the coil current control.
