Dynamic Analysis and Control for Resonant Currents in a Zone-Control Induction Heating System

This paper presents a quick and accurate power control method for a zone-control induction heating (ZCIH) system consisting of multiple working coils connected to multiple H-bridge inverters. A uniform temperature profile can be achieved by adjusting the current in each working coil. This paper proposes a new current control method based on a circuit model using real and imaginary (Re-Im) current/voltage components. The method detects and controls the Re-Im components of the coil current instead of the current amplitude and phase angle. As a result, the proposed method enables the inverters to control the coil current independently from the others. Experiments using a six-coil ZCIH system are conducted to verify the validity of the proposed method. The experimental results confirmed that the proposed method makes it possible to improve the stability of the current feedback control, not only in steady states but also in transient states.