A New Zone-Control Induction Heating System Using Multiple Inverter Units Applicable Under Mutual Magnetic Coupling Conditions

This paper proposes a new “zone-control induction heating” (ZCIH) system consisting of two or more sets of a high-frequency inverter unit and a work coil. The work coils are wound around a single susceptor as close as possible to reduce a leakage magnetic flux. The inverters independently control the amplitude of each coil current to adjust the power provided to the work coil and/or the heat generated in each zone of the susceptor. As a result, the ZCIH system enables a temperature uniformity not only in a heating-up period but also in a temperature-maintaining period. Theoretical analysis derives the control performance of the current amplitude, and implies that the phase-angle control of the coil current is required to adjust the current amplitude in a wide range. This paper presents experimental results obtained from a laboratory setup and a six-zone prototype for semiconductor processing.