Abstract: A method and system are provided for initializing a high frequency inverter in an induction heating system, to minimize the startup time and ramp-up time to a target power level of the induction heating system for precise heat distribution control in a workpiece. The system and method utilize initial inverter control frequencies approximately equivalent to a resonant frequency of the resonant circuit which varies relative to discrete sample to sample variations in the associated workpiece. The power supply control is then initialized at an initial power level substantially lower than the target power level associated with the workpiece to be heated until a phase-locked loop is locked to the actual resonant frequency, at which point the power supply rapidly increases power the target power level for the particular induction heat treatment application.

Abstract: An induction coil with inner and outer coil segments joined together by a transition segment is arranged so that the outer coil segment generally inductively heat treats an annular outer region of a workpiece positioned under the coil, the inner coil segment generally inductively heat treats an annular inner region of the workpiece, and the transition segment traverses at least a portion of the width of the overall annular region of the workpiece to be heat treated. Relative arrangement of inner, outer and transition coil segments provides for controlled induction heat treatment across the overall annular region such as the gear teeth region of an intersecting axes or non-intersecting and non-parallel axes gear.

Abstract: An induction coil with inner and outer coil segments joined together by a transition segment is arranged so that the outer coil segment generally inductively heat treats an annular outer region of a workpiece positioned under the coil, the inner coil segment generally inductively heat treats an annular inner region of the workpiece, and the transition segment traverses at least a portion of the width of the overall annular region of the workpiece to be heat treated. Relative arrangement of inner, outer and transition coil segments provides for controlled induction heat treatment across the overall annular region such as the gear teeth region of an intersecting axes or non-intersecting and non-parallel axes gear.