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Multiple zone induction coil power control apparatus and method

  • US 4,506,131 A
  • Filed: 08/29/1983
  • Issued: 03/19/1985
  • Est. Priority Date: 08/29/1983
  • Status: Expired due to Term
First Claim
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1. Induction heating apparatus for providing a desired temperature profile in a workpiece to be heated, comprising:

  • (a) an induction heating coil having a plurality of zones,(b) a high-frequency induction power supply for delivering power to the coil,(c) control means for individually controlling the power delivered to each zone of the coil, the control means comprising;

    (i) means for measuring the power in each zone,(ii) means for comparing the power in each zone to a predetermined reference and generating a first control signal based on the comparison for each respective zone,(iii) means operatively associated with each zone and responsive to the first control signal associated with the respective zone for diverting electric current around the respective zone to thereby control the power delivered to the respective zone,(iv) means for determining total power delivered by the power supply,(v) means for adding the power in each zone to determine a total power in all zones, and(vi) means for comparing the total power in all zones to the total power delivered by the power supply and generating a second control signal based on the comparison for controlling the total power delivered by the power supply.

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