Control circuit of electromagnetic induction heating device

摘要

The present invention relates to a control circuit of an electromagnetic cooker using a high frequency induction heating theory. The control circuit of the present invention has a working coil driving part 11 for switching the DC voltage supplied to the working coil 35, a working coil driving part 11 and a zero potential switching point 11 in the pulse output of the working coil driving part 11, A power transistor operation start point detection section 12 and a triangular wave generation section 13 for detecting a current waveform and generating a triangular wave synchronized with the detected current waveform and generating a control pulse with an output level specifying voltage signal of the output current detection voltage signal and the microcomputer 34 A square wave generator 19 for generating pulses for the power transistor driver 14 from the outputs of the input current controller 18 and the triangle wave generator 13 and a working coil driver 11, A power transistor overvoltage protection section 33 and a heating container presence / absence judgment section 21 for protecting the overvoltage due to the physical properties of the heating container from the output voltage of the heating container, The operation start and temperature control unit 27, the start temporary shutoff control unit 30, and the container presence / absence repetition confirmation unit (not shown) for shutting off the circuit by controlling the output cutoff unit 15 in accordance with the temporary circuit closing at the time of initial power-A control level upper / lower limit setting unit 32 for setting an amplitude magnitude of the output transistor drive pulse and compensating for an external input voltage variation, and a constant output holding unit 31 for changing the input voltage. The control circuit of the present invention always outputs a constant output with respect to the physical properties of the heating container and the fluctuation of the input voltage, thereby preventing breakage of the power transistor at the initial power-on.