Patent ID: 8064233

Claim:
A power supply regulating apparatus for supplying power from an AC power source to a heater, comprising: a rectifier circuit that rectifies alternating current supplied from said AC power source; a semiconductor inverter for high-speed switching power control that controls power rectified in said rectifier circuit using a control signal, and supplying controlled power to said heater; a temperature fluctuation detection circuit that detects temperature fluctuations of said heater; a power source fluctuation detection circuit that detects power source fluctuations of said AC power source from alternating current supplied from said AC power source to said rectifier circuit, or from power rectified in said rectifier circuit, the power source fluctuation detection circuit including a power voltage/electric current feed-forward circuit that detects the power fluctuation of the AC power source based on current input to or output from the rectifier circuit and voltage input to or output from the rectifier circuit and outputs a feed forward signal in accordance with the detected output; a load fluctuation detection circuit that detects load fluctuations of said heater from the power supplied to said heater, the load fluctuation detection circuit including a control voltage/electric current feedback circuit that detects the load fluctuation of the heater based on current and voltage supplied to the heater, and outputs a feedback signal in accordance with the detected output; and a power control signal generation circuit that calculates the amount of electric power to be supplied to said heater on the basis of detection results of said temperature fluctuation detection circuit, said power source fluctuation detection circuit, and said load fluctuation detection circuit, and that controls the duty ratio or the frequency of said control signal applied to said semiconductor inverter for power control in accordance with the calculation results, wherein the load fluctuation detection circuit further includes: a current transformer that measures the current supplied to the heater; and a voltage measurement line that measures the voltage supplied to the heater, wherein the control voltage/electric current feedback circuit: detects the load fluctuation of the heater by obtaining a difference between the current measured by the current transformer and current set for the heater, and obtaining a difference between the voltage measured by the voltage measurement line and voltage set for the heater; calculates an electric amount to be supplied to the heater based on the detection result of the load fluctuation; and outputs a calculation result thus obtained as the feedback signal.