Overvoltage protection circuit for protecting overvoltage corresponding to wide range of input voltage

A power supply apparatus for supplying a power supply voltage, the power supply apparatus comprising an overvoltage protection circuit,

• wherein the overvoltage protection circuit is connected between a rectifier circuit that rectifies an AC voltage to output a rectified voltage and a load including an input capacitor element connected to both ends of the load,
• wherein the overvoltage protection circuit comprises:
• a semiconductor switch connected between the rectifier circuit and the load;
• and
• a control circuit that controls the semiconductor switch to be turned on or off,
• wherein, when the rectified voltage exceeds a predetermined value, the control circuit turns off the semiconductor switch, and detects a voltage potential difference between both ends of the semiconductor switch, and then, for an interval when the voltage potential difference is zero or a predetermined minute value, the control circuit generates a control voltage for turning on the semiconductor switch, and outputs the control voltage to a control terminal of the semiconductor switch, and
• wherein overvoltage protection circuit comprises a current change circuit that gradually changes a current flowing through the semiconductor switch such that a conduction disturbing wave voltage in an output voltage output from the overvoltage protection circuit becomes equal to or lower than a predetermined value at least at one of (A) a timing when the semiconductor switch is turned off and (B) a timing when the semiconductor switch is turned on.