| 摘要 |
PURPOSE:To prevent generation of a beat by forming of voltage control means, a current detector of a secondary winding of a transformer, a voltage converter of its detected current value, and a state controller of a third switch element. CONSTITUTION:A voltage output from a voltage converter 230 is input to a chopper drive controller 150, compared by an operational amplifier 151, and a low level signal is output when a triangular voltage as an output signal is large or a high level signal is output when it is smaller. When the signal has the low level, a transistor 172 is turned ON, an inverter 200 is conducted, while when the signal has the high level, transistors 161, 172 are turned OFF, a transistor 171 is turned ON, a transistor 181 is turned OFF, and conduction of the inverter 200 is interrupted. According to this, since an oscillation frequency of an oscillator is synchronized with the operating frequency of first to third switch elements, a beat of these frequencies is not generated. |
