| 摘要 |
PURPOSE:To prevent the efficiency from decreasing by applying a sufficient reverse bias voltage to a switching element in the state that an input voltage to the element is high, thereby accelerating the switching speed. CONSTITUTION:An input power source 1 is controlled to be turned ON and OFF by a transistor (Tr)3 of a switching element through an input smoothing circuit 2, and supplied to a load through a voltage conversion transformer 4, a rectifier 5 and an output smoothing circuit 6. The Tr3 is controlled by a pulse width modulator 8 through drive Tr10 and drive transformer 11. In this case, the output of the modulator 8 is applied through a phase inverter 16, a differentiator 17 and a reverse blocking diode 18 to between the base and the emitter of a drive Tr19. Thus, when the Tr3 is turned OFF, a reverse bias voltage designated by waveform E is applied to between the base and the emitter of the Tr3, and can be abruptly turned OFF. |
