| 摘要 |
PURPOSE:To make a printed circuit board compact and improve the reliability thereof by keeping peak voltage at the predetermined level for application to the switching element of an inverter circuit, and reducing the quantity of parts. CONSTITUTION:An inverter control circuit is constituted of an AC power supply 11, a zero point synchronizing signal circuit 12, a rectifying circuit 13, an inverter circuit 14, a voltage control oscillation circuit 15, a D/A conversion circuit 16, a reference voltage setting circuit 17, an applied voltage detection circuit 18 and a voltage comparison circuit 19. Output signals from the circuits 12 and 19 are inputted to a control circuit 20. This circuit 20 controls the data of digital signals outputted to the circuit 16 on the timing of output signals from the circuit 12, on the basis of a unit of 1 LSB. As a result, peak voltage applied to the switching element of the circuit 14 is so controlled as to be constant. According to this construction, the quantity of parts can be reduced, and a printed circuit board can be made compact. In addition, the printed circuit board can be improved in reliability, and an oscillation frequency can be easily changed at low cost. |
