| 摘要 |
PURPOSE:To obtain an inverter which efficiently drive a motor by generating a plurality of DC voltages of different levels from an AC voltage, and selectively switching the DC voltage in response to the command frequency of an approximate sinusoidal wave, and pulse-width-modulating it. CONSTITUTION:A DC high voltage generator 33 has rectifying diodes 34-37 and capacitors 38-41, and the output is applied through a smoothing condenser 42 to a bridge circuit 43 which forms an inverter with transistors. An AC voltage supplied from the bridge circuit is doubled at the peak value by the generator 33, and four times of DC voltage is generated when a relay 45 is ON, it is pulse- width-modulation controlled by the bridge circuit 43 and a sinusoidal wave approximate wave form controller 46, thereby outputting an AC voltage of approximate sinusoidal wave. The DC voltage is switched by a voltage switching controller 44 and a relay 45, the relay 45 is deenergized by the frequency or lower of double of the rated frequency FR in response to the command of the frequency command signal input to a terminal 47, and energized by 2FR-4FR. |
