| 摘要 |
PURPOSE:To enable to control the output of an inverter so that the ratio of the effective voltage to the frequency of a motor becomes constant even if a load condition is varied by patterning and storing the data such as a reference sinusoidal wave in a data line of an ROM. CONSTITUTION:The first and second reference sinusoidal wave data outputs of an ROM21 read out by a speed command are converted via low pass filters 25, 26 into the first and second sinusoidal signals, the reference voltage data output read out simultaneously is inputted through a low pass filter 30 to a pulse width modulation controller 33. Then, the amplitudes of the first and second sinusoidal wave signals are variably controlled by the pulse width modulation signal via switching amplifiers 23, 24, and the third sine wave signal is obtained by the synthesis of the first and second sinusoidal wave signals thus modulated in the amplitude. The inverter is controlled by the comparison output of the first, second and third sinusoidal wave signals with a carrier signal converted in a triangular wave from the carrier frequency data output read out simultaneously. |
