| 摘要 |
PURPOSE:To prevent variations in a current and a torque from occuring by corresponding a voltage pattern and a frequency range so that the rate of voltage variation becomes constant in all frequency range. CONSTITUTION:A PWM signal pattern formed with logic pattern of ''1'', ''0'' is stored in a ROM5. a plurality of PWM signal patterns stored in the ROM5 are prepared in response to the prescried frequency range, and when the voltage patterns are sequentially selected and switched upon altering of the frequency, the voltage patterns are stored so that the rate of voltage variation at the altering time becomes constant at any altering point. The pattern is read out by a counter 4 from the ROM5, and applied to the switching element of an inverter through a multiplexer 6, a latch 8 and a signal distributor 9. |
