| 摘要 |
PURPOSE:To suppress the exciting sound of a motor at the light load time by outputting a current command due to the deviation between a speed command and an actual speed and controlling the induction motor so that the ratio of the secondary current to the exciting current becomes constant when the motor is driven on the basis of the command. CONSTITUTION:The speed of an induction motor 101 is detected by a resolver 102, is then converted by a converter 104 to an analog value, and is compared by an arithmetic unit 108 with a command signal. The deviation is inputted through an absolute value circuit 110 to a cubic root function generator 111, is then digitized by a converter 112, and is then applied to a microcomputer 113, which calculates it with the actual speed and produces a 3-phase sinusoidal signal having constant phase difference from the amplitude signal, and the motor 101 is controlled through an inverter 124. Therefore, the exciting current is varied in response to the torque, thereby suppressing the exciting sound at the light load time, and the ratio of the exciting current to the secondary current is maintained constant, thereby controlling the power factor constantly and the reactive power to the minimum. |
