| 摘要 |
PURPOSE:To suppress the exciting sound of an induction motor at a light load time by providing means for generating cubic root function of speed deviation and means for outputting an amplitude signal and a 3-phase sinusoidal signal with the output of the generating means and an actual speed, thereby varying the exciting current in response to the torque. CONSTITUTION:The speed of an induction motor 101 is detected by a resolver 102, is converted to an analog value by a converter 104, and is compared by an arithmetic circuit 108 with a command value. The difference is inputted through an absolute value circuit 110 to a cubic root function generator 111, is digitized by a converter 112, is then applied to a microcomputer 113, is calculated with the actual speed, and an amplitude signal and a 3-phase sinusoidal signal are outputted. Then, a motor 101 is controlled through a pulse width modulator 123 and an inverter 124. Accordingly, the speed deviation is corrected to be regarded as correct torque, thereby varying the exciting current in response to the torque and suppressing the exciting sound of the motor at the light load time. |
