| 摘要 |
PURPOSE:To reduce a noise without deteriorating the response to a torque by weakening a magnetic flux command from a rated value without setting it to zero when a torque command signal is zero. CONSTITUTION:A speed control circuit 6 outputs a torque current command signal It*. A magnetic flux command signal PHI* is decided in response to the signal It* by a magnetic flux instructing circuit 7. The characteristic holds that, even if an input signal alpha becomes zero, the command is not zero but holds the value of gamma weakened from a rated value beta. A magnetic flux control circuit 8 forms an exciting current command signal Im* in accordance with the signal PHI*. Thus, the magnetic flux of a motor 3 is proportional to the output of the circuit 6, and is controlled to hole a certain value even when the output is zero. |
