| 摘要 |
PURPOSE:To suppress an unexpected noise and an iron loss increase without generating harmonic waves by reducing a torque command value in response to the excess of a terminal voltage when the terminal voltage exceeds the prescribed value. CONSTITUTION:Motor terminal voltage detecting means 6 detects the terminal voltage of an induction motor 3. Overvoltage detecting means 7 compares the detected voltage with a reference voltage such as the DC voltage of a PWM controller to detects that the terminal voltage of the motor 3 exceeds the reference voltage. Torque command reducing means 8 superposes a negative signal on the torque command signal in response to a voltage excess. Thus, when the terminal voltage becomes the prescribed value or higher, the torque command signal E decreases as compared with the normal case, the reduced torque command signal Ee is applied to a vector calculator 5, converted to a current command signal F, applied to a PWM controller 9, and the motor 3 is controlled on the basis of the command. |
