| 摘要 |
PURPOSE:To detect the magnitude of the AC of the AC motor as a current having small ripples without delay, by converting the AC detected from the AC motor into an AC signal having more number of phases than the number of phases of the motor and rectifying the signals. CONSTITUTION:The AC flowing the AC motor is detected by a current detector. The detected output is rectified and imparted to a power converter. The torque generated by the AC motor is adjusted by said converter. A transformer 51 for phase conversion, which converts a three phase signal into six phase signal, is provided in a rectifier circuit. The detected AC is converted into six phases and full wave rectification is performed by a rectifier 52. A signal including only 3% average ripples is obtained across a resistor (r), and the frequency becomes high. Therefore, the ripples can be removed by a short time constant filter. The response in a current control system can be enhanced accordingly. As a result the response in a speed control system can be improved. |
