Asynchronous Motor´s Maximum-Efficiency Control Considering Variable Iron Loss Equivalent Resistance by Adjusting the Ratio of Active Power to Reactive Power

A novel asynchronous motor maximum-efficiency control strategy by adjusting the ratio of the motor´s active power to its reactive power is investigated. The study shows that once the motor´s desired speed is given, the motor will be running at the maximum efficiency by making the ratio of active power to reactive power reasonable, which can be adjusted by varying the variable-frequency voltage source´s output frequency for scalar control strategy. And the iron loss equivalent resistance varying at different frequency in the case of variable-frequency variable-voltage (VVVF) speed regulation and other effect such as torque and voltage at maximum-efficiency control condition are also investigated.