Torque method of detection of three phase circuit alternating current induction motor Drive by the inverter device

摘要

PURPOSE:To detect the torque of AC motor driven by an universal inverter without using a rotating speed sensor or a special microprocessor. CONSTITUTION:A microprocessor 1 for controlling an inverter 30 outputs signals corresponding to inverter voltage V, angular velocity 2pi f and phase angle omega d t to torque detection means 20. On the other hand, and the current of each phase of an AC motor 40 is detected by CT given to torque detection means 20. The torque detection means 20 calculates the torque of an AC motor 40 by the following equation: tau=K(V/omega) [Iasin {omegat-(1/6)pi-Ibcos} (omegat)] Torque of calculated AC motor 40 is displayed on an indicator or used for overload prevention for the AC motor 40.