Question

A 20kW. 3-phase, +40 V. 4 pole, delta-connected permanent magnet synchronous motor has following parameters Xs=5 ohm, Rs negligible  rated power factor = 1.0. Machine is controlled by variable frequency control at a constant (V/f) ratio. Calculate

(i) Armature current. torque angle and power factor at half full load torque and 750 rpm.

(ii) armature current, torque angle and power factor at half full load torque and 1000 rpm.

(iii) The braking torque, torque angle and power factor when working under regenerative braking at rated motor current and 750 rpm.

440V

Answer 1