Experimental Comparison of a Three- and Five-Phase Squirrel Cage Induction Machine

A three-phase (IM3) and a five-phase (IM5) squirrel cage induction machine are compared as high-efficient inverter-fed motors in variable-speed drive applications. The design of the five-phase machine is based on an IE3 three-phase totally-enclosed, fan-cooled standard induction motor with 15 kW nominal power at 1476 rpm and 400 V. The five-phase induction machine complies with the same thermal, geometrical, electrical and mechanical constraints for a fair comparison. IM3 and IM5 are measured and compared at no-load, short-circuit and rated operation. A 3<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> harmonic voltage injection is only possible for IM5. The 3<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> harmonic voltage amplitude and phase angle are varied and measured to determine the loss minimum combination (efficiency improvement by 0.15% points). IM5 achieves a rated efficiency of 93.21 %, compared to 92.64% of IM3.