Torque density improvement in a six-phase induction motor with third harmonic current injection

• Published in: IEEE transactions on industry applications Vol. 38; no. 5; pp. 1351 - 1360
• Main Authors: Lyra, R.O.C., Lipo, T.A.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2002; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Circuits; Density; Harmonics; Induction machines; Induction motors; Inverters; Magnetic flux; Mathematical analysis; Minimization; Phase current; Power system harmonics; Reduction; Static power converters; Torque; Torque control; Torque converters
• ISSN: 0093-9994; 1939-9367
• DOI: 10.1109/TIA.2002.802938

The use of six-phase induction motor for industrial drives presents several advantages over the conventional three-phase drive such as improved reliability magnetic flux harmonic reduction, torque pulsations minimization, and reduction on the power ratings for the static converter. For these reasons, six-phase induction motors are beginning to be a widely acceptable alternative in high power applications. A typical construction of such drives includes an induction machine with a dual three-phase connection, where two three-phase groups are spatially shifted 30 electrical degrees, a six-leg inverter, and a control circuit. By controlling the machine's phase currents, harmonic elimination and torque-ripple reduction techniques could be implemented. This paper describes a technique of injecting third harmonic zero sequence current components in the phase currents, which greatly improves the machine torque density. Analytical, finite-element, and experimental results are presented to show the system operation and to demonstrate the improvement on the torque density.