For anyone with access:
Boglietti, A.; Cavagnino, A.; Knight, A.M.; Zhan, Y., "Factors Affecting Losses in Induction Motors with Non-Sinusoidal Supply," Industry Applications Conference, 2007. 42nd IAS Annual Meeting. Conference Record of the 2007 IEEE , vol., no., pp.1193-1199, 23-27 Sept. 2007