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A novel criterion for the utility of reluctance torque in permanent magnet (PM) motors is developed. The criterion, reluctance torque ratio α, can be quantified by using the PM flux linkage Ψp of the stator phase windings, the current I, and the direct- and quadrature-axis inductances Ld and Lq, respectively. It has been shown that the conventional salient-pole ratio is not helpful in clearly judging the utility, while the ratio α can be used to make such judgements across various types of motors with different applications and outputs. Through both theoretical consideration and experiments, it has been proved that a motor with large PM flux linkage utilizes little reluctance torque even if the salient-pole ratio Lq/Ld is over 2.0 and that a large Lq/Ld increases iron loss, thus decreasing motor efficiency. We have also shown that the above-mentioned loss increase is caused by the significant superposition of q-axis flux due to the large Lq and have concluded that, in the above-mentioned case, selecting a rotor geometry with less saliency can improve the efficiency. Results are given for two types of four-pole prototype motors with an output power of 0.6 kW, a rated rotation number of 3600 min−1, and Y-connection. [ABSTRACT FROM AUTHOR]