The comparison of motor losses is a significant item in the study of inverter control strategies for variable frequency, variable speed ac drives. For our study, since it is necessary to differentiate small changes in loss, we have decided to use steady state temperature rise as a direct indicator of loss rather than measurement as the small difference between input and output power. An essential preliminary, the determination of temperature rise with normal sinusoidal voltages, is described here. It has established that a simple thermal model could define the steady state temperature rise with acceptable repeatability and accuracy.