Additional loss due to operation of machines from inverters

This paper presents a measurement method for determining the extra harmonic loss in an induction machine fed from a PWM inverter whilst the machine is running under any defined operating condition. The method allows the loss due to different harmonic frequencies to be segregated and enables a harmonic loss factor to be defined which can be used for loss prediction. Results are given confirming the accuracy of this prediction for a wide range of operating conditions. Particularly interesting features of the measurements are the variation of loss with load and the relatively large magnitude of the high frequency loss. Conventional equivalent circuit models predict neither of these effects