A General Model of the Laminated Steel Losses in Electric Motors with PWM Voltage Supply

A procedure is described for identifying a general mathematical model of core losses in ferromagnetic steel when the voltage supply is non-sinusoidal, i.e. PWM inverter-fed type. This model has a hysteresis loss multiplicative coefficient variable with frequency and induction and a combined coefficient for eddy-current and excess losses that is also variable with frequency and induction. The effect of the PWM supply voltage over the core losses is modeled using factors that depend on the average rectified and rms voltage values. Validation was performed on a number of different samples of non-grain oriented fully and semi-processed steel alloys.