Electric machine loss measurement and modeling - PWM versus sinusoidal feeding

Abstract

Abstract As the electrification of the automotive industry continues, the importance of high efficiency electric machines increases significantly. The ability to accurately predict the efficiency and losses in the designing stage is therefore essential. This thesis studied the degradation in magnetic properties in silicon steel strips cut with different widths. These pieces were then used to develop a model to implement manufacturing effects due to cutting in to the electric machine simulations to more accurately model the iron losses. The simulations were fed with both a sinusoidal current and a pulse width modulated voltage feeding to compare the effect of the different feeding types on top of the cutting degradation effect, and compared with each other. For all points simulated, the core losses increased when a layer of degraded material closest to the cut edges of the stator was used, up to 25% with the sinusoidal feeding. For the pulse width modulation case, five different operating points were simulated, showing an increase in core losses of up to 7% when using degraded material. Comparing the effect the feeding types had versus each other, the pulse width modulation fed simulations had core losses up to 258% higher than the sinusoidally fed case. One measurement of the actual machine was compared with the pulse width modulated feeding simulations where the difference between losses was 6.7%, showing promise in the model for the simulated points.