Experimental measurement of eddy current loss in permanent magnets of electrical machines with a PWM signal generated by a frequency converter

In today's highly automated world, permanent magnet synchronous machines (PMSMs), commonly used in the industrial automation of traction, robotics or aerospace, require higher power density and efficiency. When developing such PMSMs, the eddy current loss (i.e. permanent magnet loss) in the permanent magnets (PMs), especially with respect to temperature and frequency influence, must be considered. The increase in the temperature of PMs above the allowed maximum temperature leads to a tendency towards irreversible demagnetization and changes in the electrical conductivity of the material. Similarly, higher harmonics with different frequencies influence the eddy current loss of the PMs. The accurate analytical analysis and measurement methods of PM loss can help PMSM designers to create robust PMSMs with high tolerances and higher energy efficiency at low manufacturing costs. In this paper, measurement methods and a finite element method (FEM) simulation for the PM loss of PMSMs are presented and compared. In addition, we consider the eddy current loss (i.e. PM loss) in PMs, which are under external magnetic fields generated with a sinusoidal or non-sinusoidal pulse width modulation (PWM) signal under higher frequency effects.