Solid Rotor Core vs. Lamination Rotor Core in Fractional-Slot PMSM Motor with High Power Density

Abstract

Fractional-slot PMSM motors allow for obtaining high values of power density factors, but at the same time, they are characterized by high values of rotor losses—in the rotor core and permanent magnets. The main causes of rotor losses in this type of motor are subharmonics and a high content of higher harmonics in the distribution of the magnetomotive force MMF. The use of a solid rotor core simplifies the construction and technology of the rotor but eddy current losses in the core account for a significant percentage of the total rotor losses. It is well known that a laminated core reduces eddy currents, while for motors with an outer rotor, it complicates the construction and increases weight. Thus, the question arises about the necessity to use a laminated core in a high power density motor and the real benefits of this. The article presents a comparison of the motors with a solid rotor core and a laminated rotor core, considering the value of rotor losses, power density factor, efficiency and the range of rotational speed and range of current load. The analysis was carried out for various types of sheets for laminated core and solid steel and SMC (Soft Magnetic Composite) material for solid rotor core. FEM models were used in the analysis, and the results were partially verified with the results of laboratory tests of motor models. The object of the analysis is a fractional-slot PMSM motor with an external rotor with surface permanent magnets (SPM). Motor weight is about 10 kg, and the maximum power is 50 kW at 4800 rpm.

A novel temperature calculation method of canned permanent magnet synchronous motor for vacuum pump

“…The losses of a CPMSM include copper loss, core loss, can loss, rotor eddy current loss, and mechanical loss, where mechanical loss is obtained empirically [16]. Therefore, this section mainly introduces the calculation methods of other losses.…”

Investigation of local properties of the Fe-Si alloy subjected to mechanical and laser cutting

“…The design and production of modern, energy-saving induction and synchronous electric motors with the IE4 efficiency class is currently a major challenge for designers [1]. The correct design of this type of motor, meeting the high requirements in terms of minimizing power consumption, requires excellent knowledge of the material parameters of the core [2][3][4][5][6]. The use of catalog data of Fe-Si laminates in the design process has long been abandoned.…”