The Iron Loss Analysis of Direct-driving External-rotor Motor with Cobalt-iron Alloy

Abstract

In this paper, the iron loss characteristics of an External Rotor Permanent Magnet Synchronous Motor (ER-PMSM) for direct-driving of electric vehicle is analyzed in detail. As a kind of cobalt-iron alloy, whose saturation magnetic density is about 2.4 Tesla, is adopted to manufacture the iron core, the experimental platform has been established to test the B-H curve and the iron loss characteristics of the alloy, firstly. According to the characteristics of iron loss coefficient varying with frequency, a variable coefficient orthogonal decomposition iron loss model is proposed. Then, a magnetic loss calculation model based on cobalt-iron alloy is established. The empirical coefficient of iron loss is re-corrected, and the analysis model of the iron loss is obtained. Finally, the experimental platform is set and a prototype of ERPMSM is manufactured. The iron loss of the stator with cobalt-iron alloy is tested. The experimental results agree well with the numerical results and the calculated results, which verify the correctness of the theoretical analysis.