Prof. Myung-Seop Lim

Comparison of Performance for SPMSM using Cobalt Iron and Silicon Steel
2020-02-03 11:57:41 조회수718
Date of Conference: 2019.11
Conference: 한국자기학회 동계학술연구발표회
Authors: Jun-Woo Chin, Min-Ro Park, Young-Hoon Jung, Chung-Seong Lee, Myung-Seop Lim

Recently, the major topics of the electric machine industry are increasing efficiency and power density. Therefore electric machine designers achieve these goals by parametric design and optimizing the shape of motor [1]. The others are interested in the core materials which have better magnetic properties than the conventional core materials like the silicon steel. So, any new products such as the cobalt iron and the nickel iron were developed for the better magnetic properties [2]. The cobalt iron has better magnetic properties than the silicon steel, especially for B-H characteristic and iron loss, and the nickel iron has lower iron loss than the other materials such as silicon steel and cobalt iron at high frequency [3]. In this paper, the magnetic properties such as B-H characteristic and iron loss are compared according to the core materials, particularly for cobalt iron and silicon steel. Furthermore the performance of the proposed surface mounted permanent magnet synchronous motors (SPMSM) which employ core materials referred earlier is also compared. The process of iron loss calculation via the 2-D finite element analysis (FEA) is suggested. Also the line to line voltage, line current and efficiency at the same load condition are compared.

The proposed core of cobalt iron and silicon steel are Vacoflux48 and 20PNF1500, whose thicknesses are both 0.2 mm. The magnetic properties such as B-H curve and iron loss of the Vacoflux48 and 20PNF1500 were compared as results of the material experiments as shown in Fig. 1. In terms of the B-H characteristic, the cobalt iron has a saturation flux density of 2.1-2.3 Tesla. On the other hand, the conventional silicon steel has a saturation flux density of 1.4-1.6 Tesla. Fig. 1 (b) shows that the iron loss of Vacoflux48 is lower than that of 20PNF1500 at 1000Hz. However, not only for the frequency of 1000Hz, but also for every frequency, the iron losses of Vacoflux48 are lower than those of 20PNF1500.

To examine and compare the performances of a motor, SPMSM was proposed as an analysis model. An inner-rotor type SPMSM consists of 12 poles-27 slots, and Nd magnet was used in the rotor. By applying each core material data, the performance and characteristic of SPMSMs were investigated through the 2-D FEA. The process of iron loss calculation through 2-D FEA was proposed. Then the line-to-line voltage, line current and efficiency that can be calculated by d-q axis equivalent circuit were compared.

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