ScholarWorks@성균관대학교

초록

As the torque density of traction motors for electric vehicles (EVs) increases, hairpin winding technology with a larger conductor area is widely adopted. However, this increase also raises the impact of AC copper loss in the high-speed operating region. This paper presents an electrical winding changeover technique (EWCT) that considers hairpin winding patterns to enhance the efficiency of the interior permanent magnet synchronous motor (IPMSM) for EVs in high-speed operation. The motor operates in a two-step mode, with the first step having twice the number of winding turns as the second. The tap-change method is applied for the winding changeover as EWCT. This approach allows the IPMSM with EWCT to achieve higher efficiency at each operating point by utilizing a switching logic that selects either first step or second step mode at each speed-torque point to minimize losses. The transients during winding changeover are also analyzed. As a result, mode changes in the high-speed region reduce back-EMF and the magnitude and phase of the current, decreasing DC copper and iron losses. Additionally, the reduced eddy current effect in the conductors lowers AC copper loss, resulting in higher efficiency of the IPMSM with EWCT compared to a typical IPMSM.

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