Permanent magnet synchronous motors (PMSMs) have recently been popular and widely used for electrical vehicle developments in the automobile industry to replace internal combustion engines due to their ability to perform at higher efficiency. This paper uses the PMSM in fuel cell vehicle electric air compressors. To ensure that the PMSM performs at higher efficiency, some field performance, such as electromagnetic field, must be improved. In this paper, a comparison between the electromagnetic forces components in the presence of current harmonic. The data indicates that the amplitude of electromagnetic forces for both radial and tangential components are not the same, particularly in lower orders. However, radial forces contribution is greater than tangential forces. A structural optimization method reduces the radial electromagnetic (RE) forces to improve PMSMs efficiency. The optimization method involves changes in the PMSMs design values and improving the electromagnetic field performance. The RE forces found to dominate the tangential electromagnetic (TE) forces, and it is amplitudes corresponding to 2,4 and 6-order are minimized by 31.1%, 28.5%, and 15.9%, respectively.