I. Introduction
Air-cored permanent magnet linear synchronous motor (PMLSM) are gradually used in the field of ultra-precision application. However, for ultra-precise positioning stage with air-bearing, motor volume, and coils, quality must be strictly limited, and heat losses can affect some material deformation and the accuracy of test instruments, for example, the laser interferometer. Therefore, improvements of thrust per volume, thrust per coils quantity, thrust per copper losses, and thrust ripple simultaneously are required to improve motor performance and adaptability.