Accurate modeling and analysis of the winding inductances of a linear permanent-magnet actuator using an improved Fourier series expansion

In this paper, the winding inductances of a linear ironless permanent-magnet synchronous actuator for high-precision applications is discussed. Different from rotary motors for conventional applications, high-order harmonics and the end effect due to discontinuous structure are considered. From such considerations, an improved Fourier series expansion is applied to the proposed distributed-parameter model of the linear winding. The calculated inductance matrix is of high accuracy, and presents a new non-uniform form. New features of the inductance matrix are analyzed, and the decoupling scheme is implemented via variable transformation and real-time updating inductances.