Overview of Permanent Magnet Linear Machines with Primary Excitation

The permanent magnet linear machines with primary excitation (PE-PMLM) is a special type of linear machine derived from traditional permanent magnet linear machines, which has the advantages of high thrust force density, high efficiency, high precision and high reliability. In the field of long-stroke direct-drive linear motion, PE-PMLM exhibits its unique performance and cost advantages. This paper reviews and summarizes the research status and development trend of the PE-PMLM. First, the thrust force generation mechanism of the PE-PMLM is revealed based on the flux modulation theory. Second, the technical points and research progress of various kinds of PE-PMLM are reviewed. Third, comprehensive performances of all kinds of PE-PMLM are compared and analysed. Finally, the future development trend is discussed.