A novel analytical model of air-gap permeance in tubular linear switched reluctance actuators with hybrid flux paths

Due to simple and robust configuration, and without any coils and magnets on movers, a tubular linear switched reluctance actuator (TLSRA) is a promising candidate for applications of frequently reciprocating linear motion, such as linear compressors and automotive active suspension systems. For air-gap in a TLSRA, there are the longitudinal and transverse magnetic paths due to various mover positions. Change in air-gap permeance in a TLSRA results in the thrust force, which drives the mover for linear motion. Thus, the air-gap permeance is the crucial parameter for computing the thrust force in the electromagnetic design and estimating the real-time thrust force in force control of TLSRAs. In general, the air-gap permeance at two special positions can be calculated analytically, such as the maximum and minimum air-gap permeance. It is a challenging issue that an analytically model is developed to compute the air-gap permeance at arbitrary mover positions. This paper focuses on that permeance model development.