Computation of transient thrust force in a tubular linear motor for pumping unit

A method for the computation of the transient electromagnetic thrust force in the tubular linear motor, in which the iron saturation and the relation motion of the rotor and stator are taken into account, is given in this paper. This method is based on the finite element computation by using a dynamic model coupled with the equations of external electric circuit. To avoid air-gap mesh distortion cased by the movement of the rotor, moving boundaries are introduced in the air-gap. Finally, an example which is the application of the method is given to the compute the distribution of transient magnetic field and the thrust force of a tubular linear motor. The computed results agree with the measurement very well.