Tubular permanent magnet motor with Integrated Coaxial Transformer

A moving coil, permanent magnet, tubular, linear motor with an electromagnetically integrated coaxial transformer is presented in this paper. The soft-magnetic core of the motor consists of isotropic, soft-magnetic composite material which acts simultaneously as the flux guide for both the motor and transformer. The transformer is designed for a wireless apparent power transfer of 800 VA with a frequency of 5 kHz. 500 W of power is reserved to operate the motor at a peak force of 250 N at a maximum rated speed of 2 m/s. The surplus of wirelessly transferred power can be employed to energize additional electronic equipment on the moving platform. The working principle of the integrated design is addressed in this paper. The electromagnetic integration gives rise to mutual electromagnetic cross-coupling effects between the transformer and motor operation. It is discussed how these cross-coupling effects are attempted to be minimized in the electromagnetic design by applying an orthogonal, spatial orientation of the flux in the core due to transformer coils with respect to the flux originating from the phase coils and permanent magnets of the motor. Remaining cross-coupling effects on account of the nonlinearity of the core material are discussed and quantified by means of magnetostatic Finite Element Analysis simulations.