Computer aided analysis and design of a single phase tubular induction actuator
This thesis introduces a novel tubular linear induction actuator (TLIA) which makes use of eddy currents to produce useful thrust. Compared with normal DC or AC solenoids, it possesses advantages of long thrust, large starting force and low starting current. Unlike linear motors, it is much simpler in structure and cheaper. In order to investigate the principle of operation, design and dynamic performance of this TLIA, a time-stepping computer program named COUPV has been developed. Based on the finite element method, it couples the axisymmetric 3-D internal electromagnetic field containing eddy currents and non-linear materials with external electric circuits, involving power electronics and a moving mechanical load. The power supply can be of any kind of voltage or current waveform, such as sine wave, square wave, PWM wave or phase controlled wave. The simulated results in both steady and dynamic states are found to be in very good agreement with the measurements obtained from existing models. Two special features of the TLIA defined as the shielding effect and the inner end effect are studied. These two effects dominate its performance and make its analysis different from conventional magnets, solenoids and linear motors. With the help of the COUPV, special attention is paid to the design and control of the TLIA. Its basic construction, slot shape and materials of stator and plunger are studied. Both bang-bang and position control strategies are investigated. It is evident that COUPV can find application for many types of electromechanical devices such as magnetic bearings, fuel injectors, various electric motors and even θ guns.
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