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ABSTRACT: This paper proposes two different techniques to reduce detent force in flat permanent magnet linear synchronous motors (PMLSM). The first one is the choice of an optimal constructive design, taking into account the width and arrangement of the magnets, and the length and shape of the solid iron core. The second is the employment of a force compensator in the control algorithm, which counteracts the detent force effects. Both methods are based on a Fourier analysis of the detent force curve as a function of the machine position. The curve is broken down into harmonics. The constructive method considers that each harmonic has its peculiar source and is independent from the others. The force compensator employs a detent force model based on the Fourier series of the curve. The two methods were tested separately, and their results were compared. Experimental tests were performed to verify the effectiveness of the methods. A very important reduction with a constructive optimization of the machine was achieved. The reduction by means of a compensator in the control scheme also reaches excellent results. In order to achieve the maximum reduction of detent force, both techniques can be combined. This measure will increase the precision features of this kind of machine.
Electric Machines and Drives Conference, 2003. IEMDC'03. IEEE International; 07/2003
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ABSTRACT: The knowledge of the real stator voltages is basic for a correct estimation of stator flux and torque in direct torque controlled induction motors. In this paper, two different low-cost and effective techniques are presented for stator voltage acquisition: one based on an electronic circuit and the other based on software programming. Both of them have been developed and applied to a direct torque control (DTC) scheme. Experimental tests demonstrate their suitability when controlling an induction motor. A comparative of the two mentioned techniques is presented.
Electric Machines and Drives Conference, 2003. IEMDC'03. IEEE International; 07/2003
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ABSTRACT: The target of this paper is to establish the main problems and goals of the four most popular control strategies for induction motor drives, applied to the special case of linear motors: scalar control, direct field-oriented control (direct FOC), indirect field-oriented control (indirect FOC) and direct torque control (DTC). We introduce the peculiarities of the implementation of the different strategies for linear induction motors, the results of experimental tests of the speed controller and position controller, and a discussion of the experiments.
Electric Machines and Drives Conference, 2003. IEMDC'03. IEEE International; 07/2003
