Combined Vector and Direct Thrust Control of Linear Induction Motors With End Effect Compensation

Linear induction machines dynamics may not be as fast as that of their rotary counterparts due to a larger air gap, a bigger leakage flux, and end effect. Direct thrust control can speed up their dynamics substantially with rather high pulsations, while vector control facilitates a smoother performance but slower dynamics. In this paper, an analogy between the two control methods, when they are applied to the linear machines, is proved first. The analogy is then used to justify combining the selected parts of the two control methods to come up with a control method that provides faster dynamics than vector control and smother performance than direct thrust control. The proposed control method is realized by getting rid of demanding parts of the two conventional control methods. End effect is also considered in the modeling and control system design. Extensive simulation results confirmed by experimental results prove improved motor performances under the proposed control method. The proposed control is particularly suitable for linear applications that need fast dynamics and smooth operation.