New two-axis model based field oriented control strategy for single-sided linear induction motors

Due to the particular structure of single-sided linear induction motors (SLIMs), e.g. cut-open magnetic circuit, difference between primary and secondary width, they suffer heavily from longitudinal end-effect and transversal edge-effect. Consequently the secondary flux linkage, secondary resistance and thrust are deteriorated, which would increase the copper loss, thrust ripple, and decrease the efficiency and dynamic response. In this paper, first, a new two-axis model of SLIM that comprehensively considers longitudinal end-effect and transversal edge-effect, is proposed. Second, an improved field oriented control (FOC) strategy for SLIM based on the new model is presented, by which the secondary flux linkage, secondary resistance and thrust can be observed precisely. Third, a compensation method for excitation is implemented to balance the influence of the longitudinal end-effect. Simulations demonstrate the proposed strategy has effective improvements in thrust ripple and dynamic response.