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Description
Linear induction motors (LIMs) have been widely applied in urban transit systems, such as in metros and low-speed magnetically levitated train. Due to the inherent eddy-current loss on the secondary reaction plate, the LIM applied in urban rail transit suffers from poor power factor and efficiency. And the efficiency of the current linear synchronous motors in urban rail transit is also unsatisfactory. A high efficiency permanent magnet linear synchronous motor (PM-LSM) is proposed in this paper. This single side PM-LSM adopts coreless long stator with single turn single layer wave winding which is segmented, and the secondary is a PM array fixed under the train. As a result of the tiny stator inductance, the PM-LSM’s power factor is very high. In order to maximize the thrust in the direction of the motion of the train and get the maximum output power at some a speed, one pole of the secondary is consisted of four PMs and furthermore the magnetization direction of two adjacent PMs is 45 degrees to get an appropriate magnetic circuit. Through selecting the appropriate length of the stator segment to diminish the copper loss. Considering the facts and high efficiency, we selected the proper current amplitude of the coils, speed of the train, the length of the stator segment and number of the PM-LSMs installed on a train to build a finite element model and carry out simulation and optimization. The simulation results show that the power factor of the proposed machine can reach 0.98 and its efficiency runs up to 92%. More elaborate results of analysis and comparison will be exhibited in the full paper.
| Submitters Country | China |
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