Sensorless Control of Segmented Bilateral Switched Reluctance Linear Motor Based on Coupled Voltage for Long Rail Propulsion Application

A segmented bilateral switched reluctance linear motor (SRLM) applied to long rail propulsion system is first proposed. The electromagnetic thrust, flux density and inductance characteristics of two SRLMs are compared and analyzed by finite element method. The results show that the SRLM with segmented primary and secondary has a higher thrust and is fully decoupled, which simplifies the sensorless control system. In order to solve the problem of detection difficulty of the pulse currents, negative torque and eddy currents in traditional pulse injection method, a new position estimation method of the SRLM based on the coupled voltages of idle phase is proposed in this article. The merits of the position detection method are that it does not need to consider the accuracy of pulse currents detection, the frequency of injected pulse voltage can be further improved, and the influence of back EMF in the process of motor operation can be offset, thus greatly expanding the velocity range of pulse injection method. According to the position detection method, the specific control strategy and program flow chart of the SRLM sensorless operation are presented. Finally, a prototype test platform is built, and the experimental results verify the effectiveness of the proposed method.