Independent Control of Multiple Multiphase Linear Induction Motors Supplied From a Single Voltage Source Inverter

In recent years, multiphase machines have gained steadily increasing attention in research areas because of their superior advantages over their three-phase counterparts. Multiphase machines in comparison with three-phase machines have greater torque density, greater efficiency, greater fault tolerance and reduction in the required rating per inverter leg. Also in multiphase machines, the torque pulsations will be reduced which are a significant factor in the safety and comfort of the passenger transportation. Moreover, multiphase machines possess additional degrees of freedom which can be utilized in simultaneous and independent control of multi-motors supplied through a single voltage source inverter. This can be helpful in long trains with distributed power. In rail transport, distributed power refers to the placing and distribution of railway locomotives throughout the length of a train, remotely controlled from the leading locomotive. To achieve this, locomotives should be equipped with extra radio network equipments and sophisticated control apparatus called locotrol. Independent control of multiple motors and locomotives from a single voltage source inverter can be a proper replacement for the locotrols. Therefore, it leads to reliability increment and fault occurrence of the train control systems. Consequently, the main purpose of this paper is to present a completely independent vector control of two (or more) multiphase Linear Induction Motors (LIMs) that are supplied from a single current-controlled VSI. All the LIMs are running with the same speed but with different load conditions and various external forces. The concept is applicable to any multiphase ac machine type. The verification of the proposed concept is provided by simulation of a seven-phase three-LIM drive system running with the same speed. The principal advantages of the proposed concept are finally provided and discussed.

Keywords:

Linear Induction Motor (LIM) , Multi-motor drives , Multiphase machines , Power distribution of railway transportation , Vector control