Design and control of a linear propulsion system for an elevator using linear switched reluctance motor drives

Linear switched reluctance motor (LSRMs) for primary propulsion of a ship elevator is proposed and investigated in this paper. To achieve the stated objective, a new type of LSRM is proposed with twin stators and a translator between them with no back iron in the translator. The proposed configuration of the LSRM is designed, simulated and analyzed and compared to traditional LSRMs. The number of LSRM propulsion subsystems required is studied with a view to minimize their weights and an optimization study for that purpose is developed. Unique placement of the LSRM propulsion systems on the elevator is presented. Six sets of asymmetric bridge converters are chosen to drive the designed LSRM endowing it with high fault tolerance to the system. The propulsion force is generated using one phase or multi-phase excitation. In order to reduce force pulsations, a major requirement in elevators, controlled multi-phase excitation using one of the known force distribution functions (FDF) is an acceptable solution. The currently available FDFs are able to reduce the force pulsations but are not able to meet the peak force command is proven in this paper. Consequently, the speed and position control do not meet even the elementary performance requirements any more. A new FDF is proposed and presented to overcome the problem caused by the conventional FDF in this paper. The control system with the proposed FDF is derived and integrated for speed and position control. Extensive simulation results prove that the proposed LSRM with the new FDF exhibits superior performance and it is believed that it may be suitable for the ship elevator application