Evaluation of a Switched Reluctance Machine in an Automotive Oil Pump Application

Sammanfattning: A Switched Reluctance Machine (SRM) is evaluated in terms of torque quality and speed ripple for a particular pump application. The aim is to give BorgWarner insight into the control methodology and possible applications for a Switched Reluctance Machine. The SRM is also compared to their current BLDC machine, used as an oil pump in their torque transfer applications. The evaluation and implementation of control methodologies is done on a 4/2 asymmetric Switched Reluctance Machine. The SRM control is developed using two different approaches, namely FEA and experimental measurement of machine characteristics. The two approaches are evaluated in regard to how well they represent the physical machine. The machine models from the FEA and the measurement differ only slightly and it is concluded that FEA is an adequate tool for developing control methods for the SRM. Two control methods, "Instantaneous Torque Control (ITC)" and "Average Torque Control (ATC)", are implemented and evaluated in regard to match the BLDC application of a speed controlled oil pump. The different control methods, ITC and ATC, are compared in regard to torque-speed performance, speed ripple and feasibility of implementation. Experimental testing is performed to validate the results. The ATC, surprisingly, has less speed ripple than the ITC which is explained by non-optimized turn off angles for the ITC. Sensorless position control is evaluated in simulation and shows that sensorless control is feasible for the SRM. The BLDC machine and the SRM are compared with respect to performance and costs. It is concluded that the BLDC is more appropriate for BorgWarner's application than the 4/2 SRM. Further studies should be conducted to examine SRMs with higher pole number configurations.