Design, analysis and torque control of low voltage high current SRM for small automotive applications

The present paper deals with the design, finite element analysis (FEA) validation and the direct instantaneous torque control (DITC) if a low voltage switched reluctance machine (SRM) for small automotive applications. The machine proposed is a low voltage and high current structure able to develop the power requested by the application. The design procedure meets difficulties and solves them in manner of core saturation at high current and high power density. The analytical design procedure is detailed for the proposed machine. Discussing of high phase currents, a validation of the design needs to be approached, based on FEA method. The direct instantaneous torque control (DITC) is employed as the machine is addressed to automotive applications. As it is known that the torque ripples of the SRM are high when using only hysteresis control of the currents hence these will create discomfort to the driver. With DITC, the torque can be smoothened in order to obtain increased comfort of the passenger. In order to implement DITC method, a Matlab Simulink program was created to simulate the SRM, based on lookup tables containing the flux and torque variations function the current and rotor position, fetched from the FEA model of the machine. The program created this way offers the possibility of fast simulation of the machine and allows in the same time the possibility of implementing several control procedures.