Design of a switched reluctance machine for extended speed operation

This paper presents results from a design study investigating the feasibility of high efficiency, switched reluctance (SR) machines for application in minimal hybrid electric vehicles. The application requirements are presented, highlighting the constraining influences of the vehicle drive-line topology on the machine design. The benefit of continuous phase current excitation is reported for the first time, illustrating that constant power at extended speed operation can be realised with a higher number of phase winding turns per pole than would otherwise be achieved with conventional discontinuous current control. Thus, the torque/Ampere at, and below, base-speed is not as significantly compromised, an important consideration for the power inverter silicon rating and hence drive system cost. Validation of the design procedure and simulated results is presented via the correlation of simulated and test data taken from a prototype machine. The results demonstrate the potential of the SR technology for high performance, low cost automotive applications, combining arduous environmental and volumetric constraints.