Developing the concept for an automotive high-speed SRM drive with focus on acoustics

The automotive industry demands small and cheap drive trains to compensate for battery weight and cost. A fully integrated high-speed SRM drive train could be an answer to this demand. However, high-speed SRM exhibit some characteristic shortcomings such as torque ripple, acoustic noise and partly low efficiency. This paper presents a way to develop a concept which overcomes all these factors. This is done by the right choice of rotational speed, machine configuration and a combination of different control strategies at different speed levels. The most suited tooth configuration was found by comparing several rough machine designs regarding driving-cycle efficiency and acoustic behavior. For efficiency reasons, a three-phase SRM was chosen. The acoustic behavior of the 18/12 configuration turned out to be most suited for a high-speed drive (n_max > 20000 rpm). The machine was designed rather short but with a large diameter to shift the acoustic problems to the speed range where acoustically oriented control is feasible. The final design shows good driving-cycle efficiency and a maximum surface velocity of 55 dB re 1 μm s^-1. This proves that SRM is a promising alternative for automotive propulsion if the concept is elaborated carefully. This means that the configuration, the speed range and the control strategy have to be coordinated.