Study on energy ratio of switched reluctance motor drive based on open loop, CCC and DITC

The purpose of this paper is to investigate a parameter-energy ratio (ER) to assess the `quality' of a switched reluctance motor drive (SRD). Definition and mathematical expression are shown firstly based on the energy conversion theory of electrical machineries. It is compared and analyzed that the effect on energy conversion caused by freewheeling current state in asymmetric half-bridge power converter. According to simulations of ψ-i trajectory on a SRM with 3-phase and 6/4 poles, the influential factors are then discussed by calculating the ERs of three different control strategies-open loop, current chopping control (CCC) and direct instantaneous torque control (DITC). An experimental platform is finally developed and the measured results show a tolerable agreement with simulations, which accounts for that the returnable state when two switches of a phase are turned off and a longer conduction time will reduce ER.