A Self-Bearing 8/6 Switched Reluctance Motor

This paper describes a self-bearing 8/6 switched reluctance motor (SRM). The main challenge with such a motor is how to control both torque and radial forces. This task is particularly challenging because the double saliency of the machine type causes the characteristics of the motor to be highly nonlinear. In this paper, we first present a switching logic for the 8 stator coils. The current in the 8 phases is defined by using three current components and the rotor angle. After that, we propose a model that could be used in the closed loop control to solve the required stator currents from needed radial forces and torque. The force and torque models are based on first and second order polynomials, which are fitted to data that have been obtained by two-dimensional electromagnetic finite element analysis. In this paper we compare the performance of the analytical model with the finite element analysis data, and use the analytical model for direct open loop control. The results show that the proposed analytical model can be used to calculate the required stator currents that are needed to operate the self-bearing SRM. The models can be combined with closed loop control methods in order to properly control the machine.