Efficient control of reluctance synchronous machines

This paper shows that maximum efficiency control (ME) in reluctance synchronous machines (RSM) belongs to the class of constant angle control strategies. It is also shown that for all constant angle control strategies, efficiency is constant and independent of torque (current), being only a function of speed. Results are explored by simulation comparing ME to other typical control strategies from the efficiency viewpoint. Data from a standard RSM and an ALA-RSM (axially laminated anisotropic RSM) are used. Machine limits are taken into account. The paper presents the analytical solution in dq-currents for optimum efficiency, based on a per unit (pu) loss-model. A practical ME expression within a vector control scheme is also presented