BLDC multiphase reluctance machines: A revival attempt with 2D FEM investigation and standstill tests

In an yet another effort to produce better PM-less rotor-winding-less, brushless electric motor drives, the present paper reports on preliminary work related to multiphase (m=6) high saliency rotor, dual-flat-top alternative current control BLDC reluctance machine drives. The aim is to produce high torque density, low loss/torque in a PM-less, rotor winding-less machine by full usage of machine windings and core and of inverter kVA. A new derivation of the principle of operation, essential rotary and linear machine topologies and a 2-D FEM analysis for torque density and torque pulsations on an already built (6 phase, 6 poles) - 35Nm lab prototype are made available and show promising results. Experimental flux decay tests results are shown, which, together with standstill torque measurements, validate the FEM model. Machine geometry (Axially Laminated Anisotropic Rotor) and control (rectangular current waveform) can produce important core losses, but, as the paper will show (by advanced FEM computation) in our case they don´t represent a problem. The BLDC-MRM control is dynamically simulated for the four quadrant operation, thus preparing the ground for running tests.