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

Abstract

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.

On the Optimal Selection of Flux Barrier Reconfiguration for a Five-Phase Permanent Magnet Assisted Synchronous Reluctance Machine for Low-Torque Ripple Application

“…These types of electric motor can be categorized into (i) surface mounted Permanent Magnet Synchronous Motor (SPMSM), (ii) Interior Mounted Permanent Magnet Synchronous Motor (IPMSM), (iii) Permanent Magnet Assisted Synchronous Reluctance Motor (PMASynRM) [6]. Among these types of PMSM, the PMASynRM has attracted a huge number of investigators to study the characteristics [6][7][8][9], apply optimization processes [10][11][12][13], and perform enhancement for different applications such as electric vehicular systems [4,[14][15][16]. Therefore, a large number of studies are devoted to introducing new branches of structural design for PMSM [4,15,[17][18][19][20][21][22].…”

“…A five-phase system can be used as the drive system in PMASynRM, which brings advantages as (i) higher torque, (ii) higher efficiency, (iii) reduction of DC-Link harmonics, and (iv) reliability [23][24][25][26][27][28][29]. Moreover, it has been investigated in [8] that while the 3-phase inverter fed Multiphase SynRM would not utilize the full capacity of kVA of the inverter, the multiphase system would provide higher usage of the inverter power. Hence, the multiphase SyncRMs bring about higher torque density and efficiency along with lower values of financial issues.…”