Design of a Bi-Harmonic 7-Phase PM Machine With Tooth-Concentrated Winding

Abstract

If multi-phase machines equipped with toothconcentrated winding with half a slot per pole and per phase offer interesting characteristics (simplified manufacturing, no space subharmonic, fault-tolerant ability), their low fundamental winding factors make their designs and controls challenging. The paper addresses the case of a seven-phase Surface-mounted Permanent Magnet (SPM) machine which has a fundamental winding factor lower than the third. This so-called bi-harmonic specificity is considered in order to achieve good torque quality (average value and ripples). Regarding the design, the magnet layer is segmented into two identical radially magnetized tiles that cover about three-quarters the pole arc. Regarding the control, the rated Maximum Torque Per Ampere (MTPA) supply strategy (h1h3 control) aims at generating a third harmonic current component greater than the fundamental. A prototype has been manufactured: the ability of the machine to provide smooth torque is experimentally confirmed through the implementation of a simple MTPA control which copes with high distortion in no-load voltage.

A Review of Torque Ripple Reduction Design Methods for Radial Flux PM Motors

“…To prevent undesired back EMF harmonics, winding methods have been developed and tested in [22,34,[44][45][46][47][48][49][50][51][52][53]. For example, ref.…”

Optimized Torque Performance of a 7-Phase Outer-Rotor Surface-Mounted Permanent Magnet Synchronous Machine for In-Wheel E-Motorcycle Application

“…Optimizing the dimension of PMs and slot entrance designs, along with an optimal selection of slot/pole combinations for OR-SPMSM, has a high impact on the slotting effect and air-gap flux density of the machine and hence effectively results in the cogging torque reduction. In addition, with the advent of power electronic converters, the multiphase drive system, with advantages such as reduction of torque pulsation and providing higher torque pulsation frequencies, can apply to electric motor drive systems [19][20][21][22][23][24][25][26]. Marmaras et al [3] studied the behavior of the EV drivers and their impact on electricity and transport electrification systems.…”

“…Refs. [23,25] addresses the design of a 7-P SPMSM with tooth-concentrated winding using a maximum torque per ampere (MTPA) control strategy. Scuiller [23] focused on the design of two radially magnetized PMs to reduce torque ripple.…”

“…In addition, by injecting the fifth harmonic current, the produced torque can develop without increasing torque fluctuations. While Scuiller et al [25] investigated the simplicity and fault-tolerant ability of a 7-phase SPMSM.…”

Fractional-Slot PMSMs With One Coil Parallel Branches Made Phases—Part I: Investigation Study

“…In [19], Fan et al developed an approach to minimize the torque ripple caused by inter-turn short-circuit faults of a single-layer 20slot IPM 18-pole 5-phase FSPMSM dedicated to electric vehicle application. In [20], Scuiller et al treated the design and control of a seven-phase FSPMSM characterized by two fundamental harmonics. The so-called bi-harmonic design has been considered in an attempt to achieve a high torque density.…”