Optimization Design And Analysis Of A Five-phase Double-stator Permanent Magnet Synchronous Motor

Electric vehicles with advantages of energy-saving, low pollution has attracted moreand more attention of scholars, so the studies of the motors used in electric vehicles fellinto the boom. The main requirements of the drive motor for electric vehicles are hightorque density, high reliability and wide speed range. Nowadays, single-stator motor hasrestrictions on the increase of torque density, while the three-phase permanent magnetsynchronous motor can’t satisfy the demand for high reliability. Therefore, this paperdesigned a five-phase double-stator permanent magnet synchronous motor (DSPMSM),which with high torque density and high utilization rate of the space, but also achieves faulttolerance. At the same time, rotor structure, torque performance and fault tolerance of theDSPMSM are researched.Firstly, the electromagnetic structure of the five-phase DSPMSM is introduced,classifying the rotor structures according to the flux distribution. From the aspect ofinductance characteristics, flux density in air-gap and equivalent magnetic circuit, thecoupling degrees between the inner-stator and outer-stator with different rotor structures areanalyzed, summarizing the advantages and disadvantages of different rotor structures,laying foundations for rotor choice. To achieve high-precision control of the five-phaseDSPMSM, mathematical models of the DSPMSM which can reflect the relationship ofelectromagnetic and electromechanical are established.Then, for the rotor structure design, the rotor with single-or double-layer PMs inseries magnetic circuit are analyzed. This paper presents a novel rotor structure based onthe conventional rotors. The novel rotor structure has a strong superiority in terms ofelectromagnetic properties than the traditional rotor with single-layer PMs, and has greatertorque density than the rotor with double-layer PMs.Furthermore, analysis the torque characteristics of the five-phase DSPMSM with fewphases open-circuit under different connections, gaining that the five-phase DSPMSM inthe events of one or two-phase open-circuit, as long as adopt reasonable remedial measures,the motor can continue running smoothly without stopping，certificating the five-phaseDSPMSM designed in the paper has a strong fault tolerance. Comparing with five-phasesingle-stator PMSM and three-phase DSPMSM, proving that the five-phase DSPMSM withhigher torque density and reliability. Finally, the no-load back EMF tend to be flat wave when the DSPMSM adoptingsurface-mounted rotor, reducing the control accuracy of the motor. To optimize the EMF,adopting methods of changing the pole embrace, eccentric, roounded angle and polesegmented approach, reducing the voltage distortion.