Design and rotor shape modification of a multiphase high speed permanent magnet assisted synchronous reluctance motor for stress reduction

This paper presents the design and a novel rotor shape of a 3 kW, 25000 rpm permanent magnet assisted synchronous reluctance motor (PMa-SynRM) based on a low speed benchmark model. Multiphase PMa-SynRM can operate with low torque ripple, reduced magnet volume and extended field weakening region which makes it a potential candidate for high speed motor design. However, the challenge of high speed PMa-SynRM design lies in the mechanical stress developed in the rotor which makes it completely different from operating it at low speed region. To manage the stress in high speed design, stress equation has been developed for PMa-SynRM and included in the objective function (OF) along with other parameters. For high speed design, a low speed benchmark model of 3 kW, 1800 rpm, 5 phase PMa-SynRM has been considered as a benchmark model. With lumped parameter model (LPM) and differential evolution strategy (DES), initial design of high speed PMa-SynRM was developed. High speed design showed reduced torque ripple and cogging torque compared with low speed model in finite element analysis (FEA). To understand the impact of including stress in the design objective function, stress analysis has been done for two high speed PMa-SynRM models; one with stress included in OF and another without stress in OF. From simulation, it was observed that, in the design including stress in objective function, stress has been reduced by 30.14%. To reduce stress further, mini flux barrier (FB) has been added in the rotor without affecting reluctance torque. Again, with DES, dimension of min FB has been optimized. Simulation results showed 15.73% improvement in stress by adding the optimized mini flux barrier.

[1]  Thomas M. Jahns,et al.  A saturating lumped-parameter model for an interior PM synchronous machine , 2002 .

[2]  Thomas M. Jahns,et al.  Mechanical design considerations for conventionally laminated, high-speed, interior PM synchronous machine rotors , 2004 .

[3]  H.A. Toliyat,et al.  Online Parameter Estimation of Permanent-Magnet Assisted Synchronous Reluctance Motor , 2007, IEEE Transactions on Industry Applications.

[4]  Kay Hameyer,et al.  Rotor design of a high-speed Permanent Magnet Synchronous Machine rating 100,000 rpm at 10kW , 2010, 2010 IEEE Energy Conversion Congress and Exposition.

[5]  Ju Lee,et al.  Design to reduce the cost and to improve the mechanical durability of IPMSM for the traction motor of military truck , 2012, 2012 IEEE Vehicle Power and Propulsion Conference.

[6]  K. Yamazaki,et al.  Optimization of High-Speed Motors Considering Centrifugal Force and Core Loss Using Combination of Stress and Electromagnetic Field Analyses , 2013, IEEE Transactions on Magnetics.

[7]  Won-Ho Kim A Stress Analysis Method for the Rotor Design of an IPMSM Considering Radial Force , 2014 .

[8]  Sai Sudheer Reddy Bonthu,et al.  Optimal design of five-phase permanent magnet assisted synchronous reluctance motor for low output torque ripple , 2014, 2014 IEEE Energy Conversion Congress and Exposition (ECCE).

[9]  Alessandro Vigliani,et al.  Electrical Machines for High-Speed Applications: Design Considerations and Tradeoffs , 2014, IEEE Transactions on Industrial Electronics.

[10]  Dong-Min Kim,et al.  Multipolar High-Speed IPMSM Design for EV Traction Considering Mechanical Stress , 2016, 2016 IEEE 84th Vehicular Technology Conference (VTC-Fall).

[11]  Fengge Zhang,et al.  Design and analysis of 100kW high speed permanent magnet synchronous motor , 2016, 2016 IEEE Transportation Electrification Conference and Expo, Asia-Pacific (ITEC Asia-Pacific).