Minimization of AC Copper Loss in Permanent Magnet Machines by Transposed Coil Connection

With the increasing demand for high power density and high-speed electrical machines, ac copper loss issue becomes more severe and poses a significant challenge for machine design. This article proposes a suppression technique by transposing the coil connection in the same branch to balance the inductances of parallel strands, thus reducing the circulating current ac loss. Compared to the commonly used transposition method implemented within one coil (e.g., Litz wire), the proposed method can be beneficial to reduce the transposition points and have no influence on the slot filling factor. The proposed idea is investigated by the field-circuit coupled finite element analysis (FEA), taking the bundle-level circulating current into account. It shows that the copper loss can be reduced by 17% compared to the nontransposed one at 400 Hz for a studied 12-slot 10-pole permanent magnet machine. The influence of winding layout and slot/pole combination on the effectiveness of the proposed transposition method is also investigated. Finally, experiments are implemented on a designed test-rig to validate the FEA method and the effectiveness of the new transposition.

[1]  Jung-Pyo Hong,et al.  Investigation of AC Resistance on Winding Conductors in Slot According to Strands Configuration , 2021, IEEE Transactions on Industry Applications.

[2]  Kan Zhou,et al.  Computationally Efficient AC Resistance Model for Stator Winding With Rectangular Conductors , 2020, IEEE Transactions on Magnetics.

[3]  Md Nazmul Islam,et al.  Asymmetric Bar Winding for High-Speed Traction Electric Machines , 2020, IEEE Transactions on Transportation Electrification.

[4]  Yanping Liang,et al.  A New Global Transposition Method of Stator Winding and Its Loss Calculation in AC Machines , 2020, IEEE Transactions on Energy Conversion.

[5]  Andy Yoon,et al.  Impact of Manufacturing Tolerances on a Low-Reactance Slotless PM Synchronous Machine , 2020, IEEE Transactions on Energy Conversion.

[6]  C. Gerada,et al.  Reduction of Winding AC Losses by Accurate Conductor Placement in High Frequency Electrical Machines , 2020, IEEE Transactions on Industry Applications.

[7]  R. Qu,et al.  Minimization of AC Losses in Permanent Magnet Machines by Transposed Coil Connection , 2019, 2019 IEEE Energy Conversion Congress and Exposition (ECCE).

[8]  P. H. Mellor,et al.  Additive Manufacturing of Shaped Profile Windings for Minimal AC Loss in Electrical Machines , 2018, 2018 IEEE Energy Conversion Congress and Exposition (ECCE).

[9]  D. Gerling,et al.  Influence of the Modeling Depth and Voltage Level on the AC Losses in Parallel Conductors of a Permanent Magnet Synchronous Machine , 2018, IEEE Transactions on Applied Superconductivity.

[10]  Chris Gerada,et al.  Considerations on the Effects That Core Material Machining Has on an Electrical Machine's Performance , 2018, IEEE Transactions on Energy Conversion.

[11]  Y. C. Chong,et al.  Electrical Vehicles—Practical Solutions for Power Traction Motor Systems , 2018, IEEE transactions on industry applications.

[12]  Ronghai Qu,et al.  Effect of AC losses on temperature rise distribution in concentrated windings of permanent magnet synchronous machines with parallel strands , 2017, 2017 20th International Conference on Electrical Machines and Systems (ICEMS).

[13]  Ronghai Qu,et al.  Comparative thermal analysis of IPMSMs with integral-slot distributed-winding (ISDW) and fractional-slot concentrated-winding (FSCW) for electric vehicle application , 2017, 2017 IEEE International Electric Machines and Drives Conference (IEMDC).

[14]  Rafal Wrobel,et al.  Design of a Brushless PM Starter Generator for Low-Cost Manufacture and a High-Aspect-Ratio Mechanical Space Envelope , 2015, IEEE Transactions on Industry Applications.

[15]  Antero Arkkio,et al.  Efficient Finite-Element Computation of Circulating Currents in Thin Parallel Strands , 2016, IEEE Transactions on Magnetics.

[16]  B. Silwal,et al.  Efficiency of an Electrical Machine in Electric Vehicle Application , 2016 .

[17]  Yanping Liang,et al.  Circuit Network Model of Stator Transposition Bar in Large Generators and Calculation of Circulating Current , 2015, IEEE Transactions on Industrial Electronics.

[18]  Francesco Cupertino,et al.  Minimization of proximity losses in electrical machines with tooth-wound coils , 2014, 2014 IEEE Energy Conversion Congress and Exposition (ECCE).

[19]  Jan A. Ferreira,et al.  Current Sharing Analysis of Parallel Strands in Low-Voltage High-Speed Machines , 2014, IEEE Transactions on Industrial Electronics.

[20]  Antonio Griffo,et al.  Derivation and Scaling of AC Copper Loss in Thermal Modeling of Electrical Machines , 2014, IEEE Transactions on Industrial Electronics.

[21]  Janne Nerg,et al.  AC Resistance Factor of Litz-Wire Windings Used in Low-Voltage High-Power Generators , 2014, IEEE Transactions on Industrial Electronics.

[22]  Phil Mellor,et al.  Experimental and analytical determination of proximity losses in a high-speed PM machine , 2013, 2013 IEEE Energy Conversion Congress and Exposition.

[23]  D. Hawkins,et al.  Analytical Model of Eddy Current Loss in Windings of Permanent-Magnet Machines Accounting for Load , 2012, IEEE Transactions on Magnetics.

[24]  Theodore. P. Bohn,et al.  Transposition effects on bundle proximity losses in high-speed PM machines , 2009, 2009 IEEE Energy Conversion Congress and Exposition.

[25]  M. Albach,et al.  Optimized Winding Layout for Minimized Proximity Losses in Coils With Rod Cores , 2008, IEEE Transactions on Magnetics.