An Optimal Permanent Magnet Motor for Pumps in Electric/Hybrid Vehicles: Design and Experimentation

This paper presents the optimal design of a 1/2 HP Surface-Mounted Permanent Magnet Motor (SMPM). The motor complies with the latest department of Energy (DoE) standards for water pump applications, released in January 2020. A design procedure is performed to optimize the cogging torque and total harmonic distortion (THD), through parametric analysis. The design is executed using the ANSOFT Maxwell 3D software and proven using the lab pump test rig. The proposed design aims to produce a back-EMF close to a sinusoidal waveform, maximize the power density and reduce the cogging torque. To attain this sinusoidal back-EMF along with a reduced cogging torque, techniques like optimizing the skewing angle and modifying the windings configuration have been used. To decrease the harmonics in the back EMF, the pole pitch is calculated such that it eliminates the significant harmonics to achieve high power factor. The proposed SMPM based pump cost is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\$}$ </tex-math></inline-formula>72, which is less than the current price of the induction machine-based pump of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\$}$ </tex-math></inline-formula>113 for the same power rating. The test rig readings prove the proposed design has a better working efficiency of 2% compared to the best market pump circulators with an excellent power factor at its rated load.