Production of low impurity aluminium rotor for motor efficiency enhancement

¹ International College, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand
² National Electronics and Computer Technology Center (NECTEC), National Science and Technology Development Agency (NSTDA), Klong Luang, Pathumthani 12120, Thailand
³ Faculty of Mechanical Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand
⁴ Department of Mechanical Engineering, Tokyo Institute of Technology, Tokyo, Japan
⁵ National Metal and Materials Technology Center (MTEC), National Science and Technology Development Agency (NSTDA), Klong Luang, Pathumthani 12120, Thailand

^* Corresponding author : sompongs@mtec.or.th

Abstract

Induction motors have been widely used in various electrical applications. However, their efficiency are still limited due to losses occurring during operation, especially for smaller ratings. Higher the electrical conductivity of motor rotor by lower its impurity content is one of practical and simple way to improve motor efficiency. The aim of this work is to reduce the impurity content of aluminium rotor by addition of boron in the form of Al-5wt%B master alloy and Na₂B₄O₇-NaCl-KCl flux, and then sedimention of their precipitated particles. The purer melt was then cast as rotors for single-phase induction motors. With the amount of addition of boron in aluminium melt in this work, boron in Al-5wt%B master alloy was more pronounced in removing impurities in aluminium melt than that in Na₂B₄O₇. It was found that the rotors made of aluminium melt with lower impurity contents and hence higher electrical conductivity resulted in more enhancement of motor efficiency.