The impact of demagnetization on the feasibility of permanent magnet synchronous motors in industry applications

Permanent magnet (PM) motors are rapidly replacing the dominant induction motors in industrial applications including pumps, fans, and compressors. PM motors are also gaining ground in critical sustainable energy applications such as wind systems, photovoltaic pumping systems and electric vehicles. Compared to induction motors, PM have higher efficiency. In this paper, the financial feasibility of replacing induction motors by PM motors at various operating conditions was analyzed on a preliminary basis. The impact of partial demagnetization and full loss of excitation on the feasibility of the replacement was also preliminarily investigated. It is found that the feasibility of replacement was less sensitive to reduction in the life time of PM motors than reduction in efficiency due to partial demagnetization. While detailed and lengthy studies are planned in the future, investigation outcomes suggest that the replacement remains feasible despite risks of demagnetization when utilization rates are above 50%. Details of the investigation are reported in the paper.