Efficiency Improvement of Induction Motors with Novel Magnetic Slot Wedges

This paper introduces novel magnetic slot wedges consist of a newly developed resin-free magnetic composite material. The novel magnetic slot wedges exhibit superior magnetic and mechanical properties compared to conventional magnetic slot wedges composed of iron powder and resin. FEM analysis indicated that the efficiency improvement of a 7.5 kW 2-pole induction motor with the novel magnetic slot wedges was expected to be approximately 1.5 times higher compared to that with the conventional magnetic wedges. Installing the novel magnetic slot wedges into commercially available 7.5 kW 2-pole, 7.5 kW 4-pole, and 0.75 kW 6-pole induction motors resulted in efficiency improvements of 1.6 %, 1.1 %, and 2.8 %, respectively, at each rated output. Noticeable decreases in temperature rise were also observed. Accordingly, the novel magnetic slot wedges proved to be effective in improving the efficiency of induction motors without requiring significant design changes, such as increasing the motor size.