Design and research of deep slot universal motor for electric power tools

Abstract

In this paper, a deep slot universal motor is designed for electric power tools. The deep slot structure can reduce the cost of universal motor materials and improve production efficiency. A mathematical model of a universal motor is established and a simulation model is established by MagNet finite element software. Then, the static magnetic field distribution and load characteristics of the deep slot universal motor are analyzed. Different methods are adopted to improve the commutation spark of a deep slot universal motor. Finally, three 550-W and 9500-rpm prototype motors are tested. Simulation and experimental results indicate that an uneven air gap, brush offset by a certain angle, as well as different turns of the lead coil and the lag coil can effectively improve the commutation spark of a deep slot universal motor.