A Novel DC Motor Based on Mechanical–Electrical Hybrid Commutation

Abstract

The mechanical commutator of a brushed dc motor can arc, while the electronic commutator of a brushless DC (BLDC) motor is costly and complex. Therefore, this paper presents a novel arcless dc motor based on mechanical-electrical hybrid commutation. The hybrid dc motor is similar to a BLDC motor in that it has permanent magnets and three-phase windings. However, the permanent magnets are on the stator, and the windings are on the rotor. The mechanical component of the hybrid commutating device, which consists of a mechanical commutator and three brushes, is used to generate three square waves with a phase difference of 120°. The electronic component is a freewheeling circuit that consists of a capacitor and four diodes; this component is able to suppress arcing caused by the mechanical component. Simulations and experimental results show that arcing does not occur during the freewheeling process. Moreover, the hybrid dc motor is simple in structure, high in efficiency, and low in cost, and its control is as convenient as that of a brushed dc motor.