External-rotor 6–10 switched reluctance motor for an electric bicycle

As a cost-effective, healthy, and environmentally friendly personal mode of transportation, electric bicycles (E-bikes) are gaining an increasing market share from conventional bicycles and automobiles in urban communities. At the same time, the simple structure, high torque and power density, as well as low cost of switched reluctance machines (SRM) make them a strong candidate for E-bikes. This paper presents a 3-phase, external-rotor SRM with 6 stator poles and 10 rotor poles (6-10), designed for an E-bike application. The SRM design and simulation is initiated by evaluation of the bicycle kinematics. Analytic estimates are used to determine machine main dimensions and output power equation, followed by comprehensive finite element analysis (FEA). A torque ripple reduction control is presented and detailed thermal analysis conducted to improve the design.