An Outer-Rotor L-Shaped Modular Consequent Pole Permanent Magnet Machine for In-Wheel Electric Bike Propulsion

Electric bikes (e-bikes) have become increasingly popular as a sustainable option of transportation in megacities, effectively tackling issues such as pollution and traffic congestion. However, a significant gap still exists between the manufacturing cost and the electrical motor performance in e-bikes. Thus, this article proposes a new outer rotor unequal pole L-shaped modular consequent pole (UPLM-CPM) machine with an N-I and I-S pole configuration as an in-wheel e-bike propulsion. The proposed machine incorporates a modular consequent-pole permanent magnet (CPM) rotor to provide a strong flux-focusing effect and a high PM utilization ratio. It also utilizes an L-shaped rotor with an unequal pole structure to improve electromagnetic characteristics, such as back electro-motive force (EMF) voltage, torque ripple, and cogging torque. Besides, both PM polarities are utilized in N-I and I-S sequences to suppress leakage flux. First, a parametric analysis is conducted on the L-shaped rotor parameters to explore the best combination. Then, the proposed machine, an L-shaped modular CPM (LM-CPM1) machine, the LM-CPM1 with both PM polarities (LM-CPM2), and a modular surface-mounted PM (M-SMPM) machine are compared by the finite element analysis (FEAs) in terms of torque characteristics, no-load characteristics, and leakage flux. Finally, the proposed e-bike propulsion is fabricated and tested to verify simulation results.