A Brushless Claw-Pole Double-Rotor Machine for Power-Split Hybrid Electric Vehicles

This paper investigates a claw-pole double-rotor machine (DRM) for power-split hybrid electric vehicles (HEVs). Based on the mathematical analysis of the machine, the boundary speed-torque characteristic required by the hybrid electric system is studied. To achieve high power density with acceptable torque ripple for automotive applications, the back electromotive force (EMF) and torque performance of the DRM are investigated with respect to the configurations of permanent-magnet rotor, claw-pole dimensions, and air-gap length. Based on the optimized model, characteristics of the claw-pole DRM, such as flux density, inductance, torque, core losses, and efficiency, are investigated by finite-element method. A downsized prototype machine is manufactured and tested. The experimental EMF, inductance, and torque performance agree well with simulation data. A drive cycle containing various working modes of the DRM is carried out, and the feasibility of using the machine as a power-split device for HEVs is validated.