Design and Analysis of a Dual Rotor Multiphase Brushless DC Motor for its Application in Electric Vehicles

The main objective of this paper is to study the effect of phase numbers in the dual rotor Brushless DC (BLDC) motor for its application in Electric Vehicles (EVs). The performance of two novel 5-, and 7-phase dual rotor BLDC motors is compared against the standard 3-phase dual rotor BLDC motor. The proposed motors combine the positive characteristics of multiphase BLDC motor and the dual rotor BLDC motor thus achieving better fault tolerance capability, high power density, and less per phase stator current. Finite Element Method (FEM) was used to design the 3-, 5-, and 7-phase dual-rotor BLDC motors. The design parameters and operating conditions are kept the same for a fair comparison. The stator current and torque performance of the proposed motors were obtained with FEM simulation and were compared with the standard 3-phase dual rotor BLDC motor. It is possible to use low power rating power electronics switches for the proposed motor. The simulation results also validate low torque ripples and high-power density in the proposed motors. Finally, the fault analysis of the designed motors shows that the fault tolerance capability increases as the phase number increases.