Testing and modeling of variable airgap axial flux brushless DC motor

This paper describes the performance characterization and modeling of New Generation Motors Corporation (NGM) axial flux brushless dc motors (BDCMs) The NGM Solar Car Motor (SCM-150) was tested at different airgaps using a computer-controlled servo with position feedback. Based on the test results, an operational map was developed as a function of speed and torque range of the motor. The experimental results demonstrated that a highly efficient (>90%) operation for the entire operating envelop of the motor is possible with dynamic gap control. Detailed discussion of the test results, empirical relations between the main operating parameters of axial flux BDCM (torque, speed, airgap) and the resulting output (power output, maximum torque, power loss, maximum speed, efficiency) are described in this paper. A scalable model for the motor performance using variable airgap was developed and included in the ADVISOR model to simulate hybrid-electric sedan meeting PNGV goals.