Analysis and Calculation of Radial Electromagnetic Force of Circular Winding Brushless DC Motor.

The circular winding brushless direct current (CWBLDC) motor is a special type of multiphase permanent magnet motors with nonsinusoidal electromotive forces and circularly connected phase windings. The motor does not rely on conventional pulsewidth-modulation inverters and has high torque density and low torque ripple, making it a promising choice for high-power and high-performance applications, such as marine propulsions. This paper studies the radial electromagnetic force of CWBLDC motors. The effect of slot-pole combinations on harmonic contents of the radial force density is analytically derived. Moreover, two computationally efficient numerical methods to calculate the radial electromagnetic force density distribution are proposed based on the space-time symmetry of CWBLDC motors and the superposition principle of the magnetic field, respectively. In order to validate the analysis, vibration testing of a 10-kW CWBLDC prototype is performed. [ABSTRACT FROM AUTHOR]