EFFECTS OF ASYMMETRICAL STATOR STRUCTURE ON BLDC MOTOR PERFORMANCE FOR HOUSEHOLD APPLIANCES

Abstract

Brushless direct current motors (BLDCM) have been frequently preferred in the industry, especially in home appliances, due to their advantages such as long life, high efficiency, low maintenance costs and ease of control. In addition to these advantages, the main disadvantages of these motors are known to be high torque ripple and vibration levels. In this study, alternative asymmetric designs are realized in the stator tooth structure of the BLDCM designed for home appliances, and comparative analyses of the effects of the non-uniform air gap caused by the asymmetric tooth structure on the motor performance are presented. Two different asymmetric structures, namely the model with clockwise asymmetric design (CW) and the model with counterclockwise asymmetric design (CCW) in the stator tooth structure, are determined in the stator design. With these alternative designs, improvements are made in terms of torque ripple and cogging torque when compared with the reference motor; notably, the CCW-2 model achieves the lowest ripple at 19.4% compared to 23.1% for the reference motor, and a 42% reduction in cogging torque. The design of the motor models is made in ANSYS EDT program as two dimensional (2D) and analyzed with the Finite Element Method (FEM). In the analysis results, air gap flux density, torque, torque ripple and cogging torque are examined, and the flux density and torque spectrum obtained by Fast Fourier Transform (FFT) are presented comparatively