A Comprehensive Investigation of Tangential Force and Radial Force in PM Motor

The vibroacoustic level has become a key factor for evaluating permanent magnet motor performance in recent years. However, the influence of tangential force is usually ignored, which will lead to errors in vibration noise calculation and limit the idea of reducing motor vibration noise. In this article, a comprehensive investigation of the tangential - and radial forces and their effects on the motor vibration is conducted. First, the analytical method of the electromagnetic force is presented. Next, the finite element method is applied to analyze the electromagnetic laws of radial force and tangential force. Then, the Theorem of Translation of A Force (TTF) is introduced to describe the influence of tangential force on radial vibration. After that, the influencing factors of stator teeth and load on the radial- and tangential-force are discussed, especially the phase relationship. Finally, the electromagnetic vibration law caused by radial force and tangential force is simulated and verified by experiments. The results can provide guidance for design of low vibroacoustic motor considering radial force and tangential force.