MODELING AND TESTING OF A FRICTIONLESS LEVITATED MICROMOTOR

This paper describes a frictionless micromotor, in which an aluminium rotor is levitated, constrained laterally and rotated by electromagnet ic induction. The initial application for this motor is in a novel rot ating yaw-rate sensor. The stable levitation and torque are produced b y the use of high-frequency magnetic fields generated by a multi-pole stator coil. The results of analytic and finite-element modelling of t he static and dynamic characteristics of the motor are presented, and the factors which affect the stability of the levitation system and th e maximum speed of rotation are examined in depth, along with suggesti ons for further improvements. During initial testing the motor achieve d angular velocities in excess of 1000 rpm, with controlled levitation heights of 5-35 mu m. The motor has run for over 100 h without degrad ation, and because of the absence of friction excellent reliability is expected.