Brushless d.c. motor with improved rotor magnet position sensing

Abstract

A brushless D.C. motor has a rotor with a plurality of magnets secured to a mounting surface. Each magnet has an RF transmitter secured to a magnet surface, with each RF transmitter having stored therein a unique identification character serving to identify the magnet. A transmitter power generator having several coils mounted on the rotor and a power conditioning unit supplies power to the transmitters, which continuously broadcast their identification character. A stator has a plurality of pole teeth separated by slots, each pole tooth having a power coil wound thereabout. A plurality of RF receiver antennae are mounted adjacent the pole teeth each coupled to a different RF receiver. The position and magnet identification information received by the RF receiver is processed and coupled to a microprocessor, which extracts the information and sends it to a motor controller and driver unit, which supplies operating power to the individual power coils.