Motor system employing analog encoded hall effect sensor position information for reduced wiring

Abstract

A system has a sensor assembly mounted adjacent to a moving magnetic member such as a motor rotor to sense its position. The sensor assembly includes Hall-effect sensors each having a binary output, configured such that distinct positions of the moving magnetic member correspond to distinct digital patterns of the outputs of the Hall-effect sensors. Encoding circuitry is coupled to the outputs of the Hall-effect sensors to generate a multi-valued analog output, distinct values of the multi-valued analog output representing corresponding distinct digital patterns of the outputs of the Hall-effect sensors. The encoding circuitry may employ a ladder network with weighted-value resistors contributing different components of an analog current sensed by the controller. The sensed current can be converted to digital position information using suitable analog-to-digital conversion circuitry. The multi-valued analog output can be conveyed on a single wire in contrast to the prior art which requires one wire per Hall-effect sensor.