Differential Hall Effect Sensor Array For High Reliability Motor Commutation.
Original Publication Date: 2005-Jul-27
Included in the Prior Art Database: 2005-Jul-27
A method of providing noise immunity on hall effect sensors is provided by using diametrically placed sensors on the motor frame wiht opposing logical polarity. These signals can now be run as a differential pair and differential reciever can be used to subtract out noise common to both signals.
Differential Hall Effect Sensor Array For High Reliability Motor Commutation .
This invention works for Brushless DC motors (BLDC) which have hall sensors in them located about the stator to detect motor position.
In the past, redundant hall effect sensors have been used to improve reliability. Hall effect sensors can be placed in a multitude of locations to make this device operate properly. In the example below, three are shown, but six could be used for redundancy.
This invention improves further the benefit of redundant hall effect sensors in a BLDC motor by selecting the sensors such that half are of the "active high" type, and half are of the "active low" type.
Remember the basics of differential signaling:
For any two COMPLIMENTARY SIGNALS:
NOISE GETS SUBTRACTED OUT BECAUSE IT IS COMMON TO BOTH SIGNALS
HALL1 - HALL4