I've been trying to build a sensorless brushless speed controller using some mosfets and an arduino, and I've been able to run the motor 'blindly' using a preset delay. My problem is, I don't quite know how to switch over to a closed loop control using the back EMF from the undriven coil of the motor - does anybody have an idea as to how I might go about writing an algorithm for this?
I've been following this guide, but it doesn't have any source code: http://www.digikey.com/en-US/articles/techzone/2013/jun/controlling-sensorless-bldc-motors-via-back-emf
When I connect the comparator to the undriven coil and print out its reading to the serial monitor, I get a pattern of alternating 1s and 0s(10101010101010...) - is this the expected signal? How would I use this to decide when to commutate the motor?
Thanks in advance for any help!