Sensorless BLDC Motor Control

[Cobra_Phil]

I have read all of the Microchip application notes (AN970, AN857, etc.), and scanned most of the R/C forums for existing examples of a 3-phase, brushless, sensorless motor controller that uses BEMF (Back Electromotive Force) as the basis for commutation. But, I have yet to see an actual, working example that is designed around the PIC. Most that I have seen use Atmel controllers. I would like to find one designed for the PIC and preferably programmed in PBP. Anyone have additional info. or a link? I'm wanting to control a hard drive motor to normal rpm speeds (5400-7200rpm) with as little circuitry as possible. I have thought about using a dedicated controller such as the Toshiba TB6575FNG, but I would prefer to use a PIC if I can. This is what I am trying to accomplish.



Thanks

[George]

Why dont you just put a current regulator on it and drive it synchronously? It doesnt get loaded, so you just need to put an acceleration ramp into yr code. Add six transistors and you're done.