AC Brushless Smart Position Initialization


Thread Starter

Alex Rudermanc

There was recently some discussion on AC brushless with incremental encoder position initialization. Conventional technique for AC (sinusoidal) brushless is to use Hall sensors to start as DC (trapezoidal) brushless, find zero encoder pulse (absolute position) and then switch to sinusoidal operation. In the absence of position Hall sensors, we can bring the rotor to predetermined position by feeding two motor phases. This random "magnetic alignment" rotor movement (180 el.deg. in worst case) is unacceptable for many applications hence the need for smart position initialization that eliminates long trial movement for an arbitrary rotor position. I have wrote a report about such a smart initialization (too long to be published overhere - :) ). The report comprises 5 pages of text, 4 drawings and 6 equations with the following contents: 1. Introduction 2. 3-Phase Sinusoidal Brushless Basics (Torque Generation, Current Loop etc) 3. Smart Initialization Principle 4. Rotor Movement Equation 5. Control Algorithm Convergence 6. Conclusions Contact me for details. -Alex
Hi Alex!

I am very interested in your report. Could you please send it to my e-mail asap? I am involved in similar project right now and we experience the same problem you mentioned. Thank you in advance!