On 16 November 2010 16:55, Jon Elson <[email protected]> wrote: > If you don't use the Hall sensors, then the correct commutation for the > motor is undefined > until the encoder has passed the index pulse. Unless the drive has the > smarts to figure out which > winding to energize at power-up, I don't know how it can work.
You can run the motor in direct/syncronous mode looking for an index. You can even do it blind (the current bldc_sine does) but it is likely not to work well if there is any asymmetric load on the motor. The assumption is that the rotor aligns with the field, but as there is zero torque with the rotor aligned with the field this is only partially true. An offset pin in the driver could potentially compensate for this approximately, and approximately is probably good enough as the actual difference between a 90 degree phase-lead-angle and 100 or 80 degrees is fairly small. Hall-commutated motors run 60 to 120 and have a 13% torque ripple IIRC. -- atp ------------------------------------------------------------------------------ Beautiful is writing same markup. Internet Explorer 9 supports standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3. Spend less time writing and rewriting code and more time creating great experiences on the web. Be a part of the beta today http://p.sf.net/sfu/msIE9-sfdev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
