Originally Posted by
howardcano
That is correct, except that it is not 30 degrees of timing
advance. It is zero advance. Setting the timing to "N" on a Novak motor will make the sensor output change exactly 30 degrees (or as close as can be labeled) away from where the back-EMF on the undriven winding reaches zero (known as the "zero-crossing" point) and where the back-EMF of the energized windings is at a maximum. Other manufacturers call this the 0 degree point, because it is the place where commutation would take place on a brushed motor set at 0 degrees timing.
ESCs for sensorless motors monitor the voltage of the undriven winding for the zero-crossing point, then delay 30 degrees after it is detected before commutating to the next drive pattern for the windings. Sensored motors are designed so the sensor output changes nominally at this point, so that the software on a sensored ESC doesn't need to calculate or time this delay.
Novak calls this point 30 degrees for the reason above. They also call it "neutral", because it is the point in rotation where commutation can occur that will result in the motor having the same free-running same speed in either direction, just like on a brushed motor set at 0 degrees.
There are many sources on the internet that describe the operation of brushless motors, and explain the 30 degree delay. Here's one example:
http://www.atmel.com/Images/doc7658.pdf
See sections 2.1, 2.2, 2.3, and 3.
Are you suggesting Novak’s motor timing information is incorrect or misleading? Including this timing notice:
To adjust a Ballistic motor to 0° of physical motor timing, simply loosen the three flat head screws on the back bearing cap and rotate the cap to align the sensor harness connector with the middle solder tab as described above.
Timbuk 2 (All Versions) Motor Timing Notice
The Ballistics I have appear to be about 30 degrees advanced from this notice. Which is in agreement with other info on their site and elsewhere.
As I read it the article you originally linked explains that the back EMF zero crossing point of the coil is 30 degrees from the zero timing point. It’s the sensorless motor that requires the correction, not the sensored. I don’t see any info on timing advance of a sensored motor like a Novak. Or any discussion of advance timing.
I’ll need to take a look at your latest link at a later time.
Cheers