
Design Considerations
04/10/2020 at 13:41 • 0 commentsMy thoughts on the design and why it's differs from Carl's
A big drawback compared to standard brushless motors is the small amount of copper and therefore high coil resisntance. This limits the maximum power due to too high temperature. Also the efficiency gets reduced.
You can counteract that stacking several boards in parallel (so i ordered 5 of them) or reduce the number of turns in the coil and thicken the lines.
This unfortunatly increases the rpms and reduces the maximum torque. One factor on the rpm and the torque is the number of turns, another one is the number of magnetic poles. You can think of an electrical reduction. So I decided to use 12poles (which also is the number a lot of commercial brushless motor use) which is 3 times more than Carl does. For a good efficiency the ratio the number of stator arms and the number pols should be near 1. 12 poles, 12 arms is not able to run, so the next one is 9 arms. Which also has the advantage that all coil directions are the same.
The boards are already manufactured and wait for shipping. Looking forward to receive them