We had a long discussion with a student from SpiROSE (last year’s project with a rotative LED panel). He told us the problem they faced with the motor and ESC (Electronic Speed Controller). They could not get a constant speed output from the motor because the ESC was overheating, causing a shutdown and a boot up. It was caused by the motor asking too much current. The motor was one the had on hand and not perfectly fitted to their use. It was rated at 2100 RPM per Volt. While turning at 1500 RPM the ESC pulled 5A on 12V from the power supply, the same 60W would go to the motor, but to rotate at 1500 RPM it only needed 0.7V so the output current from the ESC was closing in on the max output, which caused overheating.
So I am looking for a motor with a lower RPM per Volts constant. I reckon a motor at around 500 RPM/V would be suitable for our project. For now I have have settled on Turnigy Aerodrive SK3 – 4250-500kv Brushless Outrunner Motor from HobbyKing.
Another problem was to convey the power through the axis. They had to scrub the anodising paint from the top of the motor to make a connexion to a ball bearing which was connected to the motor shaft. I would like if possible to stay away from passing to much power through the ball bearing as it can cause sparks and damage the balls. To replace this connection I am looking toward brush slip rings.