Newbie
Joined: 07/10/2005
Location: AustraliaPosts: 34
| Posted: 08:14am 20 Oct 2005 |
Hi Chris, I like your idea, would be great fun!
Your plan to use model BLDC controllers might be a problem though.
I used to race RC cars and currently build and fly BLDC powered RC aircraft and know that a basic model BLDC controller will not handle the power's your thinking of using. They mightl for short bursts, but not continuously.
The model controllers are very very very optimistic in their claimed power ratings.
There is however, a sensorless BLDC controller that one company(I think it was Schulze? I can't find the magazine I saw it in) was prototyping a few years ago, it handles model aircraft BLDC motors up to 5kW. Should be in production by now.
These controllers all need a servo signal for control, which is a 1.0ms to 2.0ms PWM signal.
Gizmo: I designed a BLDC controller a long time ago, but never finished it due to the Chinese imports being as cheap as they are. I never had any problems with back-emf popping the mosfets though, did you use Flyback diodes? The integral ones sometimes aren't very good.
Maybe I was just lucky with my choice of Mosfet?
Oh yeah, It's also very very important that a small pause is used between phase change switching. It's very easy to have a direct short between the two rails if the mosfet's are not switching off fast enough, then a high side and low side transistor for one phase could both be conducting and .... ffzzzzt!.
Anyway, Just a thought.