lerneaen_hydra
100 µW
- Joined
- Apr 8, 2019
- Messages
- 8
Hey all, this is just a quick sanity check to make sure that I haven't made some obvious mistake. I have a 12090 140kv outrunner (28-poles) I am planning to use for an electric outboard rebuild. What I've found so far (that I didn't expect) is:
- Running unloaded at a pack voltage of 40V (giving a speed of ~6500 rpm) draws around 25A. This gives ~1kW of no-load losses. This is very noticable in that after about 20 seconds the entire motor is heated to around 70 degrees, despite a very powerful cooling fan.
- The measured phase-phase inductance is only 1.5uH. This seems very low, I had expected at least 10uH (and maybe even more). I can only assume that the ripple current must be extremely large, especially at full speed when the high-side FET is kept on continuously.
Is there any obvious conclusion that can be drawn here? Is the motor defective (wound incorrectly)? Am I making some other trivial mistake?
- Running unloaded at a pack voltage of 40V (giving a speed of ~6500 rpm) draws around 25A. This gives ~1kW of no-load losses. This is very noticable in that after about 20 seconds the entire motor is heated to around 70 degrees, despite a very powerful cooling fan.
- The measured phase-phase inductance is only 1.5uH. This seems very low, I had expected at least 10uH (and maybe even more). I can only assume that the ripple current must be extremely large, especially at full speed when the high-side FET is kept on continuously.
Is there any obvious conclusion that can be drawn here? Is the motor defective (wound incorrectly)? Am I making some other trivial mistake?