2 BLDC motors on one shaft with the same drive?

Hey guys,

I’m new to this site, and am a university student studying Electrical and Electronics engineering. I just completed a design project controlling a BLDC motor (pretty low powered at 60V, and giving output rpm of about 6000rpm). Now I had an idea where instead of using a single BLDCM for an application, would it make sense to put two identical BLDCMs on the same shaft, in order to give double the output torque? I would operate the two using the same drive as I would use for one, but I’m still unsure of how to take into account a lot of my efficiency calculations. I have a feeling that this would just draw double the power (if not, then only provide half the output power to each motor).

Please help me out. I need some answers ASAP for an important project.

Cheers

[QUOTE=Raag90;8889]Hey guys,

I’m new to this site, and am a university student studying Electrical and Electronics engineering. I just completed a design project controlling a BLDC motor (pretty low powered at 60V, and giving output rpm of about 6000rpm). Now I had an idea where instead of using a single BLDCM for an application, would it make sense to put two identical BLDCMs on the same shaft, in order to give double the output torque? I would operate the two using the same drive as I would use for one, but I’m still unsure of how to take into account a lot of my efficiency calculations. I have a feeling that this would just draw double the power (if not, then only provide half the output power to each motor).

Please help me out. I need some answers ASAP for an important project.

Cheers[/QUOTE]

I should qualify my knowledge on Electric motors before I spout out answers: I have been working with EVs for a couple years, worked for electric vehicle companies, read some books, build a few EVs and once ran two motors off of one controller in parallel. I am certainly not the most experienced, but this should help: Two motors on the same shaft would double mechanical and electrical resistance, though (depending on how you do this) the current would be shared over a larger surface area, possibly allowing each motor to remain cooler. All parts of the system should match in terms of thermal ratings and total power output and/or there should be over-current, voltage, heat and speed protection in place.
Using two motors might make sense in some situations, though it will add complexity and cost that you can avoid by just using one motor that carries the ratings appropriate for your design.
Adding a second motor also adds another failure point to your system.
That’s about all I can think of for now.