Power Drill Motors

1. Mar 14, 2013

homer5677

Hey guys,

Currently doing a task on electric motors and their uses in things. I have chosen to do power tools (specifically cordless drills) as I am aware that many have employed brushed DC motors but now use brushless technology.

Firstly, I don't know if any of you guys have done something similar to this or not as I am having trouble finding information that I need to perform calculations (ie: effciency, synchronus speed, power, torque, work, moment of inertia...etc)
I HAVE TRIED EMAILING COMPANIES TO NO AVAIL.
If you guys have any suggestions on ways of obtaining this information it would be great.

Secondly, I need to compare these two motor types to another electric motor type being one that is AC. I don't really understand how an AC motor works and anything that I have read has not made any sense to me (including 3 phase design??).
I am planning to explain why and AC motor (such as induction??) is not used in power tools and the reasons why, comparing it to what is actually used. Any insight into why this is the case would be also great!

Equations:
So far I have these but with key missing parts.

Efficiency:
μ = Poutput/Pinput (W)

Total Speed: (I know this is already listed as max rpm on websites, however i want to be able to prove this)

Srpm = 120 * F (supply frequency-cycles/sec) / P (number of winding poles)

Torque:
τ = F * D (is this the right equation for this)

And any other that you guys think would be necessary for this investigation.

Here are some links to some of the tools i am talking about.

Any input would be much appreciated.
Thanks