quantity motor cost 4

[dpenney]

I am developing a prototype for what I hope to be an OEM application that involves motion control with constant reversing and variable speed (only about 1/4HP required).

I definitely want to use an electric motor (as opposed to pnuematic, hydraulic, etc.) and it seems like a 3-phase induction motor with a regenerative VFD will be best suited for reliability (no brushes) and cost (so I thought).

But after checking some prices for off-the-shelf, they are much more than I expected. I had originally thought that given the cost of power tools (I understand these use brushed universal motors) as low as $10, I expected to be able to buy what I wanted for $30 or less. I can't find any single quantities for less than $80 and assuming that quantity buying would bring that down 25%, $60 would make my intended product too expensive...

My questions:
1) Am I in the right ball park for 3-phase induction motor costs?
2) If so, why are induction motors so much more expensive than universal motors? They both have no magnets and I understand quality insulation, etc., but 8X worth?
3) Am I missing some obvious electric motor solution that I should be considering?

Thanks,
Dan

 

[dpenney]

Hi nbucska,
It seems like a stepper motor would be more expensive than an AC induction motor?

As far as specs, the project, and myself:
I require a motor that can provide irregular variable speed and reversal for a consumer application, at 1/4HP (initially, and then up to 3HP in later versions of the product). RPM will be relatively low. Efficiency is a don't care (within reason), but my app can't tolerate a lot of heat. After my performance and reliability requirements are satisified, I need the motor to be as inexpensive as possible to be able to price the product at a reasonable level. I do not want to use hydraulics, pnuematics, or brushed motors for this app.

I am an electrical engineer who has worked in semiconductor design for the past 15 years. In the best tradition of optimistic entreprenurial spirit, I plan to complete the design and prototyping, and then begin manufacture and sales of this product by the end of the year. Since I hope to produce in quantity in 2005, I need to make the manufacturing-ready decisions now for the prototypes and put them through stringent testing. I am looking to put in the extra custom design effort vs. the convenience of more "canned" solutions in order to help bring down the cost, if such is possible. At this point, it seems like it might be: inverter power electronics plus PIC microcontrollers plus an off-the-shelf 3-phase AC induction motor seems like it will give acceptable performance and reliability, and lowest price. Up to a point, it should be worthwhile to go after the barest components for production since they have less "Value Added" priced in. But production cost analysis can be tricky as pointed out in previous posts, lots of factors to consider...

Further detail will have to wait until I'm further along.

 

[nbucska]

Dpenney:
I see some difficulties: you will need competent mechanical design and business experience. The 1/4 Hp to 3 transition
indicates that you are still in the initial phase.

If you have high quantity, you can get very low prices.
Sometimes you can by surplus for peanuts -- I know a case
when someone sold 80,000 motors; they turned in the wrong
direction...

<nbucska@pcperipherals.com>