~75 Watt brushless motor source? Drivers?

[Guanton75]

I need an inexpensive brushless motor which will probably need a gear head. I need approximately 32 in-lb max, 10 in-lb continuous. If we can get that in a motor no larger then 3" without a gear head that would be great but... We are running on 12 Volts. Our volume is around 200 units/year. We are currently a bit beyond what Pitmann gear heads can offer.

I would also appreciate any info on a driver which uses 3, 50/50 signals for sinusoidal commutation (3 H-bridge halves with 50/50 signal).

Thanks,
Seth

 

[SERVOCAM]

Last time I posted to this post, it did not go, so I'm typing it again.

When you say 3", are you saying 3 inch length or diameter? What is your speed requrirements cause 12 VDC won't get you very far unless the motor is wound to have a high Ke, but then we better have a ton of current.

If you want to use a brushless DC servo, you will have problems fitting it in 3" long space for those trq requirements. You will probably need to use a pancake motor such as these:

http://www.danahermcg.com/prod/prod.asp?sgid=56

When you say:
"I would also appreciate any info on a driver which uses 3, 50/50 signals for sinusoidal commutation (3 H-bridge halves with 50/50 signal)."

I am thinking that you are refering to what we call Dual-Phase command input on a servo amp. It is where we have (2) +/- 10VDC analog command signals to a servo amp to do external commutation via the controller. This is how our BA amps are.

When you say your looking for a brushless motor, what type of brushless motor are you looking for? I know there are several types, so if it is not related to Servo/Stepper, sorry I won't be much help. :-(

Cameron Anderson - Sales & Applications Engineer
Aerotech, Inc. -

http://www.aerotech.com

"Dedicated to the Science of Motion"

 

[Guanton75]

Thanks ServoCam for reposting, I meant 3" diameter (or square) and about 5" length. My speed needs to be around 150 rpm. This is why I see a gearhead in my future. By brushless I mean 3-phase.

Regarding the driver, the EE guy here has set up a controller that outputs 3 PWM signals, one for each phase of the motor. A 50% PWM signal needs to result in an uncharged coil, 0% PWM results in fully charged coil and a 100% PWM results in a fully charged coil with inverted polarity. Apparently this is pretty common for fully integrated systems. I don't expect to get this off the shelf but it's worth a try. Eventually we will be make all our own hardware...

Thanks again!
Seth

 

[powertronc]

There are several different types of motors and control approaches that could be used to meet your requirements depending on your cost target for 200 systems (system = motor + control). If you tell me a short summary of your system design requirements and system cost target maybe I can help.

 

[Guanton75]

We are driving a mobile base which uses a differential drive to steer. For this reason it's important that the controllers be able to talk with one another to coordinate turns. I guess this is typically accomplished through electronic gearing. The system we currently using uses brush motors, our H-bridge driver, our micro controller to coordinate and encoder feed back. We are looking to improve performance (mainly efficiency and rpm), reduce cost (as always), replace our existing code and increase reliability. Our current system cost us around $260 per unit which includes 2 H-bridges and 2 gear motors with encoder. We will need to keep the micro controller for other reasons. Again, 10 in-lb continuous, 32 in-lb max, 150 RPM max, 3" diameter or square, 5" long, must have encoder, and 12 volts are our minimum requirements.

Thanks again,
Seth

 

[jbartos]

Suggestion: Visit

http://www.thomasregister.com

and type Motors: Brushless DC under Product or Service, which will return 189 companies to inquire about your specific motor needs

 

[powertronc]

Since you need to coordinate two motor systems, and with your existing system cost target, you might consider using a stepper motor.