easy high voltage DC motor control?

henry99

I'm trying to find an easy way to control some motors in the 45V range but low current (<1amp).·Most motor controllers I've seen use

In the propeller object exchange, there are objects for the LMD18201 and the L298 chips.· The L298 is a lot cheaper but seems to require quite a few more external components (diodes, etc).· Even the LMD18201 requires quite a few resistors and caps.· I found the following products and was wondering if anyone has used them:

http://www.anykits.com/catalog/product_info.php?cPath=46_70&products_id=244

http://www.anykits.com/catalog/product_info.php?cPath=46_70&products_id=436

Both seem reasonably priced and have screw headers + .100 header so are perfect for my application for interfacing to the prop.· With the prop objects, I would assume I could interface very easily.·

What is the advantage of the L298 vs the LMD18201?· It seems the L298 costs around $3 and the LMD costs around $15.

I am nervous about the L298 anykit part because Solarbotics offers something similar: http://www.solarbotics.com/products/k_cmd/

However when you read the data sheet here: http://www.solarbotics.com/assets/datasheets/solarbotics_l298_compact_motor_driver_kit.pdf
It says 6 to 26V operation·because the 1n5818 diodes and the LM2937 limit the upper range.

I wonder if the any kits is able to take the full 50V.

Does anyone else know of something similar to the any kits/modules but available in the US?· It seems they are in the UK or India and shipping is expensive.

Thanks in advance.


·

Timmoore

I have used the L298 and the solarbotics kit. The only problem I had was the pwm frequency I could use was a lot lower than the data sheet suggested. I haven't tried it at the same voltages you want to use though. Looking at the anykits it looks like the probelms areas could be the diodes and caps. You could get the kit and check the voltage specs for the diodes/caps and upgrade them if needed before putting the kit together. Simialr for the solarbotics kit, the lm2937 is used as a 5V regular, if you dont need it then you could leave it out and then you only have to upgrade the diodes.
How many motors do you need to drive? If I remember correctly the l298 object on obex takes a cog per motor. If you are interested I have an object that will drive up to 8 motors with 1 cog.

kevin101

Why not build a simple h-Bridge? You can tailor it to your own voltage and current limits, and it gives you control of the direction, speed, and braking of the motor. Adding a tachometer makes it even better. If you use mosfets as the gates, don't forget the diodes.

en.wikipedia.org/wiki/H-bridge

Hope this helps.

Kevin

henry99

The LMD18200 may be a lot faster and seems to be the standard in many applications. Maybe that's the price difference. The L298 is tempting because it has two motor drivers at a lower price than 1 driver on the LMD18200.

I want to use the motor in a PID loop with optical encoder. With the current PID and quad encoder objects, this seems very easy.

I've used stepper motors in the past but I'd like to move to DC servos instead.

Also, I'm not sure why all industrial applications always use a high voltage like 45V or 60V for small DC motors but hobby projects always use something 12V or 24V.

Eventually I'll just build the LMD18200 circuit into my finish design but I'm experimenting with my prop board + bread board so it is a big hassle when there are a lot of discrete components.