Regenerative Motor Controller Power Supplies

xanadu

I've read (below) that you shouldn't power a regenerative motor controller using a run of the mill bench top supply, especially a switching power supply. It's funny because I've owned a lot of motor controllers and have yet to read anything in bold print on the first page that says don't do it. Nor have I had any go bad, but I think that all of my motors are geared so low they don't regen enough to cause a problem..

So what is it safe to use? I'm assuming that a lead acid battery would love to be hooked up to a regen controller, but what about lipos?

This is a great article, http://www.roboteq.com/index.php/applications/how-to/160-understanding-regeneration

No mention of battery chemistry though.

Zoot

I would not hook up motors through a regenerative driver to a bench supply unless it has reverse polarity protection (and maybe not even then).

Re: chemistry -- a lot of regen. drivers have settings for the battery chemistry, particlarly Li based batteries that need to have the driver shut down depending on discharge. E.G.

http://www.lynxmotion.com/p-623-sabertooth-2x25-regenerative-dual-channel-motor-controller.aspx

which has settings for Li, NiCd, SLA.

If the driver is not set up for Li, you may not want to use it, unless you have another way of monitoring battery charge, current flow into the battery from the regen. driver, etc.

xanadu

Yeah I could see how a fully charged lipo would not want to be charged by regenerative controllers. The conditions would have to be pretty rare though, fully charged lipo and a robot rolling down a hill pretty quick.

I also wonder if ramping creates more re-gen or less?

What about connecting a DC motor directly to a bench supply? If you turned the power down quickly it would re-gen back into the supply as well right?

Maybe I just need a way to monitor the power wires from the motor more closely to see each scenario. The gear motor is so tight I think with ramping the re-gen would be very minimal and should be okay with a lipo.

Zoot

Regenerative drivers do not just produce power back to the supply when "coasting" or rolling. If the PWM duty cycle is <100% (almost always is), then there is always electricity being generated and captured back to the supply during the *off* portion of the PWM pulse cycle. The motor is still turning, "coasting" between the off part of the pulse. Practically, of course, this amount of regenerative juice will often be negligible, but it's there. In that sense, "ramping" would theoretically get you more regen, as you've got more "off time" while you get up to speed; not sure you would see the difference practically.

I can't speak (technically) to other issues related to brushed motor field collapse and regenerative charging.

BTW, why do you need to run this from a bench supply?

Last but not least, why not contact the manufacturer and get some guidelines about running from bench supplies, settings for battery chemistry, etc.

xanadu

All good points, thanks.

I have contacted two different manufacturer's and they both say that lead acid is the only safe bet for both controllers.

I do not need to use a bench power supply. It is nice to use for testing because I can control volts and read amps easily.