Hi all
I have two 12v dc motors and just want to find out what would be the best motor drive for them?
Please see the attached datasheet.
Many thanks guys.
datasheet RP-Q-180.pdf (47.4 KB)
The data for that motor is self-contradictory.
If says 12V 12A full load (144W), yet the motor is claimed as 180W.
Furthermore the torque values given imply more like 700W (although
that may be a stall-torque value).
About the best you can assume is peak current of 60A or so, requiring
a motor driver capable of peaks of that magnitude (and perhaps 20A
continuous).
Is the torque value before or after the gearbox ?
Its after the gearbox.
michinyon:
Is the torque value before or after the gearbox ?
It cannot be at the motor shaft, since 45Nm implies a large volume of motor
(max torque depends on motor volume for standard geometries, a little known
fact from motor theory).
Of source that's only a single H-bridge module, so two would be needed. Don't expect
it to handle full current for very long, as the PCB traces will cook/delaminate at that
current level, but the odd transient should be handled.
If you expect to drive the motors hard then this module isn't going to struggle - carrying 12A
continuous will probably need a small fan pointed at the board(s) to cool them.
Agreed. It's never a good idea to run a component at its "max" rating. Using a 43A bridge to switch 12A leaves a pretty good safety margin. I suspect the 43A rating is PEAK, not continuous and your fan recommendation is probably spot on. If the driver can get "turned on" well and only toss away a volt you are at 12W (12A*1V) which may be OK for that heat sink. Buy one and see how hot things get.
The PCB traces are the limiting factor I think, unless its 4oz copper board...
When I needed a 12V Motor Controller to drive car Radiator fans, I built my own. I also wanted to be able to stop the fan instantly by switching the H-Bridge in reverse for a short pulse. That being said, some of the newer fans run 40-50A and I wanted at least a 3x margin since reversing under load will produce some high currents. One OEM even had the fans connected in parallel and always ran them both. To get around resonances, they had a different number of blades on one motor. I used four of these FETs and used Copper Bus Bar to tie them all together. I'm very familiar with PCB traces not being well suited above about 5-10 amps.
http://www.st.com/web/en/resource/technical/document/datasheet/CD00001950.pdf
Used an Intersil HP4082 and a PIC Micro to do the speed and direction control.
rmetzner49:
I'm very familiar with PCB traces not being well suited above about 5-10 amps.
PCB traces can easily handle more than that, provided they are sized properly.
If they didn't, then magic must be what's keeping the things working in the various Vantec, Roboteq, and wheelchair motor controllers I have played with. Those can easily control well over 50-100 amps.
Obviously. I was attempting to agree with your point, but apparently that is difficult.
cr0sh:
rmetzner49:
I'm very familiar with PCB traces not being well suited above about 5-10 amps.PCB traces can easily handle more than that, provided they are sized properly.
If they didn't, then magic must be what's keeping the things working in the various Vantec, Roboteq, and wheelchair motor controllers I have played with. Those can easily control well over 50-100 amps.
Look at the photos of that eBay module - its not high current PCB AFAICT.
Look at the photos of that eBay module - its not high current PCB AFAICT.
Which is why I said in an earlier post, it would not seem it can do 43A continuously. I would be completely thrilled if all the people that made these little modules would include a manual, wherein it states how long it can conduct 43A and what the output device's ON resistance is. Visually I believe the PCB to be the limiting factor. I built mine with bus bars when I needed 80 Amps to the motor. I don't have the inclination to look up PCB copper required to reliably do 80A. I looked inside a Rockwell 7000 drive and they used busbars on their isotop IGBT's.
Hi,
I've used this one for a similar project (fixing a broken golf e-trolley).
Works like a charm so far.
The modules are stackable for higher amperage, but i have'nt tested this yet
kind regards
M.