I have a 24v DC reversible motor rated at 45 amps no-load and 145 amps loaded. Supposedly it is a Ramsey winch motor: ebay.com 230333899614 I'm using it on an electric aircraft tug. I posted some questons under "Other Electric Vehicles" and then discovered the "Control Systems" Forum, which seems more appropriate for my questions!
I have successfully wired it with 4 solenoids to accomplish forward/reverse using this diagram: wms1.com/cgi-bin/category.pl?category=inf_dwgs&pagenum=130
It has now become obvious I need a motor controller to allow variable speed.
I'm certainly a newbie to electrical motors and controllers, so I have these questions:
1) Just to be absolutely sure I'm using the correct terminology, is this a "series-wound motor"?
2) Where is the controller spliced into this setup as wired, or, should it be wired differently?
3) I assume I need a rather "heavy duty" controller such as used on a golf cart ... most seem to be rated for 200 amps or more. The least expensive new unit I've found is a Kelly: electricvehiclesusa.com/product_p/co-kd36200.htm Would this controller work?
4) I've found less expensive deals on new and used units on eBay, etc. However, they are usually for 36-48 volt controllers. I assume these will NOT work with a 24 volt motor and electrical system, correct?
Any advice or information would certainly be appreciated!
(I fixed your links)
It appears to be a series-wound however shunt-wound also has four connectors and shunt-wound requires a different controller than series-wound. It's odd that one of the connectors is on the casing. The series wound motors I've seen all had four connectors (A1/A2/S1/S2).
I don't recall how well the Kelly guys have documented this. However the Alltrax people have an excellent document repository on their site including diagrams for wiring that goes over this situation. http://www.alltraxinc.com/Doc_Depot.html
Have you calculated the torque/power requirement for your application? It sounds like you're flying this by the seat of your pants. Do you know whether the motor you've chosen has enough oomph to do what you want? And further the power level run by the controller in the end depends on the power the motor puts out.
Just because a motor is rated for a given HP doesn't mean anything. It's the controller that sends electricity into the motor and the HP the vehicle produces is based on several factors the most important being how many volts/amps/watts are sent into the vehicle.
Build your own Electric Vehicle goes over the details with formulas galore.
Motors of the sort you've found are very resilient to being run at higher voltages and power than their rating.
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
I've done a little homework (HAHA!) ...
The motor is a Ramsey-Pierce 3 post winch motor. Apparently the three posts were pretty common for winches. It IS a series wound motor.
From testing, I can verify the motor has plenty of torque! However, it really does need a speed control - the motor pulley speed is just too fast to make the idler pulley/clutch system work smoothly ... the belt "grabs".
I studied the Alltrax diagrams and of course, they're all for 4 post motors! I contacted Alltrax technical support and received the following reply:
I honestly don't know if it will work or not. I would isolate the
controller from the vehicle. Use some nylon stand offs and washers to
keep it electrically isolated from the frame.
From there using the ebay pics as reference: M- would be the black clamp
and the B+ would be the orange clamp.
So, I guess the bottom-line question is, is a three post motor essentially the same as a four post except it uses the case for a ground and do you think the technical support advice would work? If I did what they said, I would probably attach the B+ to the power wire going to the solenoids as that is what determines which post is +24 volts.
Any comments/advice appreciated. If anyone HAS actually speed controlled a 3 post motor, I certainly would like the details!
Regards,
John
I got this reply from an electrical engineer on an engineering forum:
If you do not need to be able to reverse the motor hook the controller up as shown in the controller diagram except connect M- to the isolated casing, jumper the A terminal on the motor to one of the F terminals on the motor and connect B+ from the controller to the other F terminal on the motor. If the motor runs in the wrong direction swap the connections on the F terminals.
If you need the reversing control connect the motor to the solenoids as shown in the print from your first post. Except connect B+ from the controller to the solenoid instead of the battery + (leave the solenoid control wiring hooked to the battery) and hook M- from the controller to the isolated motor casing.
Apparently, the motor casing would have to be electrically isolated, but this wouldn't be too hard with a non-conductive drive (belt) and insulated mounting bolts or insulated motor mount.