Electrical Engineers Needed: DC Motor control?
 

I have this 12vdc waterpump that comes from a BMW and I want to make it go round & round. I apply voltage to where BMW guy says to and it doesn't do anything. I also tried bring the other pins to ground or 5vdc just for laughs. This is using a lab power supply which may not have the current capacity but it doesn't even register any current at all. Per the local BMW tech for reference:

"pin 3 is b+ and pin 4 is ground. As far as the other 2 pins the one is the signal from the electronic t-stat for on and speed demand and the other is a signal from the motor electronics for speed and various other communications. If you need the specifics on these I can get them but you should only need the power and ground to run the pump at 100%."

What kind of DC motor is this? Some sort of brushless servo thing? There's 3 leads going into the windings and there's a trick circuit that sits on top.

Actually the important questions are:
How do I get this to work with no help from BMW or the pump manufacturer (Pierburg CWA200)? Are there commercially available controllers for this type of DC motor? Ideally a programmable circuit that varies speed with a 0-5volt engine coolant temp sensor :) But I would be happy just getting it to run at 100% and using a standard thermostat too.

Thanks in advance...Pics attached!

Interesting pump. The coils (windings) look similar to the layout of the eddy current coils on the brake of my dyno. Hard to tell by the pics, but there is not an actual armature? It looks like no windings on the shaft, is that correct? The coils would then be N-S-N-S... I cant actually explain how this works, but the controller for the eddy brake is DC-PWM.

Hope that is of some help.

The best I can see, there are no windings on the shaft.

So there may be permanent magnets on the shaft, can you see, or figure a way to tell?

Quick google finds this page;
http://www.ms-motor-service.com/cont...cls=02&pcat=20

If its a brushless DC motor it must have permanent magnets and will be controlled by a tyristor controller. (Pardon my english possibly...)
Same as for whats used in RC cars\planes\boats etc...

It does say it already has the necessary electronics so there should be a schematic available somewhere. Maybe from a BMW service manual?

Sell those on ebay as electric turbos.

You know it will work :P

Dann

Are you sure it's good? I've seen a few of those dead at my friends shop.

It's supposedly brand new but there's some moisture inside the seal housing as if it's been run before.

i dare you to dyno that as an electrical supercharger.

OK I promise to do so...IF you all help me get the damn thing rotating.

what pins do the large capacitor connect to? id expect those to be power and ground.

Makes sense. Pin 4 goes to ground (aluminum case) which is also connected to one side of the large grey capacitor. The other side of the capacitor is connected to Pin 1, the "signal from thermostat" according to the BMW guy who isn't sending me the circuit diagram. Should I reassemble and send 12vdc to Pin 1 & see if I let the smoke out?

I mean I'm no EE. I just know how to solder.

Yes, it's definitely some kind of "brushless servo thing." :D

Specifically, a permanent-magnet brushless DC motor, same as the capstan motor in a tape deck or the fan in the back of your PC.

The "trick circuit" is a three-phase inverter. And all else being equal, it should free-run when energized. Motors like this don't usually require any sort of external sync signal (IOW, they generate their own timebase.)

What I suspect it does require is an external trigger to cause it to turn on when commanded. Specifically, that pin that the tech mentioned as a "signal from the electronic t-stat for on and speed demand." But what is the required polarity and voltage of this signal?

Exactly. I will attempt to find out. BMW guy said it should spin without a signal to either of the extra 2 signal terminals.

I tried sending 12volts from a battery (incase the lab powersupply's limited current was doign something funky) to pin 1, the pin that's connected to the capacitor, and no luck. I also tried sending +12v to both pin 1 and pin3 with no luck. Obviously while pin 4 was grounded. I didn't try pin 1,2, &3 at 12vdc, but yesterday I tried pin 1 & 2 at 5vdc and pin 3 at 12. I also tried grounding pin 1 & 2 while 3 was at +12

Does that circuit board have anything on it which could reasonably be construed as a microcontroller?

I ask because I was looking at the datasheet for that motor at the Pierburg website, and they indicate that it is available in version which is controlled by "digital signals like the LIN-bus." (LIN is similar to CANBUS, used for simpler, lower-datarate applications)

http://www.kspg-ag.de/pdfdoc/kspg_pr...olant_pump.pdf

Given that this part was designed for a BMW, I would not be in the least surprised if they chose to use a network interface to control a pump.

I attempted to remove the board from the aluminum case but the epoxy is pretty significant. I cannot see a computer chip thru the various little windows but I wouldn't be surprised there was one in there. I saw that on their .pdf as well.

I know BMW likes to do things the hard way if at all possible.

Is there something simple (inexpensive simple permanent-magnet brushless DC motor controller) that I can connect to the 3 motor wires that can make it spin? I remember building a Y type circuit back in school but that was 12 years ago. I'd need to purchase and go at this point.

I am thinking it's easier to attach the impeller housing to a standard 2 wire motor or easier still just run the damn OEM waterpump. It would be nice to clean up the front of the engine and give more room for the turbo.

Thanks for your help Joe.

i thought that WAS your turbo :)

fwiw: http://www.bmw-planet.com/diagrams/release/en

these are badass. some of the images arent coming through on my computer (looking at the e90, speically the wiring diagram for the cooling system)


I think once you find the proper application, you need to look for the "temperature control" diagram.

I found on BAV auto that the waterpump P/N for the oldest BMW's with electric water pumps is "11 51 7 586 925," which I'm guessing is basically the same as yours. I pulled up the attached diagram, which makes me guess that Pin 4 is ground, Pin 3 is +12v, and some type of signal differential between 2 and 3 is what runs the controller.

Good luck. This would be really awesome if it ends up working.