Can somebody help identify this 12V fridge compressor motor and driving circuit functioning

Thread Starter

patpin

Joined Sep 15, 2012
401
Hello, I would like to repair this brushless 12V fridge compressor motor (Danfoss 2.5) but first of all understand how it functions.
Inside are 3 coils.
It has an electronic driving unit: 2coils (photo 3)pin1-pin3 and pin3-pin4 of them are driven by mosfets. Total number of mosfets=3:
(the third one is for the fan). There is no mosfet driving the coil between connectorpin 2 and 3 ("WT" on PCB).
Control Unit Danfoss 102N3033-detailed.JPGI add a diagram (temptative).
IMG_20201025_124934[1].jpg
IMG_20201019_113527[1].jpg
 
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MaxHeadRoom

Joined Jul 18, 2013
21,636
I am assuming it is not an induction motor but P.M. field?
What is that 18 pin IC part No?
The Danfoss site shows it as a piston motor.
Max.
 

Thread Starter

patpin

Joined Sep 15, 2012
401
Motor has 4 permanant magnets on rotor (outer side).
microprocessor: 2840 9247 FADA AAC 102N3500
driving mosfets (left and middle on PCB): ST99231 P50N06 replaced by me by IRFB4332
mosfet at right of PCB is for the fan : ST9A235 P50N06
a lot of proprietary stuff I guess.
 

Delta prime

Joined Nov 15, 2019
580
hello there :) it has been my experience with 12 volt portable refrigerator compressors they use 8 bit micro processors that controls your mosfets to give varying compressor speeds at diferent temperatures
interface is between terminals C and T on the controller where the change in current varies the speed of compressor
if the temperature rises too high the processor then gives a higher compressor speed. then reduces it when the temperature is nearer where it should be.;)
 

Thread Starter

patpin

Joined Sep 15, 2012
401
hello there :) it has been my experience with 12 volt portable refrigerator compressors they use 8 bit micro processors that controls your mosfets to give varying compressor speeds at diferent temperatures
interface is between terminals C and T on the controller where the change in current varies the speed of compressor
if the temperature rises too high the processor then gives a higher compressor speed. then reduces it when the temperature is nearer where it should be.;)
Hello, Thanks for helping!
Whats the normal sequence of switching of the 2 driving mosfets? Can you probe with a scope?
Can you tell me how that compressor starts? Is there a prepositioning=>rampup=>synchronic rotating sequence?
Whats the purpose of the 2.7ohm winding between 2 an 3: speed control? Position of crankshaft/rotor?
What can the D11 R12 D13 C8 subcircuit achive?
Is the cryostat between C and T a analog signal or a ON/OFF?
A lot of questions...
 
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Delta prime

Joined Nov 15, 2019
580
A lot of questions
Whoa hey,I just wanted to hit this thread not marry it. Please forgive me I must attend a peer review for my company. It'll be 6 hours until I can respond to your request. My superiors on this site love helping people to a fault like they're trying to get into heaven or something anyway I got to go bye bye I wish you well. :cool:
 

debe

Joined Sep 21, 2010
1,200
First of all what is wrong with it? Heres some information from when i repaired one. These are a very old obsolete compressor, the controler has not been avalable for many years. They are the first generation Danfoss 12V compressor & are only one fixed speed. A lot of problems arise from low voltage, usualy from not heavy enough cable. T & C is analogue ON/OFF thermostat. The newer BD35F is mutch more versatile & draws less current & is variable speed. 1.JPG3.JPG4.JPGDanfoss BD2.5 control.13.JPGDanfoss BD2.5 control.14.JPGCOMP DRIVE.A.JPGCOMP DRIVE.B.JPGDRIVE TO MOSFET.1.JPGDRIVE TO MOSFET.2.JPGFEED BACK WINDINGS..JPG
 
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Thread Starter

patpin

Joined Sep 15, 2012
401
Whoa hey,I just wanted to hit this thread not marry it. Please forgive me I must attend a peer review for my company. It'll be 6 hours until I can respond to your request. My superiors on this site love helping people to a fault like they're trying to get into heaven or something anyway I got to go bye bye I wish you well. :cool:
Thanks anyway! See you again later I hope.... not to marry!
 

Thread Starter

patpin

Joined Sep 15, 2012
401
First of all what is wrong with it? Heres some information from when i repaired one. These are a very old obsolete compressor, the controler has not been avalable for many years. They are the first generation Danfoss 12V compressor & are only one fixed speed. A lot of problems arise from low voltage, usualy from not heavy enough cable. T & C is analogue ON/OFF thermostat. The newer BD35F is mutch more versatile & draws less current & is variable speed.
Many thanks for yr intervention!
Can you tell me how the drive signal of A relates to B. Do the signals are synchronic of do they alternate (A high when B low and vice-versa).
When I short C-T, I only have a signal on the blue wire and only 1 gate signal and switching mosfet . The motor tries to start but does only <1/4 rotation (or less eg 10 degrees: depends on starting position of crankshaft).
I see the 156Khz signal you mention on the white connector of the feed back winding.
After 1 second the starting attempt stops and the system waits about 1 second and the retries, etc.
I already replaced both mosfets by IRFB4332 (60Amp) because one died. (Didn't had a-less-Amp-one)
 
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debe

Joined Sep 21, 2010
1,200
This is the CRO view using 2 CH for the 2 drive windings. Un fortunately i have just last week gave my only good compressor to a freind who is restoring a fridge that had a faulty compressor. All i have now is 2 controlers, i will investigate later to day what i can with out the benifit of a compressor.Danfoss BD2.5 windings. time1ms.div. volts 5.div.JPG
 

debe

Joined Sep 21, 2010
1,200
I would suspect the feed back circuit. The controler uses this to determine where the rotor is. If it doesnt see it it will give one kick & not continue. Is the feed back winding ok, check at the pins on the board Brown/White leads.
 

Thread Starter

patpin

Joined Sep 15, 2012
401
I would suspect the feed back circuit. The controler uses this to determine where the rotor is. If it doesnt see it it will give one kick & not continue. Is the feed back winding ok, check at the pins on the board Brown/White leads.
Here are my signals (relative to grnd) during start attempt: (present about 1 second)
-on gate of mosfet 2 (first image);
-feed back signal
-both together.
When I open te CT (cryostat) then I have the feed back signal in 1/2 (180° segment) of the crankshaft positions and not in the other 1/2 . (image 4).
Do you have an idea of how the feed back signal changes depending on the position of the crackshaft?
I am also wondering where the -12V (minus?) on your diagram is coming from. Thanks for yr help!
 

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debe

Joined Sep 21, 2010
1,200
My boards are a 94 & a 93 model & there is slight differences in the copper tracks on the boards depending on what year of production. My board number is the same 102N1300. In my circuit R is your R4 which is part of current sensing, & my Neg 12V on my circuit goes to the battery Neg. I am wondering if theres a problem with the compressor. The feed back wave form does not look good to me (disslojed magnets) I have not cut one of these model compressor apart only a later BD35F) My friends faulty compressor would cause the controler to screech then shut down, then attempt to start again.
 

Thread Starter

patpin

Joined Sep 15, 2012
401
My boards are a 94 & a 93 model & there is slight differences in the copper tracks on the boards depending on what year of production. My board number is the same 102N1300. In my circuit R is your R4 which is part of current sensing, & my Neg 12V on my circuit goes to the battery Neg. I am wondering if theres a problem with the compressor. The feed back wave form does not look good to me (disslojed magnets) I have not cut one of these model compressor apart only a later BD35F) My friends faulty compressor would cause the controler to screech then shut down, then attempt to start again.
I opened the compressor and the coils are not burned. The resistances are 0.2 instaed of 0.3 and there is no connection to grnd. The crankshaft can rotate easily bij hand (cylinderhead removed). Rotator is OK and magnets are well fixed. I recentered the rotor at reassembly. So I guess it is OK?
You have an idea of the feedback-coil variation when motor turns?
 

debe

Joined Sep 21, 2010
1,200
Would be nice if you had a known good controler to try. Thats how we diagnosed my friends faulty compressor, he was blaming the original control unit. His compressor winding resistance were all good, but it was faulty & would not run at all.
 

Thread Starter

patpin

Joined Sep 15, 2012
401
Would be nice if you had a known good controler to try. Thats how we diagnosed my friends faulty compressor, he was blaming the original control unit. His compressor winding resistance were all good, but it was faulty & would not run at all.
Would indeed be the easiest way. Then I could measure the normal signals also.... but I dont have one....
But it's good to know that "good resistances" does not equals "good compressor". There should be a way of measuring the winding behaviour. I could switch the black and the blue wire and see if gate signals follow the switching?
 
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