DC refrigeration compressors such as Danfoss BD50 F have a magic box attached which controls the compressor motor.
I would like to know how these work to the detail of a circuit diagram.
I can guess at two functions, motor start and motor speed.
So there possibly would be a relay for motor start and given the large heat sink on the back, and, that the motor speed is determined by an external resistor, I expect a large MOSFET stuck to the heat sink.
I don't have one available for dissection, so I am hoping someone can assist me.
Thanks Greg

 

Google is your friend.
https://www.secop.com/fileadmin/use...340_101n0650_12-24vdc_08-2019_desi101e502.pdf

 

This is whats inside. The MOSFETs on the heat sink generate up to 40V dc from 12/24V DC. Theres 6 MOSFETs to drive the Star winding of the compressor

 

Google is your friend.
https://www.secop.com/fileadmin/use...340_101n0650_12-24vdc_08-2019_desi101e502.pdf

Thanks. I have this already. It was athe maximum level of detail that Danfoss will share gratis. But it does not tell whats in the "black Box"

 

This is whats inside. The MOSFETs on the heat sink generate up to 40V dc from 12/24V DC. Theres 6 MOSFETs to drive the Star winding of the compressorView attachment 292463View attachment 292464View attachment 292465

Thanks for a very helpful and detailed reply. Another bloody inverter. I have a dozen camping generators in my shed, all with dead inverters, dropped of by hopeful friends only to be horrified at the cost of inverter replacement.
To the true beginning. My Waeco CF110 was working spasmodically now does not work. Isolated and setup as per the diagram I get a 5 flashes error but nothing is hot and the current is zero which leads me to suspect this control board is crook. These cost over $200 so replacement will not happen. I only use the freezer for holding Ice 24 hours prior to fishing so it gets/got little work. The question becomes can I run the compressor without the control board? and control the temperature with an external thermostat.? I will need to test the motors windings to ensure the motor is ok.
Looking at your drawings, is the motor of this compressor actually an AC motor?

 

I would not be feeding AC voltage to the compressor windings. Im pretty sure its a BLDC type motor thats uses 3 phase variable freq drive. Pict of one phase CRO wave form, Also you could maybe buy a BLDC motor drive that does not need a Hall sensor feed on Ebay. But you will also need about 35V DC @ 6A to power it.

 

Thanks Daryl

Laurie Stoppa from DC fridge in QLD told me the controller "sends low voltage AC to the comp". A bit more detail would be nice.
I thought knowing the motor winding resistance may assist in determining if it be AC or BLDC.
I could not find the motor winding resistance for the BD50 only the BD35 but I guess are similar; these are 0.06, 0.08 and 0.08 as decibed here:
www.penguinfrigo.co.uk

I imagine these are Ohms not KΩ.
I thought these should be these same, and it was only single phase motors that has the start winding different to the others.
I have not yet got the compressor out of the Fridge.
My geriatric hands are not as nimble as the Chinese ones that assembled this thing.

Thanks very much for your assistance and the detail of your tuition.

Greg Paterson

 

Have previously tried using a BLDC driver & a 12V DC to 35V DC booster to drive a BD35 compressor. It is doable but the DC to DC converter i chose was no big enough & does over heat.

 

It is worth noting that in any of the fridges that use a 12/24V compressor, that there is adaquate air flow through the condenser & over the compressor controler. If not the controler will eventualy fail due to over heating.

 

Hi T,
I don't know if this is helpful or not, but have you considered BLDC ESCs for electric bikes, scooters or models?
C.