Danfoss AEO controller

[OzePete]

Originally Posted by Richard Kollmann

Rich, The Cool Blue is the most energy efficient eutectic holding plates system because it can be operated with Danfoss BD35 at 2000 Rpm without a speed change. Really! what is the logic and evidence behind this vague statement or are you also of the school that believes a smaller compressor is more efficient because it has a lower A/H rate!

Have you ever heard of the BD compressors while running shutting down on a low speed LED signal? Where was the reference to; BD compressors while running shutting down on a low speed LED signal? Read what was said Richard and if any one in the industry has not witnessed that then they are simply quite inexperienced!

Pete also talks about the need for soft start modules. Absolutely I do and hopefully by now you have worked out how they function and the benefits or are you still suggesting that the DOL modules are/were without major failure problems? Because if you think the old DOL module type is ok, there are many thousands of peed off users out there who have spent big dollars on replacing those crap things, and who would totally disagree with you!

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[a64pilot]

From a cooling standpoint, most efficient is large condensers and evaporators and a compressor that runs on an almost 100% duty cycle.

I had very efficient heat pumps on my house, three of them. They each had twin compressors, when the temp was three degrees off of set point the large compressor ran, when set point was reached, the large one turned off and the smaller one kicked in, I believe it was half the capacity of the large one.
The smaller compressor running pretty much continuously was significantly more efficient than the larger one running occasionally.

[a64pilot]

Oh, and are BD compressors really DC compressors, or does the controller invert DC to AC to run the compressor? If so then the power is as stable as the controller is, My Magnum inverter for instance is much more stable and therefore “clean”than the AC power from the dock.

[a64pilot]

They are apparently DC brushless motors, which means of course that they are electronically commutated.
Maybe the third pin is to determine speed?

[OzePete]

Originally Posted by a64pilot

Oh, and are BD compressors really DC compressors, or does the controller invert DC to AC to run the compressor? If so then the power is as stable as the controller is, My Magnum inverter for instance is much more stable and therefore “clean”than the AC power from the dock.

Yes these days all the so-called 'DC' compressors are actually three phase AC. A solid state processor driven device (The black box! called a Motor Driver Module) accepts DC current and converts it into three phases of alternating current to drive the compressor motor. As with most AC motors the AC pulse width determines the motor speed.

A DOL module has the compressor going from stopped to maximum speed virtually instantly and this causes the massive spike of current and component stress on start up. A major cause of Motor Driver Module failure.

A soft start module takes several seconds to go from start to run speed thus eliminating the massive current inrush.. see a better explanation here: Soft Start compressor Motor Drive Modules | Ozefridge

Also like to mention that all power supplies are suspect! The RMS voltage, peak voltage, pulse width, total harmonic distortion etc are just some of the areas where variations occur but I would suggest that your mains supply is truer than your inverter. (Unless you are in SE Asia! )

Cheers OzePete

[a64pilot]

Originally Posted by OzePete

Yes these days all the so-called 'DC' compressors are actually three phase AC. A solid state processor driven device (The black box! called a Motor Driver Module) accepts DC current and converts it into three phases of alternating current to drive the compressor motor. As with most AC motors the AC pulse width determines the motor speed.

I thought that as well, was sure of it in fact, but Secop’s literature plainly states that there BD compressors are electronically commutated DC brushless motors.

[a64pilot]

Originally Posted by OzePete

Also like to mention that all power supplies are suspect! The RMS voltage, peak voltage, pulse width, total harmonic distortion etc are just some of the areas where variations occur but I would suggest that your mains supply is truer than your inverter. (Unless you are in SE Asia! )



Cheers OzePete

The proof would be with an O scope that I don’t have, but both my Honda generator and my Magnum Ms 2812 are more stable in both voltage and frequency than mains in the US. I monitor both Hz and voltage, cause I can I guess and it’s easy to do.

[OzePete]

Originally Posted by a64pilot

I thought that as well, was sure of it in fact, but Secop’s literature plainly states that there BD compressors are electronically commutated DC brushless motors.Attachment 171032

A good play on words!!
You could say that all three phase motors are 'electronically comutated DC brushless motors. What I stated and what you believed is correct, Secop are just saying the same thing differently! (That is why there are three pins!)
And yes to properly analyze your AC supply you need a CRO as there is more than voltage and frequency to check if you want the whole story.

Cheers OzePete

[a64pilot]

No, a brushless DC motor is not an AC motor, brushless DC motors are very common now and are extremely long lasting. 150,000 hours MTBF is common.
Seeing as how they even said speed is controlled by voltage, it’s either a DC motor or they are deliberately concealing the facts, which is illogical , cause they never had to explain current or speed control.

Can you find data from Secop that says it’s an AC motor?

[SV THIRD DAY]

Originally Posted by a64pilot

Can you find data from Secop that says it’s an AC motor?

The Danfoss Compressors operate on 3 Phase AC.
The Black Box Converter takes DC (12v/24v) and turns it into 3 phase AC.

[a64pilot]

Originally Posted by SV THIRD DAY

The Danfoss Compressors operate on 3 Phase AC.
The Black Box Converter takes DC (12v/24v) and turns it into 3 phase AC.

OK, before I found data in print from Secop disputing that, I also thought that.
However if nothing else how do you supply three phase power through only three wires, you have to have a ground, and that takes four of course, five if you do it with a neutral.
Can’t be grounding through the case of the compressor, there is no direct connection of the battery ground to compressor frame.

Has anyone actually measured output of the three pins? I would but getting my controller out is a bear to say the least.
See I can see how logically three wires could be DC+, DC- and the third for RPM sensing.
Of course without data, you can make most anything sound logical.

Secop link
https://assets.danfoss.com/documents...3086415696.pdf

[a64pilot]

I can’t make sense of this.
To test compressor one check is to check resistance on all three windings, I assume the pins.
Then on the high temp protection of the controller, apparently the PC board that is the inverter is sensed with 100c being max.
So inverter and three windings sure seems to point to three phase AC, but how do you account for the detailed speed control explanation on page 51?
Are they being intentionally misleading, if so why?

[Frankly]

Three phase three wire systems (delta or Y) are very common. No safety ground or neutral needed on a low power system. AB told me that it was a three phase motor driven by a rather rough approximation of a 3 phase voltage (lots of harmonics) and that was why it was raising so much He** with my HF radio. They sent me an alumium shield but it made no difference. Turning off the breaker to the frig works every time, just have to remember to turn it back on.

This was years back maybe later designs have changed to brushless DC motor. If you put some of the electronics inside the compressor case might work.

[a64pilot]

Frankly,
further digging into it, apparently ALL BLDC or brushless DC motors are AC driven, through an inverter or switching circuitry. Not sure if it’s actually AC or pulsed DC or if it even matters.
Then digging even further, it appears that even a brushed DC motor actually is AC or maybe pulsed DC by the way it operates, with the commutator powering first one field then the other quickly.

I just can’t fathom why Secop would put that explanation in both how the controller works and again in how the compressor is speed controlled.

[SV THIRD DAY]

Originally Posted by a64pilot

how do you account for the detailed speed control explanation on page 51?
Are they being intentionally misleading, if so why?

Maybe because they are selling a DC Compressor and are not wishing to cause confusion or give away proprietary info. Since you HAVE to use the Danfoss Controller with the Danfoss Compressor you are splitting things apart and analyzing them in a way that is never intended by Danfoss. I don't know....I'm not Danfoss. But I can tell you it's an AC Compressor despite what their manual says, which I think is just for easy of marketing and not confusing people.