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power ground and signal ground in Power converters

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mess123

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Hey Guys,
Do we connect the power ground (-ve) terminal with the signal ground (the groundings of the controller) together in the power electronics equipments like DC/DC converters? If not, could you explain why??

Thanks in Advance.
 

Miguel Gaspar

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It is a good practice separate high power from low power stages. That is because could bethat high power transitions flow to the low power devices and destroy them.
 

SkyHigh

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YES, if your signal ground is a common reference ground for all ICs, including controller, and it is the only signal return path back to the source (i.e. power ground)
However, wherever possible, try to use a Star Topology, so as to isolate any noises (e.g. SSN and GB) between power circuits, digital circuits & analog circuits in the same system.

NO, if your signal ground is a biased DC point to provide an offset for analog circuits. You will short circuit any capacitors in the -ve part of the biased circuit.


Hey Guys,
Do we connect the power ground (-ve) terminal with the signal ground (the groundings of the controller) together in the power electronics equipments like DC/DC converters? If not, could you explain why??

Thanks in Advance.
 

dick_freebird

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Most likely you will connect them together, in a nonisolated
positive ground-returned converter. But that is not as simple
in reality, as in "paper space".

Some nonisolated DC-DCs have true remote sensing. Here the
"ground" is passed through and load return current comes
back on the same "wire" and on to the prime source. If you
want the load, at some remote distance, to be the set value
across load-current range, you will connect the signal ground
(Kelvin -) to the load's local ground, and feedback to the load
as well, taking out forward and return I*R drop.

An isolated converter does not return current to the prime
source. But converter <-> load drops remain and you would
again attach feedback to load {in, gnd} points.

A converter without a designed remote feedback may have
little controller-ground common mode range before bad
things happen. A cheap integrated controller may attach
FET driver GND to analog GND internally and use one pin.
This becomes messy for anything but a very tight physical
design, and forces you to common them up and do your
best to minimize (rather than null) the drops.
 

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