Filters and DC/DC Converters in parallel

[Runei]

Hello there people.

Hopefully someone will have a bit of insight into how a possible solution to my problem could look.

Im designing a power distribution unit for a piece of equipment, and there has to be galvanic isolation between the primary power input and the loads.

I have a DC/DC Converter with a built in EMI Filter that converts from 28Vdc, to 5V,+12V and -12V. These voltages will be used to run various electronics such as microcontrollers, op-amps, sensors and the like.

However, there is also a stepper-motor involved that needs to run on 28V. And since we need galvanic isolation and I am not interested in building a separation transformer (neither is my boss), we need a 28V to 28V DC/DC Converter. I found one, but now the problem arises at the EMI filter. Since the 28/28 converter has no built in filter, I am thinking I will need an external one.

But since both converters will run from the same 28V power source, I am thinking that the filter coefficients will be changed when they are connected thus in parallel.

Here's a picture of the setup. Any thoughts?

https://www.physicsforums.com/attachment.php?attachmentid=61188&stc=1&d=1377603320

 

[berkeman]

If the source of your 28V power is low impedance (most likely it is), then the two parallel filters will not interact much with each other.

 

[Runei]

Thank you very much for your response berkeman :)