Filters and DC/DC Converters in parallel

by Runei
Tags: converters, dc or dc, filters, parallel
Runei is offline
Aug27-13, 06:36 AM
P: 135
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 im 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, im thinking I will need an external one.

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

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

Attached Images
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berkeman is offline
Aug27-13, 01:08 PM
berkeman's Avatar
P: 39,683
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 is offline
Aug27-13, 01:35 PM
P: 135
Thank you very much for your response berkeman :)

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