PCB Design Considerations for a Motor Power Distribution PCB?

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gatesw

Joined Feb 28, 2011
6
Hello,

I am considering designing a PCB that would provide connector B1 to a battery/ cable. It would then distribute power to a set of eight motors. Four of the motors have one set of ratings while the remaining motors have a second set of ratings. Below is a "static" power budget based on the motor specifications rather than test data. It is not anticipated that the motors would operate at the specification values but rather well below. It is also unlikely that all the motors would ever reach the specification values or max values all at once. I am using these values as my "worse case" design criteria.

Most of my PCB experience is in the embedded world and I have never dealt with values like this or even considered them for a PCB. I have done some reading but of the PCB articles out there "high power / high current PCBs" are centric to power transformation and the like topics i.e. regulators and transformers etc...

This PCB is basically a passive power bus i.e. no components or regulations etc... other than connectors. I am looking for suggestions and insights on best practices and considerations. Particularly:

  1. Are there any immediate reasons why this is a bad idea?
  2. Trace width calculators out there seem to fixate on a single trace on a single layer. Can trace widths be reduced if they are routed/ganged on multiple layers? I cant seem to find such calculator or topics that may support this approach?
  3. Are the specification values I am using as my starting point unreasonably high to start with?
  4. I do not really have a very good intuition on safe and reasonable thermal rise /dissipation values any inputs here would be appreciated.
  5. I am using M12-K connectors and the footprint provided by the vendor suggested "1.6mm" PCB but from what I have read about power carrying PCB I should be expecting to use 2oz or 3oz Cu so I also expected a thicker PCB. Perhaps some thoughts on stack would be appreciated also?


MotorPowerBoard.jpg
 

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Sensacell

Joined Jun 19, 2012
3,475
The PCB can be 1/16" (1.58mm)

Use the widest traces you can fit, and heavy copper.
Beware of connector pin maximum current ratings- read the datasheets for the connectors carefully.

You can find trace calculators on line to verify the ampacity. Increase the thickness, layer count and width to meet your power loss objectives.
 
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