Quote:
Originally Posted by e*clipse
In general, I am concerned about the data line recieving the noise. I figured the motor controller would be THE location of maximum noise. Those poor signal wires would be within inches of the IGBT's that are switching 650V, 150A @ 20kHz. 
The differential pair wires are ( sorry - sorta OT ) on the BMS, communicating the info from the data gathering IC's to the central computer. Data is transmitted at about 1Gb/s, and unfortunately I have no control of the speed, just the amplitude.
**EDIT** this is exactly like CAN on the physical level!  So, I guess it's ON topic, 'cause I would like to communicate things to/from the motor controller using CAN and Paul has already supplied CAN port hardware. 
CAN bus - Wikipedia, the free encyclopedia
In my case, I'm trying to reduce the number of wires and connections. This is why I was so happy to find that intermittent twisted-pair cable. I am dealing with a system where the cable length could approach 10 feet, and the voltage between the low side and high side could approach 650V. |
We run Devicenet (a variant of CANbus) in electrical rooms, run in the same cable tray with 575VAC, within a couple of feet of 4160VAC. It is *VERY* robust. But the data rate is comparatively low. There is a conductor described as ground, but the cables have no overall shielding, and no shielding on the differential pair. There is a terminating resistor at each 'end' of the bus .. but that's it.
The way that Devicenet powers communication is .. interesting ..
A separate 24VDC power supply, that is rated for the Devicenet spec, is used to supply the power for the isolated side of each communication board, in each device on the network. That's ALL that is powered up by that power supply. It disables on short circuit, ground fault, and a host of other problems but by doing that it protects the communication boards for each device.
Would that method give you good isolation between the DC bus and the communications? I'm not sure if that is paranoid enough for the communications between controllers in a car. But it's something that is used in industry and I thought it might apply.