[adamj12b]

Originally Posted by NiHaoMike

You only need one DC/DC with multiple isolated outputs. Adding additional outputs to an unregulated push pull converter is just a matter of adding more secondary windings and rectifiers.

The only problem with using one supply with multipal outputs is you would need to make sure all the output leads are the same length to minimize delay from wire inductance. The problem with a single supply is you cant pick a common gnd point between 3 IGBT modules and have everything be the same length.

Originally Posted by NiHaoMike

As for signal isolation, Analog Devices makes some very impressive isolators. The ADUM7441 is good for 3 signals in one direction and one the other, such as 3 phase drive one direction and fault indication in the other.
ADUM7441 | 1 kV RMS Quad-Channel Digital Isolator | Digital Isolators | Interface | Analog Devices
I have used another Analog Devices chip that isolates USB and I'm very impressed at its performance.

The opto's that are in use now in the DC controller and are planed to be used in the AC controller are the HCPL4504. This high speed opto has a 3.75KV isolation rating.

-Adam