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Fran explained it to me a bit, and I'm trying to fill in the details. Basically, you use a $3 line filter, which is a 3mH 1:1 transformer with thousands of volts of isolation from primary to secondary..
On the primary side, you send a 15v AC signal (or 12v or 24v or whatever you want). The AC signal is the output of a mosfet driver, at about 50kHz to 100kHz. I'm going to just use a 555 timer to generate the pulses that will be the input to the mosfet driver.
Now, the secondary side will have an AC signal, so then you just rectify it with 4 schottky diodes, and clamp it with a zener diode, and then you use a good bulk capacitor so that you now have nice clean isolated DC power. That DC power can be used to power an optocoupler and then a driver for the IGBT or Mosfet bank. Fran's used it for years, and it is WAY cheaper than a vla501 or whatever. It will be a particularly good cost savings for the AC controller, since you need 4-6 isolated supplies in that case.
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