Richard J Kinch wrote:
xray writes:


I know this can
get deep, but at a first level I'd like to hear the the basic theory
about how the input power might be adapted and controlled.



A typical VFD is just a switching mode power supply feeding a programmable
signal generator. The hard part is doing it reliably at high voltage and
current.

Oh yes. the word "just" involves a whole lot of grief

We once ran some tests on a tiny little 1/2hp toshiba inverter. After
slamming it from regen voltage limit into motoring current limit, it
locked up at about twice rated current. for a short time

we then ripped it apart, and found the DC bus cap was about the same
size as my little finger. what the ?! buried deep in the manual was a
requirement to replace it every *year*

Cheers
Terry