One concern, though, may be the inrush current when the motors start up; that may cause the voltage at the inverter to sag enough to cause it to drop off line.
Thanks for that point.
I learned a lot this morning!
This is from 2004, but the basic idea with inrush seems to be- cut it of at the pass!
http://powerelectronics.com/site-fi...archive/powerelectronics.com/mag/404PET20.pdf
Power transformers for isolation
and voltage step-up (or down) are
among the most dated technologies
still in use. Today’s ac power grids
evolved from the early days of the last
century, when Tesla’s generators faced
off against Edison’s dynamos to decide
whether ac or dc power distribution
would rule. Much has changed in
a century; much has not. Materials
have improved, manufacturability has
increased and designs have moved
from engineer’s charts to computer
software. Nevertheless, power transformer
theory and math have remained
relatively unchanged since
Tesla and Edison’s time.
An excellent transformer reference
source is the 1954 Radiotron Designers
Handbook, published by RCA,
which bears a remarkable magnetic
similarity to today’s reference books.
The design approaches, rules-ofthumb
and decision-making criteria
it offers could be considered as contemporary
to the design approaches
offered today. However, a quick comparison
of electrical steels reveals the
improvements in the last century. Although
advanced for their day, the
steels listed in the RCA 1954 Radiotron
Designers Handbook can be characterized
by as lossy, low in permeability,
and as having soft hysteresis loops
with long linear portions.
Today’s grain-oriented steels work
with a fraction of the losses, at higher
permeability, and they can be driven
harder at elevated induction levels.
But there are consequences. The mag-
netizing curve is no longer soft and
round, because it has turned square
and hard. However coincidental, the
combination of high permeability and
square loop comprise a major component
of the formula for inrush.
Improved steels have enabled
smaller, lighter and less costly transformers.
Yet, those same improvements
have created a generation of
transformers that draw immense
amounts of current at start up.
Although it probably was not a problem
in 1954, inrush current is definitely
a problem today—one that concerns
every primary circuit designer.