DIYbanter - View Single Post - Crazy thought -- converting 480v drives to 240v

Jon Elson

wrote:
Not impossible but you would have to know a lot about the
detail design of the drive and be prepared for a lot of messing
about with the printed circuit board.

The output stage should be OK but,in addition providing the
correct supply voltages to the control and drive circuits, you
would also need to modify the output voltage regulator system and
protection circuits to enable them to make them compatible with
the lower output voltage.

There is no "output voltage regulator". The CPU measures DC bus
voltage and calculates the correct pulse width to get the
desired voltage. If you hack the resistor voltage divider so
the CPU reads the expected voltage when it is really half of
that, it will calculate the right pulse width. You still tell
it it is running a 480 V motor, and it dutifully puts out 240 V
due to the two changes (reduced DC voltage, incresed sense
voltage) cancelling out.
An interesting project for the hardened experimenter with
adequate experience and test equipment but not a job to be
undertaken lightly!
Iggy is INDEED a hardened experimenter, who hacked a DC TIG
welder into a square wave AC TIG machine. So, I think he COULD
do this. I don't know if it makes any sense to do just one
unit, but if you had a bunch of the same model, it could be
quite a successful project.

Jon