last week, i thought of a easier idea about converting a vfd.
there's the usual approach of getting a large drive ( 75hp +), tapping into the dc bus, and you are good to go. this is easy, but this drives cost a fortune ( $ 2000 + for a used drive supporting vector control, encoder, and computer interface.
what if you could get a very cheap 100hp drive, and couple it to a small cheaper drive?
i set out to do just that.
got this from ebay. reliance gp2000, 100 hp, 480v, working when removed from service, $150. had to pick it up 150 miles away, but it was worth it.
got it home and opened her up, and it was full of goodies.
400 amp 1200v igbt's complete with laminated insulated busbars, and a large square d 250 amp x 3 contactor.
this drive weighs 260lb, and is in a 5' x 2' x 3' cabinet. so whatever plans i have would involve getting all this goodies out of this cabinet, and designing a smaller lighter housing.
after gutting, this is what i got:
power modules on large heatsink, with 300 amp fuse, and snubber boards
4 x 6800uf 450v caps
gate drive board
gate drive power supply
square d 250 amp switch
3 x 200 amp fuses.
size 1 assorted cables.
why gut it? this drive does not support vector drive, or any form of feedback. its old, and only does a blind v/f profile. (although it has current sensors on two of its outputs). so the control circuitry has got to be replaced by something more modern.
it has a powerful gate drive board, so im planning to tap into the gate drive. just the heatsink and power modules weigh over 100 lb, might have to be changed later, for weight saving. probably go watercooled.
interesting thing is, the power supply board takes 240v ac, although the drive is a 480v version. so im deciding between 230v or 460v conversion.
will probably go 460v since the current rating would have to double if i went with the lower 230v.
looking and studying this components, im beginning to see the design requirements of high hp ratings in this drives. from gate drive design to insulation, snubbing, and wiring.
going this way is also a good idea, since the cost would add up, if these components were purchased separately.