Is it possible to fool a 3ph input VFD into using 1ph input for household use? - Page 1
Forum section: electronics / projects

author: superUnknown
author_rank: Regular Contributor
timestamp: June 11, 2013, 06:27:43 pm
content: I just blew up a cheapo huyan yang 7.5kw 1phase input inverter. I've had much better luck with the automation direct GS2 variable frequency drives. BUT the biggest one they make for 1ph input is 3hp.In the past, when I tried to hook up a larger GS2 to single phase, it (not surprisingly) shows an input phase error. I don't have a big GS2 to try it out on anymore.Since the DC bridge doesn't care where it gets power from, I'm wondering if it's possible to fool the drive by connecting two terminals to the same single phase "hot"?(Yeah, yeah, "shouldn't", "not rated for amperage"... "gets hot"... "let the smoke out"Is it possible to "fool" the phase detect part of a VFD?

author: Smokey
author_rank: Super Contributor
timestamp: June 11, 2013, 10:30:30 pm
content: The three AC phases support the rectified voltage since they overlap. With only one phase, there is a lot of time for the DC cap to discharge when you are pulling that much current out of it. The DC is going to droop like crazy every cycle. Even if you hacked the drive to work, the control electronics might not be set up to work with that much input ripple. You might trip on an under-voltage or something.I looked into getting 3P pulled into my garage once. If you don't meet the monthly minimum demand, they fine you. HA! That was the end of that.

author: PaulAm
author_rank: Frequent Contributor
timestamp: June 11, 2013, 11:02:12 pm
content: I've been using a 5 hp Yaskawa inverter for years to run 3ph equipment off of single phase.It depends on the inverter circuitry, but since you're turning 3ph AC to DC and then synthesizing the output from that, many inverters will run fine from single phase, you just have to derate them somewhat. Mine doesn't care that it's on single phase.

author: digsys
author_rank: Unknown
timestamp: June 11, 2013, 11:08:34 pm
content: Apart from the ripple factor, many "smart" designs have extensive current waveform analysis for controlling the "loop".So there are many types that wouldn't work at all, or continually trip. You could always just try it. Ripple and noisewill be quite bad though, just de-rating it may help. ymmv

author: superUnknown
author_rank: Regular Contributor
timestamp: June 12, 2013, 12:34:59 am
content: I decided to follow Dave's advice!Lookee, lookee! phase to phase short. Maybe the trace delaminated from the board?Man this thing is garbage!I soldered in some botch wires. The old Chinese drive lives again!!!

author: ignator
author_rank: Regular Contributor
timestamp: June 12, 2013, 03:54:10 pm
content: Quote from: superUnknown on June 12, 2013, 12:34:59 amWow, that is a burnt board. You do want to remove any of the good copper from the carbon burnt area.The first design error I ever made back 30 years ago, was with FR4 board in avionics application. This was for +28VDC system. Happened to be a open/+28 discrete input from the aircraft into the autopilot. In this case it was a pitch trim discrete input. Lesson #1 +28 discrete inputs are sourced from the +28volt power system, there is a 2amp fast blow circuit breaker (takes 900milliseconds with 1000% over current to trip). 900 milliseconds of fault current is an ETERNITY. As the discrete input had 300Kohm resistance, this was the max load current I worried about. BUT there was a test connector for the flight test engineer to plug his equipment into. The SOB hot plugged a 50 pin cannon D connector on what were exposed pins (lesson #2, never use pins with power that can be shorted by flight line mechanic), and as these are avionics quality connectors the shells were all metal, and he shorted just one of these discrete pins to ground. Well that blew up the circuit trace in a 8 layer PWB. The CB never tripped. There was a ground plane in this board, and this discrete input signal now had a path to ground. FR4 board material (G10 with some fire retardant) converts to carbon real easy. This now was a smoke releasing firecracker fuse that continued to burn along the path back to the input connector. However there was +28 power traces, and other open/+28 discrete inputs, found along this burning trace, which also started to burn like a firecracker fuse.My point is to make sure you grind back the copper traces if you haven't already so that there's no way your AC input can continue it's joy of releasing lots of smoke. It's interesting to find that an insulator can be converted into a good conductor, which will continue until the black carbon is converted into gray ash.It looks like Huyan design put in places in the solder resist, I wonder if the intent was to apply extra solder for current carrying along those strips. But production simplified assembly. Or the original design used 3 or 4 oz PWB copper, which was found to cause solder problems on fine pitch parts.At least this thing don't fly in air planes.

author: SeanB
author_rank: Super Contributor
timestamp: June 13, 2013, 04:08:01 pm
content: I feel the pain.......16 layers of flexiboard soldered to assorted connectors and the backplane and a maintenance connector with 200 pins that are so fine....... Break a pin there and you have a problem. Especially as each layer of the flexiboard had to be ordered singly, and each cost around $1000. There were a lot running around with broken pins, as luckily not every pin in that 200 pin connector was used, some were not connected, and some were redundant grounding connections for screened cables in the test cable, and it worked well enough with only one end of the screen connected. We could never get all of those flex boards off intact, way too many connections on the whole pile of panel connectors.I was lucky with the majority of my equipment, there it was all wire wrapped connections on the backplane, 10 000 wires on pins, all white, and all with a modified wrap and then soldered for good measure. I only ever broke one pin, and took a week to change that plug.