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View Full Version : Multi HP single phase in VFD's now available



Forrest Addy
05-29-2008, 03:14 PM
Looks like the VFD people are looking around for potential markets. Gold Star has 5, 10, 15, and 20 HP VFD's featuring 230 V single phase in. No de-rating.

I don't know the particulars but you with larger single motor machine tools on phase converters might be interested.

Search on eBay, using "phase converter vfd"

Doc Nickel
05-29-2008, 04:36 PM
Speaking of, is there such a thing as a VFD for a single-phase motor?

Doc.

RobbieKnobbie
05-29-2008, 05:12 PM
I posted this a while back...

single phase motor vfd thread (http://bbs.homeshopmachinist.net/showthread.php?t=28582)

J. R. Williams
05-29-2008, 07:54 PM
Nothing new -- I installed a 75 hp, 480 volt, three phase unit on two boiler forced draft fans about 25 years ago. Emerson Electric was the manufacturer. The larger units have been around for while but out of the price range for the home shop.

JRW

MickeyD
05-29-2008, 09:36 PM
Those look pretty sweet. Anyone know anything about the manufacturer? I have generally stuck with Teco Westinghouse VFDs and have been very happy with them. I hope that they bring out something similar. The next step will be one that you can feed DC into and get 3ph out of (would make a sweet little electric car).

J Tiers
05-29-2008, 11:18 PM
The next step will be one that you can feed DC into and get 3ph out of (would make a sweet little electric car).

EVERY vfd has that feature....... it just isn't talked about much. Every single one converts AC into high voltage DC and then "chops" that to make an output sufficiently similar to a sine wave to successfully run a motor.

As a practical matter, there may be reasons why you can't actually do it, such as the input diodes can't take full current in a single set (they are often rated to take it only when it is spread out among them). But the addition of two terminals (or clever soldering of wires inside unit) would allow it.

Incidentally, my boss is actually the US agent for the UK company which makes the VFDs (single and 3ph input, single and 3ph out) mentioned in the other thread. I have considered selling them into the HSM market, since I could get them at a comparatively good price, but most of them have features (and price) that are not needed here, and which do drive up the price. That may change.

barts
05-30-2008, 01:28 AM
Those look pretty sweet. Anyone know anything about the manufacturer? I have generally stuck with Teco Westinghouse VFDs and have been very happy with them. I hope that they bring out something similar. The next step will be one that you can feed DC into and get 3ph out of (would make a sweet little electric car).


http://www.curtisinstruments.com/index.cfm?fuseaction=cProducts.dspProductCategory&catID=8


- Bart

NiftyNev
05-30-2008, 06:05 AM
Is a VFD and a VSD the same thing?

http://cgi.ebay.com.au/Variable-Speed-Drive-2hp-still-in-sealed-box-warranty_W0QQitemZ260243384309QQihZ016QQcategoryZ1 54951

Nev

tmarks11
05-30-2008, 08:54 AM
http://www.curtisinstruments.com/index.cfm?fuseaction=cProducts.dspProductCategory&catID=8

You had me hoping that we had stumbled onto an DC-AC controller which would allow normal 3phase motors to be used for electric drives in boats or cars.

Not the case. These Curtis controllers are designed to work with AC induction motors designed around a 0-30V input range. I am guessing sticking a 3ph Lesson motor on this controller will cause the motor to burn up.

From curtis' FAQ page:
Can I use an industrial motor with the Curtis AC controller?
No, the industrial motors are wound for high voltage operation. The AC induction motor controllers designed for material handling applications are wound for low voltage, typically in the 15 50 V rms range. We work closely with motor suppliers and can help you to locate a suitable motor.

MickeyD
05-30-2008, 11:52 AM
Curtis does make a line of DC motor controllers but they do not have a great reputation for reliability in electric vehicles. I hope that they get a little more serious about the market with the predictions of $200/bbl oil coming around the corner.

http://curtisinst.com/index.cfm?fuseaction=cProducts.dspProductCategory&catID=11

tmarks11
05-30-2008, 01:51 PM
Curtis is known for cheap golf cart controllers, but those are DC->DC somutions.

It would be nice if there was a 24Vdc->240Vac packaged controller, which would allow you to use cheap 3ph industrial motors (at least cheap compared to the price of brushless DC motors).

I haven't really seen any canned solutions; it would be energy prohibitive to use a 24-240 inverter to take battery voltage and produce 240Vac to drive a VFD.... and kind of pointless since the VFD doesn't really need AC input power.

24->240 Vdc solid state solution would probably be expensive, the economical solution would be 24vDC-24vAC inverter (square wave, don't need a nice power robbing sine wave here, just need something to drive the transformer)->24-240V step-up transformer->VFD.

RobbieKnobbie
05-30-2008, 06:22 PM
I can't imagine an induction motor - even a three phase induction motor - having the start up torque that would be needed for a vehicle application. DC motors on the other hand put out gobs of torque way down low, which is why they're used.

Wirecutter
05-30-2008, 07:50 PM
Believe it. Probably the three most famous performance EVs use 3 phase AC power. All three get their motor and controller from the same company, and the systems are essentially the same. The Tesla Roadster, the Wrightspeed X1, and the Tzero all use various vintages of the AC150 drive system made by AC Propulsion. What's more, they're all powered by a bunch (6813) of 18650 cells. 18650s are the ones slightly bigger than AAs that make up all those laptop battery packs. They're 18mm diameter and 65.0mm long.

Yeah, I've done some EV research. The thing that keeps AC induction motors out of the hands of most of us is that suitably sized control systems are really expensive. If you want to try and run a vehicle off of an industrial VFD, better get a big one. That means it'll probably run on 3-phase 480v. That's 480v RMS, so the DC bus in after rectification is closer to 650v. That's a big string of batteries.

Sorry for the hijack - for more go to www.diyelectriccar.com/forums (http://www.diyelectriccar.com/forums)

Members here will be familiar with the format.

(I have no affiliation with any of the vendors I mentioned.)

-Mark

tmarks11
05-30-2008, 09:03 PM
I can't imagine an induction motor - even a three phase induction motor - having the start up torque that would be needed for a vehicle application.
I am more interested in electric drives for boats, which have the advantage of not needing alot of torque at low speeds.

barts
05-31-2008, 12:01 AM
I am more interested in electric drives for boats, which have the advantage of not needing alot of torque at low speeds.

For a displacement boat, a DC drive works quite well - you're just limited in terms of range. Displacement boats need 1.5 to 3 hp/ton (that's what steam launch power levels are). Lead acid batteries get you about .035 KWH/kg,
so 1000 lbs of batteries will yield around 20 hp-hours, so a 2500 lb boat w/ a 2.5 hp motor should run all day at 5 knots or so, depending on length and fineness of line...

The real advantage of AC drives is a more efficient and flexible power band. A displacement boat drive is a much simpler problem...

- Bart

Forrest Addy
05-31-2008, 12:37 AM
Don't ever think AC motors develop less "torque" than AC inductin motors. It's my experience whereever this topic came up apples were inevitably compared to oranges.

In days of yore diesel electric locos had DC drives. Now they are AC motor drives running from a specialized VFD fed from an alternator connected to the engine and not only a bit more efficient and lower in cost to maintain - no brushes, brush rigging, contactors, or comm to fiddle with.

It's true there is a bit more very low RPM torque associated with a compound wound DC motor but how much of driving time is spent smokin' the rear tires. An DC chopper drive is pretty efficient too but given the expense and complexity of a DC motor I would prefer an AC motor with its two essential parts that are reboust and almost trouble free. And they still start those enormous inertia loads and haul them over mountains.

I don't say this to stir up a controversy but the big money is shifting to AC controls and technology. DC brush motors will be around for some time but sooner or later brushless DC will take over. Even now small brushless DC motors are driven with a single chip and competing very nicely with brushed motors where long trouble free service is a factor..

barts
05-31-2008, 01:32 AM
I'll completely agree w/ Forrest - one of the big advantages of AC drives is that the torque stays strong at high rpm. I test-drove an EV-1, which had an AC drive that wound out to something like 8000 rpm. Smooth - no tranny, just smooth torque, a slight whine/whistle from the controller, and excellent acceleration.

- Bart

BobWarfield
05-31-2008, 11:47 AM
I can't imagine an induction motor - even a three phase induction motor - having the start up torque that would be needed for a vehicle application. DC motors on the other hand put out gobs of torque way down low, which is why they're used.

Take a look at vector drives for low end torque. Sensorless drives have a much broader torque band than a vanilla VFD, and adding an encoder can get you full torque at 0 rpm for many units.

These two have come down radically in price lately. Vector drives are commonly used for CNC spindles these days and they perform well over extremely broad ranges usually with only 1 hi/lo gear range.

Cheers,

BW