Building a VFD for single phase input to control a 3HP 3 phase motor
Building a VFD for single phase input to control a 3HP 3 phase motor
(OP)
Can anybody tell me where I could find a detailed schematic to look at so that I could possible build my own variable frequency controller for some of my machine tools?
The controller would have to be 220V single phase input to run the equipment which is 3HP or smaller . Maybe somebody has already built one at home and can give me their lessons learned.
The controller would have to be 220V single phase input to run the equipment which is 3HP or smaller . Maybe somebody has already built one at home and can give me their lessons learned.
RE: Building a VFD for single phase input to control a 3HP 3 phase motor
http://www.patents.ibm.com
or
http://www.delphion.com
or
http://www.delphion.com/patquery
and type the below patent number.
us4730242: Static Power Conversion and Apparatus Having Essentially Zero Switching Losses
Inventor: Divan; Deeppakraj M., Madison, WI, USA
This item will need to engineer, design and build a rectifier from a single phase to DC according to your specifications.
RE: Building a VFD for single phase input to control a 3HP 3 phase motor
Anyway, to the answer you are seeking, I can't give you a specific reference (or a specific design) to help you design a single to three phase VFD from scratch. If you are interested in building one for the fun or challenge of it (more power to you!), there are "hobby" books available with cookbook designs for electronics which may include what you seek. Try Barnes and Noble (they have a website). If you just need to come up with a VFD, I can tell you that the device you are describing is commercially available and relatively cheap. For the heck of it, try WW Grainger (they have a website too), you may decide that it is not worth design/building it yourself from a cost versus hassle standpoint.
RE: Building a VFD for single phase input to control a 3HP 3 phase motor
RE: Building a VFD for single phase input to control a 3HP 3 phase motor
http://www.thomasregister.com
under Service/Product
RE: Building a VFD for single phase input to control a 3HP 3 phase motor
Not knocking your idea - go for it.
But, a collegue of minor is very into woodworking machines at home and I suggested he use an obsolete vf drive we had for his machines he said that when you are slowing the tools down you are usually looking for a lot of "grunt" and you get that by changing the belt "ratios". His experience prior resulted in a burnt out motor.
Now if that isn't a concern to you try browsing through the local second hand machinery sellers there may be a cost saving there.
If you go ahead I suggest browsing thru the hobby electronics mags and your local electronics hobby stores for data books.
In Australia try www.siliconchip.com.au.
keep us posted hey
regards Don
RE: Building a VFD for single phase input to control a 3HP 3 phase motor
Even if you do not overload the motor (ie. never exceed nameplate current at any speed), you will probably still burn it up. The killer here is cooling, or lack of it. For a standard TEFC motor, the speed range over which you can operate at full torque may vary from less than 2:1 to as much as 4:1 (don't confuse with gear ratios/torque multiplication). This means that a 1800 rpm motor may be able to run full torque at 900rpm (a.k.a. 2:1 constant torque speed range) or even down to 450 rpm (4:1 CT speed range) before the lack of cooling causes it to exceed the insulation temperature rating (ie. burn up). The variables here are fan design, type of enclosure, and insulation temperature rating. Normally you need a motor with a separate blower (ie independent of shaft speed) to achieve speed ranges greater than 4:1. My guess is that a machine tool (woodworking, etc) motor has very little constant torque speed range (it certainly wasn't designed for one).
I don't know what type of pulley ratios you have, but I would bet that there is some serious speed reduction/torque multiplication going on. If so, the pulley system you have is the best way to do what you want. It would be quite costly and electrically ineffecient to size a motor for direct drive (ie many times bigger than what you have now) and then add the requirement for a wide constant torque speed range.
I know you were hoping for a different answer, but I hope this helps.
RE: Building a VFD for single phase input to control a 3HP 3 phase motor