There's a couple different pieces to the puzzle, and as always, "best" will depend on more of your applications details. Psedo-sine waves from PWM is a well established technology (it's the underlying process in the commercial VFD as well) Here's a low-ish level article aimed at the Arduino crowd. http://web.csulb.edu/~hill/ee470/Lab%202d%20-%20Sine_Wave_Generator.pdf And a more thorough treatment https://www.wpi.edu/Pubs/E-project/Available/E-project-042711-190851/unrest= ricted/PWM_Techniques_final.pdf Neither is the most definitive I've read on the subject, but it should give you enough to start asking google good questions. Microchip's app notes for their motor control boards absolutely show how to do this. You actually have a _huge_ simplification here because you're looking for fixed frequency where they're constantly adjusting for the movement of the motor. You can also significantly improve the output waveform through filtering. Filters are about as unique as snowflakes, but a cap or two, and an inductor should get to a fairly close approximation of sine wave - my suggestion of the low voltage motor board and using "filament" transformers in reverse to step up the voltage was based on the intent that the transformers them self act as part of the filter. As to the commercial VFD option. I've not used the Schneider part. It was the first one I found that seemed to meet your specs. At the heart of it _all_ VFDs take the incoming line voltage, rectify and filter it to a smooth DC before chopping it back up at a different frequency. The smallest ones use 110V single phase as the input and the larger ones move to three phase, but this is based on available input energy. 110V single phase becomes impractical at 100s of amps. :-) The PDF datasheet for the Schneider unit I linked (pg 11) gives: ATV12****F1 100 to 120 single-phase input, 200 to 240 three-phase output I think I missed that on the first pass, sorry. I thought this one had 110 V output capability. It may still be an option, but you would need step down transformers, which at your power level is pretty much any transformer with a center tapped primary winding. Since you need transformers anyway, I'd point you at Automation Direct. Their smallest unit ($99) http://www.automationdirect.com/adc/Shopping/Catalog/Drives/GS1_(120_-z-_23= 0_VAC_V-z-Hz_Control)/GS1_Drive_Units_(120_-z-_230_VAC)/GS1-10P2 It really depends on you and your application. If you are just playing with something on the bench, I'd do one thing, if you are setting up something for other people to use, I'd do something different. If you're setting up something instrument grade for testing, I'd do yet a different thing. Also depends on your budget for both time and money. -Denny On Tue, Sep 15, 2015 at 3:05 PM, Brooke Clarke wrote: > Hi Denny: > > The Microchip BLDC eval board drives the 3 phases with bipolar DC pulses, > not sine waves so probably will not work for > the 22,000 RPM motor (I think it's an induction motor, but can't find tha= t > information in the manual). > > The Schneider Electric variable frequency drive looks very interesting. > But their web page is very user hostile (only > works with WIN 8) and on WIN XP displays two overlapping pages and so > links don't work and no way to contact them to ask > questions, such as do you need 3-phase input on the unit that has 3-phase > output (that's what the manual shows). > > > Mail_Attachment -- > Have Fun, > > Brooke Clarke > http://www.PRC68.com > http://www.end2partygovernment.com/2012Issues.html > http://www.prc68.com/I/DietNutrition.html > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .