1 1/2 HP motor conversion

[henjulfox]

I've finished my 1 1/2 HP motor conversion. It's certainly been fun, frustrating, and educational. Thanks to the folks who helped me through the frustrating parts, both with answers to questions and previous posts I was able to look through.

I've got tested output figures. Wired in the stock delta configuration going into a 24 volt battery bank I get:

Cut in at 210 RPM

90. Watts at 300 RPM
    
220. Watts at 400 RPM
     
340. Watts at 500 RPM
     
     

I can't test higher RPM without popping the circuit breaker...

2 Questions. 1) How do my output figures look? Have I done a job that would make Zubbly proud or do I have an expensive boat anchor? 2) For a matching blade I know the answer is to use the blade calculator. Could someone give me a little more detail on how to use the calculator to derive a matching blade size/TSR.

Thanks,

-Henry

[Warrior]

Henry,

I think it's quite good figures. It all depends on how much money you spent on the project. With lotts of magnet material, it quite easy to get decent power, but neos are expensive. I couldn't spend that much so I made pole pieces to concentrate the flux and get the gap really tiny. I used (per pole) four 30 mm x 4 mm round magnets stacked in pairs plus two 24 x 3.5 mm stacked on top of these, and on top of that the pole pieces. Here's what I got with a 3/4 conversion @ 12 volts:

225. rpm  12.6 watts
     
335. rpm  28.8 watts
     
433. rpm  53   watts
     
590. rpm  93.5 watts
     
777. rpm  132  watts
     
1000. rpm 150  watts
      
      

As you can see my genny needs too much rpms. I had to use a chain drive with it. Your set up it will run slower and make more power with a direct drive prop.

Let us know how it works when it's flying.

Good Luck,

Warrior

 

[zubbly]

hi Henjulfox!

sounds great!

a few questions.   what is the name plate data, what and how many mags have you used,

                   how many leads on the stator and how are you calculating your                      output?

zubbly

[henjulfox]

Zubbly,

Plate reads 1 1/2 HP, Service factor 1.15, volts 230/460, 3 phase, 60 Hz, Amp 5/2.5, RPM 1735, Time rateing Cont. She is a nice, finned cast aluminum body.

Magnets are 4 pole, 2 arc neos per pole, neos 7/8" wide by 1 1/2" long each. The neos go beyond the end of the rotor (wasted) by around 1/4". On each side of the pole are 2 samurium magnets I had laying around. My poles aren't quite wide enough so they help. All glued on with lots or JB Weld.

Wireing is the stock "low voltage" scheme which I believe to be delta. I tried twice to find the connection point and gave up twice for fear of ruining it.

Testing was spinning it with a 90 VDC 1/2 hp motor which has an attached generator/tachometer rated at 20 RPM/Volt. I would run the output directly to my main 24 volt battery bank through an amp meter. I would get her running, read the amps and battery bank volts, volts X amps = watts, and record the generator/tach voltage X 20 to get the RPM.

I spent some time searching the board and the 1 1/2 conversion you sold on E-Bay was the only posting I found that showed Watts vs RPM (though I swear I've seen other postings in the past). My output looked to be a little below yours, but not enough to be ashamed of.

Thanks,

-Henry

[zubbly]

hi again Henry,

approx 99% of motors that size in dual voltage 3 phase come from the factory as 1 and 2 circuit star.  but don't worry about it, your output is pretty good as is and will make a fine gen. (with no skew to your mags, how is the cogging? ).

if you connect your stator for high voltage, you will have cut in at 1/2 the rpm and may work out as a super low speed gen. you could use a contactor arrangment to switch from 1 to 2 star depending on your wind comditions.

i think a 9.5 foot diam prop at tsr of 6 or 7 may work out very good.

fantastic job!

zubbly

[henjulfox]

Thank-you for the words of encouragement!

Yes, in the "high voltage" configuration the cut-in was around 100 rpm. The wattage I could get out of it was enough lower that (for now) I'm sticking with the low voltage.

I never understood the 1 and 2 star description but as I read your reply and picture the diagram it just clicked. It is wired for 2 stars with short legs instead of the 1 star with longer legs I could get from breaking the star point. I get it! I may try the third time to find and break the star connection.

The magnets are skewed, following the laminations on the rotor. I can just barely start it with 2 fingers. I don't think I will have any problem with a large blade starting it.

My big question is how did you get the 9.5 diameter prop number? The "equation" with wind speed, prop diameter, and TSR has 1 too many variables for me to "solve". I just know that there is a trick out there for solving that I haven't found yet.

Thanks again,

-Henry

[zubbly]

henry,

lol, there are too many equations for me to.  i picked the 9.5 foot from observations i have done with my other similar units. usually i am pretty close.

you may wish to have someone help you along with a more scienticfic approach with the proper calculations.

let me know how close i was please.

zubbly

[henjulfox]

Fair enough.

I'll try plugging in your numbers, see what I get, and then mess around for a while and see where I end up.

If your ever in Oregon I'll buy you a beer.

-Henry