bigmoose wrote:Guys I think I will have some data to offer that might help when I can get a little time to create the external flux maps for a quadrant of the large Turnigy outrunner. A really good friend of mine got me one for my birthday! So now I have no excuse to not get busy and work on sensoring it. Below is a little picture of me with my Bell 9640 Gaussmeter. First off, the Turnigy leaks flux out the backshell, we know that because the paperclip sticks. But now we know the magnitude, around 900 Gauss maximum. But the flux leakage end effects make for a very, very interesting pattern... it looks like they even reverse polarity when running in the same radial position but scanning axially from bell to bell. I haven't tried measuring the effects of an energized coil does to the backshell residual flux. That will need to be done also after the static case. Preliminary results says that folks are placing the sensors in a non optimum position, too close to the static bell.
If you want a measurement in a specific spot, let me know and I'll try to knock it out first for you before I do the labor of the mapping.
Bear with me, I don't work on as fast as you guys do on the non client work.
If you have time to test the performance of a true 30- 60 or 120 vs the 34.3 I would really like to know
Thud wrote:I will trust a gaussmeter over my "guessmeter" any day.
Your explanation makes sence, but It is a different view point.
You don't sound so certain yourselfBut we need 3 equally spaced sensors, 51.42/3 = 17.14 degrees between the sensors (I think .)
I don't know enough to make it a debate, My thoughts were based upon the stator teeth & 3 phase power.
logicly, the magnet poles are the hall trigger for the coil charging sequence, but they are angularly varient by quantity.
I thought the charge angles in the stator (60 degrees) would determine the correct spacing of the triggers. The magnetic pattern of the poles are a repeating pattern.
you may have a formula though that does the exact same thing
If you have time to test the performance of a true 30- 60 or 120 vs the 34.3 I would really like to know.
Wheres Fechter when you need him?
Thanks for the info. T
bigmoose wrote:Luke, there is always a twist and turn in the road. I went back and looked at your twin Turnigy bike build thread, and it looks like I have the new Generation 2 Turnigy C80100-130; and your build might have used the first Generation. My silver outrunner bell looks longer than yours and is 3.130 in. ish from memory. Also mine has a big, like 2 inch ish bearing on the stator bell, I also have the screws on each end. (ish is a technical term that means I'm too tired to go back downstairs and remeasure it... so I go from memory!)
That said, I may have much more dead space in my version of the C80100 near the fixed bell than you do.
Looking at my flux chart it implies my magnets are around 1.5 inches long. Do you know how long yours are?
Always a twist, isn't there?
Burtie wrote:Thud wrote:Burtie,
Can you (or anyone please) give quick explanation of the math to arive at the 34.3 deg?
I justified it to myself like this:
Given that we accept 120 mechanical degree spacing works for a 3 phase motor like this one.
The can has 14 evenly spaced magnets around it.
So for one revolution, the magnetic pattern repeats 7 times.
We could put a hall sensor in any one of 7 positions and it would give the same signal.
The spacing of those positions is 360/7 = 51.42 degrees.
But we need 3 equally spaced sensors, 51.42/3 = 17.14 degrees between the sensors (I think .)
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