ELECTRIC TRANSMISSION DELTA /WYE and SERIE/PAPALLEL stator

I bet that's a custom chainring? If not where can I get one. I'm thinking one could slap that on the LHS of the rear wheel and drive it with a motor to get a one-stage reduction.
Sorry for hijacking the thread :oops:
 
Hi Paul,

You can get up to 75t chainrings, from stock, here: http://www.ligfietsshop.nl/en/webshop/cog-wheel.html

80t from Greenspeed, at a price... http://www.greenspeed.com.au/gsparts.html
 
80T $290.00? WOW!!!

that would be about 12.75 inches diameter. a big ring. but i think the one in the picture is still bigger. if the wheels are 26 or 27 inch that thing must be around 20inches in diameter and over 120 tooth.

if he can pedal that from a standing start i'll bet his legs are strong enough to crack Brazil nuts between his kneecaps.

rick
 
Another update for me, I just got my motor the other day, but I got it apart (with the help of an air hammer (just a little metal damage on the side cover)) and removed the old wiring w/ big rubber casing. The wires them selves didn't seem all that bad, so I re-used them, cut them in half, and shoved all 6 + hall wires down the shaft.

I un-soldered all the old connections, and now have everything soldered up again. I'm now looking for some small string to tie up the wires like it was when it came.

Now I am just waiting on the relays to get here! (well that, and getting the thing laced up in a rim.)
 
OK Gurus!

More questions. I have almost finished my throttle interrupt circuit (it works) but I would like to have the throttle cut out slightly before the realys switch from delta/wye as this allow the phase lines to come to 'rest' so there is no load for sure. my question is how long from when throttle cut off will this take? if it is instant then great. I was planning on having about 10ms. Will this allow the controller to come to rest in time?

fechter made this comment:
caleb7777 wrote:If the +5v to throttle is interrupted, it will send a throttle output of 0 yes? or no?
Click to expand...


Yes. Interrupting the 5v to the throttle will do about the same thing as pulling down on the throttle line, but with less chance of frying the throttle.
Click to expand...


Which route is safer? (and fast, we are talking ms) I can easily cut the 5v+ to throttle because of where this circuit will be but I could also do the pull down method if I must

If I should how do I implement it?
 
I just did some on road tests tonight, at 1am, on my un-lit road... speed limit is 45mph :oops: (a little dumb... I know).

In wye, I get 20mph with great acceleration up to about 17 mph. Cruise at around 7 amps at 20mph.
When I flip my switch to go to delta it accelerates up to 30mph top speed. I went a little over a mile and the motor was hardly warm to the touch.

I will have pictures up soon!

Edit: So I was just thinking to my self, my CA is set to a max speed of 30mph. I will increase that limit and re-test tomorrow after I make my self a torque arm.
 
that is impressive a 50% jump in top speed at the flip of the switch.

you did not mention - how well did it accelerate from when you flipped the switch until you hit 30mph?

rick
 
rkosiorek said:
that is impressive a 50% jump in top speed at the flip of the switch.

you did not mention - how well did it accelerate from when you flipped the switch until you hit 30mph?

rick
Click to expand...
VERY WELL! It was just like going from a start to 15, if pedaling along it goes even faster.

My friend clocked me today going 40 driving his car next to me... I didn't think to look at my CA until I came to a stop though, so I don't know if I really was. It took a lot of pedaling to get it up there.
 
After a 6 mile ride, I am averaging 24 wh/mi. I was hardly pedaling, with a lot of hard starts and speeds in between 20 to 30 mph the whole time. My Bafang was warm to touch, but I could keep my hand on it without any discomfort.
 
Just a data point for you boys wanting to run your 9C hard
All last week I ran my 9C 9x7 at 88.8V lipo and >100A current limit
I hammered that 9C testing my new 18 fet controller
Admittedly I had the tiny stock wires inline and they got so hot that I burned my hand at one point.
Motor never got hotter than I could keep my hand on.

Motor did great.
I would say that if you pay attention and know what you are doing you can safely run 24S lipo with an 80A current limit
Just dont keep it under load too long.

I was making 5KW and 7.5KW rips and they were amazing :twisted:

Ok - 88V Delta / Wye -> 200MPH top speed :roll:

-methods
 
So I want to know how many people have damaged their controller using SPDT relays and switching while on the throttle?

I have done it about 10 times now forgetting to let off, but nothing bad happens, just a big burst of speed! lol
 
Yeah I was talking to a friend about this and it seems the only issue should be accidentally switching back to WYE when your at top Delta RPM. Durring the time that the switch from Y to D you open the output so why would this be a problem... I don't know. But the opposite switch at the top delta RPM will send a lot of voltage backward to the controller/batteries. I think that issue is probably not as big as folks make it out to be but I am a NEWB :)

I still want to build that rockin Y to D setup :) and I am lernin bout it.
 
Well switching back hasn't been an issue at all for me either because of the internal freewheel. I know John has a bafang with d/y mod, I wonder if he has had any issues either?
 
Back a few years ago Crystalyte had "Dual Speed" motors. these motors had a tapped "Y" winding. you could power the motor either from the ends of the winding or through the tap. one popular size was a 4011 tapped at 8 turns so you could have a 4011 or a 408.

there was a lot of speculation then, that when switching between windings there would be huge variations in BEMF potentially resulting in blown controllers. turned out that this was not really an issue. the BEMF change was very transient and dissipated very quickly.

not sure that the same would apply for Delta/Star. the Delta configuration creates recirculating currents not present in the Star configuration. i don't know how much effect that is going to have in practice.

rick
 
Joepostal said:
Yeah I was talking to a friend about this and it seems the only issue should be accidentally switching back to WYE when your at top Delta RPM. Durring the time that the switch from Y to D you open the output so why would this be a problem... I don't know. But the opposite switch at the top delta RPM will send a lot of voltage backward to the controller/batteries. I think that issue is probably not as big as folks make it out to be but I am a NEWB :)

I still want to build that rockin Y to D setup :) and I am lernin bout it.
Click to expand...
I know the main issue that Doc had with spdt relays, was that they might not switch instantly and in sync, and short out the phase wires. And if under throttle, that would blow the mosfets. It just seems like if it were going to happen, it would have already after doing it quite a few times.

Anyone with more knowledge want to chime in?
 
One thing I will point out is that switching relays under an inductive load causes a spark.
Not when they close, but when they open.
Each time you do this the contacts get more and more pitted and covered debris

With a low quality relay this could lead to a situation where the performance you experience early on changes over time.
They have fancy Relays (doc has some) that are backfilled with gas to help mitigate this problem but they are big and expensive.

When the rubber hits the road -
I would (and will) without doubt be switching mine under load - (heavy load) - but then I am reckless and i have 37 controllers sitting in my hobby room just in case I blow one one up :mrgreen:

Totally unrelated - When I tune the shunt in controllers I use a big oil heater for a load. It gives me about 10A @ 100V DC. When I pull the lead away I can yank a spark about 1" long. It is like a light show and my wife about has a heart attack every time I do it. After 4 or 5 times the solder pad on the board is trashed. Granted the inductance of this heater is insane, but the same kind of thing happens when you disconnect any circuit that is flowing current through an inductor.

We are relieved of this nasty kickback when we switch the mosfets on and off because they have internal diodes to shunt the surge current back. If there were not giant diodes in the mostfets our boards would be smoke in like 5mS with those tiny little air gaps between the phase and power lines.

-methods
 
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