#$%@$#@ <--- (insert favorite swearword here), IT WORKS !!!!

[Arlo1]

Since I can now do sensorless I modified a small RC motor I have
lying around. It's seen some abuse (notice the wiggle in the rotor)
It's a Scorpion 4025 with the factory windings removed.
(4025 = 40 mm diameter, 25 mm magnet length). It was much harder
to start sensorless (needs messing with the parameters) and took several
attempts but I got it going. My bicycle motor starts very very easy but
after watching the video I think you'll agree this RC motor is a bit
too extreme I did this test just to indicate the capabilities of my
controller.

The video shows the motor running, first fast, then very slow. After that
it shows the (low inductance) stator windings and the output stage.

33 V supply, 97 kHz PWM, 40kHz loop frequency, current controlled.

What inductance? 97khz? how warm do your fets and fet drivers get? You should put a load on it. Maybe put some heat sinks on the fets first.

[deVries]

Wouldn't it have been much easier to start with more poles wound? 20 pole RC motor vs 10 pole?

Sounds Sweet. You took it all the way up to 33v at how many amps?

[Lebowski]

Got it dailed in a bit more now You can see how easy it is to (sensorless)
start this 3 x 5 windings RC motor. The laptop (next to my ugly mug in the
reflection) shows the real-time phase information available in the algorithm.
Notice when i spin the motor by hand to start it, the algorithm almost immediately
knows the phase.



to Arlo: the 97 kHz is pretty random, it's a non-integer multiple of 40kHz (the main
loop frequency). In the above vid I changed it to 77 kHz. At 77 kHz the output
stage takes 10 W to switch, the motor takes an additional 5 W at 2000 rpm.
It takes (additional) unmeasurable power at slow.

[Lebowski]

Wouldn't it have been much easier to start with more poles wound? 20 pole RC motor vs 10 pole?

Sounds Sweet. You took it all the way up to 33v at how many amps?

that's the whole sport, to use a motor with minimal back-emf and low L and still get it to work

[Arlo1]

I just found these boards for someone who wants to see if they can use this chip and thier own powerstage to make somethign cool!
http://www.ebay.ca/itm/MCU-BOARD-DEVELO ... 1c200b3dcb

[deVries]

Time for a friction belt like on an exercise bike or some kind of quick & dirty load... hand with thick gloves on... rim/disc brakes... anything!

[flathill]

Wouldn't it have been much easier to start with more poles wound? 20 pole RC motor vs 10 pole?

Sounds Sweet. You took it all the way up to 33v at how many amps?

that's the whole sport, to use a motor with minimal back-emf and low L and still get it to work

Sweet! That is low L for sure...think it would work with one of these ultra low L motors:



"The stator is made from 29 gauge, M15 electrical steel laminations that are stacked and bonded. Trapezoidal bars of aluminum are inserted into the stator core, exceeding 90% slot fill (compared to less than 50% for motors with traditional copper windings)."

These type of motors would cease to give low wage countries an advantage (no hand winding)

I wonder if you could combine your tech with a current source inverter http://www.ornl.gov/adm/partnerships/ev ... ersion.pdf

[liveforphysics]

We have a solid-slot motor like that at work. It actually comes with giant inductors made to mount in-line with each phase lead to make it kinda/sorta controllable.

The work that Lebowski and RickNZ are doing here with ultra high speed PWM and current control is the key to enabling designs like solid slot motors.

[flathill]

Yup they are laying the groundwork for when SiC MOSFETS come down in price

What are you using that motor at work for?

[Lebowski]

We have a solid-slot motor like that at work. It actually comes with giant inductors made to mount in-line with each phase lead to make it kinda/sorta controllable.

The work that Lebowski and RickNZ are doing here with ultra high speed PWM and current control is the key to enabling designs like solid slot motors.

Isn't Ricky building the (known) sensorless FOC as decribed in the Microchip / NXP application notes ?
Here I'm using something that is not sensorless FOC. There are no extra inductors in series with the
RC motor. Tomorrow I'll try to see what happens if I go to 3 x 4 windings or even less...

High speed PWM... we're talking like anything over 20kHz is fast but audio class D amplifiers work at 300
to 700 kHz.

[Lebowski]

sensorless startup



It's a variant of forcing commutation. A certain torque generating current is fed to the motor.
The phase determining algorithm is very sensitive, even a small wiggle of the motor will tell
it whether we're going in the right direction or not. Wiggle in the wrong direction -> phase
remains constant. Wiggle in the correct direction -> phase is increased. The wiggle in the
wrong direction will at a certain point reverse (as the constant phase means the motor is forced
in a certain position, if it wiggle's in the wrong direction it will 'bounce' back, as if an elastic
band is attached to the rotor). A wiggle in the correct direction will advance the phase, encouraging
the wiggle to continue in that direction). Net effect of this is that the motor starts up.

The video shows both immediate startup (initial wiggle is in the correct direction) or a 'bounce back'
for an initially wrong wiggle. Notice that in all cases the motor spins in the same direction in the end.

What happens if initially there's no wiggle ? The noise in the phase algorithm will 50/50 detect a
correct / incorrect wiggle. So 50% of the time the phase is increased. This will drag the rotor along
which is interpreted as a 'correct' wiggle -> motor starts.

This is very useful for if you have a Mac motor with a one-way clutch in it, with this startup
addition the controller can now operate the Mac in sensorless mode.

It's quite stubborn and would probably be able to start under load (notice its pulling in one direction) :


HAPPY NEW YEAR EVERYBODY !

[deVries]

This is very useful for if you have a Mac motor with a one-way clutch in it, with this startup
addition the controller can now operate the Mac in sensorless mode.

It's quite stubborn and would probably be able to start under load (notice its pulling in one direction) :

HAPPY NEW YEAR EVERYBODY !

My Mac says Happy New Year to You!

I'm really very excited about your progress...

Thanks

[flathill]

Damn dude I think you are a natural! Time to build dyno

What is your special signal to initiate the wiggle on sensorless startup? You can try signal injection at 20khz or more ideally a resonant frequency of the coils to sense position so there would be no initial jerkback

[Lebowski]

powertest on my hometrainer 'dyno'

Sensorless startup, under load. The power supply that I have is almost maxed out during this test.
6 FET uncooled output stage (when you're not running it for too long of course).

I see $700 worth of batteries in my future

You can hear when the sinewaves start clipping by the sound the motor is making. The rateling
noise is the motorchain tensioner, is has one of those rattling derailleur wheels in it. In the
second half of the video the mechanical output power , powerstage and supply voltage/current
is shown. Efficiency on the flay looks good . If you're wondering, the pedals of the bike
need to turn for the hometrainer/dyno to work, else it cut out thinking you're taking a break.

[deVries]

Outlandish

At your pace within a month or two we'll have 100v 100amp out of this beast

[c_a]

...we'll have 100v 100amp...

400amps please well done L.!

[Lebowski]

Outlandish

At your pace within a month or two we'll have 100v 100amp out of this beast

Well, with SWMBO out of the country I had lots of time during the holidays
The spectacular part is over now as it all works as expected. What I need to do
now is add a throttle to the controller (I now have throttle over CAN bus). I'll
make it such that you can choose to be a 'throttle master' or a 'throttle slave'
The master has the (analog) throttle connected to an ADC (with calibration of course)
and has the option to transmit the throttle information over the CAN bus. A
'throttle slave' controller then can receive this info and use it. This to be able
to build a dual motor bike with dual controllers operating on 1 throttle.
Then I need to upgrade the RS232 menu system to include all possible parameters
for the user to play around with.

About regen, would you guys want to have regen ? It's easy to implement, the throttle
signal is a 2's complement value. Positive means the motor drives the bike, negative
would mean regen. At the moment I only use positive values...
How does the throttle look for regen ? To me either 1 of 2 scenarios looks feasable. One
is where you have a spring loaded twist grip which you rotate one way for acceleration
and the other for regen. Another scenario would be where you have two 'throttles', the one
on the right handlebar a twist or thumb type for acceleration and on the left handlebar
a thumb throttle for regen. The second scenario (two analog signals, one for throttle one
for regen) is by far the easiest to implement...

At the moment when I close the throttle (motor current = 0) there is a tiny amount of regen.
I've seen over a 110V on the displays of my 60 V supply, thanked the lord on my
knees it didn't blow my power supply !

The 400 amps you'll have to try out yourself Christian

[Miles]

Truly inspirational thread Lebowski.

Yes, we definitely need regen. I'm in favour of the second scenario (separate throttles) - this would also suit pedelec type control.

Another feature which would be useful is instant reverse. I think we'll see more retro-direct gear change systems in the future...

[flathill]

Two throttle with variable regen is more flex
You always can just use one if thats all u need and you want to brake with a preset "engine brake"
please i need this feature

[deVries]

Truly inspirational thread Lebowski.

Yes, we definitely need regen. I'm in favour of the second scenario (separate throttles) - this would also suit pedelec type control.

+++inspirational... especially, if this goes to completion to actually work on the road... I dare say, no, I know, Lebowski you're going to be extremely famous and mostly appreciated (if you shun the fame ) on ES.

If you want to do regen, then I'm with Miles.

Instant reverse is very spooky. Is that technique done elsewhere in the transport universe?

[Miles]

Instant reverse is very spooky. Is that technique done elsewhere in the transport universe?

Seems to be more popular in the communication universe

[nieles]

what kind of power stage are you going to design for this?

[Gordo]

Second tumb throttle for regen, Please.

[Lebowski]

Second tumb throttle for regen, Please.

I'm thinking about putting 2 what I call 'polynomal' throttles in

x1 = raw analog voltage throttle pin 1 but scaled and calibrated to result in a 0..1 range, then
y1 = -1..1 (range) = a1*x1 + b1*x1^2 + c1*x1^3

x2, same as x1 but different analog throttle pin on 30F
y2 calculated using a2, b2, c2 and x2

Then motor current (so torque) = max phase Current * (y1 + y2)

With the a, b and c parameters you can get creative and make linear, exponentional or square root type curves.
For regen you just have to make a,b,c such that the resulting y is negative. Different curves for positive
(motor powers bike) and negative (regen) with different ranges are possible in this way. I think this is the
most flexible setup and relatively easy to calculate in assembly (as the 30F has a hardware multiplier).

[Lebowski]

what kind of power stage are you going to design for this?

That'll be the next step... first I want to finish the 30F4011 brain so people who want can
do a transplant in an existing controller or build their own output stage around it and test
it on their motors. Now that it runs under load and with a bike and an RC motor I'm getting
really curious on how it will perform with different motors

For my own bike I'm considering 6 or 12 4115 's as I'll be running around 100 V on my bike (for a
battery I think I'll put two ping 48V10Ah in series, > 100V hot of the charger). That or I'll stay
with a combination of NMOS and PMOS transistors.

Stuur me een PM als je handig met een soldeerbout bent en mijn controller op je motor wilt uitproberen.