Voltron-Evo; jonescg's new electric race bike

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Post by jonescg » Mon, 09 Jun 2014, 05:51

Haha, we checked the GPS data and the gearing is way too low. We were more like 150 km/h as the bike exited the corners. At Wanneroo today the new gearing gave us 170 km/h, which was still way too slow, but the bike is handling really well despite the weight. The motor refuses to spin any faster than 3600 rpm or so. Lots of homework to do on this motor controller combination...

https://www.youtube.com/watch?v=I0AclCx ... e=youtu.be
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Post by g4qber » Mon, 09 Jun 2014, 07:07

https://www.youtube.com/watch?v=I0AclCx ... e=youtu.be

for easy clicking.

one of the chargers 8.7A @ 250V = 2.1 kW

70 - 75 secs per lap.
2011 i-MiEV - k kms 217

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Post by jonescg » Mon, 09 Jun 2014, 17:54

Thanks Joseph. The battery pack performed flawlessly. Despite having a bike that's as heavy as my Blackbird with 2/3rds the top speed, he's already lapping faster. Says what a good rider can do eh?

We need to improve the motor cooling, and once that's done we can gear up for more top speed - won't be long before we approach a 1:1 ratio! There is still no regen or field weakening - no idea what's going on there. So much to learn on this inverter.
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Post by winners » Mon, 09 Jun 2014, 21:20

Hey Chris,
                   That all sounds good, if the weight was such a problem it would be showing in the lap speeds and confidence your rider has. That bike is a great achievment I am sure you must be very proud of it.   

The Rpm regen and field weakening could all be a related problem as far as the controller is concerned? Can you see the activation from the bike happening for regen field weakening? While on line to the bike?

Mark

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Post by jonescg » Tue, 10 Jun 2014, 02:15

Hi Mark,
We don't currently have any data collection while at the track - hopefully Mike will have that sorted out by the end of the week. Base speed at a 670 V bus should be something close to 3900 rpm. We're hitting a wall at about 3600 rpm, but the tyre calculations could be off (with rolling diameter at leans and such). It just refuses to spin any faster.

We also have no regen. I can't work out why either, but there's a billion settings we've not started playing with yet. We have the option of a pot which varies regen torque, or a brake switch activated one, which is perhaps better as it means less for Danny to think about.

Today Mike and I added swapped out the radiator with a slightly bigger one and moved the original one right up in front of the ram air intake. It adds yet more resistance to the coolant flow, but hopefully it will shed more heat this way. We were getting the motor pretty warm at Wanneroo.

Of greater concern is the stresses being inflicted on the swingarm. Aluminium has very poor yield strength, so we really need to get onto a custom swinger, ideally with a big enough space for a 6" wide rim.
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Post by jonescg » Tue, 10 Jun 2014, 16:12

Some video of the last couple of testing sessions.

https://www.youtube.com/watch?v=SeonwpE ... e=youtu.be
Last edited by jonescg on Tue, 10 Jun 2014, 06:13, edited 1 time in total.
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Post by Johny » Tue, 10 Jun 2014, 17:13

Sorry if this is over-simplistic Chris. It's not that the Max_speed parameter in the controller is set to 3600-RPM is it?

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Post by jonescg » Tue, 10 Jun 2014, 17:30

Thanks, but that was one of the first things we checked Image
It's pretty close to base speed, perhaps a bit less. So it has to do with field weakening I'd say.
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Post by weber » Tue, 10 Jun 2014, 21:15

Hi Chris, I've finished scouring the manuals
https://app.box.com/s/jqr2e8x17h/1/332470357
and checking the parameter settings you emailed. I sent off two messages to Reinhardt about errors in the inverter manuals. Neither of which help you.

Mistake on page 27 of the CAN manual
https://app.box.com/shared/jqr2e8x17h/1 ... 72424133/1
In the fifth row (-10 Nm regen), byte 0 should be 156, not 246.

Mistake on page 40 of the software manual
https://app.box.com/shared/jqr2e8x17h/1 ... 24798119/1
In the second row, "IQ_Limit_EEPROM_(Amps)_x_10" should be "ID_Limit_EEPROM_(Amps)_x_10".

Regarding field weakening:
You have Veh_Flux_EEPROM_(Wb)_x_1000 set to 147.
The manual says it's the back-EMF constant in milliwebers, but presumably that's really milliwebers per radian which is the same as millivolt seconds per radian. I understand your motor is the AFM-140-4 which is shown here
http://www.evo-electric.com/inc/files/A ... t-V1.1.pdf
as 1.08 Vs/rad. That's 1080 mWb/rad which is 7 times your present setting!
EVO have some very confusing notes after that table:
"Kt, Ke for Star configuration; Ke in Vrms,pp"

I didn't think you got a choice about star or delta since there are only 3 wires and what the hell does "Vrms,pp" mean? RMS and pp (peak to peak) are very different things. The latter being about 2.8 times the former for a sine wave. I'll assume yours is star, and the 4000 rpm base speed with 600 Vdc suggests that the 1.08 Vs/rad figure is based on RMS voltage which is what I'd expect the inverter to want.

So yeah. Try setting Veh_Flux_EEPROM_(Wb)_x_1000 to 1080.

If that alone doesn't fix it, the next thing to try is to reduce Break_Speed_EEPROM_(RPM) from the 4100 that you have presently. Bring it down to something that is obviously lower than your actual base speed, say 3000 r/min. Then if that works, try 3500 r/min etc in a binary search to find the highest value that reliably gives field weakening.

My thinking on this is based on what it says on page 50 of the software manual. "The purpose of this curve is to reduce the torque limit so that the accel input does not try and command torque that the motor cannot deliver. "

It doesn't say what happens when you try to command torque that the motor cannot deliver in field weakening, but I'm guessing it refuses to go into field weakening in that case.

I don't see anywhere that you set the Torque/current constant Kt for the motor so I assume that's implicit in the relationship between the two parameters Motor_Torque_Limit_EEPROM_(Nm)_x_10 and IQ_Limit_EEPROM_(Amps)_x_10. You have the first set to 4000 which means 400 Nm which is correct according to the EVO data sheet. But you have the second set to 4240 for 424 amps. But 400 Nm divided by the Kt of 1.81 Nm/A is only 221 amps. So I think you should have IQ_Limit_EEPROM_(Amps)_x_10 set to 2210. And ID_Limit_EEPROM_(Amps)_x_10 set to something like 500 to 1000.

Regarding Regen:
I have no solid suggestions for this one except try setting Regen_Torque_Limit_EEPROM_(Nm)_x_10 to something like 800 rather than the 250 you have now. And make sure connector J1 pin 31 (Regen disable) is not connected to anything, particularly not GND.

Regarding safety:
You really need to arrange your accelerator pot mechanically so that that the two extremes of 0 V and 5 V never occur in normal operation so that you can set Pedal_Lo_EEPROM_(V)_x_100 to something definitely greater than 0 and Pedal_Hi_EEPROM_(V)_x_100 to something definitely less than 500. This is so that wiring failures to the pot will be detected and torque set to zero. As it stands now, if either the ground lead or the wiper lead go open circuit, the bike will be stuck on full forward torque. The latter happens because they have pullups! on their analog inputs. And as it stands now, if the 5 V lead goes open it will be stuck on full regen until it drops below 200 r/min.

I don't see any value in a "coast" zone in the accelerator mapping for a racing bike. It just seems like wasted twist-grip travel and a nasty discontinuity in what could otherwise be a straight line. e.g. if you have max regen torque being 25% of max motoring torque then the two "coast" parameters could be set together at 20% of twist-grip travel. If max regen was 33% then they could be set at 25% of travel.
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Post by jonescg » Tue, 10 Jun 2014, 22:18

Thanks Dave - things like milliwebers per radian are not compatible with my throttle-hand / seat-of-pants interpretations. But I figured there would no doubt be some motor specific parameters which need to be set correctly.

I understand the IQ value to be amps rms, but will hopefully find out soon enough.

Thanks again,
Chris
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Post by weber » Wed, 11 Jun 2014, 00:11

I wrote: "You really need to arrange your accelerator pot mechanically ...". That's not true. You can do it electrically. e.g. If it's a 5k pot, connect two 220 ohm resistors, one on each side of the pot, one in series with the 5V lead and one in series with the 0V lead. It doesn't matter if they are at the pot or at the inverter, provided they are suitably relieved from strain and vibration. Then you'd set
Pedal_Lo_EEPROM_(V)_x_100             ,     10  
Accel_Min_EEPROM_(V)_x_100            ,     20  
Coast_Lo_EEPROM_(V)_x_100             ,    112  
Coast_Hi_EEPROM_(V)_x_100             ,    112  
Accel_Max_EEPROM_(V)_x_100            ,    480  
Pedal_Hi_EEPROM_(V)_x_100             ,    490  
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Post by Sutho » Wed, 11 Jun 2014, 00:36

Much of the above would sound very familiar eh Chris....albeit in a slightly longer format. Image

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Post by jonescg » Wed, 11 Jun 2014, 01:02

Hehe, yes, and then it all seems different when you start pulling 1.3 g out of a turn Image. Danny was looking at his GPS data and found he was accelerating harder than he was braking Image

I reckon between Rinehart, Brett and Dave we might be close. I didn't realise that field weakening required a very specific set of circumstances to occur - I was kind of hoping it just spun all the way up to 5000 rpm as requested.

I hadn't played with any of the Pedal_xxx settings either, other than to set the values of 10 and 490 for Lo and Hi respectively. We actually adjusted the throttle so there was no dead spot between chopped and slightly cracked. It makes fine tuning your speed through corners much easier.

I'm going away camping for a couple of days so Katherine can have her husband back, but come Friday I will make some more changes and take it up the stree... er... racetrack. I now have the ability to log data as it's sent, but I might yet need a laptop Velcroed to the tank cover.

Cheers,
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Post by weber » Wed, 11 Jun 2014, 04:26

Sorry if I'm somewhat verbose, but I try to make sure I can be understood, particularly when lives are at stake. On the other hand, I'm afraid I have completely failed to understand the following:
jonescg wrote:... milliwebers per radian are not compatible with my throttle-hand / seat-of-pants interpretations.
How does one interpret a manual with one's throttle hand or the seat of one's pants? But hey, you're a biologist and I'm a physicist and computer scientist. Image
We actually adjusted the throttle so there was no dead spot between chopped and slightly cracked.

Chopped? Slightly cracked? I rode a motorbike up until my first child was born, and somehow failed to learn this jargon. But Google is my friend, so I eventually obtained a translation.

This suggests that maybe the reason you're not getting any regen is that you're not allowing any voltage from the pot less than Coast_Lo_EEPROM_(V)_x_100 (0.92 V).

The way this inverter implements throttle regen is to have a huge dead zone between chopped and slightly cracked. Your parameter settings assume this is the first 20% of the travel. It's dead when you're starting off, but when you're doing more than 200 r/min, it becomes the regen part of the throttle. i.e. the zero torque position is fixed at 20% throttle. Less than 20% is negative torque.

We have throttle regen in the MX-5 with no dead zone because we wrote the code ourselves in C such that the zero torque position of the throttle is not fixed, but smoothly moves up from 0% throttle as the speed of the motor increases. But you don't have that option, unless you use something like the Tritium EV Driver Controls unit to drive the inverter via CAN bus. And I don't think you want to get into that sort of thing at this point in time. Image

So what voltages do you get out of the pot for chopped and fully cracked positions?
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Post by weber » Wed, 11 Jun 2014, 05:05

jonescg wrote:I understand the IQ value to be amps rms, but will hopefully find out soon enough.

I'm assuming it is RMS too, although I eventually realised on the WaveSculptor that the Iq telemetry was giving the peak value. But if the Rinehart inverter wants the limit as RMS, and you care about the warranty for that motor, you shouldn't be setting it past 221 A. If the parameter is peak then you can set it to 312 A. But I don't see any way to justify setting it to 424 A.

The way I read it, by setting the inverter torque limit parameter to 400 Nm you are not really limiting the torque, you are just telling it what torque corresponds to the Iq limit you've given it. But I think you are lying to the inverter. I think with an Iq limit of 424 A you could be pulling nearly 800 Nm, if I understand the motor specs correctly. That could well explain why your motor is getting hot.

Given the mass of the bike, the gear ratio and the tyre radius you can calculate what torque is required to obtain 1.3 gees acceleration. I'm guessing it's a lot more than 400 Nm.
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Post by jonescg » Wed, 11 Jun 2014, 05:43

I might have been exaggerating a little on the g-forces Image However the forces the swing arm are experiencing are big, and potentially quite hazardous. We're getting it built up around the joints and heat-treated this week.

Unfortunately I don't understand electric motors at the level you do. My understanding of them is high school level, maybe first year Physics. So for me to read an instruction manual and fine tune a motor to a controller, it would need to be in fairly general terms. OK, I know a few basics like the concept of torque, mechanical power being a product of angular velocity and torque, and that more amps = more torque.

Evo told me that 600 Nm was not unheard of with these motors, albeit for a few seconds. Might be fine for some applications, but not racing, where the loads are hard and sustained.

As for the throttle - it's all about setting it up to where Danny feels comfortable. The more ICE-like it can be the better, as that's what he knows. However it's not impossible to learn how to ride a machine which is primarily torque-controlled instead of speed. A big dead spot at the start of the twist is very unsettling, as it makes it harder to find the ideal position when feathering the throttle through a turn. I don't think that was the cause of the lack of regen though. I do know that there is regen as the BMS modules tripped after spinning the motor up at full charge, causing an over-volt condition. Quick ride around the block sorted that out.

Anyway, I better get on with it. Will keep you all posted.
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Post by Sutho » Wed, 11 Jun 2014, 05:50

Hi Weber,

We have been providing Chris with some advice on settings....including recommended and upper limit of parameters he should work with. He needs to install some method of monitoring/logging the operational parameters before he pushes it too hard. I believe he is working on this.

Chris Brune (Rinehart Motion Systems) welcomed your advice about errors in the manual and asked me to pass on the following comments on your post:

"The flux is set in milliwebers / rad/s, the rad/s is in electrical frequency, not mechanical. The 147 setting is correct and should not be changed. EVO gives the back emf (flux) in terms of mechanical frequency, not electrical which is why it is different.

Vrms, pp --- the pp is likely phase to phase, or most often would be called line to line.

Changing break speed has no effect on the field weakening process. It is completely independent. Now of course if you request less torque then less field weakening will be applied. The break speed parameter is used to reduce "dead" throttle when operated at high speeds. If you don't do this then you will be requesting much more torque than you can get and the throttle will have a dead zone at the top.

For the torque limits I believe he is confusing RMS amps and peak amps. The torque settings we have discussed are correct, as well as the current settings. Id and iq limits are set in peak amps, not rms amps.

The rest I pretty much agree with."


Based on the EVO spec sheet, the motor should produce 543Nm at 300Arms = 424Apk.

Cheers,
Sutho
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Post by weber » Wed, 11 Jun 2014, 07:26

Thanks Sutho, and Chris Brune. That (nearly) all makes sense. Pity both the motor and inverter datasheets/manuals don't make these things clearer. But they will in future, right? Image

The only one I'm still having trouble with is the back-EMF parameter Veh_Flux_EEPROM_(Wb)_x_1000 = 147. Neither the motor datasheet nor the inverter software manual mentions anything about the number of poles. I'm guessing it's implied by the inverter parameter Motor_Type_EEPROM = 16. There's a note saying "See motor setup manual" but I can't find that inverter manual online. I eventually found this paper that says the AFM-140-4 has 8 poles (the "-4" apparently meaning 4 pole pairs). http://www.evs24.org/wevajournal/php/do ... 4-4074.pdf

But that factor of 4 only takes the back-EMF parameter down from 1080 mWb/rad to 270 mWb/rad. How do you (Chris B) explain the remaining factor of 1.84 to get it down to 147 mWb/rad?

You wrote "milliwebers / rad/s" but I assume you meant "millivolts / rad/s" or "milliwebers / rad". The parameter would be better called
"Veh_Flux_EEPROM_(Wb/rad)_x_1000" or
"Veh_Flux_EEPROM_(Vs/rad)_x_1000", except what's with the "Veh"? I assume "vehicle", which unfortunately sounds mechanical rather than electrical.

I see that the Iq and Id parameter descriptions in the inverter manual do mention "peak amps". Unfortunately I read (past tense) "peak" as a synonym for "maximum", since they are limits. I can only suggest making it "peak (not rms) amps" to avoid future misunderstanding by other dummies like me.
Sutho wrote:Based on the EVO spec sheet, the motor should produce 543Nm at 300Arms = 424Apk.

Agreed. So I presume Motor_Torque_Limit_EEPROM_(Nm)_x_10 should be set to 5430, not 4000, so that any torque telemetry is calibrated correctly.
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Post by weber » Wed, 11 Jun 2014, 08:14

jonescg wrote:As for the throttle - it's all about setting it up to where Danny feels comfortable. The more ICE-like it can be the better, as that's what he knows. However it's not impossible to learn how to ride a machine which is primarily torque-controlled instead of speed. A big dead spot at the start of the twist is very unsettling, as it makes it harder to find the ideal position when feathering the throttle through a turn.
If you do as I'm suggesting with the pot voltages and the two "coast" parameters (and it seems Sutho agrees), there will be no deadspot when feathering the throttle through a corner. The only time there would be a dead spot is on a standing start. In that case only, nothing happens for the first 20% (or whatever) of throttle rotation. At least that's how I read the inverter manual. Sutho? Chris B?
I don't think that was the cause of the lack of regen though.
Easy to find out. Stick a multimeter between GND and pot wiper input to the inverter and turn the inverter on. Measure the pot voltage without touching the throttle.
I do know that there is regen as the BMS modules tripped after spinning the motor up at full charge, causing an over-volt condition. Quick ride around the block sorted that out.

Then maybe it is as I suspected in my first post yesterday, that you have the regen torque set so low that you can't feel it against the background of air drag and rolling resistance.

That also sounds like you could set DC_Volt_Limit_EEPROM_(V)_x_10 down a bit lower, say 7000 or 6900 so the inverter backs off the regen to limit the DC bus voltage and avoid any cell overvoltage when the cells are fully charged. This assumes they are top balanced. Are you top balancing or bottom balancing?
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Post by jonescg » Wed, 11 Jun 2014, 15:22

They're top balanced, but I don't think the over voltage thing is that big a deal on a race bike. It's fully charged before a race and the warmup lap washes that last bit off.

I have to remove the swingarm this morning, and get it reinforced. Hope to try some new settings afterwards.
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Post by Sutho » Wed, 11 Jun 2014, 15:49

Hey Chris: Check your email

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Post by weber » Wed, 11 Jun 2014, 16:10

In email, Chris Brune (Reinhart Motion Systems) wrote:The EVO AF140 family (all winding types) are 12 pole, not 8.

The -4 is a winding configuration. The most common configurations are the -4 and -3, but there are several others.

Yes you are correct that I should have said millivolts not milliwebers.

The way I calculate the back emf constant is in terms of peak volts from line to neutral divided by the electrical frequency in rad/s

You are correct that if you are stopped (standing start) then the first part of the throttle won't do anything if you have it setup for regen.

Do not change the DC volt limit down. I generally do not like people to use this feature as it can have strange results. I probably should just delete it.

Assuming that the throttle settings are correct then my assumption is that 25Nm of regen is just too small to be noticed.
Thanks Chris B. That's all very clear.

Re the back-EMF constant: Assuming the motor has 6 pole-pairs and assuming the EVO datasheet uses rms voltage where you use peak, line-to-line voltage where you use line-to-neutral, and mechanical angle where you use electrical, then I finally agree it should be
=1080*sqrt(2)/sqrt(3)/6 = 147. Phew!

You've now debunked all my suggestions to enable field weakening, and so I have no idea what's going on there. But I'm glad we all agree on the two likely causes of the lack of regen (throttle voltage range in relation to throttle parameter settings, and too low a regen torque limit setting).
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Post by weber » Wed, 11 Jun 2014, 16:20

jonescg wrote: They're top balanced, but I don't think the over voltage thing is that big a deal on a race bike.
I totally agree. I just thought there was a simple fix for that minor annoyance, but Chris B has put the kibosh on that. It works fine in the WaveSculptor, Chris B. Image
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Post by 7circle » Thu, 12 Jun 2014, 04:56

Just wondering...
With field weakening of this PM motor...
Say you get the revs up to 5000 rpm and the controller goes to a fault state.
In fault state it is no longer controlling the 6 pulse bridge for motor current field weakening.
So will the Motor Bemf Voltage increase up to meet th Kv relationship for 5000rpm?
And if this occurs then the motor pk-pk voltages would be way over the battery pack voltage.
This V-dif would drive huge currents into the battery pack and huge regen braking torque.

Or am I missing something?
If 3700 is max at 690V then at 5000 you would be 690 x 50/37 so 932V

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Post by coulomb » Thu, 12 Jun 2014, 13:46

7circle wrote: Just wondering...
With field weakening of this PM motor...
Say you get the revs up to 5000 rpm and the controller goes to a fault state.
In fault state it is no longer controlling the 6 pulse bridge for motor current field weakening.
So will the Motor Bemf Voltage increase up to meet th Kv relationship for 5000rpm?
Yes, it will.
And if this occurs then the motor pk-pk voltages would be way over the battery pack voltage.
This V-dif would drive huge currents into the battery pack and huge regen braking torque.

That is correct, and it's a known problem with permanent magnet motors when you use field weakening. You can't just turn off the gate drive to the MOSFETs/IGBTs if you detect this; the back diodes will conduct anyway.

Manufacturers seem to have determined that this condition is rare, and even if it does happen, the consequences will not be too dire. I sure hope it never happens to me, though...
Last edited by coulomb on Thu, 12 Jun 2014, 03:47, edited 1 time in total.
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