Johny's Electric Vogue

Post up a thread for your EV. Progress pics, description and assorted alliteration
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Post by Johny » Tue, 21 Aug 2012, 19:18

Thanks Dave - I can always rely on you to make me feel better about my lot.
I'm doing pretty much what you say - 180mA on the pack that was just to hard to get at (which has finished at 59.1V for 16 cells) and individual cell charge on three packs so far. Any cells I have load tested seem fine, so my only critism of Headway so far is this balance issue. It's also different cell positions in each pack so if it's the BMS - it's random. I haven't measured any sizable BMS current flow on idle packs either. End to end it's 300uA.

I made an auto switching gizmo about 1.5 years ago that uses a power FET to switch the charger through until the current drops below 400mA (BMS switched charge path off) then swaps to 180mA CC. I bought parts for 12 but only ever made one....
I may make the other eleven, meanwhile it's in constant use this week.

Laurel won't let me take the Vogue to work until it's got it's new door liners and painted wheel rims anyway.Image

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Post by Johny » Mon, 03 Sep 2012, 17:07

All the battery packs appear to be well balanced and fully charged so that saga is on hold for now. I'll have to re-adjust all the on board chargers before too long but I have bigger fish to fry (where did that come from?).

Next issue. How to not have regen on an AC system.

Some history.

When I first got the Lenze VFD on ran it up on a 2.2kW motor and pretty much proved that motor control for my EV was possible. It had Speed control or/and Torque control. Initially I thought I had to furnish these signals using some external analog manipulation but as time went on I realised that the "Function blocks" in the controller could do everything I wanted.

Early experiments clearly showed the DC Bus voltage momentarily rising when the motor was actively de-accelerated. These experiments used speed (V/Hz) control. So regen. was as straightforward as it should be.

Torque control in the Lenze is not allowed in V/Hz mode - it must be in Vector mode. Vector mode is not practical unless the motor has successfully auto-IDed. Once I got the proper motor, auto ID worked (long story) and I shifted to vector control then tried Torque control.

Essentially I set the Lenze up for Torque control and the software sets up a whole bunch of controls and such, then I went through and changed the I/O to suit my purposes and fed the Speed and Torque signals from my set of functions. One of the main areas of change (as against additions) was to get rid of "Quick stop" which is a little piece of logic that says if you dont have a forward or reverse signal (2 Inputs used) then the drive does a controlled stop (a wire breakage protection system). I use only a reverse signal figuring that if a wire breaks then forward is fine - so no Quickstop (QSP).

Here is the control intention.

Image

The purple line is accelerator input. The yellow is speed demand to the Motor control block in the Lenze, and the blue line is Torque demand.
Essentially, when you release the accelerator, I ask for 0 speed but some controlled torque - the motor should move into generator mode.
As you push down on the accelerator, the speed signal goes to 100% but we control the torque.

Forward and reverse motion work really well - now smooth and very easy accelerator action - but no regen. at all. Even If I increase the torque in the no-speed condition - still no regen.

Here is where some commitment from readers has to kick in.
I have placed the relevant Lenze manual at:
https://dl.dropbox.com/u/46309508/Lenze ... ibrary.pdf

The other document for normal setups is at:
https://dl.dropbox.com/u/46309508/Lenze ... 6-0_EN.pdf

If you load G Lenze 9300EV E 00416037_Function_Block_Library.pdf and select section 'L' then Signal Flow Charts then Torque control. You can see the two pages of standard torque control. It helps to print out these two pages.
I am feeding my Speed signal ) 0% or 100%) into MCTRL2-N-Set and my Torque signal (35%/0%/100%)into MCTRL2-M-ADD. In the standard setup they are both fed via external analogue inputs.

The Lenze PC software shows me that these two signals are doing the correct thing (following the graph above).

I have the Vogue on axle stands at the moment and there is no difference from coast down (controller disabled) to the "accelerator off" condition.

FCR motion, the Australian Lenze distributor have not been helpful in the past - I'll try them again but hold no hope unless I pay for a full engineer visit. Given that all my stuff is working - except for regen. I really can't bring my self the "get professional help".

I thought I'd at least post this up and see if anyone is keen (or has enough spare time) to peruse the Lenze document and get to know it well enough to ask me the questions that will trigger any neurons into revealing the answer - or God forbid - see what I have done wrong.

There is LOTS more details but that's the crux of it.

Now, how bored are you?

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Post by woody » Mon, 03 Sep 2012, 17:21

Johny wrote: Here is the control intention.

Image

The purple line is accelerator input. The yellow is speed demand to the Motor control block in the Lenze, and the blue line is Torque demand.
Here is where some commitment from readers has to kick in.

...

I am feeding my Speed signal ) 0% or 100%) into MCTRL2-N-Set and my Torque signal (35%/0%/100%)into MCTRL2-M-ADD.

...

I thought I'd at least post this up and see if anyone is keen (or has enough spare time) to peruse the Lenze document and get to know it well enough to ask me the questions that will trigger any neurons into revealing the answer - or God forbid - see what I have done wrong.

There is LOTS more details but that's the crux of it.

Now, how bored are you?
Hopefully it's not this simple, but shouldn't the torque be negative for regen?

Is what you've implemented called "hill hold"? Image

Edit: missing Quote formatting
Last edited by woody on Mon, 03 Sep 2012, 07:35, edited 1 time in total.
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Post by Johny » Mon, 03 Sep 2012, 17:35

woody wrote:Hopefully it's not this simple, but shouldn't the torque be negative for regen?

Is what you've implemented called "hill hold"? Image
Hi woody. Good question. To go into reverse I reverse the sign of torque. Way back I tried reversing speed but it did nothing - no effect. Negative speed works in Speed mode, but not Torque mode. In Torque mode the Lenze uses negative Torque for reverse rotation. It's in their orginal Torque mode diagrams. You see the R/L signal just flip the torque signal to a negative value.
Good try though (Edit: it turns out woody was right - see following posts).
Last edited by Johny on Tue, 04 Sep 2012, 12:30, edited 1 time in total.

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Post by Johny » Mon, 03 Sep 2012, 17:37

BTW. For anyone trying to read the Lenze diagrams.
A circle for input/output means an analogue signal.
A small square for input/output means a digital signal.

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Post by coulomb » Mon, 03 Sep 2012, 18:31

Johny wrote: To go into reverse I reverse the sign of torque.

Right. So that's what you need: regen is the same as reverse drive, except you don't want the speed to cross zero into negative values. Setting the torque negative and the speed zero should achieve this, except for regen in reverse. It's not clear whether you will get regen in reverse, it depends on how you invert the torque requests, but as long as the requested speed is zero at pedal up, nothing bad should happen.

Actually, I think that regen in reverse would be useful and intuitive.
Last edited by coulomb on Mon, 03 Sep 2012, 08:32, edited 1 time in total.
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Post by Johny » Mon, 03 Sep 2012, 18:54

coulomb wrote:
Johny wrote: To go into reverse I reverse the sign of torque.

Right. So that's what you need: regen is the same as reverse drive, except you don't want the speed to cross zero into negative values. Setting the torque negative and the speed zero should achieve this, except for regen in reverse. It's not clear whether you will get regen in reverse, it depends on how you invert the torque requests, but as long as the requested speed is zero at pedal up, nothing bad should happen.

Actually, I think that regen in reverse would be useful and intuitive.
Hmmm. Some interesting thoughts there - based on so little info. Woody alluded to this as well.
I think you may be right. The original analogue input for torque would have allowed for +10VDC and -10VDC so that fits.

I select reverse by multiplying my final torque output by -100% so that should work fine.
To get a negative value for torque I actually remove a function block - an ABSOLUTE.
AIN1 is analogue input, DB1 is a deadband (coast and some gain), ABS1 is Absolute, CONV1 is gain just for braking so setup is easier, ASW1 is an analogue switch - again just so I can control braking gain separately.
ASW2 is an analogue switch again controled by digital speed. Min or Max speed request. ARIT1 is a multiply 100%*100%=100%. 100%*-100%=-100%. This does reverse and regen inhibit on pack alert etc.
The whole lot pivots around CMP2 which output switches at the regen/accelerate pedal threshold. There's other stuff but it's not relevant - overvoltage, alerts, Fwd/Rev.
Image

BTW. For anyone trying to read the diagrams.
A circle for input/output means an analogue signal.
A small square for input/output means a digital signal.

Edit: Not Dave - lots of edits....
Last edited by Johny on Mon, 03 Sep 2012, 08:58, edited 1 time in total.

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Post by Johny » Mon, 03 Sep 2012, 19:17

Sorry Mike, I didn't mean to call you Dave. Your Avatars are the same and I didn't look at the post name until later.

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Post by Huub35 » Tue, 04 Sep 2012, 02:14

Hi all,

just some thought. In forward direction, with positive torque, the requested power from the Lenze is also positive (positive * positive = positive). This is then power going from the batteries through the VFD to the motor/wheels.

Assuming that regen would then be considered negative power (from the wheels back into the batteries) either torque or speed command has to be negative, and none of both commands has to be zero ??! With one of them zero, the requested power would also be zero (from my limited analysis at least).

I understand that having a negative speed might be not wished for, but would a small positive speed be OK (like the crawling of a normal auto-gear)? With a negative torque command this then would give negative power command.

If I remember well, Eric Tisher (of diyelectric car and the electric passat) has had similar issues with the programming of his VFD as well. Maybe good inspiration? In the end he went for a Encoder-based torque control, but in-between he also had good results (incl. regen) with open-loop vector control.

Regards,


Huub

edit: clarified regen with small positive speed command
Last edited by Huub35 on Mon, 03 Sep 2012, 16:15, edited 1 time in total.

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Post by Johny » Tue, 04 Sep 2012, 04:01

Hi Huub. Long time no hear.
Requesting zero speed worked fine in speed control (slowed motor and upped DC Bus) and what the guys came up with makes a lot of sense. I have a config ready to go (negative torque at zero speed for regen) and may get time later tonight but house duties call at the moment. I'll post the results at most within 24 hours from now.
I am using encoder feedback and vector torque control.

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Post by Huub35 » Tue, 04 Sep 2012, 06:05

Hi Johny,

very happy to be back again :-). Lot's of other tasks (venturing in a new business) so EV is on low fire currently activity-wise.

I had forgotten that you have encoder control. Would be great if with the negative torque you would solve the regen issue.

Good luck,


Huub

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Post by coulomb » Tue, 04 Sep 2012, 13:36

Huub35 wrote: Assuming that regen would then be considered negative power (from the wheels back into the batteries) either torque or speed command has to be negative, and none of both commands has to be zero ??!

I believe that this will be fine. It's the *target* power that is zero, not the power needed to get there. The present motor power is positive, the target is zero, so that's a net change of negative power (the integral of this will be the regen energy). The motor controller can use up to the requested negative torque to get the speed and hence power to the target value, which happens to be zero. Remember that in torque control mode, it will be using torque as its primary variable to achieve the target.

[ Edit: present motor speed -> present motor power; regen power -> integrate to regen energy ]
Last edited by coulomb on Tue, 04 Sep 2012, 03:42, edited 1 time in total.
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Post by Johny » Tue, 04 Sep 2012, 14:50

I ran out this morning and squirted a config without the ABSolute function block in the torque path and - guess what - it's got regen.
The back wheels stopped pretty damn quick when I took my foot of the pedal (on axle stands).

Thanks to woody and coulomb for their wisdom.

I'm pretty sure now that the diff has no oil in it. It leaks and when I think about it, I haven't checked it for about 10 years. No terrible noises but a huge rumble of crown wheel and pinion running dry.
Hmmm. I'll get some hypoid oil this lunchtime.


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Post by Johny » Tue, 04 Sep 2012, 14:51

Oh and the current display went to negative values (5 or 6A) for a second or so and I had never seen that - definitely regen.

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Post by woody » Tue, 04 Sep 2012, 15:53

Johny wrote: I ran out this morning and squirted a config without the ABSolute function block in the torque path and - guess what - it's got regen.
Great News!
Johny wrote: I'm pretty sure now that the diff has no oil in it. It leaks and when I think about it, I haven't checked it for about 10 years. No terrible noises but a huge rumble of crown wheel and pinion running dry.
Hmmm. I'll get some hypoid oil this lunchtime.
I should do the same, I can hear the diff whine over the engine now, imagine when the engine is gone!
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Post by Huub35 » Tue, 04 Sep 2012, 22:19

Hi Johny,

great news. Good to hear it was that simple. Curious about the driving experience, but 5-6 A does not feel like to brisk a braking torque.

Best regards,


Huub

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Post by Johny » Tue, 04 Sep 2012, 22:26

No, it's not much. I was just happy to see anything. It is on axle stands so the current going into the pack lasted less than a second and the battery current display is heavily integrated (smoothed). I'll have to drive it to set up some reasonable values. The controller does motor current and I stupidly didn't run the battery current hall effect output into the controller even though I had spare analogue input/output. I ran the wiring on the other side of the engine bay to the dash.

If motor current doesn't work out to control regen rate as I want then I will rethink wiring (it's difficult to convince yourself to re-work when you are not finished yet).
John

Edit: Added self-convincing argument.
Last edited by Johny on Tue, 04 Sep 2012, 12:28, edited 1 time in total.

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Post by Johny » Wed, 05 Dec 2012, 16:31

Next issue.
This one is for the mechanically inclined folk.
I have a serious tailshaft vibration above 70kmh.
I have the car on axle stands again and the vibration starts at about 70kmh and by 80kmh is pretty bad. At 100kmh it's scary.
Rotating the tailshaft by hand and it looks absolutely true.
The diff. pinion bearing feels fine.

Here is the funny thing. The Vogue has never been a happy traveller above 80kmh. It's ALWAYS had a tailshaft type vibration. I stuffed around for a along time back when it was an ICE with new UNIs, getting tailshafts balanced etc. and never got on top of it. Except now it's got a brand new tailshaft - none of the old bits were used. I would be utterly sure that it's balanced fine.

I think the diff pinion end UNI is maybe 3 degrees down and the UNI at the front is 2 degrees. I have no accurate way to measure this though.
The unis are aligned correctly - same orientation at both ends.

I haven't removed the wheels to check that yet but it sure feels like a 3000RPM vibration - not wheel speed. I'll try without rear wheels tonight.

Should I try to measure rear UNI angle vs the front UNI angle more accurately - could that be enough to cause this?

Ideas, comments?
Last edited by Johny on Wed, 05 Dec 2012, 06:42, edited 1 time in total.

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Post by Richo » Wed, 05 Dec 2012, 20:33

Tailshaft needs a balance perhaps
So the short answer is NO but the long answer is YES.
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Post by jonescg » Wed, 05 Dec 2012, 20:51

My Toyota Crown used to get a serious tailshaft vibration at >80 km/h after someone changed the clutch for us. I took it to a mechanic and he hoisted it up, loosened a bolt on a universal joint, tapped it with a hammer and tightened it again. Problem solved Image
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Post by Johny » Wed, 05 Dec 2012, 21:53

Thanks guys. The tailshaft was made from scratch by a mob in Ferntree Gully called Precision Balancing. They made the coupler as well.
While it's possible (and I'll call them tomorrow after running less wheels), I seriously doubt it's tailshaft balance.
As I said - it's a pre-existing condition that appears not to be changed by this new drive train (except diff).

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Post by Johny » Thu, 06 Dec 2012, 14:48

Well you were right guys.
I removed the rear wheels and had William (14yo) tickle the accelerator for me with instructions to hold it at 70kmh. He quickly got a lesson on Torque control - the motor accelerated straight through to 130km/h and the VFD shut down with an overspeed error (must up that a bit).

Take #2 he managed to hold it around 80kmh and I crawled under to have a look. The motor end was running true (that's the end I expected to see problems), but about 400mm from the diff end it was running out by 1 to 2mm. I couldn't get a good look at the diff flange but I thought it was OK just before.
So it looks like the tailshaft isn't straight.
I have a dial gauge but I have to mount it on something to get reasonable readings. I'll do that, and armed with some facts, approach the folk who made the driveshaft.

Just a lesson for me here. When I got the tailshaft made I had them reduce the diameter to save a bit of weight. (Original was 3" this one is 2 1/2" (not sure of these figures I'll have to check again). The result is it tends to whip easily if out of balance - perhaps a mistake.

I'll update results here - not sure whether to blog this bit.
Last edited by Johny on Sat, 08 Dec 2012, 04:03, edited 1 time in total.

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Post by marty11 » Thu, 06 Dec 2012, 18:54

"but about 400mm from the diff end it was running out by 1 to 2mm. I couldn't get a good look at the diff flange but I thought it was OK just before."

1 - 2 mm at speed ,and high tailshaft revs, may not necessarily need a new tailshaft. Maybe examine lining up the diff to the flange better, and if it can be made a more accurate fit, "whip" may not be a problem then.

Would certainly be a better result if the fit was better at the diff end by the sound of it, regardless of whether you stick with the tailshaft you had made, or had another one made. Maybe change the angle of the diff /to tailshaft coupling flange.

Could you get this adjusted where you had the tailshaft made? (might be easier than in the home garage Image

Also, I assume you had the wheels balanced properly? just a thought..

You are so close to fully usable , and its been a great project so far , you must be proud. .and "keeeeen" to get this last bit sorted..

Cheers. .

Marty
Last edited by marty11 on Thu, 06 Dec 2012, 07:56, edited 1 time in total.

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Post by Johny » Thu, 06 Dec 2012, 19:44

Thanks Marty. Yes I will be taking it back to the guys that made it. I'm sure they will be happy to sort it out. I just need to make sure it's not my fault first. As long as it's running true at both ends I can feel confident to remove it and take it back to them. I'll try to get that sorted out tonight.

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Post by Johny » Sat, 08 Dec 2012, 02:26

I set up a dial gauge under the car and measured wobble on the tailshaft. Given that the tube section is 1200mm long, the following readings are taken from the rear of the tailshaft where the tube section meets the universal jount mounting.

DISTANCE    WOBBLE
FROM
DIFF END
-------------------
0 mm        15 thou (0.38 mm)
390 mm      32 thou (0.813 mm) about the worst here
600 mm      22 thou (0.56 mm)
860 mm      12 thou (0.3 mm)

I couldn'r easily get to the motor end as there is a crossmember in the way.

So from this, there is a slight misalignment at the diff flange but the pipe is certainly not straight.
This tailshaft is 2 1/2" diameter, the original was 3".

Anyone have any experience on this? Is this amount of side play normal or excessive?
Last edited by Johny on Fri, 07 Dec 2012, 15:27, edited 1 time in total.

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