Fiat Uno EV conversion

[Charles Gibbs]

Good day all From Namibia.

I would like to ask if there is anyone that would be able to help me with issues I am having
on a self built Fiat Uno also known as a 146 I think in USA and EU.

This car was converted in 2006 and was done by a German gentleman here in Namibia.
When I got the car it had an old VPA inverter in it that needed replacing.

The gentleman had already some years back acquired and MES DEA SA Tim400.
He was not able to work on the car any further as he got sick and so I was able to buy it
from him.

The motor is also of German origin can't remember the name now, it is an ac induction motor and runs though a small differential, presumably the motor is a 30KW (I know it is small) on the name plate is written the following.

100V
200Hz
86 Amps
6000 Rpm
The Tim is 80 -400 VDC 280A capable.

I have a 60Ah 180 VDC CALB cell pack.....

Please note that when it comes to EV cars I am a complete noob, I have built a few ebikes that
are high powered so am familiar with ev tech.

BUT the parameters on this inverter are not english...... They are in technician.....

And I am not there yet...

Ok, so, I built everything in and got things running.
The controller has an auto tune function in it, I just had
to enter in a few easy things of the motor and battery pack:
Motor voltage: 100V
Motor Amps Nom: 86A
Motor Poles: 4
Number of absolute encoders: 2
Number of motor pulses /RPM: 25
And then battery pack stats for over and under voltage.

The problem:

When I am driving and reach an almost no load speed the motor surges and slows and surges and slows causing the car to buck back and forth until I either put my foot down further onto
the accelerator or let off. The Ammeter needle drops to zero and goes back up in sympathy with the motor. it can be at 30 kmh or 60 kmh does not matter, as soon as there is very little load on the motor this happens.

When I come to a complete stop, I can sometimes feel the motor rocking and if I put the laptop onto the controller the RPM meter confirms this by going to 50 and then -50 RPM, if I take my foot off the brake and pull up the hand brake it'll stop.

If I disable the regen then it does not do it.

Now, if the manual did not describe the setting in a plain readable language I left it alone
as I am in way over my head when it comes to ev car inverters......

I do hope that someone will be able to advise me in my predicament.

Thank you in advance

Charles Gibbs

 

[Thevenin]

Hi, Charles.

I'm sorry I didn't notice your post earlier. I hope I can still help. I have never used your inverter, and I can't say for sure what's going on, but hopefully I can give you some ideas.

I recommend checking the connectors and cables first, to see if they're corroded, broken, or if an animal chewed on them. Be sure to feel along the cables to see if you can find internal faults. If the cables are damaged or mismatched or coiled or bent, it can alter the current delivery to the AC motor. If one of the AC motor's phases isn't activating fully, then it can effectively "backfire" near zero-slip conditions.

If that's not the problem, then I recommend increasing the amperage limit of the motor controller. If you're feeding your motor 100V at 86A, then you're only feeding it 8.6kW. If the motor is meant for 30kW, it will probably run better if you give it more power.
If your motor controller has a low amperage limit, and the motor tries to pull too many amps, the controller will think there's a short circuit and cut off the power. Once the power is cut off, the motor may generate back-EMF until the motor controller turns the power back on. This cycle could explain the surging/stuttering torque and the wild ammeter.

If you're still having problems with stuttering at a standstill, that's a sign the motor controller is reading a voltage on your throttle input when there shouldn't be one. You can try re-calibrating the throttle, but you should also make sure to shield the wires from interference (and definitely make sure the throttle's ground wire or return wire is isolated from the car chassis). An AC inverter can produce a lot of electrical noise, and the throttle wires may be picking that up.

The TIM400 motor controller has a lot of features, and you'll have to go through them one by one to make sure they're working properly. It could be attempting to activate regenerative braking, for instance.

 

[Charles Gibbs]

Hi, Charles.

I'm sorry I didn't notice your post earlier. I hope I can still help. I have never used your inverter, and I can't say for sure what's going on, but hopefully I can give you some ideas.

Hi Thevenin.

no worries, but thank you for taking the in getting back to me.

I recommend checking the connectors and cables first, to see if they're corroded, broken, or if an animal chewed on them. Be sure to feel along the cables to see if you can find internal faults. If the cables are damaged or mismatched or coiled or bent, it can alter the current delivery to the AC motor. If one of the AC motor's phases isn't activating fully, then it can effectively "backfire" near zero-slip conditions.

OK, so there was an old VPA230 inverter in, the gentleman said it was giving problems and needed replacing, he said it was surging under power, so I replaced it with the tim400 that he had already procured a few years back prior to falling ill, I then proceeded to "replace" the inverters. From here I can confirm the goodstanding of all wiring.

If that's not the problem, then I recommend increasing the amperage limit of the motor controller. If you're feeding your motor 100V at 86A, then you're only feeding it 8.6kW. If the motor is meant for 30kW, it will probably run better if you give it more power.

I can not confirm that the motor is indeed a 30Kw motor, I am going on what I have been told by the person I bought it from, the motor name plate does not have much to go by other than 100V, 86A and 200Hz.. The controller should be fine as it can give 280A phase current and I am not consuming that much.

If your motor controller has a low amperage limit, and the motor tries to pull too many amps, the controller will think there's a short circuit and cut off the power. Once the power is cut off, the motor may generate back-EMF until the motor controller turns the power back on.

This I can understand and would make sense, if the problem was present under load, but it's not.

This cycle could explain the surging/stuttering torque and the wild ammeter.

The problem is that this surging is happening at speed on a slight downhill with only a 20A draw, that is why I said at an almost no load condition...... This is why it does not make sense, there is zero stuttering under power at all the motor runs 100% smoothly.

If you're still having problems with stuttering at a standstill, that's a sign the motor controller is reading a voltage on your throttle input when there shouldn't be one. You can try re-calibrating the throttle,

I have set up the throttle according to the tim specs with a constant reading of 5 @ zero throttle and a constant reading of 95 @ max throttle, there is a graph that this is verified on in the tim programming, I have verified this numerous times and even had it at full zero and 100% and there is no difference the surging still persists. Even at stand still with my foot on the brake the rocking will sometimes be present and other times not, off the brake and the rocking stops. I sometimes get the rocking shortly after switching on the inverter as well with out my foot on the brake.

But you should also make sure to shield the wires from interference (and definitely make sure the throttle's ground wire or return wire is isolated from the car chassis). An AC inverter can produce a lot of electrical noise, and the throttle wires may be picking that up.

The inverter comes with its own wiring loom that is wrapped. I have no choice but to run the loom under the phase wires as they all exit on the same side I cant change this unfortunately, it has been designed this way, I have for the rest of the way made sure to isolate the loom from any other source of noise as best I can.

The TIM400 motor controller has a lot of features, and you'll have to go through them one by one to make sure they're working properly. It could be attempting to activate regenerative braking, for instance.

This much is true, allot of functions indeed, the problem is, that I do not have a manual that explains all these parameters in "english" that one can understand,
the terms are very technical and without an understanding of these I am unfortunately lost, the company also no longer exists, it was one hell of a mission to just get hold of the program to set it up with..

It could well be that the inverter is trying to enable regen, but why? When I am at a complete stop or stand still this does not make sense that it would do this,
what you are saying makes sense, I have disabled the regen function and then it all stops even the surging, but I need to know what to set to stop this.
As I do not know what could be causing this issue. I am unfortunately lost....

Any further assistance would be greatly appreciated.

Regards
Charles

 

[Thevenin]

You're one step ahead of me, Charles.

The problem is that this surging is happening at speed on a slight downhill with only a 20A draw, that is why I said at an almost no load condition...... This is why it does not make sense, there is zero stuttering under power at all the motor runs 100% smoothly.

It could well be that the inverter is trying to enable regen, but why? When I am at a complete stop or stand still this does not make sense that it would do this,
what you are saying makes sense, I have disabled the regen function and then it all stops even the surging, but I need to know what to set to stop this.

It really sounds like the motor controller is trying to enable one-pedal driving. One-pedal driving means if the motor spins faster than the controller expects (like when going downhill) it will enable regen. The TIM400 has this feature, so let's disable it.

Parameter: P201 (Max torque in regenerative drive mode.)
DEFAULT VALUE = 50
Set P201 VALUE = 0.
Setting this parameter to zero should disable one-pedal driving.

If that doesn't fix the stuttering at steady speed, you can try some other parameters.

Parameter: P221 (Max regenerative torque in brake state.)
DEFAULT VALUE = 70
Set P221 VALUE = 0.
Setting this parameter to zero should disable regen braking even when using the brake pedal.

Parameter: P18 (Clockwise speed reference maximum limit)
Parameter: P19 (Counter-clockwise speed reference maximum limit)
DEFAULT VALUE = 105
Set P18 and P19 VALUE = 110.
I think this means you can spin the motor 10% faster before one-pedal driving regen is enabled.

I don't know what's making the motor stutter while at a standstill. I would recommend experimenting with some more parameters.

Parameter: P7 (Digital speed reference JOG1)
DEFAULT VALUE = 0
Set P7 VALUE = 0.
If P7 is set to a negative number, then it will try to torque the motor in a different direction when you take your foot off the throttle.

Parameter: P43 (Maximum torque in negative rotation direction)
DEFAULT VALUE = -400
Set P43 VALUE = 0
This might actually disable the reverse gear. So be careful.



EDIT: In order to change some of those parameters, you'll need to enter a password. Set P60=95.

 

[Charles Gibbs]

You're one step ahead of me, Charles.




It really sounds like the motor controller is trying to enable one-pedal driving. One-pedal driving means if the motor spins faster than the controller expects (like when going downhill) it will enable regen. The TIM400 has this feature, so let's disable it.

Ok. I will try the steps given.

221 and 201 are set so that I can do one pedal driving, there are allot of hills so I benefit from the regen.
I do not use the digital jog so have not set it but will check it. have also not set P18 or 19,
Have left them alone, but did set analogue 1 P01/ P02 as prescribed as this is what I use for accelerator. Will check P18/19 and revert back.

I Have also not touched P7 but will check. Yes, P43 is at -400 also thought it would be reverse so left it.

I will try your settings and revert back to you, Will probably only be next week though as I will only be driving again on Sunday with the car.

Thank you very much for taking the time to help me.

I will try all settings and let you know how it goes.

Kind regards
Charles

 

[Charles Gibbs]

Hi Thevenin

Ok, so a report back.

The only thing that helped was disabling the regen.

Parameter: P43 (Maximum torque in negative rotation direction)
DEFAULT VALUE = -400
Set P43 VALUE = 0
This might actually disable the reverse gear. So be careful.

As said this did disable the reverse but also stopped the jarring at no load speed.

I did disassemble the motor and compact diff assembly. It would seem that I have diff slippage which could I think be the route
of the jarring at the no load speed. As you said the motor could be slowing and then the differential catches up and it speed up and
once the load is gone it tries to slow down again, rinse and repeat........

My problem is to find someone here who KNOWS differentials but also can understand emotor differentials...... This is going to be a mission.
Then also the price.......

Once this is sorted I will revert back to you.
Thank you for all your help.

 

[Charles Gibbs]

Hi Thevenin.

A belated happy new year!

I was able to get the diff slap sorted, there is no more jarring when I now drive. I do however have another question.
The starting torque on my little car is very much lacking, when driving and all is up to speed then it's all ok.

How do I get more starting torque? It barely draws 30Amps when I start pulling away and on a hill this is a problem.
Can you help me out please? I have set P200 to 300 but there is only a difference when the inverter is at speed not on pull away.

As always thank you kindly for any advice..

Regards
Charles