Suzuki Cappuccino

[tom3141]

I've been floating around on here for a while but never got around to starting a build thread. I've now got a bit of a dilemma with which way to go with the project so thought I'd start a thread to see what you guys think.

The project is a Suzuki Cappuccino with an Enova 90kw motor fitted (direct drive to the prophsaft) controlled by the original Enova inverter using Damien's combi board. If you've followed the threads in the hardware v1.0 section you'll have seen that I've had some encoder issues and general problems setting up parameters for this motor proper go!)

The test drive was generally a success. It drove pretty well and everything seemed to work other than a couple of issues. The mechanical vibration in the propshaft that I'd previously noticed was still present although a little better than before. It occurs when lifting off the throttle at around 30mph. I'm pretty sure it's an alignment/play issues with the propshaft to motor connection. As well as this, I found there was another much worse vibration when on the throttle at higher speeds. I assumed this was related to the other vibration and so decided to carry on to work. Just after I left to come home, I was accelerating at around 40-50mph and it was vibrating quite badly. I heard a pop and the inverter tripped. I reset and carried on. It seemed ok but the vibration was now occurring at lower speeds as well. The next time I came to a stop, I was unable to start again, the motor was super jerky, like it was running on two phases...

I managed to limp home by avoiding coming to a complete stop. I suspected that I had blown an IGBT so had a look inside the inverter the next day. There wasn't the carnage I was expecting but I'm pretty sure one of the IGBTs is broken. One of them had a clear gooey substance on the outside and what appears to be a hairline crack.

I'm now thinking that the vibration at higher speeds under load could have been caused by the motor rather than the a mechanical issue.

So to summarise my current problems are:
- 99% sure I have blown one of the IGBTs (although I would like to be absolutely sure before I do anything else, what's the easiest way to check for sure?)
- Problems with getting this motor set up correctly, I knew the parameters weren't great although they were good enough to be usable. I had a very sluggish take off but it was better once moving.
- Vibrations potentially caused by the motor (parameters? an existing problem with the IGBT or control board?)
- Vibrations cause by the the propshaft to motor connection

So, assuming the IGBT is definitely blown, I'm thinking I have three options:

Option 1 - Replace the broken IGBT (if I can find one), try and figure out some parameters that work, sort the mechanical vibration and find the cause of the other vibration. My worry with this is that I don't know exactly what caused the failure and I don't want to keep popping IGBTs. I'm also worried that I'll never be able to get this motor running properly judging by the trouble that Damien and some others have also had with it.

Option 2 - Ditch this inverter and use a Prius/Yaris/Lexus based one and continue to try to get this motor working. Not sure if there would be much point to his option other than if the problems I've had are inverter rather than motor based but seems unlikely.

Option 3 - Ditch both the inverter and motor and switch to something else. At the moment, a Yaris/Prius inverter driving a MGR is the most appealing. This would obviously mean getting rid of a lot of the work that I've already done but I'd rather do that than keep banging my head against a wall with this Enova. I'm just concerned that I might be jumping from the frying pan into the fire as these options seem pretty new and untested too (especially the MGR - is there anyone who's had this driving a vehicle yet?).

Thoughts, suggestions, and advice welcome!

[Kevin Sharpe]

Option 3 - Ditch both the inverter and motor and switch to something else. At the moment, a Yaris/Prius inverter driving a MGR is the most appealing. This would obviously mean getting rid of a lot of the work that I've already done but I'd rather do that than keep banging my head against a wall with this Enova.

Damien repeated his advice at this weekends course... do not use the Enova motor or inverter! I think everyone on the course will follow the advice and I suggest you do the same.

I'm just concerned that I might be jumping from the frying pan into the fire as these options seem pretty new and untested too (especially the MGR - is there anyone who's had this driving a vehicle yet?).

AFAIK the MGR has not been proven in a car. If it's a simple installation and you can stomach another disappointment then it's got to be worth a try.

I've watched the Prius Gen 3 inverter being used with multiple motors and receiving lots of abuse. It never fails to impress.

[tom3141]

I’m definitely leaning towards option 3. I’ve been very resistant to giving up on the Enova but have got to the point where I’m not sure I want to spend any more time or money on it, especially when the Toyota and Lexus stuff is so cheap. Maybe I should have listened a while ago...

I’m starting to look into it by catching up on all the threads and videos on the Toyota inverters. I guess I’ll find this out by reading through everything but if I have the choice which is the inverter to go for? I’m leaning towards the Yaris inverter (which I believe is virtually identical to the Prius Gen3) simply because there are loads of them for sale and they seem to be the cheapest but would there be any reason to go for a Gen2 or Gen3 Prius inverter over that for my application?

[Peter]

Hi Tom. Sorry you are having issues. Send me your parameters, I will compare with mine. Peter
P.S. Ask Damien if he has any Enova igbts for sale.

[Kevin Sharpe]

P.S. Ask Damien if he has any Enova igbts for sale.

Please do not ask Damien (he has enough to do) but rather post a wanted to buy in the classifieds.

[Kevin Sharpe]

would there be any reason to go for a Gen2 or Gen3 Prius inverter over that for my application?

We've just had 10 novices on the NEI course using the Prius Gen 3 inverter and tuning a Gen 3 transaxle. It's early days but I think we will soon have a large number of people using the Gen 3 inverter with all the benefits that brings to the wider community.

I can't advise you directly having not used the parts myself but I can say the Gen 2 support thread is a nightmare whereas watching the LandYacht drive along the motorway with the Gen 3 inverter is extraordinary.

[Peter]

Thanks Kevin. I was only trying to relieve Damien of some redundant parts and give him a chance to recoup some funds.

[Kevin Sharpe]

Thanks Kevin. I was only trying to relieve Damien of some redundant parts and give him a chance to recoup some funds.

I fully understand but despite all our efforts he's still getting more than 10 emails a day plus numerous other electronic communications

Enough said, lets get back to the Suzuki Cappuccino

[Jack Bauer]

My Enova inverter in the E39 did the exact same in January having lasted just over a year in service and never giving me more than 30kw without problems. Now running a gen 3 prius inverter and Siemens motor and the car is perfect and so much fun to drive. Do yourself a favor and get rid of that enova.

[tom3141]

Thanks for your replies.

I think I'm going to go down the Toyota inverter route. Ignoring the motor side of things for now, it just makes more sense to switch to this rather than fix the Enova. It will mean that I can use a synchronous motor if I want to and will also be much easier to swap in a replacement in future if I blow things up again (although it seems that's quite difficult to do with a Toyota inverter!).

I'm just trying to decide on which inverter and PCB combo to go for. I'm leaning towards the Gen2 Prius with Johannes board. I like the idea of leaving the inverter intact and the PCB being outside. The fact that the Gen2 sorts out it's own deadtime and Damien has confirmed it doesn't shut off until 350A seem like plus points too. They are also cheaper and more plentiful than Gen3 Prius inverters. I'm a little wary of using a Yaris one having seen the mention of a capacitor with a lower voltage rating. I see your point about the Gen2 support thread Kevin but it seems most of the issues are to do with tuning a PM motor not with the hardware itself.

In terms of the motor, I'm not fully decided. I might leave the Enova in for now to test the inverter once I have that sorted but I'm not sure whether that's a good idea... I've had a quick measure up for an MGR and it will fit although the driveshafts may be slightly too long. It may be possible to move the MGR slightly forward and upward from the diff's current position in order to make the driveshafts fit unmodified. If I can do this it would be pretty simple to install one.

Part of me wants to see if I can fit a Lexus gearbox in but that's probably a bit mental. Does anyone know if the IS300H/GS300H gearboxes are physically smaller than the GS450H?

[tom3141]

Well I’ve taken the plunge, ordered a Gen 2 Prius inverter, RX450h rear diff, and a kit from Johannes.

Since the car is basically already converted, I’m hoping that I can get it up and running fairly quickly but we will see. I know how these things tend to go...

I’ll keep you updated.

[tom3141]

The Prius inverter, MGR, and Johannes control board arrived in the last week.

I got the board powered on and the wifi connection checked today. Now need to sort out the connections to the Prius 32 pin connector so that I can start the tuning process.

[tom3141]

I’ve had the MGR running on the bench at 30V and all seems good

Also got the Enova inverter and original diff removed today so I’m hoping to test fit the MGR on Monday to see how much work is required to adapt the driveshafts and get it mounted.

[tom3141]

The MGR fits in the car but the driveshafts will need shortening. I’ve purchased a set of spare secondhand driveshafts to do the modification on. I’ll also need to machine some adaptor plates as the flange bolt PCDs don’t match. They’re annoyingly close - Cappuccino is 4x100mm, MGR is 4x95mm.

[tom3141]

First proper drive of the Cappuccino with the MGR and Prius inverter today. It went pretty well but I have a couple of issues:

- Pulling away from a standstill is a bit jerky. Super smooth once you are rolling, it’s just very low speed control when manoeuvring that isn’t great. I’ve found making the throttle ramp parameter really low and increasing the throtcur parameter helps but it’s still not perfect. I have throtcur set to 10 at the moment which seems too high but I’ve never seen more than about 80A when driving.

- I seem to run out of steam at about 40mph. It accelerates well up to that point but there’s a noticeable sudden drop off. Any suggestions on parameters to try changing? I’m thinking it could be a field weakening thing, but the only parameter that seems related is fwkp and I’m not entirely sure what this does.

[celeron55]

As I didn't notice it mentioned in this thread, I want to ask: What battery voltage are you using?

[tom3141]

As I didn't notice it mentioned in this thread, I want to ask: What battery voltage are you using?

About 320V

[celeron55]

40mph with 165/65R14 wheels would be about 630rpm at the axle or 4296rpm at the motor.

I'm browsing through the MGR thread and according to it the motor should be in the ballpark of 14.5rpm/V, so 4296rpm would create 296Vrms in back EMF. You could be entering field weakening just about there.

[tom3141]

40mph with 165/65R14 wheels would be about 630rpm at the axle or 4296rpm at the motor.

I'm browsing through the MGR thread and according to it the motor should be in the ballpark of 14.5rpm/V, so 4296rpm would create 296Vrms in back EMF. You could be entering field weakening just about there.

That all adds up. I’ve been reading through Bexander’s Clio project and he has exactly the same problem with the MGR but at a lower speed due to his lower pack voltage.

I’m not fully clued up on field weakening but the way that the power suddenly disappears seems strange to me. I understand that the field weakening will reduce torque but would have expected this to be more gradual. There’s a very noticeable change, almost like a turbo lag that is inverted!

Is the rate/amount of field weakening something that we can play around with?

[180jacob]

Almost feels too obvious to suggest but just in case (and because you described it as a sudden drop off), make sure fmax is set high enough. I haven't used a gen 2 inverter but assuming its the same as the gen 3 the default is 200hz, and the motor has 4 pole pairs...

[tom3141]

Almost feels too obvious to suggest but just in case (and because you described it as a sudden drop off), make sure fmax is set high enough. I haven't used a gen 2 inverter but assuming its the same as the gen 3 the default is 200hz, and the motor has 4 pole pairs...

Yeah, I double checked that, I have it set at 600Hz. Always worth checking the obvious though

[celeron55]

I think the MGR is the case where openinverter field weakening is truly tested.

Somebody correct me if I'm wrong, but for what I understand, it is a permanent magnet reluctance motor with its magnets being buried inside the rotor's steel laminations, and due to that field weakening should be fairly effective.

Can you collect a plot of fstat, id, iq, ud, uq of an acceleration from 0 to 40mph all the way to where the speed has plateaued so that we can see what FOC is doing when the car doesn't accelerate anymore?

[tom3141]

Can you collect a plot of fstat, id, iq, ud, uq of an acceleration from 0 to 40mph all the way to where the speed has plateaued so that we can see what FOC is doing when the car doesn't accelerate anymore?

I’ll give this a go tomorrow

[Peter]

Hi tom3141. Could you post your parameters please, may help to see what they are set to Happy New Year from Lancashire

[tom3141]

I wasn’t able to get a plot today. I discovered that the rear motor mount had broken which may explain the jerkiness at low speed. It was a temporary mount that I had made to test fit it so I will need to machine a proper mount now. It may be a week or two before I can do this and get it fitted.

I will get the current parameters next time I’m out at the car.

Happy New Year to all!