[subcooledheatpump]

Yeah I could do both of those pretty eaisly.

thanks for the tips

I'm thinking of doubling up the brackets, one on the inside of each side in addition to the outside.

I'll be working on that conduit for a while, I've got to get the right adapters for it to actually fit the conduit box. I just tied it up with plastic cable ties for a quick fix since I wanted to take it for a quick drive.

Speaking of which, I took it for a drive. I hit probably about 50 MPH (going to get a GPS speedo). Definitely more power, torque and speed. Throttle is a little too sensitive so parking can be a bit of a problem.

I since I now have 4 poles and before I had 6, each increase in frequency means 1.5 times more speed, which makes the throttle potentionmeter 1.5 times more sensitive.

My modified inverter seems to be okay but it hums pretty loud now. Peak current 150 amps.

overall I'm happy but still, much more works needs to be done

[subcooledheatpump]

Well today I've been working out the controller programming. I think I've got it where I like it.

I'm having some issues with the batteries though, I think they may not be able to supply the current I require safely. I can smell a sulfur like smell where the batteries are in the van. I'm thinking I've exceeded their maximum discharge rate.

I'm thinking of getting more batteries and adding them in series, then leaving them only partially charged to allow more headroom for Regenerative Braking. Any thoughts?

Also, does anybody know of some decent batteries that don't have a high capacity, but have high current discharge abilities?

I don't want alot of capacity, because I don't want the van to take forever to charge, I won't be driving it long distances anyway. I just need the high current (150, maybe 200 amps) delivered without explosions or gasses building up

[Nathan219]

The A123 20 ah cells can supply 20C and are available. That is your best bet for a low capacity fully capable system. Example you can extract ~400 amps from the 20 Ah cell for 3 min.
You could add a string of Lithium in parallel with your pack This would allow the Lithium cells to supply current during acceleration and absorb current during regen because of their low internal resistance. IMO some lithium cells are almost like capacitors with the way they can handle current.


Good luck,

And keep up the posts I know I am interested in your progress!

[subcooledheatpump]

New video, motor and driveshaft turning in the end just cause

Batteries seems to be okay now

[JRoque]

Excellent! thanks for the video.

I would charge the batteries full and then, if possible in the VFD, limit the bus voltage max and regen current peak to protect the batteries. I agree with the previous comment on going with A123. Even if you just get enough of them to get to your bus voltage (serially connected), it will help with the high current draws and to soak up the quick rising regen.

I think you will notice a nice difference in low end torque if you install an encoder and run the controller in vector mode.

JR

[subcooledheatpump]

Thanks for the advice guys.

I'll have to work out how to get some of those A123 cells.


Yeah I do need a FOC/vector drive with a little more intelligence as to what the motor is actually doing.

The motor controller I have now is sensorless, does a pretty good job of making peak torque happen in the low end, but it's still too confused and the motor can step out sometimes

[Otmar]

Originally Posted by subcooledheatpump

Yeah I do need a FOC/vector drive with a little more intelligence as to what the motor is actually doing.

The motor controller I have now is sensorless, does a pretty good job of making peak torque happen in the low end, but it's still too confused and the motor can step out sometimes

First of all, Nice Job!
I love the idea of leveraging engineering that was done for higher volume applications and applying it to us hobbyists.

I have a early Honda Insight sitting here converted to electric with a GM EV-1 motor and a Zilla 3 phase power section that really needs a control board. I am not willing at this time to program my own (too many other things to do!) but would like to get the car running and maybe also work toward a open solution to drive my small pile of EV-1 motors so others could make use of them. I am very interested in the idea of using a industrial VFD brain for this if I can get what I want without too much work.

Electrically I'm fine since the Tri-Zilla has plenty of current capability and gate drives built in, but I'm concerned about choosing the right VFD for the control since I am not familiar with the various options. I'd love some advice on this part. I've spent enough on this project that a few hundred $ is not a problem, so it doesn't have to be the cheapest one on ebay. The motor is essentially a 137hp (wired as if it were a 60V 60hz) 4 pole Y connected unit that wants a ~312V battery and 400hz. It has a quadrature encoder with about 180 PPR IIRC.



A few concerns that I have that may be non issues, but I'd love advice on them:
1) I see in the Toshiba VF-S11 data sheet that it can do "open loop vector". Does this mean it can't do vector with a speed sensor? I know from other AC drive projects that a speed sensor and a fast control loop is critical for smooth high torque starts. Once the rubber mounts and drive shafts start winding up the motor speed can change very rapidly and start up oscillations. Ideally I'd like a controller that is designed to handle that sort of thing.
2) The inverter running my milling machine will shut off if the load goes too high, in the EV we want it to just limit to maximum torque. Is this what the S11 calls "constant torque" operation?
3) My intention for this car is to put it in a local car share. Therefore I'll need to include all the usual safeties and it will need to drive like a normal car. Right now if you try to accelerate too fast it shuts down and you have to coast to a stop to restart it, clearly it's too much of a "science project" right now (the current software was a local college senior engineering project). Is there anything about the VFD conversions that would stop it from being a nice turn key operation?

Thanks to all of you doing VFD conversions for blazing the trail and for any advice you can offer!

[JRoque]

Hello Otmar, I'll let the OP comment on your questions.

I bought an SJ300 drive some time ago to make the VFD conversion. I found that it did everything I needed except for proportional regen based on the brake pedal variable input. I suspect it will do that as well if I add a shaft encoder. You need an optional encoder board that's ~$130.

You can certainly limit current going forward or coming back from the motor. You can also fault on high/low bus voltage. You can regen on decel as many others do. The drive has a separate 24VDC logic power supply input so bus voltage can be independent. You can feed it 2 phase power or bypass the diode bridge altogether, though these would be moot once you've replaced the power section. It also supports RS485 and has a number of programmable I/O pins. The drive will adapt to most any motor automatically or you can enter the motor specs manually.

So it will move your car and do basic functions needed for that. If you contrast what's provided with what you get out of a Curtis drive, there's a wide margin for improvement and refinement, of course.

JR

[subcooledheatpump]

Hi Otmar,

Yes the VF-S11 is only Sensorless.

It does have current and voltage limiting abilities that will prevent the drive from shutting off during any kind of overload, which as you said is essential

The drive has a feature which it calls "autotuning" which automatically detects the resistance, and inductance of the motor stator and makes a model of what it thinks will be the best V/Hz ratio for the motor. It works in the van but as I said it's not perfect because it isn't always right. It makes an educated guess and it's reasonable, but not ideal.

As JRoque said, what is needed is a variable torque response Regenerative Braking system, so that when the brake pedal is pressed, the drive will serve negative torque proportional to the pressure on the pedal.

The acceleration is pretty good though. Sometimes the motor steps out and you can hear the motor hum. If the accelerator is lifted you can feel the acceleration come back and you know that you're in synchronization again. This is due to what I said before, it needs a speed sensor and true vector control, not just sensorless.


At the moment I have a pretty wild and crazy idea, which will probably never work out in the real world, but I'm thinking of trying it none the less, and that is to modify a VFD and try to sell it on ebay, As is with no warranties. Not sure who would be interested but I am seeing more and more people getting interested in Induction motors and high voltage in EVs. So you never know

As far as driving the Tri Zilla, Just about any VFD with true vector control should do the job, and long as the encoder is compatible. I don't have any specific recommendations because there are so many VFDs out there, it's hard to say which one is the best. Most VFDs will autotune, that is automatically set the parameters/programming. So I'd say look for one with autotuning and a compatible input. I'd also check for switching frequency compatibility, just to make sure it will work with what the Tril Zilla gate drivers are expecting. I would say, but I'm actually not sure what the original tri zilla switching frequency was supposed to be. Also the voltage, I'd imagine the tri zilla works from a relatively higher voltage. 240 volt 3 phase VFD will need 340 DC to turn on and run so the Tri Zilla should be compatible with that

Also I'll be happy to answer any more questions you may have about VFDs and induction motors in EVs

[Otmar]

Originally Posted by subcooledheatpump

At the moment I have a pretty wild and crazy idea, which will probably never work out in the real world, but I'm thinking of trying it none the less, and that is to modify a VFD and try to sell it on ebay, As is with no warranties. Not sure who would be interested but I am seeing more and more people getting interested in Induction motors and high voltage in EVs. So you never know

Doesn't sound too wild to me. Few people have the skills to upgrade a drive and doing several of the same at once could save some money.

Thanks JR for the SJ300 info. So that one looks like a good possibility for my application with the SG-FB card added. I've been looking through the instruction manual and it looks like most settings can be changed on the fly with the RS-485 serial port. It looks pretty ideal to me.

I see the SJ300 is obsolete and the SJ700 seems to be the new version of it. I wonder if it's worth the upgrade? http://www.hitachi-america.us/suppor...-ac-drives.pdf

We could use an Arduino to send torque and speed commands for drive and regen and control while reading the accelerator and brake pedals. I like that since it allows us to add any feature that we normally would want such as gradually reducing current as the battery voltage reaches the high or low limits and controlling the precharge and startup.

Any other suggestions of the best drive to start the project?