EV-1 Conversion

[paultrafalgar]

Hey JCG,
Moved my ammonia intervention to here:
viewtopic.php?f=1&t=20325
so as not to hijack your EV1 thread.
Best wishes,
Paul

[GCinDC]

... we need to plan for more than the engine. Also the generator head, a small radiator, the tank, and the SCR phase angle current limiter... man I need more money. Another thing that needs doing is tuning the engine's controller for ammonia fuel.

Quiet summer. Any news?

[JCG]

Hi Greg,

Engine testing with ammonia in a converted 4-cylinder Toyota diesel (2.5 L, good for tests but too big to be the actual donor engine), and some rebuilding is necessary due to a bent push rod. Didn't make the deadline for the NH3 conference in Detroit (which ended yesterday). Good news is that we've located a good 2 cylinder block that should work nicely. I'm going to keep hounding the supplier about that. I have heard that another dollop of GM money may be arriving soon to help wrap up the project, which would be great as I'm ready to get the generator head and phase angle current limiter for charging the caps (already have heavy 3 phase rectifier to go between the AC and DC sides). Should be an active winter.

[paultrafalgar]

Hey JCG,
What's new?

[JCG]

Hey Paul,

Sometimes no news is good news. Though the project's funding hasn't been restored yet (it should be in place by the New Year), our presentation at the Ammonia Fuel Network meeting in September has been making the rounds. A group of investors has offered to buy an engine for further testing in Michigan - meaning the diesel won't need to be rebuilt again. The fuel and engine style (direct injection gasoline, usually found on very expensive cars) have caused this to take on a life of its own. In the meantime, I'm ready to purchase the generator head and SCR power controller once the GM funding is restored to the project. If something hits a snag and delays the work on the EV-1, I'll probably get my own engine, probably a 2-cylinder air-cooled diesel. But it's looking like a February-March time frame to make that decision.

Jason

[paultrafalgar]

Thanks for the update, Jason. All the best - look forward to developments in Spring.

[JCG]

Generator (alternator) head arrived today from the Mecc Alte warehouse in Illinois.

It's about 2 ft long, 1 ft high (at the back) and 1 ft wide. The connection shaft is 1-3/8 in (actually 35 mm) and is keyed.



Nameplate... the unit is a "mere" 80 kg (176 lb).



For those that haven't seen this before, the nameplate voltages of 133/230/266/460 correspond to the nominal voltages produced for several winding wiring arrangements. 133/230/266/460 correspond to parallel delta/parallel star/series delta/series star (DD/SS/D/S) at 60 Hz. This alternator is connected in series delta (D, 266 V) to give about 375 VDC after rectifying when the operating frequency is 60 Hz (3600 generator rpm). A look inside the control box:



The voltage regulator and controller board is on the left, and the windings are connected in series delta on the terminal block on the right. I'll use the proportional gain potentiometer on the regulator to make sure the generator isn't overloading the engine when charging the caps.

Now to get that engine...

[fechter]

Wow! that's a monster.

Does that have a separate field winding? I see something 16.6v at 1A on the nameplate.

[JCG]

Wow! that's a monster.

Does that have a separate field winding? I see something 16.6v at 1A on the nameplate.

Dang fetcher, you're up early. It is a monster; word on the street is that Honda recently picked a couple of these up (the same model) to work with their latest hybrid mule... I have to assume it will be a Volt clone. Anyway, yes, there is an exciter for the main rotor windings, and those numbers you saw on the plate are how to power the exciter (via the regulator, unless I'm mistaken). 16.6 V to the exciter power supply on the regulator, and then the control board will put between 300 mA (no load) up to 1.1 A (full load) of current through the exciter stator. The exciter stator has a resistance of ~16 ohms at room temperature so that seems to add up.

If there are issues with overloading that can't be resolved by the tweaking the regulator's on-board pots, I'll try to directly control the main rotor field by doing feedback control of the exciter field. Have to try it out to see what happens first.

[GCinDC]

Generator (alternator) head arrived today

So for us folks in the slow class, this is half of the genset, right? the wee thing that'll convert the ammonia engine's motion into electricity? is this the size you've been expecting? will it fit in the trunk w/ the ammonia engine? pardon the ignorance, but why so large?

[JCG]

Hey Greg - well, size and weight (although not too outrageous here compared to some other options) is the price you pay for the simplicity of air cooling. There's just nowhere to put another radiator right now, although that could change in the future. I definitely will do testing using a v-twin gasoline engine until the ammonia engine is ready. The v-twin will also be air cooled, so I'm going to be punching some holes in the trunk floor and adding heavy duty fans! As far as the fit, it's long but not tall, so it should fit well in the trunk.

[fechter]

It might be necessary to have some kind of current measurement/feedback to limit the current when the caps are starting out. I assume the regulator is a CV only. With the right current limit, the ICE should never be overloaded.

Ideally the regulator should hold the ICE at its most efficient operating point (or most powerful operating point depending on whether you're racing or not). Once the caps reach full, it should shut down completely.

It might be possible to use a brushless controller with the generator to make it into a starter motor for the ICE. This would be handy if the motor needed to stop and start frequently.

[JCG]

It might be necessary to have some kind of current measurement/feedback to limit the current when the caps are starting out. I assume the regulator is a CV only. With the right current limit, the ICE should never be overloaded.

Good stuff. The regulator is set up to just take care of maintaining CV, but I recently found that it's also got a stability block to it, which is supposed to govern the response of the generator to changes in load. For this application, my first shot at it is going to be to try and overdamp the hell out of the voltage response to load changes (using the "stability" pot), so that exciter current creeps up somewhat slowly and limits the charging current that way.

It's also set up to do what they call "overload intervention," which means that if an overload exists for a certain amount of time (I think 20 s) then the exciter current is reduced to drop the voltage. There is a way to tweak that intervention as well with a pot (in this case, the "amp" pot).

In case anyone would like to look at the manual (and hopefully see the best answer right away!), here's the manual for the regulator.

[JCG]

Engine time. Nice color match, right?



The generator head is to be coupled to a 690 cc Honda v-twin engine, which produces up to 22 hp at full speed (3600 rpm). I'll be running at around 3000 rpm, before the torque falls off too much, and where I can still expect decent BSFCs. All that stuff is to be tested later.

The engine and generator head are joined using a flexible shaft coupling assembly, two steel pieces with a Hytrel solid spider:




To my surprise, there wasn't any need to raise one device or the other to get the right vertical shaft alignment. My buddy Chris and I worked together late one night to mount the two pieces together on a frame of strut channel and steel plate. While cutting some of that plate (half inch thickness), Chris ran his DeWalt Sawzall out of juice, so we hooked it up to a car battery to finish the job.



I mentioned it before, but the garage is exceedingly dusty with this ridiculously thick, black dust everywhere. Yukon tried to sleep on top of stuff, but the yellow Labrador gradually turned into a black lab by the end of the night.



We got the genset mounted on the frame and I was able to start it up later on.




This past week I redid the frame slightly to help with shaft alignment as well as add a bit of strength to the bracing. The engine sounds a lot better with a muffler attached as well.




The three power phases from the generator go to my 6-diode rectifier, which feeds DC to the caps.






The generator is self-exciting, and after wiring it up, I could measure open circuit phase-to-phase voltage as the engine idled. Here, the generator is in an "underspeed" condition, where the regulator cuts the excitation current to drop the voltage. Speeding the engine up would clear the error and provide 240 VAC phase-to-phase.



My hope was that the engine and generator would be able to handle the short-circuit type of condition that exists when the caps are mostly dead, but that was not the case. The generator's regulator was constantly demanding 266 VAC delivered at precisely 60 Hz, and the engine couldn't keep up. Faults kept tripping, and it was clear that some kind of external control would be required. Here is the short version of what's been done so far.

First, I eliminated the route for the regulator to "talk to" the exciter coil by removing two quick disconnect leads. Here, the blue wire is the exciter negative, and the yellow wire is the exciter positive.



As I mentioned to fechter in a previous post, the exciter is supposed to be run between 0.3 A (no load) up to 1.1 A (full load) excitation current. I used a current-controlled DC power supply to vary the field on my own.



To maintain a consistent engine speed, I've got a knob-type throttle installed now. The tachometer uses an optical sensor, with a patch of reflective tape placed on the shaft coupling. Idle speed is around 1850 - 1950 rpm.





This morning, Chris adjusted the engine speed while I supplied a few different excitation currents to the winding and wrote down data, while everything was at open circuit. The voltages were measured on the DC side of the rectifier, so this is not the true open-circuit delivered peak voltage. However, it was a good guideline.




So, using an excitation of 0.35 A at 3000 rpm, we charged the capacitor bank until it settled at 362 V. It turned out that the true peak voltage was somewhat lower than what appeared during our test, so we had to boost the excitation to about 0.45 A in order to top the bank off at the desired 380 V.




While I can certainly do the work related to figuring out the optimum engine speed for cruising, I do NOT want to be playing around with excitation currents manually to maintain a constant current-type charging of the capacitor. One option was to connect a current-controlling SCR, like you would use for a three phase heater, to the generator outputs.



I am positive this would have worked, but it would take up a bunch of space, would require cooling, and would cost about 3000 USD. First I'm going to try a cheaper method using a brushed DC Kelly motor controller at 12 V:



Here, a current transducer is placed on one of the incoming generator phases before the rectifier. Depending on the current it detects, it sends a 0-5 V signal (0 for no current, 5 for my choice of 10, 20 or 50 phase amps) to the Kelly Controller's throttle input. The throttle input is most commonly arranged for 0-5 V, that is, 0 V input causes zero throttle/current demand, and 5 V is full throttle/current demand. However, it may also be configured to 5-0 V input. Then, when the phase current is the prescribed maximum, it will be at +5 V, and asking for no "throttle" (zero current to exciter winding). If the current drops off, there will be more current sent to the winding, increasing the delivered voltage and therefore raising charging current. The Kellys are great in that they may be programmed for a current limit, which I'll set to about 0.5 A at 12 V. That should prevent overexcitation. Thanks, by the way, to Jeremy Harris for discussing this with me over a PM.

That system will have to be tried out when all the parts arrive. For now, things are coming together.

[GCinDC]

The generator head is to be coupled to a 690 cc Honda v-twin engine, which produces up to 22 hp at full speed (3600 rpm).

Running off ammonia, or have I missed something?

[JCG]

Running off ammonia, or have I missed something?

Gotta bust my chops, eh Greg?

No ammonia 'til the carburetor gets modified - I gave up on an my ground-up ammonia engine supplier! We'll get there eventually. For now I can hack on the electronics side.

[GCinDC]

Gotta bust my chops, eh Greg?

If I wanted to bust your chops, I'd mention the noise...

[lesdit]

What happened to the super cap ebike project? Dead ?
I hope the EV1 project does well, without fizzling out!

[JCG]

Still have the cap bike, it served its purpose! I think I'll continue modifying it now and then, but the main thing I wanted out of that was to get some experience with the capacitors and regen before messing around with the EV1. Thanks for the good wishes!

[vanilla ice]

Geeze lesdit, talk about busting chops..

BTW we want some new pics!

[lesdit]

Are you using a switching boost supply to drain the caps most of the way, BTW ?
I ordered a bunch of supercaps to play with on my bike, and don't see any other way than to use a boost supply to effectively use the energy from the caps.
The caps are for burst sag control.... charge slower from the battery, drain fast for a few seconds when the bike wants 300 amps.

Pretending the caps are a battery just does not work well at all, as the voltage drop due to discharge drops right away in a linear fashion to zero, quite the opposite of a good battery.
You need a joule thief.

[JCG]

BTW we want some new pics!

Yes sir! Waiting on one more piece to the current controller scheme, and have tested the other parts on the bench. Hope to run a full charge test under control this week.

Are you using a switching boost supply to drain the caps most of the way, BTW ?
I ordered a bunch of supercaps to play with on my bike, and don't see any other way than to use a boost supply to effectively use the energy from the caps.

I'm not sure if you're talking about driving drain or testing drain (draining between charge tests). in the case of testing (what I'm doing now), to re-drain the caps between charge tests I'm just using a bank of 100 W light bulbs. It takes a little while, but I also like to run the high voltage system to the the 12 V system (through the DC converter) to run the water pump, auxiliary charging, etc. That helps speed the draining up a bit.

For driving, the inverter will run as long as the DC bus is between 400 V (max) and about 180 V (min). I never like to see it drain that far, because then motor currents get a bit high when accelerating. Back on the capacitor bike, my Kelly Controller would keep chugging for all voltages from 60 V down to about 18 V before it tripped an undervoltage fault.

Some of the old benefits of the supercap have kind of gone away, since some of the newer lithium polymer batteries can handle very high discharges without blinking. A lot of the impetus for using a battery-supercap combo was to protect the battery from high discharge peaks, the importance of which is really set up by the chemistry you choose. What kind of battery is on your bike?

[lesdit]

My bike has emoli cells, 14s 12p . ( it's a zero pack ).
It sags under power, and acording to another zero owner that just got a brand new pack, he sags as well.
I hope to make a switching supply to take from 5V to 22V from the supercaps and make 48 volts while the caps are above 5v . The supply should be able to make 100 amps to help out the battery. Boost supplys are not that complex, really.
A possible chip that can be used. Inductors and switching need to be way beefier, but the data sheet shows a 4 phase boost supply.
http://cds.linear.com/docs/Design%20Note/dn453f.pdf

On your bike, I imagine that the power was really falling off as the cap voltage ramped down ? Or did the controller compensate ?

Does the EV1 also just compensate by drawing more amps from the caps as the voltage decays ?
You really would be better letting the caps get to near-zero volts, to get the most from them. The caps don't care, they are happy to oblige !

Are you the guy selling the various caps on ebay , may I ask ?

The EV1 was a great car, funny how GM would like it to be hushed up.
I have a daily driver Honda Insight with over 250,000 miles on it, I want to EV it when the ICE dies.

[JCG]

On your bike, I imagine that the power was really falling off as the cap voltage ramped down ? Or did the controller compensate ?

Does the EV1 also just compensate by drawing more amps from the caps as the voltage decays ?

You're right, the controllers in both the bike and EV1 cases compensate by drawing more current, but you were still stuck with the lower top speed in the bike's case since that fell off along with the voltage, regardless of power. I can see how you'd like a nice steady DC value to be humming along with your bike's (assuming BLDC hub) motor.

I think that ultracaps can still be used to prevent the voltage sag you're seeing, but it may involve using larger caps than what you've got at the moment, and that can get expensive. With basically only one company (Maxwell) making them, there's no competition (or even serious mass production going on) to bring the prices down.

A boost converter is a good idea. My concern is that it'll be tough to find one that isn't really bulky to handle the higher power you need. You may want to have a look at a few of these:

Zahn Electronics Boost Converters

I like the idea of converting the Insight. I've come to believe that good aerodynamics is the best starting point.

[GCinDC]

J,

check out this vid. no idea what they're using for batts on KERS, but doesn't it seem like ideal (or better) use for caps? short term storage of high V? quick discharge... thought of you when i saw it...