Simple Series Hybrid
 

I would like to eventually made a series hybrid I just need to gather my ideas and key features.

I plan on making a series hybrid that cannot be moved when the ICE doing the powering is not running , and without battery banks.... Yes I know this will lose some efficiency unless regulated precisely with a computer to vary output to match. Including at idle of the ICE without a battery bank to charge with the wasted energy.

But my ideas are besides reliability , simplicity , practicality , cost , weight , space.

So for my purposes of what I would like to make one I feel that no battery banks and no transmission and relying on the low end torque of an electric motor of adequeate power will do the job while keeping the weight down while accomplishing the others key ideas also.

I have a question to whether or not I can power my electric motor for the ICE output whether a motor or generator I have yet to decide... By transfering full output of the engine directly to the motor without a controller , and use my pedal or throttle to meter the output of the engine , with a switch at the beginning position of the throttle to close the gap from the power generated to allow me to idle my engine without any movement without needing to hold a brake.

Also I am going to research to see if I can find one but am wondering. Are there any dual shaft electric motors with a built in differential? I highly doubt it from my basic understanding of electric motors if its at all really possible without extensive cost , size , and weight.

re: differential, series aside, you can use dual motors and that will allow them to rotate at different speeds. Dave clouds dolphin uses two motors (with separate controllers and battery banks IIRC).

Hi 88FieroGT,
What you are describing could be called an electric transmission. As long as you are willing to take a hit on efficiency this is quite possible. I agree with dcb, a dual motor design would probably be easiest. There would be no problem with having the engine directly power a generator which is wired to the traction motors without a controller. At idle the generator would only be making enough power the make the motors creep anyway, like an automatic trans. All you'd need is a way to switch the wiring between forward, neutral and reverse.
-mort

dual motors also allows you to do a series/parallel mode, where you can apply all the current in series to the motors for more torque then switch the motor configuration to parallel for more top speed, *sorta* like a two speed transmission, with switches instead of gears.


i.e.
http://www.4qd.co.uk/faq/bmnc2.html#diff
http://www.diyelectriccar.com/forums...lel-16415.html

but there may be an assumption about a current limiting controller or something.

Thanks for the replies... Im going to save the link to this thread to my favorites and look into those links a little later... I was just coming to check to see if I had any replies , while im waiting on some help with some heavy engine/transmission lifting.

A serial hybrid without batteries is similar to the Volt. It is not an efficient way to do it, because you have to vary the RPM's and you need to be able to meet the *peak* power required, rather than just the average. And you have to run the ICE all the time, instead of about half of the time (or less).

So you have to increase the power of the ICE, and therefore you lose the main advantages of a serial hybrid has.

Having even a small battery bank to act as a buffer would allow you to have a much smaller gas engine, smaller generator and greatly improve your acceleration, pretty much any small lead acid starting battery would work and your weight and space savings by having a smaller gas engine would make up for the weight and space of the batteries.
It would be crude, but you might almost be able to get away with just having a contractor to switch the battery pack in to the loop for charging and another to switch it in for powering the vehicle and if you have dual motors it could be easier to switch it in for regen braking as well, all without a solid state speed controller, of course I like how smooth solid state speed controllers work but it sounds like that is one of the things that you want to avoid.

Sorry for the late getting back , had alot of running around to do. Also looking for missing parts , which I think I may have to replace but not too much of a biggie its something small.... But its kinda late now so I still dont have alot of time to look at those links.

But keep with the input ill chime in when I have a chance to look over everything and absorb.

Is there supposed to be some sort of benefit to this electric transmission? :confused: I know it works for locomotives, but their situation is different.

Hi Frank Lee,
The advantage is that you're always in the best gear. There are some design and layout virtues, only wires from the engine to the motor(s). But the efficiency just isn't there and it's very expensive to implement.
-mort

yah, and even electric vehicles can benefit from having actual gears to choose from downstream of the motor, i.e. so you can climb hills AND go 70mph.

They are beginning to figure that out dcb.
regards
Mech

It takes a transmission specifically designed for electric motors. Regular car transmissions cannot handle the instant torque -- ask the good folks who built the Illuminati '7'. Even the differential was destroyed by the electric motor.

And Tesla tried a 2-speed transmission, and then discarded it. Direct drive is better, and more efficient.

I got alot going on right now , so im going to have to just quit my planning , researching , and deciding. Too much stuff on my mind right now so need to put all this on hold.

But from everything trying to decide in my head without being able to really sit down and think it through cause of stuff that always comes up and has come up now.

I think im going to go to the ICE setup and just do the best I can with mpg with the performance im looking for. Alot of reasons which I havent fully sit down and figured out pros and cons and how accurate my reasons are but cant right now. But think im going that way.

Electric motors have efficiency curves like ICE's do; and if the vehicle has wide enough variations in environmental demands placed on it (low neighborhood speeds AND turnpike speeds; steep hills and flats; empty and heavy loads) an EV with gears has a definite leg up.

As far as "regular" transmissions being too weak, well, that was just a poor choice of transmissions on the part of the builder(s). If people build 1000 hp street machines with transmissions, you can sure build an EV with one.

As far as the Fiero, you can expect 90+% efficiency with a stock a/t and, oh, 94+% efficiency with an m/t. ICE>generator>motor would certainly be far worse.

He will figure it out eventually Frank. Direct drive EVs need motors that are too large and they can't regenerate 30% of any decelerative energy, without some way to raise the motors RPM.

A 60-0 panic stop only takes about 20-25 revolutions of the wheels, he can't explain how you are going to pack 600 HP seconds of energy into a chemical battery in 25 revolutions of an electric motor generator unless its as big as a power plant, and the battery weighs several tons. He will avoid the point by saying you should never have to panic stop.

regards
Mech

Might actually learn something if he read the link. Even EVs can benefit from capacitive load levelling with a capacitor or accumulator. but it won't happen with direct drive which still requires a differential or two motors.

Electric Hydrid

regards
Mech

Green Car Congress: Getrag introduces new dual clutch transmission for electric drives, prototype of range extender, mild-hybrid dual-clutch variant

Green Car Congress: Antonov study of multi-speed transmission for EVs finds improved efficiency over different drive cycles

Green Car Congress: On-road testing of new multi-speed transmission for EVs from Oerlikon Graziano/Vocis begins; potential for increased range or reduced pack size

It would seem ludicrous for these major international corporations to think it is cost effective to actually have a transmission in an electric car.

Wonder how they could so stupidly waste precious resources.

regards
Mech

things have calmed down for the moment so I have time , especially since its dark out. I cant go outside and get things done and etc...

I have decided to just go the route of a full ICE setup , 1-2L displacement because I can get enough N/A power out of that sized displacement and gear towards what I need for what I want. While keeping the reduced weight im looking for.

170+ HP from 1L minimum, but peaky and narrow powerband so not much down low but quick revving if geared enough to not struggle to make up for it. tuned where peak power occurs at a healthy and reliable mean piston speed. I dont know what efficiency would end up being with this because I would still be able to cruise with low HP but in lower rpms with an engine which favors higher rpm.

came concept as formula one to where it should perform well still?

Motorcycle engine? Lots of shifting but if the power is there it should move. Possibly somewhat more efficient than a stock Fiero, but possibly not.

Maybe would be the easiest option but then tune them to produce the power a little lower for reliability, newer bike engines shouldnt be too hard to get a hold of i wouldnt think either even with the improved technology of today on them still.

But also this isnt for my fiero its a project in the future. Maybe some design cues of the fiero but im not sure. But custom built to be alot lighter , unless I just find a really light car chassis and or body that I might would want.

http://www.youtube.com/watch?v=QJa7B...eature=related

Motor cycle engine maybe would work , althought idk the weight of a stock geo not to mention a gutted one. Atleast gives me something to think on.

Long as its fast enough speed and acceleration to keep from being dull and have me bored when I drive it while also handling amazingly I'd be happy.

They started with a METRO transmission/diff neil!!! and put it to a powerplant that does 0-60 in 6 seconds (down from maybe 14 seconds for a stock metro). electric motors don't have some magical "instant torque" that destroys any transmission you show to it, and even if it did, it could be fixed with a software patch to the controller. Plenty of mild EVs on evalbum that are using them.

better? more efficient? You have not thoroughly analyzed this to make such a blanket statement. Lets look at some of your assumptions:
1. electric cars should have 300HP motors
2. There was no engineering issues in the gearbox
3. Drawing higher currents and providing more cooling (making more heat) is more efficient than having gearing options.

My low power electric scooter was much "better" when I made it a two speed, it could climb hills and had better top speed, trust me on this. Yes there is a fixed efficiency hit for having selectable gears, in this case it is the extra chain and freewheel drag, but that could also be addressed directly (two chains with 4 dog clutches to completely disengage the unused chain and sprockets).

http://ecomodder.com/forum/showthrea...ter-14889.html


Tesla had engineering problems, they really wanted two speeds because that makes sense. Electric motors do not have a flat efficiency curve either and might have to be oversized (inefficient) if they don't have a transmission:
Discussion of the Nissan Leaf Transmission and Efficiency

So they took a METRO transmission designed to take a 2000 lb car from 0 to 60 in 14 seconds, and put it in a 3300 lb car where it goes from 0 to 60 in 6 seconds.

Recall that F=MA (Force=Mass*Acceleration). M is 1.65 times greater and acceleration is 2.3 times greater so they were overloading the transmission forces by about a factor of FOUR times its design capacity!! (3.85)

Right, and the difference in efficiency between 3rd gear and 4th gear was about 2%. You lose that much by introducing the best gear reduction "transmission" like the Borg Warner unit used in the Aptera. And Tesla used a "proper" transmission, and they discarded it after having similar problems. The torque of an electric motor is much harder to deal with than an ICE. There is an order of magnitude of difference in the quickness of the increase in torque, and this is very hard on the gears.

Back on topic: it is the buffering function of the battery that gives a series hybrid all of it's major advantages. So, I don't think it should be eliminated.

1) You can plug in and charge the battery which is the most efficient way to get electricity in the car. An electric motor is the most efficient way to power a car, so this makes sense.

2) When the battery is nearing depletion, the ICE can be started to spin the generator. This is best done at a fixed RPM, so the engine can be run at it's peak efficiency. The valvetrain and intake and exhaust can all be optimized for this RPM; with no need for variable valves. (Although on one recent genset, they designed it without a throttle and used the valves to control the RPM, I think?) It might be possible to eliminate the throttle altogether?

3) The ICE needs to only meet (or slightly exceed) the average load, and not the peak load. So the displacement of the ICE is minimized, and then along with that, the cooling system can be minimized (which pays dividends in lowering the aerodynamic drag), and the fuel tank and exhaust systems are smaller and lighter weight. The ICE will warm up more quickly.

4) Since the genset can charge the battery more quickly than it gets depleted, the ICE only has to run periodically. This obviously save a lot of fuel, too. The cooling system can have an active louver to closed when the ICE is not running, or during warm up to get to optimum temperature as quickly as possible.

So, having a battery pack of a certain size depending on the efficiency of the car makes a very big difference.

Actually they are saying a 3 speed can improve EV efficiency by about 20% in real world conditions.

Do you have even one link or source to back that claim up? Ever seen the oscillations pistons introduce to a driveline? The tesla isn't a two speed because of marketing pressures and poor design:

Tesla CEO on Brush With Death Due to Transmission Troubles — Cleantech News and Analysis
"We learned that the car industry is unbelievably good at delivering what they’ve done in the past with a little tweak — faster, or in yellow. But if you want something a lot different — a simplified transmission that’s electrically actuated — that’s too radical. The designers and engineers who can do radical changes all left Detroit forty years ago."