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Defining Terms : Parallel vs. Series Hybrid

6K views 28 replies 9 participants last post by  Yves M. 
#1 ·
I've seen some people (especially magazines) confusing these terms. For example, calling Prius "parallel" and Civic "series" hybrid. Or vice-versa.


PARALLEL = Car can be pushed by both engine and/or motor. The power flows along a parallel path. Example: Prius & Civic

SERIES = The car is pushed *solely* by the electric motor. The gasoline engine recharges it, so the power path is connected in series. Example: EV1 w/ gasoline generator trailer.
 
#2 ·
Sorry you are mistaken,
Honda Hybrids are only Series systems (electric assist only works with gasoline engine on)
Toyota Hybrids are Parallel systems (because electric motor and gasoline engine can run independently.)

The terms used refer to two different types of basic electronic circuit designs.
 
#4 ·
Troy's definition for series hybrid is correct. The auto manufacturer's skew the "hybrid" definition to make it mean what they want it to mean. Consider that none of the hybrids on the road today are actually hybrids.
 
#5 ·
Well the term "series" comes from electrical circuits, and it describes how the power flows:
Battery ---> Lightbulb ---> Radio ---> Battery

Same applies to hybrids:
Engine ---> Battery--> Motor ---> Wheels


...where the engine has NO connection to the wheels. Neither the Prius nor the Insight not use the above "series" design.
 
#6 ·
Err, I don't think you can really argue a likeness to electrical circuits regardless. If you want to get technical with the electrical analogy, a series hybrid would be something that requires both motors to run all the time - as if you removed one you would break the circuit.

However, errr. Well, a series circuit would have a series of cumulative boosts to the power, while a parallel system would have an independant sum of all motor systems. Neither term really applies to mechanics like it does to electronics, however.

If I had to pick one, I would say that the Insight is MOST like a series system, as the output of the gasoline engine affects the output of the electric motor - so they are not truly independant. However, I don't think that electronic terms can be fairly applied to a mechanical situation which is completely different from the concepts of potential difference and resistance present in an electrical circuit.

I can't speak for the Toyota Synergy drive, as I am not familliar with it's operation.
 
#7 ·
You call it "mechanical" but I see the car as a giant "electrical" circuit. To me, a series hybrid is an electric car with unlimited range:

EV1 + generator trailer = series hybrid
 
G
#8 ·
Hi ElectricTroy:

___The GM EV-1 never was capable of towing a trailer with a generator. You are thinking of the T-Zero if I am not mistaken.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:djqftkjx]Waynegerdes@earthlink.net[/email:djqftkjx]

 
G
#10 ·
Hi ElectricTroy:

___I have never seen one on a RAV4-EV but here is the T-Zero with its trailer in tow. While towing this monstrosity, you can only expect ~ 30 - 35 mpg when on the trailer unfortunately. That is pretty pathetic actually.

Range Extending Trailers



___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:3h9jmxoz]Waynegerdes@earthlink.net[/email:3h9jmxoz]

 
#11 ·
In this Troy's thread, I have to agree with him.

In a series, only one of the engines can turn the wheel and in a parallel, any of the engine can turn the wheel.

Series can be seen as in a train (diesel-generator-electr_motor-wheel) or a T-Zero plus generator (like others have wrote)

Parallel is as per the Insight and the Prius where any engine gas or electric can turn the wheels. I need to point that in the Insight, if only the electrical engine was used, it would not be efficient since the gas engine would turn and create friction.

A reference for this would by in 'How stuff works' :
http://auto.howstuffworks.com/hybrid-car2.htm
 
#13 ·
xcel said:
T-Zero with its trailer in tow. While towing this monstrosity, you can only expect ~ 30 - 35 mpg when on the trailer unfortunately. That is pretty pathetic actually.

Yeah well, it was only intended for long-distance travel. You're supposed to use the "free" energy provided by your home-based solar cells otherwise. :wink:
 
#15 ·
Wayne, if you know a machinist, he/she could redo the IMA engine rotor center section. The section that bolts to the flywheel on one side and bolts to the presure plate on the other

All one needs is (sorry, don't know how to say this) an 'adaptor' inside the rotor. With cylinders that jam on the inside the IMA rotor and that are turned by the gas engine.
If the gas engine has more RPM, cylinders are crushed to the IMA rotor and make it rotate. If the IMA engine has more RPM, the cylinders are free and the gas engine does not rotate while the transmission receives the torque and rotates from the IMA only.

All this in the center section of the IMA rotor. So that the Gas engine rotates the IMA (which rotates the transmission) but the IMA engine can turn without the gas engine.

And you would get regen braking with the IMA engine turning and the gas engine would not be turning at all. A plus.


Similar to kids bicycle engagement of the chain gear to the hub. The hub can turn without the gear turning but if you turn the gear, the hub will turn. There are cylinders in grease that squeez both parts to rotate as one.
 
#16 ·
I'm not quite sure how exactly you are proposing this, but it sounds kind of like a ratcheting action or possibly a centrifugal clutch kind of setup. It sounds like you might lose some efficiency though as your friction/clutch/adapter thing is probrably going to have some slippage.
 
#17 ·
Hi Eves, there are problems with having the IMA rotade without the engine. The Ima could not start the engine so there would be no auto stop. The IMA could not supplement the engine smoothing of the flywheel. The engine would rev freely untill it caught up with the speed of the IMA and transmission at which point it would engage suddenly. The apparatus would probably be quite large and heavy in order to withstand the force of sudden engagement. The IMA would need a separate set of bearings.
 
G
#18 ·
Hi Yves:

___Honda has to be the world engineering masters of clutch designs given all the ICE’s and transmissions they are involved with. If Honda wanted to make the Insight, HCH, or AH EV mode capable, they could use a clutch similar to that used in the rear wheels of the new SH-AWD RL or the electro-hydraulic units from the VTM rear differential on the MDX. I believe they are keeping the packs small so they have a light hybrid capability while keeping the costs below everyone else for future hybrid releases. This design compromise will not allow EV modes given the extremely short range you would have. Can you imagine what Toyota’s Prismatic Ni-MH Prius II pack costs with maybe 4 X’s the cap of the AH’s vs. what Honda pays Sanyo for the Ni-MH sized cells in the same?

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:26gdm9ar]Waynegerdes@earthlink.net[/email:26gdm9ar]

 
#20 ·
I prefer having NO electric mode. It's actually very inefficient to run off the battery because:

engine--->motor--->battery--->motor---->wheels

...introduces a LOT of internal resistance losses.
 
#21 ·
On the whole series thing it should be noted that the defination of a terms must take into accout the field in which it is used. The abbreviation RC can mean:

Road Construction
Royal Crown (cola)
Rosin Coated (photography paper)
Radio Controled
Reinforced Concrete
etc.

Parallel lines are one along side another in the same direction that never touch. Series can mean one thing after another or a bunch of ball games.

It really depends on what the writer or speaker intends. To me the Honda's are in series because the ICE and IMA are in a line one after another. If the industry standardizes on a different definition then my understanding would become incorrect.
 
#23 ·
Right! COAXIAL, duh, bonk, bonk, why didn't I suggest that!

Perhaps the Toyota should be called co-dependant as the gas motor will not start or run properly without the electric motor(s) and the electric motor will only drive an impractically short distance without the gas engine.

Then again, thud, the main motors on the Prius are coaxial too, though not not on the same shaft and bearings. Shucks, grumble grumble.
 
#24 ·
I see the confusion. The Insight engine and IMA motor are physically in series as they are bolted together. But that is besides the point here.

One needs to thing of the end result propulsion. The term series/parallel is tought to be like in the electrical term. The engine is a battery and the wheels (load) are a lamp. Each battery has an On*/Off switch.

With parrallel batteries connected to a lamp, any of the battery can separatly give current to the lamp.
With series batteries, each battery give to the next until the current reaches the lamp. If one battery is Off, no power can result.

So the Insight can not be a series. Each engine can drive the wheels separatly, meaning with the other engine to Off. If it was series, the gas engine could not be turning the wheels alone.
As for the IMA engine turning the wheels, one needs to have no gas left (one or two persons did experience the not efficient EV situation)

Like you guys wrote, more precices terms could be used. But in the parallel/series, there is no doupt for me.
 
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