Hybrid designs (HEV's)

[skinny]

given that the electric motor has excellant torque characteristics to drive vehicles, and all engines are optimally run at a certain speed (for best torque (and/or power) / fuel economy), surely the best solution to integrating the two systems is in a series hybrid rather than a parallel?

in the series hybrid, the fuel motor runs (as and when needed) at a certain speed optimised for power and economy under a specific load (very easy conditions under which to optimise an engine), the power output going to a generator (again optimised to convert power at a certain rate). this generator then charges a battery off of which the electric motor runs to drive the vehicle.

As i see it, this has many advantages:
- As many parts as possible are optimised & dedicated to certain and exact performance conditions
- It is very easy to vary the components as needed, for example if you wanted a larger fuel motor and smaller battery, or if you wanted a smaller fuel motor and larger battery. you can also change the electric motor size depending on whether you want higher economoy or performance
- performance can be comparable to any modern car (including sports cars / high performance cars) instead of the usual compromise (or limit) on performance that a hybrid car usually imposes
- As peak power needed is a huge amount higher than average power, the fuel motor can be drastically downsized with no loss in performance - the system acts like a buffer
- there will also be no limit on range like pure electric vehicles as you will just fill the car up at a conventional fuel station as per normal
- low speed driving requires less energy as no power is being wasted (for example in idling or coasting in traffic, you would be using negligible amouts of enery, if any at all). you could drive in towns without the need for the fuel motor to run. similarly short runs would not require the starting of the fuel motor
- it will be a good platform for manufacturers to start investing in technology leading to pure electric vehicles, giving an opportunity to develop electric motor and battery (or alternative energy storage) technology whilst testing it in the real world. the fuel motor can then simply be phased out over time if need be
- the system and integration of the components will be simple and cheap
- the 'drivetrain' allows a wide choice of engine, including those more efficient and cleaner than petrol 4-stroke, such as relatively clean and efficient gas turbine engines
- torque characteristics of certain electric motors are perfect for vehicles, with a flat torque curve across their whole speed range up to their maximum (and often very high) speed, increasing efficiency and performance even more
- electrical braking system can directly charge up the battery instead of just converting kinetic energy supplied by the fuel into heat, thus further reducing wasted energy

I must be missing something though. why do the major hybrid electric vehicle manufacturers insist on a parallel design where a weedy little motor has to (inherently innefficiently) travel up and down the rev range, with a complicated integration of electric motor assistance when extra power is needed, the torque curves and speed range of the engine are still fundamentally flawed for vehicle use (hence the use of a 5-spd gearbox or whatever, losing more energy), and it doesn't go any of the way to producing a valid electric vehicle.

please can someone explain their choices as i simply don't get it



>>> Edited by skinny on Thursday 9th December 12:04

[skinny]

i can't imagine that the honda insight for example was cheap for honda to produce either tho, didn't most governments heavily subsidise it to keep the puchase price reasonable?

also, even if this powertrain was £2000 more to the customer than a conventional set-up, this would be offset against fuel costs i would have thought...