MinisterofDOOM wrote:Looneybomber wrote:I'm still waiting for cars propelled exclusively by electric motors. A highly efficient turbine engine will turn a generator to power the electric motors and small battery banks can be used to absorb extra energy produced. That would require a LOT less weight than using an internal combustion engine and a large battery bank.
That's how the Volt works. Unfortunately GM bungled the power generation aspect of it, and is has now effectively become an expensive power-laundering machine, with the gas engine still doing all the real work.
I never read up on the volt. Maybe I should have though.
MinisterofDOOM wrote:
Low-rpm torque-tuned diesel generator with electric drivetrain is the way to go IMO.
Turbines are high-rpm, low torque, the opposite of what you want when turning a generator.
High speed generators run directly off a turbine have a big advantage over typical low speed generators in that they are much smaller and thus lighter, but still able to put out the same amount of power (increased power density). Turbines can be built to be extremely efficient in a narrow rpm range, more so than an internal combustion engine could be. They can also use variable vein geometry's to widen that rpm range or be built to be less efficient but in a wider rpm range. Same as with any turbo we put on our cars.
I couldn't really find any good "white pages" with my 15sec search.
http://www.high-speed-generator.com/
MinisterofDOOM wrote:
I definitely agree about using batteries as a ballast or buffer. Produce a constant supply of electricity to the batteries, which can then provide a variable supply to the motors as needed. Design the power buffer right and you're never going to run short, but you also won't impair efficiency by expecting the combustion engine to operate over a wide RPM range.
I actually thought about this quite a bit when I worked in the warehouse unloading trailers and driving the fork truck. (2.5yrs ago)
I would have the car designed to run entirely on the engine (the power produced by it's generator) when driving at 70mph with only the driver at the engine's maximum efficiency rpm. Any deviation then will marginally effect gas mileage due to having the engine spin at a rate different than where it's most efficient. Going up hills, it could use some of the energy in the battery buffer. Going down hill, engine rpm does not change and helps to charge the battery back up, ultimately trying to keep the battery around 75-80% capacity.
In town, the engine would again run at it's most efficient rpm, and shut off once the batteries are 100% charged. At 30% it would start back up and run at maximum efficiency and keep cycling.