Quote:
Originally Posted by serialk11r
The issue with PM generators (especially in gasoline engines) is that the amount of power available increases with rpm, but vehicles need the same amount of electrical power at idle. As the vehicle is moving and the engine is running many times higher than idle speed, the PM generator is running at very low load, and that's where PM motors/generators are not efficient.
|
True. But the extended idea is to use a lithium battery of some sort as a store for the energy produced at higher rpms, for use at those lower.
Also to run the generator as a motor during acceleration, charge allowing...
Quote:
Originally Posted by serialk11r
I don't really understand magnetic hysteresis very well but I know eddy current losses (which dominate at higher speed) can be cut drastically if you spend more money making thinner laminations for the rotor. Money is hard to come by though :P
|
Yep; its an issue that can only truly be solved with an electromagnetic clutch for coasting... although a centrifugal clutch may work.
If one's buying an efficient motor/generator; the manufacturer's done the thin laminations already. But as you say; cost...
Quote:
Originally Posted by serialk11r
Basically, this is not stuff you can do in your garage. The most DIY-able way I can think of where you mostly work with hardware off the shelf is cycle a normal alternator between 0 field current and maximum voltage, charging a bigger lithium ion battery through a step down converter, and using a larger pulley on the alternator to reduce its speed.
I think you could probably raise the alternator efficiency 20% (relative) by doing this, while losing 10% charging the battery, so you'd still be ahead.
|
Yep. get that low hanging fruit.
Rounding the edges of the fan thing with a file and sandpaper strips is also something I'd do.
There was a doodat on sale here that cut the power to the alternator's rotor field on acceleration.
It also 'opened' the aircon pump's clutch on acceleration.
No idea what difference it made or how the circuit 'decided' when you were accelerating.
An aircon's "ECON" mode does the same thing nowadays I think..? Or is it just a thermoset switch?