Alternator wisdom

[swiss]

OK, now I know I should know this after three years of tuition, so please don't tell my lecturers.

How is the frequency regulated from a car's alternator? Or if it isn't, how does it run at such wildly varying frequencies without blowing stuff up? The only method I've really learnt about concerning frequency regulation is using banks of big-arse thyristors in a diesel-electric propulsion system...

[Doggy]

It doesn't - frequency is dependant on speed alone - an alternator works by rotating a magnetised rotor within the stator coils, each magnetic flux reversal causes a half-cycle in the winding it passes. The resulting AC produced is simply rectifed into DC. Output is controlled by regulating the excitation current to the rotor, which in turn alters the output voltage.

[swiss]

Oh, God damn it, of course. The car doesn't actually use AC, the whole thing is rectified right away.

Jesus, talk about a blonde moment...

[steve_earwig]

OK, now I know I should know this after three years of tuition

Looks like that was 3 years wasted then

[Welly]

Doggy knows his electreeks then

That's the sort of thing I would read over and over, understand for a second, and then forget

Whilst on this topic the Volvo's charging system has pulse width modulation - what's that?

[steve_earwig]

Look it up on Wiki, you lazy bugger

[swiss]

Ah, see, now this I do know about. You have full-wave rectification then you use computer-controlled thyristors to 'chop' the wave form so only the parts of the wave the system actually needs get through. In this way you control the amount of electricity available to the load

[steve_earwig]

I knew that