View Single Post
  #25  
Old 02-11-2026, 09:53 PM
andrewwynn's Avatar
andrewwynn andrewwynn is offline
Member
 
Join Date: Jun 2015
Location: Racine, WI
Posts: 12,476
andrewwynn will become famous soon enoughandrewwynn will become famous soon enough
Quote:
Originally Posted by Clavurion View Post
Doesn't it cause phase shift and lag on the alternator or is the optimal phase shift so close to 180 degrees that the change is negligible?

Alternator has no idea. The phase of the 3 AC phases is shifted but the start point is completly arbitrary and as 80s mentioned the ≈ 400hz three phase AC is rectified to DC.

I wondered for decades how on earth does the car regulate the output and can usually maintain 13.8 ± 0.2v regardless of the RPM or load.

It's actually so simple: there's a direct feedback loop that increases the field winding current if voltage is less than the set/design voltage.

Higher field current, stronger magnetic field, higher 3-phase AC voltage that's rectified.

It's fully automatic and virtually instantaneous.


–awr–

Using Tapatalk VIP on iPhone
__________________
2011 E70 • N55 (me)
2012 E70 • N63 (wife)
Reply With Quote

Sponsored Links