Help understanding generators/alternators

  • Thread starter Thread starter wall6ly
  • Start date Start date
AI Thread Summary
DC generators were commonly used in cars until around 1970 due to the limitations of early rectifiers for high-current AC from alternators. These generators featured a stator excitation field coil and produced DC output via a commutator, often struggling to charge batteries at idle speeds. Modern automotive alternators, however, utilize a DC-excited armature coil to create a rotating magnetic field, generating a high-frequency AC output. This AC is then rectified into DC using solid-state diodes, resulting in lower voltage ripple compared to single-phase systems. The design of modern alternators requires laminated magnetic components to handle the AC frequencies effectively.
wall6ly
Messages
1
Reaction score
0
Dumb question, inappropriate forum. Sorry
 
Last edited:
Engineering news on Phys.org
This not an inappropriate question, and this is not an inappropriate forum.
Dc generators were used on cars up to about 1970, because the rectifiers for a high-current ac current (generated by an alternator) were not sufficiently compact or reliable. So the old generators had a stator excitation field coil, and the dc current output was taken off the armature via a commutator. These dc generators were often unable to produce a sufficient voltage and current at idle speeds to charge the battery.

In the modern automotive alternators, the armature coil is excited with a dc current via slip rings, producing a rotating dc multipole magnetic field. The alternator output is taken off the stator as a high frequency ac 3-phase current. Rectified 3-phase voltage has significantly less voltage ripple than recifiied single-phase voltage. Three pairs of rectifier solid-state diodes, usually inside the alternator case, convert the ac to dc. Because of the ac frequencies, the magnetic components (especially stator) have to be laminated.
Bob S
 
Last edited:

Thread 'Following up on the recent thread about Earth Resistance measurements'

I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
View full post »
Thread 'Electromagnet magnetic field issue'

Thread 'Electromagnet magnetic field issue'

Hi Guys We are a bunch a mechanical engineers trying to build a simple electromagnet. Our design is based on a very similar magnet. However, our version is about 10 times less magnetic and we are wondering why. Our coil has exactly same length, same number of layers and turns. What is possibly wrong? PIN and bracket are made of iron and are in electrical contact, exactly like the reference design. Any help will be appreciated. Thanks. edit: even same wire diameter and coil was wounded by a...
View full post »
Thread 'Beauty of old electrical and measuring things, etc.'

Thread 'Beauty of old electrical and measuring things, etc.'

Even as a kid, I saw beauty in old devices. That made me want to understand how they worked. I had lots of old things that I keep and now reviving. Old things need to work to see the beauty. Here's what I've done so far. Two views of the gadgets shelves and my small work space: Here's a close up look at the meters, gauges and other measuring things: This is what I think of as surface-mount electrical components and wiring. The components are very old and shows how...
View full post »

Similar threads

Design
Replies
4
Views
1K
Alternator run at zero power factor lagging
Replies
2
Views
1K
AC generator, current and ground
Replies
26
Views
2K
Odd box that connects to alternator and produces 120 volt DC....
Replies
22
Views
2K
Synchronization of an alternator to the grid
Replies
15
Views
3K
Generator load sharing
Replies
4
Views
2K
350W car power inverter vs tiny generator
Replies
11
Views
2K
Magnets with Halbach array in an AC generator
Replies
6
Views
2K
In an Alternator, is the armature an electromagnet?
Replies
8
Views
8K
Can power supplies/adapters be used to clean up dirty generator power?
2
Replies
61
Views
9K

Hot Threads

Recent Insights

Back
Top