Do AC generators make use of interpoles?

In summary: There is no difference between rectification and commutation as far as the operation of an alternator is concerned. Coils in an alternator need to be aligned radially or the magnetic fields will cancel each other out, causing the alternator to fail. The arrangement of magnets in a halbach array does not affect the magnetic fields in any way.
  • #1
Jacob Anderson
3
0
Hello, new member here. I'm giving myself a crash course and can't find a direct answer to my query outright, so here I am:

Do A.C. generators make use of interpoles? I understand the concept of interpoles in D.C. machines, offsetting neutral plane shift; however, if we have, say, a brushless ac generator that has an external prime mover and uses permanent magnets in lieu of excitation windings, are we even worried about neutral plane shift? If it's a 3-phase machine my gut says no, but again it's a self-inflicted crash course... Any help would be greatly appreciated!
 
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  • #2
Your intuition is correct. Without a commutator shift of magnetic field is of no consequence.

Armature reaction in alternators is what's behind their "Synchronous Impedance" .

old jim
 
  • #3
HUZZAH, thank you. That's been driving me crazy all day.
 
  • #4
Whilst we're here, is there any particular benefit of commutation over rectification?

Also, going with the pmac concept, would aligning all the poles in the same orientation have a negative effect other than reducing the available flux? Alas, at least for now, my final question: were one to arrange said magnets in halbach arrays, would they need to be aligned with the magnetic fields aligned axially or transaxially? That question is more for clarification, I'm leaning greatly towards transaxial so the coils cross the field lines more uniformly.
 
  • #5
Jacob Anderson said:
Whilst we're here, is there any particular benefit of commutation over rectification?
The only benefit for commutation would be if the brushes were on a rotating assembly , then you could change the output voltage and even direction by rotating the brush assembly, this would also change the emf constant and torque constant, so it would function like a variable gear ratio. Might be useful for a primitive diesel electric locomotive, where the primer mover was constant speed.?? I think the Ward Lenard set achieved this effect and dominated the variable DC motor control industry from 1900 on Ward Lenard Control
 

1. How do AC generators work?

AC generators work by converting mechanical energy into electrical energy through the process of electromagnetic induction. This is achieved by rotating a coil of wire within a magnetic field, creating a changing magnetic flux, which induces an alternating current in the wire.

2. What are interpoles?

Interpoles are small electromagnets placed between the main poles of a generator. They are used to improve the performance of the generator by reducing voltage fluctuations and increasing the efficiency of the machine.

3. How do interpoles work in AC generators?

Interpoles work by creating a counteracting magnetic field to the main poles, which helps to neutralize the armature reaction caused by the changing magnetic field of the rotor. This results in a more stable output voltage and reduces the need for external voltage regulation.

4. What is the purpose of using interpoles in AC generators?

The main purpose of using interpoles in AC generators is to improve the machine's voltage regulation and efficiency. By reducing voltage fluctuations, interpoles help to maintain a constant output voltage, making the generator more reliable and stable.

5. Do all AC generators make use of interpoles?

No, not all AC generators make use of interpoles. Interpoles are typically only used in large generators with high output voltages, as they are more complex and expensive to manufacture. Smaller generators may not require the use of interpoles for efficient operation.

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