easy way to generate an ac signal

There are times when your ignorance is so apparent.

I can assure you that the rotor of an alternator carries DC. Slip rings normally carry the current.

This link might help regards cogging:

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pays to understand and have knowledge first and remember second

Reply to
Fredxx
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harry wrote:

Not sure what the ???????? are for. It may be a modified sine wave for

Do you know the difference between capacitor and a battery?

Have you sussed yet the apparent capacity of a standard lead-acid car battery?

You seem to have conveniently ignored inductance of the alternator stator windings in reducing current ripple.

The link you give says no such thing. I have asked before if you could produce real alternator waveforms/graphs showing all your claims, and you have failed miserably.

Reply to
Fredxx

te:

*ALL* circuit elements have inductance and capacitance.

You do not necessarilty need specific capacitors or inductors.

A brushed DC motor driven by a high frequency PWM will effectively see DC due to the motor inductance, as one example.

MBQ

Reply to
Man at B&Q

That's a bit like saying that a power station runs from direct (not alternating ) Gas.

Reply to
The Natural Philosopher

Reply to
polygonum

Ho ho. :-)

I could go with alternating gas, sort of. But please don't introduce alternating water and sewage.

Reply to
polygonum

That's more a semantic argument, assuming that a switched reluctance drive requires some form of commutation. Truthfully the field windings require an alternating waveform to rotate the iron rotor.

Most DC motors use a combination of attractive and repulsive magnetic forces through magnetic fields in both rotor and stator, either through permanent magnets or currents.

Reply to
Fredxx

Of course it requires commutation (external) but this is simply sequencing the activation of the windings with DC. The current is never reversed in contrast with, say, a BLDC where the windings will have current flowing in both directions during a cycle of rotation.

[cue pedantic argumant about AC with DC offset]

MBQ

Reply to
Man at B&Q

er no. First of all DC is elative to something,.

And the current in the windings DOES reverse every 180 degrees..

Reply to
The Natural Philosopher

Only after inversion.

Reply to
harry

Only for cheapness. The motor has to be derated if it is not a sine wave due to increased iron losses causing overheating.

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is virtually impossible to generate a true sine wave with electronic devices.

Reply to
harry

,

Yes tell me.

Reply to
harry

Is that so? So what is this then if not AC?

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Reply to
harry

Damn. I wanted to hear his explanation . :-)

Reply to
harry

Obviously your comprehension is poor. (Quote):- To provide direct current with low ripple, a three-phase winding is used and the pole-pieces of the rotor are shaped (claw-pole) to produce a waveform similar to a square wave instead of a sinusoid. (Unquote)

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Reply to
harry

rote:

On some they are negligible. And sometimes they cancel one another out.

If that were so it would not function.

Reply to
harry

Does it rotate? And is it necessary to rotate to function if it does? You're clutching at straws now.

Reply to
harry

Of course it rotates! I would not have thrown a non-rotating motor into the discussion.

Reply to
polygonum

So the output voltage is only dependent on speed and excitation current? So no limit on voltage?

their dependency on speed, voltage and output current.

The wiki article is rather unhelpful in that it doesn't specify precisely what waveform they say is "similar to a square wave".

Reply to
Fredxx

Purity is relative. I have many pieces of equipment which have fundamental to higher order ratios better than 100,000.

Reply to
Fredxx

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