Motor Generators

[Rakarskiy]

By the way, even in the Britannica the principle by which an EMF is induced in the conductor of a synchronous generator with closed magnetic fields is not indicated; there is only a statement of the result.

Electric generator | Types, Uses & Advantages | Britannica

Rotor


elementary synchronous generator

An elementary synchronous generator is shown in cross section in Figure 2. The central shaft of the rotor is coupled to the mechanical prime mover. The magnetic field is produced by conductors, or coils, wound into slots cut in the surface of the cylindrical iron rotor. This set of coils, connected in series, is thus known as the field winding. The position of the field coils is such that the outwardly directed or radial component of the magnetic field produced in the air gap to the stator is approximately sinusoidally distributed around the periphery of the rotor. In Figure 2, the field density in the air gap is maximum outward at the top, maximum inward at the bottom, and zero at the two sides, approximating a sinusoidal distribution.

Stator

The stator of the elementary generator in Figure 2 consists of a cylindrical ring made of iron to provide an easy path for the magnetic flux. In this case, the stator contains only one coil, the two sides being accommodated in slots in the iron and the ends being connected together by curved conductors around the stator periphery. The coil normally consists of a number of turns.

When the rotor is rotated, a voltage is induced in the stator coil. At any instant, the magnitude of the voltage is proportional to the rate at which the magnetic field encircled by the coil is changing with time—i.e.,the rate at which the magnetic field is passing the two sides of the coil. The voltage will therefore be maximum in one direction when the rotor has turned 90° from the position shown in Figure 2 and will be maximum in the opposite direction 180° later. The waveform of the voltage will be approximately of the sine form shown in Figure 1.

I made my own drawing which is exactly consistent with the maximum EMF with a three-phase winding and an implicitly polar magnetic rotor.

480452977_9226741477409199_1244883750594752467_n.jpg?_nc_cat=103&ccb=1-7&_nc_sid=bd9a62&_nc_ohc=4C5fZtzzN8oQ7kNvgH9qPo4&_nc_zt=23&_nc_ht=scontent-iad3-2.xx&_nc_gid=fZ79WcEDj4_MyBqCKKc-aw&oh=00_AYH7Pxe3WIHgknznnljXs5BA-BR_HpXctxTo calculate the maximum EMF in a three-phase generator, you need to use this position. By the way, one of my friends asked his acquaintances in Israel to perform a registration of the maximum EMF depending on the rotor position on very good equipment. Unfortunately, these results were not provided to me for review, although I was the initiator of such a study. They wanted to prove me wrong. I wonder why they refused?

[bistander]

Rakarskiy,
Change subject somewhat.

Your red and blue dynamo model isn't a very good design. It appears that half of the armature turns are ineffective. Therefore 250 instead of 500 should be used in the generated voltage calculation.

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The upper two coil segments indicated with blue circle/dot are enclosed by the main magnetic circuit, or anapole, passing through A & B on the rotor, whereas the lower two, blue circles with cross, are not inside the main flux loop.

Except for the single line in your FEMM connecting the bottom of the stator. If there is a flux linkage there, it will render the lower armature copper (circles with cross) counterproductive.

Poor design.
bi

[Rakarskiy]

This illustrative model of an alternator is inefficient, but it is a model that shows students a real example of an alternator with a core. In a real armature, there are two windows (two focuses) or in a real turbo generator, both magnetic anapoles also participate with maximum generation efficiency.

[bistander]

...

If we consider the components of the magnetic circuit and the EMF diagram, we see that the induction of electromagnetic force occurs when the cross-section in which the magnetic circuit is closed changes. Induction is induced only in the wire that is in the focus of the changing magnetic circuit. At the same time, with a complete closure in the minimum or maximum value, the cross-section in which the magnetic circuit is closed, the induction of EMF is not induced. The main element in this case is the change in the cross-section of the conducting circuit in which there is a closed source of constant magnetic field.
Ф = Bm*S, where S = a*b changes

[/QUOTE]

Rakarskiy,
Your latest example contradicts the above observation, doesn't it?
bi

image_26148.gif

[Rakarskiy]

This does not contradict, because these are two different systems. In addition, if you simulate an armature with a current that creates its own magnetic field of the armature, then everything works according to the algorithm of magnetization and remagnetization of the armature during rotation. I have already made the appropriate modulation. Rotation at idle is different from rotation with a current in the armature winding. I will make a video with explanations and animation.

463238777.gif75952967.gif

As for the drawing that you tried to attach to the moving armature, in this case the algorithm of my previous slide will be executed, a classic simpler AC generator with a moving magnetic rotor.
In the video we will also analyze this option.

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[bistander]

The main element in this case is the change in the cross-section of the conducting circuit in which there is a closed source of constant magnetic field.

Ф = Bm*S, where S = a*b changes

Why you refer to it as "main element"? It is nothing more than saliency There are salient pole dynamos and non-salient ones. But the main "element" is changing magnetic flux influencing armature conductor(s). Look it up.
bi

Reference:

Subject entered to Google search: -saliency in generator design-

AI generated

In generator design, "saliency" refers to the presence of protruding poles (salient poles) on the rotor, which differ from the smooth, cylindrical rotors of non-salient machines, impacting performance and application suitability.

Here's a more detailed explanation:
What is Saliency?
Definition:
Saliency, in the context of electric machines, refers to the degree to which the rotor poles "stand out" or project beyond the general outline of the rotor surface.

Salient Pole vs. Non-Salient Pole:
Salient Pole: Features protruding poles (salient poles) attached to a magnetic wheel.
Non-Salient Pole (Cylindrical/Turbo): Has a smooth, cylindrical rotor surface, often with slots for windings.

Inductance Variation:
Saliency is also characterized by a variation in inductance depending on the rotor position, also known as inductance saliency or magnetic saliency.

Impact on Generator Design and Performance:
Application:
Salient pole rotors are commonly found in synchronous AC generators operating at lower speeds, such as those used in diesel engine generators and hydroelectric plants. Non-salient rotors are used in generators connected to high-speed prime movers like steam turbines.

Torque and Load Angle:
Saliency influences the torque characteristics of the generator. The effect of saliency caused by reluctance torque shows that the load angle during rated operation increases, and the pull-out torque is obtained at a power angle greater than 90 degrees.

Overload Capability:
For applications where overload capability is important, saliency must be considered, and the generator design adapted according to the behaviour at overload operation.

Design Considerations:
The design of salient-pole wound-rotor (inner rotor) synchronous generators involves considering the air-gap between pole shoes and the internal diameter of the stator.

Saliency Ratio:
The saliency ratio is the ratio between q- and d-axis inductances.

Examples:
Salient-pole, ferrite generator: Has lower maximum torque than an NdFeB generator and a larger voltage drop at high current.
12/10 DC-VRM sensorless drive: Reconstructing saliency effect in a 12/10 DC Vernier Reluctance machine can achieve sensorless operation in zero/low-speed regions.

https://youtu.be/YZlc8OIc4mw?si=IrLQDgDvSzUvpw3o

[Rakarskiy]

There are also interesting electromagnetic generators - PARAMETRIC! They do not have alternating current, only pulse current. And the essence is still the same, the cross-section of the core changes from rupture to complete closure. And a conductor cannot cross magnetic lines in general, even in a dream.

Wise Eye OverUnity: Parametric Pulsed Generator

VALVE INDUCTION GENERATORS

Currently, work is underway to use valve-inductor generators (VIG) as an autonomous energy source for passenger cars, which increase power, have better specific indicators and improve reliability and maintainability, as well as reduce the consumption of non-ferrous metals and structural materials.

VIG refers to parametric electric machines, the principle of its operation is based on the periodic change in the inductance of the stator winding depending on the angular position of the rotor. The magnetic circuits of the stator and rotor have protruding poles - teeth. The stator slots contain a concentrated winding, the rotor teeth are not covered by the winding and serve to close the magnetic flux. With this design, the inductance of the stator winding changes from the maximum value when the axes of the stator and rotor teeth coincide (tooth-tooth position) to the minimum value at the tooth-slot position. The shape of the winding inductance curve is affected by the degree of saturation of the magnetic circuit in addition to the angular position of the rotor.

The configuration of the teeth and depressions is selected so that the difference between the maximum and minimum inductances of the winding, depending on the angle of rotation of the rotor, is as large as possible. This contributes to the efficient electromechanical conversion of energy, since the electromagnetic torque and, ultimately, the energy supplied to the electromagnetic circuit of the generator depend on the rate of change of inductance.

The generator operates as follows (Fig. 1). Mechanical energy is supplied from the wheel pair to the generator shaft. When the power source (excitation) is connected at a moment close to the coincidence of the stator and rotor teeth of the excited phase, current begins to flow in the stator winding along the circuit: C—VT1 — W—VT2—C. The energy accumulated in the capacitor C serves as an excitation source. Under the action of the mechanical torque applied to the VIG shaft, the rotor teeth move away from the stator teeth. In this case, the winding inductance decreases, which is accompanied by the induction of EMF in the stator winding in the direction coinciding with the current in the winding. The current flowing in the winding under the action of the induced EMF is added to the excitation current, increasing the reserve of electromagnetic energy in the VIG circuits.

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Fig. 1. Operating principle of a valve-inductor generator
When the rotor, moving under the influence of external forces, reaches a position close to the tooth-groove position, the semiconductor switches VT1 and VT2 are closed by the signal from the rotor position sensor. The energy spent on excitation and obtained by electromechanical conversion from the external mover (wheel pair) enters the external circuit: C-VD1-W-VD2-C. The closed state of the power semiconductor switches (VT, VT2) falls on a strictly defined area of the angular position of the rotor relative to the stator - the generator mode area. This area is determined by the rotor position sensor, the signal from which is fed to the control system.

Switched Reluctance Generators | kaskod.ee

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Something like that, all education about electromagnetic generation is lying. Engineers don't listen to them, so they build various electromagnetic generators.

[Rakarskiy]

My slide requires an additional type of electromagnetic generator. All induce EMF on the phenomenon of changing the Anapol moment.

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Updated my post a little:
EMF, CURRENT, VOLTAGE, RESISTANCE. | Patreon

Establishing patterns between the main parameters of an electric circuit is of great importance for science. After all, it made it possible to quantitatively measure the properties of electric current.

I = U/R = E/R+r

We have returned to the starting point of our story, to understand what is what, we need to look at the starting points for the electromagnetic circuit:

Electrical induction: [∇ E = ρ/εo ] = [∇ D = ρ ]

Magnetic induction: [ ∇ B = 0 ]; [ B = μ0/4π(I/2r) ]

The Biot–Savart–Laplace law (also the Biot–Savart law) is a physical law for determining the induction vector of a magnetic field generated by a direct electric current. It was established experimentally by Biot and Savart and formulated in general form by Laplace.

Thus, the result of the decrease in the electric potential E from the source is the formation of magnetic induction B around the conductor. Current I is an expression of the relationship between the magnitude and dimension of the electric induction E, transformed into magnetic induction B. This is what we saw when solving the problem for the generator winding circuit and the load.

Maxwell's equation for Ampere's law should be written as follows:

[ ∇×B = j/εoc^2 ] = [ (1/c2) ∂E/∂t ] Circulation theorem of B on Ampere's law.

∇×B = - ∂E/∂t Circulation theorem of B on Ampere's law.

To avoid confusion, the magnetic induction of an external magnetic field should be designated Bm, and the magnetic induction around a conductor Bi, which is formed as a result of the transformation from electrical induction E. Уравнения максвелла примут вид:

• ∇ E = ρ/εo Gauss's law for E
• ∇×E = – ∂Bm/∂t Electromagnetic induction Faraday's law
• ∇ B = 0 Gauss's law for B
• ∇×Bi = - ∂E/∂t Electromagnetic induction on Ampere's law / Biot–Savart law.

If the law of electromagnetic induction on the laws of Ampere and Biot-Savart fully corresponds to the proportion on the law of conservation of energy, then there is no data that the magnetic induction of the external field Bm is spent to form the electric induction E. For example, the costs of excitation of the magnetic field in turbogenerators of power plants are 0.5-3% of the generator output power. Permanent magnets in magneto generators are practically inexhaustible. This point can be attributed to the Over Unity of electrodynamics.