JP2017093274A - Wind power generation device with variable magnetic flux field type synchronous generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a generator at a maximum output point of a wind turbine since a permanent magnet synchronous motor is frequently used in wind power generation utilizing a small-sized wind turbine and the generator can be operated only one maximum output point of the wind turbine if a wind speed is considerably varied, as a disadvantage, a capability for converting mechanical energy produced by the wind turbine into electrical energy is lacked.SOLUTION: A variable magnetic flux field type synchronous power generation device can be provided by integrating only a DC excitation electromagnet or a permanent magnet and the DC excitation electromagnet into a field and creating a field magnetic flux corresponding to a rotational angular velocity of a wind turbine, thereby operating a generator at a maximum output point over a wide range of angular velocities of the wind turbine while controlling an input torque of the wind turbine. Therefore, waste of mechanical energy produced by the wind turbine is saved, the quantity of power to be generated by the generator is increased and the need of a speed-increasing gear is eliminated by a multipolar structure that is suitable for low speed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wind turbine generator having a variable magnetic flux field type synchronous generator.

  The mechanical energy produced by the windmill is proportional to the cube of the rotational angular velocity, and the locus of the maximum output point is proportional to the square of the rotational angular velocity in the coordinates of the rotational angular velocity and torque. In a small-sized or smaller wind power generator having a relatively small power generation capacity, a permanent magnet synchronous generator using a permanent magnet as a field magnet is often used as a power generator. In order to increase the rotational speed of the generator, a speed increaser is often used.

Ushiyama Izumi Morikita Publishing Co., Ltd. Introduction to Windmill Engineering P110

  The torque of power for driving the permanent magnet synchronous generator is proportional to the rotational speed. On the other hand, the maximum output torque of the power generated by the windmill is proportional to the square of the rotational speed. Therefore, since the straight line and the curve intersect only at one point, the generator torque and the wind turbine torque intersect only at one point, and the other points cannot be operated at the maximum output point. It is an object of the present invention to generate power at a maximum output point in a wide range.

FIG. 1 represents the coordinates of torque and rotational angular velocity, curve 14 represents changes in torque and angular velocity when the wind turbine is loaded with a constant wind speed, and curve 13 represents the output of the wind turbine obtained by multiplying the curve 14 by the angular velocity ω. represents a curve obtained by connecting the trajectory of the torque when issuing the maximum output is a curve 12, the torque is proportional to omega ^2.

When the torque curve (straight line) 11 of the conventional permanent magnet synchronous generator is placed on the graph of FIG. 1, it intersects only at one point. In other words, the torque curve of the conventional permanent magnet synchronous generator is a straight line that is almost proportional to ω when the angular velocity is not high, and when the angular velocity is further increased, the frequency of the induced voltage increases and impedance increases and the armature core magnetism increases. Since the electric power generated due to saturation or the like is reduced and the torque is lowered, the torque curve of the wind turbine proportional to ω ² intersects only at one point.
Considering points other than point A, for example point C, a generator having a torque that essentially intersects at point B can be operated at the maximum output point of the wind turbine. Then, since it operates at point C, the angular velocity increases, but the torque decreases by ΔT and the output decreases by ΔP, resulting in waste.
This shows that output is wasted even at points where the angular velocity is lower than point A, for example, point D. That is, the torque increases, but the angular velocity decreases, so the output is reduced and waste occurs.

  In the present invention, in order to eliminate such waste, particularly in a high angular velocity region, a DC excitation electromagnet is provided in parallel to the generator field in addition to the permanent magnet, and the field magnetic flux is increased. By increasing the induced electromotive force, increasing the torque required for the generator, and passing through the maximum output point (such as point B) in the high speed region, it becomes possible to generate power at the maximum output point of the windmill, It is an object of the present invention to prevent generation of waste ΔP in the output of the windmill by taking in all the mechanical energy produced by the windmill into the generator.

Based on FIG. 2, the synchronous generator 1 of this application is demonstrated.
A field support member 29 is attached to the shaft 30, and 2n field iron core teeth 231 are provided radially on the outer diameter portion thereof, and a plate-like 2n permanent magnet 24 is sandwiched between them, The 2n field teeth 231 are divided into two groups every other one, the protruding end of one group is attached in contact with one exciting iron core 25, and the other group contains an exciting coil 27. And the other exciting iron core 26 fixed to the bracket 20 is opposed to the end face thereof via an excitation gap, and the outer diameter portion is opposed to the armature iron core 21 via an air gap. The armature core 21 is fixed to the nonmagnetic bracket 20, and bearings 28 are attached to both ends of the shaft 30 and are fitted to the bearing housing of the bracket 20.

2B and 2C show field structure examples. The field magnet is suitable for a multipolar structure in which the number of poles is increased because thin plate-like permanent magnets 24 are arranged in the rotational direction. When the field is made of multiple poles, the induced voltage becomes high even at a low speed, so that the speed-up gear can be omitted, and the current supply to the exciting coil 27 is also non-contact, so that the reliability can be improved. A high synchronous generator can be formed.
In addition, in the case of a DC excitation synchronous generator that does not use a permanent magnet 24, since a magnet is not used, a space in the radial direction can be provided and the number of poles can be increased, which is suitable for a low-speed generator. It can be said.

The permanent magnet 24 is magnetized and magnetized in the rotational direction, and the flow of magnetic flux is as follows: the N pole of the magnet → the adjacent field tooth → the air gap → the armature core → the air gap → the adjacent field tooth → the S pole of the magnet. It flows to. On the other hand, the DC excitation magnetic flux is N pole of the shaft → excitation iron core → N pole field teeth → air gap → armature core → air gap → S pole field teeth → excitation gap → excitation iron core → excitation gap → It flows with the south pole of the shaft, and flows independently and in parallel.
This field magnetic flux has a feature formed by a composite magnetic flux formed by two magnetic fluxes, a fixed magnetic flux by a permanent magnet and a variable magnetic flux by a DC exciting magnet.
When the field is rotated by power such as wind power, these two magnetic fluxes create a rotating / moving magnetic field in the armature core, which generates an induced voltage in the armature winding, and functions as a generator.
In addition, this synchronous generator can change the amount of fixed magnetic flux by adjusting the amount of permanent magnet used, and can also form a field with only a DC magnet without using a permanent magnet. Have

Next, a method for controlling the torque of the generator will be described. The armature winding of the generator may be multiphase or single phase, but here a single phase will be described as an example.
First, the case where a permanent magnet and a DC exciting magnet are used together will be described.
The voltage generated in the generator is proportional to the magnetic flux of the field × rotational speed. If the load is a resistor R, the flowing current I is as follows.
[Formula 1] I = K · Φ · p · ω / [(p · ω · L) ² + (R _m + R) ² ] ^1/2
Where I: armature current, Φ: field magnetic flux, K: constant, ω: rotational angular velocity,
p: number of pole pairs, L: winding inductance, R _m : winding resistance, R: load resistance In equation 1, (p · ω · L) is abbreviated smaller than (R _m + R), so It can be approximated as follows.
[Formula 2] I≈K · Φ · p · ω / (R _m + R)
Therefore, as the torque T _g Hatsugi generator.
[Formula 3] Tg = [I ² × (R _m + R) + W ₁ ] / ω
Where T _g : generator torque, W ₁ : loss (iron loss, mechanical loss, etc.)
W ₁ : Since the loss is small, equation (3) can be approximated as follows.
[Formula 4] T _g ≈ [I ² × (R _m + R)] / ω
Substituting Formula 2 into this, the following formula is obtained.
[Formula 5] T _g ≈ (K · Φ · p) ² ω / (R _m + R)
From this equation 5, if the field is only permanent magnets, [Phi so is constant, the generator torque The T _g seen to be proportional to the angular velocity omega.

The wind turbine torque T _f and the output P _f are expressed as follows.
[Formula 6] T _f = Aω ²
[Formula 7] P _f = Aω ³
Here, A: constant Further, the torque T _F at the maximum output of the windmill is [Formula 8] T _F = Bω ²
Here, B: constant If the generator can always be operated at the maximum output point of the windmill, the generator can convert more mechanical energy generated by the windmill into electrical energy. However, since the curve of Formula 8 representing the torque locus of the maximum output point and Formula 5 representing the torque of the generator intersect only at one point, wind power is not effectively used at other points.
In order to take wind power into the generator as much as possible and convert it into electrical energy, it is necessary to match the torque of the generator and the torque of the windmill at the widest possible angular velocity.
Therefore, when the angular velocity exceeds the intersection of the generator torque and the maximum output point torque of the wind turbine, the magnetic flux of the DC excitation electromagnet is added to the field that was only the magnetic flux of the permanent magnet so far to form a composite magnetic flux. It can be seen that it is sufficient to increase the DC excitation magnetic flux so as to always match the torque of the wind turbine by increasing the power generation capacity of the generator and increasing its torque.

First, the case where a permanent magnet and a DC exciting magnet are used together will be described.
[Formula 9] T _g ≈K ² · (αi + Φ ₀ ) ² · p ² · ω / (R _m + R)
From Formula 9 and Formula 8, K ² · (αi) ² · p ² · ω / (R _m + R) = Bω ²
From this formula:
[Formula 10] i≈ [(((R _m + R) · B) ^1/2 / (α · K · p)] · ω ^1/2 −Φ ₀ / α
That is, since the torque at the maximum output point of the windmill is proportional to the square of the angular velocity, it is operated only with a permanent magnet up to an angular velocity ω ₀ that is the same as the angular velocity of the generator, and when that angular velocity ω ₀ is exceeded, The excitation current i proportional to the square root of the angular velocity ω is passed, and the DC excitation magnetic flux 34 proportional to the DC excitation current is superimposed on the permanent magnet magnetic flux to form the composite excitation magnetic flux 33, thereby increasing the field magnetic flux and enhancing the power generation capacity. By making the generator torque close to the wind turbine torque, wind power can be used effectively.

Next, a case where only a DC excitation magnet is used without using a permanent magnet will be described.
The torque of a generator having a field only for the DC exciting magnet is as shown in Equation 11.
[Formula 11] T _g ≈K ² · (βi) ² · p ² · ω / (R _m + R)
From Formula 11 and Formula 8, K ² · (βi) ² · p ² · ω / (R _m + R) = Bω ²
Therefore, the relationship between the DC excitation current and the angular velocity is as follows.
[Formula 12] i≈ [(((R _m + R) · B) ^1/2 / (β · K · p ² )] · ω ^1/2
When such a DC excitation current 36 is passed, a DC excitation magnetic flux 34 proportional to this is generated, and the resulting torque approaches the torque 12 at the maximum output of the windmill, so that the mechanical energy generated by the windmill is always from 0 at the angular velocity. Can be effectively incorporated into the generator.

A method of controlling the magnetic flux, that is, the excitation current based on the above formulas 10 and 12, will be described.
FIG. 4 shows a configuration example of a control circuit of a power generation system to which the present invention is applied. The rotational speed of the variable magnetic flux field type synchronous generator 41 is detected by a rotational speed detector 42, the signal is sent to the excitation current control circuit 44, and a current corresponding to the angular speed is supplied to the DC excitation coil 26 to cause the field magnetic flux. And the torque of the generator is brought close to the vicinity of the maximum output point of the wind turbine, and the maximum output that can be output by the wind turbine at the wind speed at that time is taken in as the mechanical input of the generator.
In the case of using a permanent magnet and a DC excitation magnet together, the DC excitation current i flowing through the DC excitation coil 26 does not flow until a certain angular velocity ω ₀ , and at an angular velocity exceeding that, √ω In the case where only a DC excitation magnet is used without using a permanent magnet, a DC excitation current proportional to √ω as shown in Equation 12 is applied in the entire range of angular velocity. The generator torque can be brought close to the wind turbine torque curve.
The generated AC power is charged to a storage battery (battery) 47 through a rectifier circuit 45 and a charge control circuit 46, and supplied to a load 48 as necessary. The control power supply 43 is a circuit for converting and supplying the output of the storage battery 47 to a voltage suitable for the excitation current control circuit 44.

Effect of the invention

  By implementing the present invention, the field magnetic flux can be controlled in accordance with the rotational angular velocity as compared with the conventional permanent magnet synchronous generator, so that the generator can always be operated at the maximum output point of the windmill. It is a power generator suitable for small wind turbine generators with a lot of fluctuations, and an increase in generated power can be expected. Moreover, since the structure is suitable for multi-pole field use, the speed-up gear can be omitted, and the power supply to the exciting coil is a non-contact type, so that a synchronous generator with high reliability and low maintenance costs can be obtained. I can do it.

By applying the present invention, it is expected that a small wind power generator that operates at a low speed under a fluctuating wind speed will particularly effectively work on a high-speed wind blowing in a short time and increase the overall efficiency. it can. Moreover, since it is suitable for multipolarization, there is an advantage that a speed-up gear is not required and maintenance costs are not required, and it can be applied as a small power generator to a place where there is no commercial power source.
Eliminating the waste of wind power can also be expected to have an economic effect of downsizing the windmill and reducing costs.
In addition, this generator can be expected to improve overall efficiency and maintainability as a small hydroelectric generator with drastic changes in water flow.

  FIG. 1 shows the relationship between the torque of a windmill, the torque of a generator using the present invention, the torque of a conventional permanent magnet synchronous generator, and the rotational angular velocity of the windmill.   FIG. 2 shows an example of a structural diagram of a generator to which the present invention is applied.   FIGS. 3A and 3B show the relationship between the rotational angular velocity of the present invention, the DC excitation current, the field magnetic flux, and the generator torque. Fig. 3-1 shows a case where a composite magnet of a direct current excitation magnet and a permanent magnet is used for the field.   Fig. 3-2 shows the case where only a DC exciting magnet is used for the field.   FIG. 4 shows an example of a control circuit configuration diagram of the generator.

[Figure 1]
11 Torque Line 12 of Permanent Magnet Synchronous Generator 12 Torque curve of variable magnetic flux field type synchronous generator and torque curve of wind turbine {the two curves are almost overlapped} in the present invention
13 Curve representing the relationship between the angular velocity and output of the characteristic curve of torque and angular velocity passing through point B of the windmill (point B is the maximum output point)
14 Example of a curve representing the relationship between the wind turbine torque passing through the unloaded angular velocity 5 and the angular velocity A Point at which the permanent magnet synchronous generator torque and the wind turbine torque intersect (maximum output point)
B Example of maximum output point of wind turbine in case of variable magnetic flux field type synchronous generator C Example of output point of permanent magnet synchronous generator when angular velocity exceeds point A D Permanent when angular velocity falls below point A Example of output point of magnet synchronous generator ΔT Example of showing waste of torque in case of permanent magnet synchronous generator ΔP Showing waste of output in case of permanent magnet synchronous generator (example at high speed)
dP Indicates the waste of output in the case of a permanent magnet synchronous generator (example at low speed)
[Figure 2]
1 Generator 20 Bracket (Non-magnetic material, aluminum, etc.)
21 Electron Core 22 Electron Winding 23 Field Core 231 Field Iron Core Teeth 24 Permanent Magnet 25 S-Pole Exciting Core 26 N-Pole Exciting Core 27 DC Exciting Coil 28 Bearing 29 Field Support Member 30 Axis (Ferromagnetic)
[Fig. 3]
[FIGS. 3-1 and 3-2]
(A) FIG. 31 Torque at wind turbine maximum output and torque of variable magnetic flux field synchronous generator 32 Torque of permanent magnet synchronous generator (b) FIG. 33 Composite excitation magnetic flux 34 DC excitation magnetic flux 35 Permanent magnet magnetic flux (c) 36 DC excitation current [Fig. 4]
DESCRIPTION OF SYMBOLS 1 Variable magnetic flux field type excitation synchronous generator 26 Excitation coil 41 Generator 42 Rotational speed detector 43 Control power supply 44 Excitation current control circuit 45 Rectifier circuit 46 Charge control circuit 47 Storage battery 48 Load

Claims (5)

  Synchronous generator that can variably control the field flux so that it can always generate power at its maximum output point even if the rotational speed changes due to the wind speed in a wind power generator that has at least a DC exciting magnet in the field and is powered by wind power Wind power generator with   In claim 1, the teeth of the field core are divided into two groups of N pole and S pole. The N pole group is magnetically connected in one axial part, and the S pole group is magnetic in the other axial part. The whole teeth are fixed to the shaft by a non-magnetic support member on the inner diameter side, the S pole connecting portion and the shaft are connected by an exciting iron core, and the N pole connecting portion and the shaft are connected. Between them, each is connected with a U-shaped or L-shaped exciting core fixed to a non-magnetic bracket via an exciting gap, and a DC exciting coil is provided inside it, and the magnetic flux of the field is N-pole exciting core → excitation gap → S pole group teeth → air gap → armature core → air gap → N pole group teeth → optional excitation gap → S pole excitation core → axis → excitation gap → N pole excitation core Armature iron by flowing and rotating field A rotating magnetic field is generated, an AC voltage is induced in the armature winding, and the outer shell of the armature has an inner rotor type variable magnetic flux field type synchronous generator formed of a nonmagnetic material such as aluminum. apparatus   In claim 1, the teeth of the field core are divided into two groups of N pole and S pole. The N pole group is magnetically connected in one axial part, and the S pole group is magnetic in the other axial part. The whole teeth are fixed to the shaft by a non-magnetic support member on the inner diameter side, the S pole connecting portion and the shaft are connected by an exciting iron core, and the N pole connecting portion and the shaft are connected. Between them, each is connected with a U-shaped or L-shaped exciting core fixed to a non-magnetic bracket via an exciting gap, and a DC exciting coil is provided inside it, and all N-pole teeth and S-poles are provided. A plate-like permanent magnet is inserted between the teeth of the magnet so that the polarity increases in the direction in which the magnetic flux increases, and the flow of DC excitation magnetic flux is as follows: N pole excitation core → excitation gap → S pole group teeth → air gap → electric machine Core → Air gap → N pole group teeth → Omissible Excitation gap → S pole excitation core → Shaft → Excitation gap → N pole excitation iron core, magnetic flux of permanent magnet is N pole → S pole group teeth of permanent magnet → Air gap → Armature core → Air Gap → N pole group teeth → Permanent magnet S pole flows to rotate the field, generating a rotating magnetic field in the armature core, inducing an AC voltage in the armature winding, Wind power generator having an inner rotor type variable magnetic flux field synchronous generator whose outer shell is made of a non-magnetic material such as aluminum   2. The wind turbine generator having a variable magnetic flux field type synchronous generator according to claim 1, wherein the direct current excitation current can be controlled as a function of the square root of the rotational angular velocity in all or a part of the angular velocity.   A hydroelectric generator having a synchronous generator according to claim 1, 2, 3, and 4.