JPS62166753A - Brushless ac generator - Google Patents

Abstract

PURPOSE:To minimize the holding torque by providing a constitution where the magnetic repulsive force is generated between a stator section and a rotor section opposing to the magnetic attractive force action. CONSTITUTION:When a repulsive pole piece 32 of high permeability is situated right under the third static fields 28a and 28a' of N poles, affected by the magnetic repulsive action to the rotor 24, the holding torque to a rotor 24 is reduced. Then the one end of a pole piece 30 of the rotor 24 is situated right under an S pole field core 18b, while the other end of a pole piece 30 is situated right under an N pole field core 20b. At this moment, the rotor 24 receives the magnetic attractive action through the pole piece 30. In addition, as a pole piece 32 receives the action of flux from N poles of field cores 28b and 28b', the repulsive action is given to the rotor 24. At this moment, suppose the current of the field winding of the third static pole 28 is controlled so as to balance the magnetic attractive action and the magnetic repulsive action given to the rotor 24, the holding torque of the rotor 24 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (11) Objects of the Invention (Field of Industrial Application) The present invention relates to an alternating current generator, and more particularly to a compact and highly efficient brushless alternating current generator.

(Prior Art and Problems) Conventional brushless alternators have the advantage of being easy to maintain, but they cannot avoid generating holding torque due to the magnetic attraction force that acts between the stator and rotor during power generation. This holding torque increases in proportion to the load current of the generator. When a generator is driven by a prime mover such as an engine or an electric motor, if an overload is applied to the output side of the generator, the holding torque becomes too high, causing the prime mover to be in an unreasonable operating state called lag mode. becomes.

At this time, not only abnormal frequencies and voltage pulsations occur in the output of the generator, but also mechanical damage tends to occur to the internal structure of the prime mover. Preventing this problem necessarily required the use of large capacity prime movers or rather complex and expensive protection circuits.

(2) Structure of the Invention (Means and Effects for Solving the Problems) In order to solve the problems of the conventional art, the present invention is designed to solve the problems of the conventional art by countering the magnetic attraction between the stator section and the rotor section of a brushless alternator. , a brushless alternator that minimizes holding torque by providing a structure that generates magnetic repulsion between the stator and rotor parts, and thus does not cause abnormal frequency or voltage pulsation in the generator output due to load fluctuations. The purpose is to provide

To achieve the above object, the present invention provides a stator section, first and third stationary field poles spaced apart in the axial direction within the stator section, and a rotating shaft extending within the stator section; A rotor portion having magnetic flux switching magnetic pole pieces for causing periodic magnetic flux changes between the first and second field poles by rotation of a rotating shaft, and power generation by the magnetic flux changes occurring between the first and second field poles. and an output winding supported within the stator section.

According to an important feature of the invention, a third stationary field pole is arranged in the stator section at an axial distance from one of the first and second field poles. On the other hand, the rotor portion is provided with magnetic repulsion magnetic pole pieces provided at intervals in the axial direction from the magnetic flux switching magnetic pole pieces, and the magnetic repulsion m pole pieces are periodically opposed to the third field magnetic pole. Arrange in. An excitation device is connected to the first, second, and third stationary field poles for supplying a field current according to the load of the generator, and the first and second stationary field poles are connected to the excitation device for supplying field current according to the load of the generator. An excitation current corresponding to the load of the generator is also supplied to the third stationary field pole.

In the above configuration, when the first and third stationary field poles are excited by an excitation current that corresponds to the load of the generator, and at the same time the third stationary field pole is excited by an excitation current that corresponds to the load of the generator, the rotor Since the rotor section is simultaneously subjected to magnetic attraction and repulsion, the holding torque of the rotor section is extremely small. Therefore, the influence of pulsation on the rotor section due to load fluctuations can be minimized.

(Example) Next, an example of the present invention will be described based on screens.

FIG. 1 shows a perspective view, partially in section, of a preferred embodiment of a branless alternator according to the present invention. Some parts have been omitted.

In FIG. 1, a brushless alternator, generally indicated by the numeral 10, has a cylindrical housing 1 made of non-magnetic material.
It has a stator part 17 consisting of a stator 14, 16 supported concentrically within 2. Stator 14 is made of a magnetic material with high magnetic permeability, and stator 16 is made of a non-magnetic material. Further, when the stator 16 is made of a magnetic material, a non-magnetic spacer (not shown) may be installed between the stator 14 and the stator 16.

First and second stationary field poles 18,20 are fixedly supported on the stator 14 at intervals in the axial direction.

The first stationary field pole has a plurality of field cores 18a, 18'a, 18b, 18'b (see FIG. 3) extending radially inward, and magnetic pole pieces fixed to these field cores.

Similarly, the third stationary field pole 20 includes a plurality of field cores 20a,
20''a, 20b, and a magnetic pole piece fixed to these field cores.The field core of the first stationary field pole 18 and the field core of the second stationary field pole are aligned in the axial direction. N1 field cores 18a, 18b fixed within the stator 14
are arranged so that the magnetic poles are opposite to each other, that is, the north pole and the south pole. Field core 18b is field core 1
A field core 20b is disposed at a position 1800 electrical degrees out of phase with respect to 8a, and axially faces this field core.
is set to the north pole. The field core 18'a has the same N pole as the field core 18a facing in the radial direction.
°b has the same S pole as the field core 18b facing in the radial direction. In this way, the field core 18a.

18b, 18'a, 18'b N, S, N,
The field cores, which have S poles and are axially opposed to these field cores, have S, N, and S poles, respectively, so that their polarities are opposite to each other.
S, has a north pole.

As is clear from Figure 1.2.3, the first stationary field pole 18
Rod magnetic cores 18a, 18b, 18'a, 18'b
have field windings 18aw and 18bw for excitation, respectively.

18'aw and 18°bw are supported. Each field winding consists of a main winding and an auxiliary winding, and is driven by the method described below. Similarly, the field core of the second stationary field pole 20 also has field windings 20aW+20'aw for excitation.

20 bw is supported. Each field winding consists of a main winding and an auxiliary winding, and is driven in the manner described below.

In FIG. 1.3, a trochoidal output winding 22 is fixedly supported within the stator 14 by suitable means between the first and second static fields ff118, 20 so as to surround the common rotor section 24. The common rotor 24 is mounted on a rotating shaft 26, and the rotating shaft 2G is rotatably supported via end housings and bearings (not shown) provided on both sides of the stator section 17. The rotating shaft 26 is connected to an electric motor or other suitable drive source and is rotationally driven.

According to an important feature of the invention, a third stationary field pole 28 is fixedly supported on the stator 16 at an axial distance from the second stationary field pole 18 for the purposes described below. 1st
．． In Figure 2.4, the third stationary field pole 28 has four field cores 28a, 28b, 28''a, 28'b k, corresponding to the four field cores of the first and second stationary field poles. However, each of these field cores has a magnetic pole piece.Field core 28
a, 28 b.

28°3 and 28°b are field windings 28aw and 2, respectively.
8bw.

28'aw, 28'bw f supporting these field windings m
is driven as described below.

The field cores of the first and second stationary field poles 18 and 20 had north and south poles arranged alternately every 180 degrees in electrical angle, whereas the field core of the third stationary field pole 28 had All magnetic poles are set to either the north pole or the south pole. In Figures 2 and 4, N
Illustrated as being set to pole.

Again No. 1, 2, 3, 4. Returning to the diagram, common rotor 2
Reference numeral 4 denotes a non-magnetic section portion 24a made of stainless steel or other low magnetic permeability material, and a pair of magnetic flux switching magnetic pole pieces 30.30 fixed to the non-magnetic section portion 24 and extending in the axial direction.
' and a magnetic repulsion pole piece 32 extending in the radial direction. The pole pieces 30, 30' are comprised of a stack of high permeability laminates and are installed in radially opening axial grooves 24b, 24'b formed in the non-magnetic section 24a of the rotor 24. , screws, welding or other suitable means within the rotor grooves 24b, 24'b. As is clear from FIG. 12, both ends of the magnetic flux switching magnetic pole piece 30 are arranged directly below the field cores 18a, 20, 3 of the first and second field poles 18°20, and similarly, the magnetic flux switching magnetic pole piece 30' Both ends are the first and second stationary field poles 18.20
The magnetic pole pieces 30, 30' act as magnetic flux paths, and simultaneously change the magnetic flux between the first and second stationary field poles cyclically.

In FIG. 1.2.4, the repelling pole piece 32 is constructed from a stack of high permeability laminates and is inserted into a groove 24c formed in one end of the non-magnetic section 24a of the rotor 24 by suitable means. Fixed. The magnetic pole piece 32 and the magnetic pole piece 30, 30' are separated from each other by a cross section 24d that acts as a spacer so that there is no magnetic influence from each other. Pole piece 32 is connected to pole piece 30 for purposes detailed below.
．． 30'.

In the position shown in FIGS. 1-4, pole piece 30 is located directly below field cores 18a, 20a, and pole piece 30' is located directly below field cores 18'a, 20°a.

In this way, in FIGS. 1 to 3, a magnetic flux circuit is formed between the two N-pole field cores on the left and the two S-pole field cores on the right. The magnetic flux is transmitted from the N-pole field core 18a+18'a to the S-pole field Wtv 20a via the magnetic pole piece 30.30'.
20'a, and further returns to the N-pole field core 18a, 18°a via the stator 14. At this time, since the magnetic flux interlinks with the output winding 22, a current flows in the output winding 22.

In FIG. 5, at time t1, the magnetic pole pieces 30 of the common rotor 24 are N-pole and S-pole stationary field magnetic poles 18a, 20.
a, and at this time the rotor 24 receives a magnetic attraction force. At this time, in the same phase, since the repulsive magnetic pole piece 32 with high magnetic permeability is located directly below the third stationary field pole 28a+28'a of the N pole, a magnetic repulsive effect acts on the rotor 24, and the rotor 24 The holding torque is reduced. Next, at time t, the rotor 24 moves clockwise, that is, in the direction indicated by the arrow in FIG.
The rotated state is shown on the right side of FIG. That is,
At time t, one end of the tan piece 30 of the rotor 24 is located directly below the S-pole field core 18b, and the other end of the magnetic pole piece 30 is located directly below the N-pole field core 20b.

At this time, the rotor 24 receives a magnetic attraction effect via the m-pole piece 301. At time t2, N-pole field core 28b
, 2B'b, in the same phase as the magnetic pole piece 30,
The magnetic pole pieces 32 face each other. At this time, the magnetic pole piece 32 is acted upon by the magnetic flux of the north pole of the field cores 28b, 28'b, so that a repulsive action is given to the rotor 24. At this time, if the current in the field winding of the third stationary field pole is controlled so that the magnetic attraction and repulsion effects on the rotor are balanced, the holding torque of the rotor can be significantly reduced. has advantages. Note that since this rotor balancing action is performed at a position independent of the output winding 22, it does not adversely affect the output value of the output winding.

Next, returning to Figure 1.3, the common rotor 24 is
As the rotor 24 rotates clockwise from the rotor position shown in the figure, the magnetic flux decreases and the rotor 24 rotates 90 degrees clockwise in Figure 3.4.
, that is, when rotated by 180 electrical degrees, the magnetic flux flows in the opposite direction with respect to the output winding 22. At this time, the magnetic flux flows from the N-pole static field pole iron core on the right side of FIG. 1 to the S-pole field magnetic pole iron core 18b on the left side.

18°b, passes through the stator 14, and flows to the right N-pole field pole iron. In this way, current flows in the output winding 22 in the opposite direction. When the common rotor 24 is continuously rotated, changes in magnetic flux are repeated alternately in two directions, and an alternating current is generated in the output winding 22.

6A, 6B, and 6C show examples of connection diagrams of the field windings of the first stationary field coil 18, the third stationary field pole 20, and the third stationary field pole 28, and FIG. An example of an excitation device 40 for exciting field windings of three stationary field poles is shown.

In FIG. 6A, the field winding 18 of the first stationary field pole 18
a, 18'a, 18b, and 18'b each include a field winding 60 for passing an excitation current based on a load current component and a field winding 66 for passing an excitation current based on a voltage component. In FIG. 6B, second static field g & field winding #i of pole 20! 20a, 20'a, 20b, and 20'b each include a load current component field winding 62 and a voltage component field winding 68. In FIG. 6C, the third stationary field pole 2
8 field windings 28a, 28'a, 28b.

28''b each include a load current component field winding 64 and a voltage component field winding 70.

In FIG. 7, the current component field windings 60, 62, 64 and the voltage component field windings @ 66, 68, 70 are connected to the excitation device 40. The excitation device 40 includes a current transformer 72 connected to one output line 22b of the AC output winding 22, a rectifier 74, an accelerator 76 connected to the other output line 22a of the AC output winding 22, and a reactor 76. Output line 22 via
A is shown as a self-exciting device consisting of a rectifier 78 with one end connected to output line 22b and the other end connected to output line 22b, which acts as a voltage regulator as described below.

A capacitor 78 is connected between the output lines 22a, 22b, a capacitor 82 is connected to the bridge input of the rectifier 78, and a capacitor 84 is connected to the auxiliary field windings 66, 68.70.
connected to the input end of the These capacitors act to cancel the inductive reactance of the voltage component field winding,
As a result, the efficiency of the rectifier 78 can be significantly improved. Similarly, capacitors 86,88 are connected to the rectifier 740 input and output to improve efficiency.

In the above configuration, when the generator is started, the frequency of the output voltage of the AC winding 22 is low, so the residual magnetic flux causes A
The voltage appearing in the C winding is rectified by a rectifier 78 via the reactor 6, and is supplied to the windings 66, 68, 70 as an exciting current based on the voltage component. When the generator reaches steady speed and the output frequency is a constant frequency, reactor 76 supplies a voltage lower than the line voltage to rectifier 78.

Next, when a sudden change occurs in a load such as an induction motor connected to an AC winding, a current proportional to the change in load current is extracted by the current transformer 74, and the field winding 60 is connected without any time delay. Since the feedback is .62.64, the characteristics of the generator exhibit extremely excellent compound winding characteristics.

(Effect) In this way, the voltage component field windings of the first, second, and third stationary field poles of the generator are always excited according to the voltage of the generator from the start of the generator to full-load operation. A current flows, and an excitation current corresponding to the load current is also supplied to the current component field windings of the first, second, and third stationary field poles, thereby adjusting the output voltage of the generator. At this time, the Ni and S poles of the first and second stationary field poles 18 and 20 are excited by the aforementioned voltage component field current and current component field current, respectively, and are proportional to this strength. It is clear that the magnetic attraction force is acting on the rotor. However, the N-pole field pole of the third stationary field pole 28 is also excited by the voltage component excitation current and the current component excitation current, and a magnetic repulsion force proportional to this strength is applied to the rotor via the magnetic pole piece 32. It is given to the department. Therefore, since a magnetic attraction force and a magnetic repulsion force proportional to the load current are simultaneously acting on the rotor section 24, the holding force of the rotor section 24 is extremely small.
It is always constant regardless of the size of the load.

As described above, the brushless alternating current generator according to the present invention can extremely effectively prevent abnormal output frequencies and output voltage pulsations due to load fluctuations with a simple and low-cost structure. Furthermore, since the holding force of the rotor portion is extremely small, there is a remarkable effect that the output ratio to the input of the generator can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional perspective view of a brushless alternator according to an embodiment of the present invention, FIG. 2 is a cross-sectional view from ■ to ■ in FIG. 1, and FIG. 3 is a cross-sectional view from ■ to ■ in FIG. Cross section zM = Figure, Figure 4 is a book-sized cross-sectional view of the damage diagram, Figure 5 is a developed view for explaining the phase relationship between the rotor and the field poles, and Figure 6 is a
Figures A, 6B, and 6C are connection diagrams of the field windings of the first, second, and third stationary field poles, and Figure 7 is the excitation device for exciting the first, second, and third stationary field poles. One example is shown for each. 14.16... Stator 18, 20.28... First, second, third field poles 24... Rotor 22... Output winding 4
0...Exciter Applicant Hi-Tech Laboratory Co., Ltd. 3z Retirement 6/6"aw 4th Ward East 5 Figure and 'I; 2 Stone Shiro A z Bottom 68z: 4,6c Collection 7 figure

Claims (1)

[Claims] a stator section, first and second stationary field poles that are fixedly supported on the stator section with an interval in the axial direction; a rotor section having magnetic flux switching magnetic pole pieces that periodically generate magnetic flux changes by rotation of the rotor shaft between the field poles; and a stator section configured to generate electric power by the magnetic flux changes occurring between the first and second stationary field poles. a third stationary field pole fixedly supported on the stator section at a position axially distant from either the first or second field pole; A magnetic repulsion magnetic pole piece provided at a position axially apart from the magnetic flux switching magnetic pole piece is periodically opposed to the third stationary field pole, and a first and second excitation windings are wound, the first excitation winding is supplied with an excitation current based on a load voltage component, and the second excitation winding is supplied with an excitation current based on a load current component. A brushless alternator characterized by being equipped with a device.