JP2893353B2 - Two stator induction synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

 The present invention relates to a synchronous motor.

[Prior art]

In general, a synchronous motor requires a starter that accelerates the rotor to near the rotational speed of the rotating magnetic field generated by the stator winding, that is, near the synchronous speed, and DC excitation of the rotor winding. An induction synchronous motor was devised to omit this starter and give the synchronous motor its own starting torque, which requires a start-up to start as an induction motor by short-circuiting the rotor windings at startup. However, a brush is required for DC excitation of the rotor winding required for synchronous operation.
That is, when the rotation speed of the rotor approaches the synchronous speed, the short circuit of the rotor winding is opened, and a DC current is supplied from an external DC power supply to the rotor winding via a brush to create a magnetic pole in the rotor. The magnetic poles are pulled by the rotating magnetic field created by the stator winding, and the rotor rotates at a synchronous speed. Since this brush requires maintenance and inspection, maintenance costs are increased, and development of a brushless synchronous motor is desired. As the synchronous motor having the brushless structure, there are a permanent magnet type and a reluctance type conventionally. However, since the starting torque of the induction motor is small because the induction motor cannot be started, it is limited to a small capacity motor. In addition, the synchronous motor of the Landel type or the inductor type has a drawback that the configuration of the magnetic path is complicated and large. The same applies to a method using an AC exciter and a rotary rectifier. Also, a brushless self-excited three-phase synchronous motor that uses a harmonic magnetic field generated by the inverter square wave voltage by connecting a diode to the rotor winding has the disadvantage that sufficient output cannot be obtained due to insufficient magnetic field magnetomotive force of the rotor. is there. Furthermore, a diode is inserted in one phase of the three-phase stator winding, and static excitation is superimposed on the positive-phase rotating magnetic field generated by the stator, and the alternating current due to the static magnetic field is applied to the rotor winding rotating at the synchronous speed. Induce a voltage,
There is a brushless self-excited three-phase synchronous motor that rectifies this with a diode, excites the rotor windings with direct current, and applies a positive-phase rotating magnetic field to generate synchronous torque.
This is because it is impossible to start the induction machine, so that the rotor is started by the eddy current of the rotor core and the starting torque is small. In Japanese Patent Publication No. 54-34124, starting is performed by the principle of an induction machine, and synchronous operation is performed by creating a DC magnetic field in the axial direction and thereby forming a magnetic pole on a rotor core. There is a disadvantage that the shaft is oscillated because it is asymmetric with respect to the rotating shaft.

[Problems to be solved by the invention]

Accordingly, it is a technical object of the present invention to provide a synchronous motor which has a large starting torque, a large synchronous torque, does not require a brush, is easy to maintain and inspect, has a simple structure, and does not require a dedicated starter.

[Means for Solving the Problems]

In order to solve the above-mentioned problem, two rotor cores provided at arbitrary intervals on the same rotation axis are constituted by permanent magnets, and communicate with the two rotor cores on the outer periphery of the rotor core. A plurality of conductors, two ends of which are connected by a short-circuit ring, two stators circumferentially opposed to the rotor core, and a specific stator among the two stators. Is constituted by a voltage phase shifter that generates a phase difference between a rotating magnetic field generated around the rotor core facing the rotating core and a rotating magnetic field generated around the rotor core facing the other stator. The magnetic poles of the two rotor cores constituted by the permanent magnets are paired with the N pole and the S pole, and the N pole of one rotor core and the S pole of the other rotor core are the same. And the S pole of one rotor core and the N pole of the other rotor core are located at the same position. It was constructed by location. In addition, the rotor core composed of a permanent magnet was composed of a cylindrical type or a salient pole type. Further, the power source for exciting the stator is a commercial frequency AC power source or a variable frequency power source using an inverter, and is a single-phase AC power source or a multi-phase AC power source. Further, the voltage phase shifter is configured so that the relative position of the two stators is mechanically rotated, or the terminals of the stator windings are switched by a switch and connected to a power supply.

[Operation]

The applicant of the present invention has described in detail in Japanese Patent Application No. 61-128314 the operation of the voltage phase shifter of a two-stator induction motor. According to the present invention, a cage-shaped conductor is first provided with two rotor cores formed of permanent magnets on the same rotation axis, a plurality of conductors communicating with the two rotor cores, and both ends short-circuited. And the two stators circumferentially opposed to the two rotor cores, a plurality of rotors are activated by a rotating magnetic field generated by the two stators at the time of startup. The voltage phase shifter is operated to start up as a general induction motor so that the voltage induced in the conductors is in phase, that is, the current flows between the rotor conductors. At this time, the magnetic poles of the two rotor cores composed of permanent magnets are paired with the N pole and the S pole, and the N pole of one rotor core and the S pole of the other rotor core are located at the same position. In addition, the S pole of one rotor core and the N pole of the other rotor core are arranged at the same position, and the rotating magnetic field generated around the two rotor cores by the two stators is Since the phase difference θ is θ = 0 ° (in-phase), the repulsion and the attraction between the magnetic poles of the rotor core and the rotating magnetic field are canceled on the same rotation axis, so that the permanent magnet forming the rotor core is Does not interfere with startup. After startup, when the rotation speed of the rotor increases and approaches the rotation speed of the rotating magnetic field, that is, the synchronous speed, the induced voltage of the rotor conductor due to the rotating magnetic field decreases. Up to this point, the operation is as an induction motor, but when the slip S approaches S = 0.05, the synchronous operation starts. This is performed as follows. First, of the two stators, one stator has a rotation angle of 180 degrees between the rotating magnetic field generated around the rotor core facing the same and the other stator generated between the rotating magnetic field generated around the rotor core facing the same. The voltage phase shifter is operated so as to generate a phase difference of In this way, the current that has been flowing between the rotor conductors so far does not flow. On the other hand, the magnetic pole of the rotor core composed of permanent magnets is 180
す べ て All magnetic poles created by two rotating magnetic fields having a phase difference are attracted to each other to reach a synchronous speed. Therefore, the induction synchronous motor of the present invention is constituted by one rotor and two stators, but is constituted by one stator and one rotor since it has two rotor cores facing each other. This is equivalent to twice the capacity of a synchronous motor. As described above, the two-stator induction synchronous motor of the present invention
At the time of starting, since the starting is performed based on the principle of the conventional induction motor, the starting torque is large, so that no other special starting machine is required. In addition, at the synchronous speed, the permanent magnet of the rotor core is attracted to the rotating magnetic field, so if the magnetic pole of the rotor core is strengthened, the synchronous torque is large and it is possible to provide a synchronous motor that does not require maintenance such as brushes. became. As a voltage phase shifter, the present applicant has filed Japanese Patent Application No. 61-12 / 1986.
No. 8314 describes two methods, a method of changing the position of the stator by mechanically rotating it around a rotation axis, and a method of switching the connection of the stator winding by a switch. With the above configuration, it is possible to provide a synchronous motor that has a large starting torque, a large synchronous torque, and does not require a brush, is easy to maintain and inspect, has a simple configuration, and does not require a dedicated starting device. It became. Incidentally, as a power supply for exciting the stator winding, an AC power supply having a commercial frequency or a variable frequency power supply using an inverter can be used. It can be used in a single phase or in a multiphase. The use of the above-mentioned variable frequency power supply makes it possible to easily change the synchronous speed, and in that case, it is possible to start with the starting torque of a normal induction motor, thereby greatly expanding the field of use and providing an inexpensive synchronous motor. became.

【Example】

An embodiment of the present invention will be described with reference to FIGS.
First, in FIG. 1, reference numeral 20 denotes a stator side of a two-stator induction synchronous motor. Reference numeral 30 also indicates the rotor side.
On the stator side 20, two star-connected stator windings 21, 22 are connected in parallel to three-phase AC power supplies R, S, T. On the other hand, two rotor cores 81 and 82 are attached to the rotation shaft 10 on the rotor side 20.
The rotor cores 81 and 82 are constituted by permanent magnets having a pair of N pole and S pole. Further, a plurality of rotor conductors 31 and 32 mounted on the outer periphery of the two rotor cores 81 and 82 are connected to each other in a communicating manner, and short-circuit rings 33 for short-circuiting the conductors at both ends thereof are provided. Are formed in a basket shape. FIG. 2 is a sectional view of a cylindrical rotor core, and FIG. 3 is a sectional view of a salient pole type rotor core. As shown in FIGS. 2 and 3, two rotor cores 81 and 82 are provided.
Magnetic poles are paired with north and south poles,
The N pole (or S pole) of the other rotor core 81 and the S pole (or N pole) of the other rotor core 81 are arranged at the same position. Here, the voltage induced on the rotor conductor 31 facing the stator winding 21 is denoted by E in the direction shown in FIG. 1, and the voltage induced on the rotor conductor 32 facing the stator winding 22 is shown in FIG. Let Eε ^jθ be in the direction. Here, θ is the phase difference angle of the voltage. The operation of the above configuration will be described. First, at the time of start-up, the power is supplied to the power supply with the stator windings 21 and 22 connected so that the phase difference angle θ of the induced voltage due to the rotating magnetic field of the rotor conductors 31 and 32 becomes θ = 0 °. I do. In this way, three-phase currents flow from the power supply to the stator windings 21 and 22, and in-phase rotating magnetic fields are generated, respectively, and voltages are induced in the rotor conductors 31 and 32. Since the phase difference angle θ = 0 °, the current flowing through the rotor conductor flows from the rotor conductor 31 back to the rotor conductor 32. The current flowing through the rotor conductors 31 and 32 and the torque due to the rotating magnetic field generated by the stator windings 21 and 22 are the same as the torque of the conventional induction motor. Here, two rotor cores 81, 8 composed of permanent magnets
Consider the interaction between the two magnetic poles and the magnetic poles of the rotating magnetic field created by the stator windings 21 and 22. FIG. 4 is a sectional view of two rotor cores 81 and 82 and stators 21 and 22. The two rotor cores 81 and 82 are
Are connected by Also, as shown in FIG.
The pole and the S pole of the rotor core 82 are arranged at the same position, and the S pole of the rotor core 81 and the N pole of the rotor core 82 are arranged at the same position. The magnetic poles of the rotating magnetic field created by the stator winding 21 as shown in the figure.
N and S and the magnetic poles N and S of the rotating magnetic field created by the stator winding 22 both rotate in the same direction at a synchronous speed, but the two stator windings 21 and 22
The phase difference angle θ between the two rotating magnetic fields created by
゜, the magnetic pole N of the rotating magnetic field generated by the stator winding 21
(Or S) and the magnetic pole N (or S) of the rotating magnetic field generated by the stator winding 22 are always at the same position. Therefore, when the N pole of the rotor core 81 and the N pole and the central angle of the rotating magnetic field generated by the stator winding 21 are α at a certain moment,
N of the rotating magnetic field generated by the S pole of the rotor core 82 and the stator winding 22
The central angle with the pole is also α. Accordingly, the repulsive force of the N pole and N pole acting on the rotor core 81 is equal to the attractive force of the S pole and N pole acting on the rotor core 82. Therefore, the repulsive force and the attractive force are canceled, and the magnetic pole of the rotor core is not affected by the rotating magnetic field. That is, the magnetic poles of the rotor core are not restricted by the rotating magnetic field. Therefore, the two-stator induction synchronous motor of the present invention starts with the same torque characteristics as the conventional induction motor. Thus, the starting torque is high and does not require a special separate starter. After start-up, when the rotation speed increases and slip S approaches S = 0.05, synchronous operation is started. This is performed as follows. First, the position of one of the two stator windings 21, 22, for example, the stator winding 22, is changed by rotating it around a rotation axis by a voltage phase shifter to change the two stator windings 21, 2.
2 so that the phase difference angle θ between the two rotating magnetic fields created by the method 2 becomes 180 °. In this way, the phase difference angle θ of the induced voltages of the two rotor conductors 31 and 32 becomes 180 °, and the sum of the induced voltages of the rotor conductors 31 and 32 becomes E + EεP ^jθ = E−E = 0. No current flows through the rotor conductors 31,32. Here, two rotor cores 81 and 82 composed of permanent magnets
And the magnetic poles of the rotating magnetic field created by the stator windings 21 and 22 will be considered. During the synchronous operation, the phase difference angle θ between the two rotating magnetic fields formed by the two stator windings 21 and 22 is θ = 180 °, and therefore, as shown in FIG. N (or S) and the magnetic pole N (or S) of the rotating magnetic field generated by the stator winding 22 are always at positions 180 ° different in electrical angle. In other words, the N pole of the rotating magnetic field generated by the stator winding 21 and the stator winding 22
Are always at the same position. Accordingly, the N pole of the rotor core 81 repels the N pole of the rotating magnetic field generated by the stator winding 21, and similarly, the S pole of the rotor 82 repels the S pole of the rotating magnetic field generated by the stator winding 22. And rotor core 8
The position 1,82 is retracted to the position shown in FIG. 6, and all the N and S are stabilized in the suction state. That is, the magnetic poles of the rotor cores 81 and 82 are pulled by the magnetic poles of the rotating magnetic field formed by the stator windings 21 and 22, and the rotor rotates at the same speed as the rotating speed of the rotating magnetic field, that is, at the synchronous speed. This method has the advantages that the structure is simple, the starting torque is large, and if the permanent magnet of the rotor core is made strong, a large synchronous torque can be obtained and the efficiency is good. In addition, since the synchronous motor of the present invention is activated by an induction motor, a power source generally used for the induction motor can be used. In other words, a commercial frequency AC power supply or a variable frequency power supply using an inverter can be used. It can also be used in single-phase and multi-phase.
In the above embodiment, the two stator windings are connected in parallel to the power supply, but they may be connected in series. Although the number of magnetic poles is two, the number is not limited to two and may be more.

[Effect]

From the above configuration, the two-stator induction synchronous motor of the present invention
At the time of starting, it performs with the same torque characteristics as the conventional induction motor,
The slip S shifts from, for example, around S = 0.05 to the synchronous speed, and the operation is performed with the torque characteristics of the synchronous motor. This two-stator induction synchronous motor does not require a starter or a brush, so its structure and configuration are simple. In addition, it can be started with the same torque characteristics as a conventional induction motor, so that it can be started with a heavy load applied. And synchronous operation becomes possible. By the way, the two-stator induction synchronous motor of the present invention has both the torque characteristics of the induction motor and the synchronous motor, and therefore can be used with the torque characteristics of either motor. This means that even if the motor loses synchronism for some reason during operation at the synchronous speed, the torque characteristic of the induction motor can be switched from the torque characteristic of the induction motor to the torque characteristic of the induction motor. There is no. As described above, since there is no brush and no complicated structure is required, maintenance and inspection are easy, and a synchronous motor having a large starting torque and a large synchronous torque can be provided.

[Brief description of the drawings]

FIG. 1 is a simplified structural view of the stator winding side and the rotor side of the present invention, FIG. 2 is a sectional view of a cylindrical rotor core, FIG. 3 is a sectional view of a salient pole type rotor core, FIG. FIG. 4 is a diagram schematically showing the action of two rotor cores and two stator cores at the time of startup in a cross section, FIG. 5 is a diagram showing an example of suction at a synchronous speed, and FIG.
The figure is a diagram schematically showing a cross section of two rotor cores and two stator cores of synchronous speed. 10 ... rotating shaft, 20 ... stator side, 21 ... stator winding, 22
... stator winding, 30 ... rotor side, 31 ... rotor conductor,
32: rotor conductor, 33: short-circuit ring, 81, 82: rotor core.

Claims (7)

(57) [Claims] 1. Two rotor cores provided at arbitrary intervals on the same rotation axis are constituted by permanent magnets, and a plurality of rotor cores communicated with the two rotor cores on the outer periphery of the rotor core. A rotor provided with a conductor, both ends of which are connected by a short-circuit ring, two stators circumferentially opposed to the rotor core, and a specific stator among the two stators A rotating magnetic field generated around the confronting rotor core and a voltage phase shifter for generating a phase difference between the rotating magnetic field generated around the opposing rotor core by another stator. Features two stator induction synchronous motor. 2. The two-stator induction synchronous motor according to claim 1, wherein the magnetic poles of the two rotor cores constituted by permanent magnets are paired with an N pole and an S pole. N of rotor core
The pole and the S pole of the other rotor core are arranged at the same position,
Further, the S pole of one rotor core and the N pole of the other rotor core
A two-stator induction synchronous motor, wherein the poles are arranged at the same position. 3. A two-stator induction synchronous motor according to claim 1, wherein the rotor core comprising a permanent magnet is cylindrical. . 4. A two-stator induction synchronous motor according to claim 1, wherein the rotor core comprising a permanent magnet is of a salient pole type. Electric motor. 5. A two-stator induction synchronous motor according to claim 1, wherein a power source for exciting the stator is a commercial frequency AC power source or a variable frequency power source using an inverter. A two-stator induction synchronous motor characterized by being a power supply. 6. A two-stator induction synchronous motor according to claim 1, wherein a power supply for exciting the stator is a single-phase AC power supply or a multi-phase AC power supply. A two-stator induction synchronous motor. 7. A two-stator induction synchronous motor according to claim 1, wherein the voltage phase shifter comprises:
A two-stator induction synchronous motor characterized in that a relative position of two stators is periodically rotated or a terminal of a stator winding is switched by a switch to be connected to a power source.