JPH03270667A - Dual stator synchronous induction motor - Google Patents

Abstract

PURPOSE:To increase starting torque by an arrangement wherein the pole of a rotor core comprising a permanent magnet is attracted to the pole of two rotating fields having phase difference of 180 deg. and the rotor reaches the synchronous speed. CONSTITUTION:N pole of a rotating field produced by a stator winding 21 is always shifted by an electrical angle of 180 deg. from N pole of the rotating filed produced by a stator winding 22. Consequently, N pole of a stator core 81 and N pole of the rotating field produced by the stator winding 21 repel each other. S pole of a rotor core 82 and S pole of the rotating field of the stator winding 22 also repel each other and the rotor cores 81, 82 are attracted and settled in a state where all N and S poles are attracted. In other words, poles of the rotor cores 81, 82 are attracted to the poles of the rotating fields produced by the stator windings 21, 22 and the rotor rotates with same speed as the rotational speed of the rotating field, i.e., the synchronous speed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a synchronous motor.

[Conventional technology]

Generally, a synchronous motor requires a starter that accelerates the rotor to the rotation speed of the rotating magnetic field generated by the stator winding, that is, close to the synchronous speed, and DC excitation of the rotor winding. The induction synchronous motor was devised to omit this starter and give the synchronous motor itself its own starting torque.This requires starting because the rotor windings are short-circuited at the time of starting and the motor starts as an induction motor. However, brushes are required for the DC excitation of the rotor windings required for synchronous operation. That is, when the rotational speed of the rotor approaches the synchronous speed, the short circuit in the rotor winding is opened, and a DC current is passed from an external DC power source to the rotor winding through the brushes to create magnetic poles on the rotor.
These magnetic poles are pulled by the rotating magnetic field created by the stator windings, causing the rotor to rotate at a synchronous speed. This brush requires maintenance and inspection, which increases maintenance costs, and there is a desire to develop a synchronous motor with a brushless structure. Conventionally, there are permanent magnet type and reluctance type synchronous motors with this brushless structure, but they are limited to small capacity ones because they have the disadvantage of low starting torque because induction motor cannot be started. Furthermore, Ransol-type and inductor-type synchronous motors have the disadvantage of having complicated magnetic path configurations and being large. Also, the method using an AC exciter and a rotating rectifier is similar. In addition, brushless self-excited three-phase synchronous motors that connect diodes to the rotor windings and utilize the harmonic magnetic field generated by the square wave voltage of the inverter have the disadvantage that sufficient output cannot be obtained due to insufficient magnetomotive force of the rotor's magnetic field. be. Furthermore, by inserting a diode into one phase of the three-phase stator winding, static excitation is superimposed on the positive phase rotating magnetic field generated by the stator, and the alternating current voltage due to the static magnetic field is applied to the rotor winding rotating at a synchronous speed. There is a brushless self-excited three-phase synchronous motor that generates synchronous torque by inducing a DC current and rectifying it with a diode to excite the rotor winding and applying a positive-phase rotating magnetic field. Since it is impossible to start the induction motor, the starting torque is low due to the eddy current in the rotor core. In addition, in Japanese Patent Publication No. 54-34124, there is a method in which starting is performed using the principle of an induction machine, and synchronous operation is performed by creating an axial DC magnetic field and thereby forming magnetic poles in the rotor core, but this method has a method in which the generated torque is It has the disadvantage that it is asymmetric with respect to the rotating shaft, causing vibration of the shaft.

[Problem to be solved by the invention]

Therefore, the technical object is to provide a synchronous motor that has a large starting torque and a large synchronous torque, does not require brushes, is easy to maintain and inspect, has a simple structure, and does not require a dedicated starter.

[Means to solve the problem]

In order to solve the above problem, two rotor cores arranged on the same rotating shaft at an arbitrary interval are made of permanent magnets,
A plurality of conductors connected to two rotor cores are provided on the outer periphery of the rotor core, and a rotor whose both ends are connected by a short-circuit ring, and two conductors provided around the rotor core facing each other. A rotating magnetic field generated around a stator and a rotor core that a specific stator of the two stators faces, and a rotating magnetic field generated around a rotor core that faces another stator. The magnetic poles of the two rotor cores made of the permanent magnets are composed of a voltage phase shifter that generates a phase difference between the rotating magnetic field and the rotating magnetic field, and the magnetic poles of the two rotor cores made of the permanent magnets are paired with an N pole and an S pole. The N pole of the child core and the S pole of the other rotor core are arranged at the same position, and the S pole of one rotor core and the N pole of the other rotor core are arranged at the same position. Configured. Further, the rotor core made of permanent magnets was made 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. Moreover, the voltage phase shifter is 2
The structure is such that the relative positions of the individual stators can be mechanically rotated, or the terminals of the stator windings can be switched using a switch to connect to the power source.

[For use]

The details of the operation of a voltage phase shifter for a multi-stator induction motor have been described by the present applicant in Japanese Patent Application No. 128314/1983. According to the present invention, first, there are two rotor cores made of permanent magnets on the same rotating shaft, and a plurality of conductors communicating with the two rotor cores are provided, and both ends of the conductors are short-circuited to form a squirrel cage conductor. In a rotor constructed of a rotor and two stators disposed around the two rotor cores, the rotating magnetic field created by the two stators causes the rotation of the plurality of rotors at startup. The voltage phase shifting device is activated so that the voltages induced in the conductors are in phase, that is, the current circulates between the rotor conductors, and the motor is started as a general induction motor. At this time, the magnetic poles of the two rotor cores made of permanent magnets are made into a pair of north and south poles, and the north pole of one rotor core and the south pole of the other rotor core are placed in the same position. Furthermore, the S pole of one rotor core and the N pole of the other rotor core are arranged at the same position, and the two stators
The rotating magnetic field generated around the two rotor cores has a phase difference θ
Since θ=0° (in phase), the repulsion and attraction between the magnetic poles of the rotor core and the rotating magnetic field cancel each other out on the same rotation axis, and the permanent magnets forming the rotor core become an obstacle to starting. Must not be. After startup, when the rotational speed of the rotor increases and approaches the rotational speed of the rotating magnetic field, that is, the synchronous speed, the voltage induced in the rotor conductor by the rotating magnetic field becomes smaller. Up to this point, the motor is operating as an induction motor, but when the slip S approaches S=0.05, it enters synchronous operation. This is done as follows. First, there is a difference of 180 degrees between the rotating magnetic field generated around the rotor core of which one of the two stators faces and the rotating magnetic field generated around the rotor core of which the other stator faces. The voltage phase shifter is activated to create a degree phase difference. By doing this, the current that used to circulate between the rotor conductors will no longer flow. On the other hand, the magnetic poles of the rotor core made of permanent magnets are 180
The magnetic poles created by two rotating magnetic fields with a phase difference are all attracted to each other, resulting in a synchronous speed. Therefore, the induction synchronous motor of the present invention is composed of one rotor and two stators, but since it has two rotor cores facing each of the two stators, it is composed of one stator and one rotor. This is equivalent to twice the capacity of a synchronous motor. As described above, since the two-stator induction synchronous motor of the present invention is started based on the principle of a conventional induction motor, the starting torque is large, and therefore no other special starter is required. Furthermore, at synchronous speeds, the permanent magnets in the rotor core are attracted to the rotating magnetic field, so if the magnetic poles of the rotor core are made stronger, the synchronous torque is large, making it possible to provide a synchronous motor that does not require maintenance such as brushes. became. The voltage phase shift device was developed by the applicant in Japanese Patent Application No. 1986-1.
No. 28314 describes two methods: one in which the position of the stator is changed by mechanically rotating it around a rotating shaft, and the other in which the connection of the stator windings is changed 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, does not require brushes, is easy to maintain and inspect, has a simple configuration, and does not require a dedicated starter. It became. By the way, the power source for exciting the stator winding can be a commercial frequency AC power source or a variable frequency power source using an inverter. Moreover, it can be used in both single phase and polyphase. By using the variable frequency power supply mentioned above, it becomes possible to easily change the synchronous speed, and even in that case, it can be started with the starting torque of a normal induction motor, greatly expanding the field of use and making it possible to provide inexpensive synchronous motors. became.

【Example】

The present invention will be explained in detail with reference to FIGS. 1 to 3. First, in FIG. 1, reference numeral 20 indicates the stator side of a two-stator induction synchronous motor. Further, the reference numeral 30 similarly indicates the rotor side. The stator side 20 has two star-connected stator windings 21.
22 are connected in parallel to three-phase AC power supplies R, S, and T. On the other hand, two rotor cores 81 are attached to the rotating shaft 10 on the rotor side 20.
．． 82 is provided, and this rotor core 81.82 is composed of a permanent magnet having a pair of north and south poles. Further, a shorting ring 33 is provided to connect each of the plurality of rotor conductors 31 and 32 mounted on the outer periphery of the two rotor cores 81 and 82 in a continuous manner and short-circuit the conductors at both ends thereof. are arranged in a basket shape. FIG. 2 shows a sectional view of a cylindrical rotor core, and FIG. 3 shows a sectional view of a salient pole rotor core. Two rotor cores 81.8 as shown in FIGS. 2 and 3
The second magnetic pole is a pair of N pole and S pole, and the N pole (or S pole) of a specific rotor core 82 and the S pole (or N pole) of the other rotor core 81 are arranged at the same position. has been done. Here, the voltage induced in the rotor conductor 31 facing the stator winding 21 is set as E in the direction shown in FIG.
The voltage induced in the rotor conductor 32 facing the rotor 2 is assumed to be EεJ6 in the direction shown in the figure. Here, θ is the voltage phase difference angle. The effect of the above configuration will be explained. First, at startup,
The stator windings 21 and 22 are connected so that the phase difference angle θ of the induced voltage due to the rotating magnetic field of the rotor conductor 31 and 32 becomes 0°, and the power supply is turned on and started. In this way, three-phase currents flow from the power supply to the stator windings 21, 22, generating rotating magnetic fields of the same phase, and the rotor conductors 31, 22 generate rotating magnetic fields of the same phase.
A voltage is induced in the rotor conductor 32, but since the phase difference angle θ of the induced voltage in this case is 0°, the current flowing in the rotor conductor flows back from the rotor conductor 31 to the rotor conductor 32. The torque caused by the current flowing through the rotor conductors 31, 32 and the rotating magnetic field created by the stator windings 21, 22 is the same as the torque of a conventional induction motor. Here, the magnetic poles of two rotor cores 81 and 82 composed of permanent magnets and the stator winding 2
Let us consider the interaction between the rotating magnetic field created by 1.22 and the magnetic poles. Figure 4 shows two rotor cores 81.82 and stator 21.2.
2 shows a cross-sectional view of two rotor cores 81.8.
2 are connected by a rotating shaft 10. Further, as shown in the figure, the N pole of the rotor core 81 and the S pole of the rotor core 82 are arranged at the same position, and similarly, the S pole of the rotor core 81 and the N pole of the rotor core 82 are arranged at the same position. has been done. In addition, as shown in the figure, the magnetic poles N and S of the rotating magnetic field created by the stator winding 21 and the magnetic poles N and S of the rotating magnetic field created by the stator winding 22,
S rotate in the same direction at a synchronous speed, but since the phase difference angle θ between the two rotating magnetic fields created by the two stator windings 21 and 22 is θ=0° at startup, the stator winding 21 The magnetic pole N (or S) of the rotating magnetic field generated 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, if the N pole of the rotor core 81 and the central angle of the rotating magnetic field created by the stator winding 21 are α at a certain instant, then the rotating magnetic field created by the S pole of the rotor core 82 and the stator winding 22 is α. The central angle with the N pole is also α. Therefore, rotor core 81
The repulsive force between the north pole and the north pole acting on the rotor core 82 and the attractive force between the south pole and the north pole acting on the rotor core 82 are equal. Therefore, the repulsive force and attractive force are canceled and the magnetic poles of the rotor core are not affected by the rotating magnetic field. That is, the magnetic poles of the rotor core are not constrained by the rotating magnetic field. Therefore, the two-stator induction synchronous motor of the present invention starts with the same torque characteristics as a conventional induction motor. The starting torque is therefore high and no special separate starter is required. After startup, the rotation speed increases and the slip S becomes S=0.05.
When approaching , synchronized operation is initiated. This is done as follows. First, the two stator windings 21,22 are connected by a voltage phase shifter.
On the other hand, for example, by changing the position of the stator winding 22 by rotating it around the rotation axis, the phase difference angle θ between the two rotating magnetic fields created by the two stator windings 21 and 22 is set to 180.
°. In this way, the phase difference angle θ between the induced voltages of the two rotor conductors 31 and 32 becomes 180 degrees, and the rotor conductors 31 and 32 have a phase difference angle θ of 180 degrees.
The sum of the induced voltages in the rotor conductors 31.32 becomes E+Eε"=E-E=0, and no current flows in the rotor conductors 31.32. Here, the two rotor cores 81.8 made of permanent magnets
Let us consider the interaction between the magnetic poles of the stator windings 21 and 22 and the magnetic poles of the rotating magnetic field created by the stator windings 21 and 22. During synchronous operation, the phase difference angle θ between the two rotating magnetic fields created by the two stator windings 21 and 22 is θ=1800, so as shown in FIG. 5, the magnetic pole N of the rotating magnetic field created by the stator winding 21 (or S) and the magnetic pole N of the rotating magnetic field created by the stator winding 22
(or S) are always at positions different by 180 degrees in electrical angle. In other words, the N pole of the rotating magnetic field created by the stator winding 21 and the S pole of the rotating magnetic field created by the stator winding 22 are always at the same position. Therefore, the N pole of the rotor core 81 and the N pole of the rotating magnetic field created by the stator winding 21 repel each other, and similarly, the S pole of the rotor core 82 and the S pole of the rotating magnetic field created by the stator winding 22 repel each other. As a result, the rotor cores 81 and 82 are retracted to the position shown in FIG. 6, and are stabilized in a state where all N and S are attracted. That is, the magnetic poles of the rotor core 81, 82 are at the stator winding 21°22
The rotor is pulled by the magnetic poles of the rotating magnetic field, and rotates at the same speed as the rotational speed of the rotating magnetic field, that is, at a synchronous speed. This method has a simple structure, a large starting torque, and if the permanent magnets in the rotor core are made strong, a large synchronous torque can be obtained and the advantages are good efficiency. Furthermore, since the synchronous motor of the present invention is started by an induction motor, the power source used for the induction motor for boat fishing 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 or polyphase.

【effect】

From the above configuration, the two-stator induction synchronous motor of the present invention performs startup with the same torque characteristics as a conventional induction motor, and the synchronous motor shifts to the synchronous speed from around S = 0.05, for example. It operates with the torque characteristics of This two-stator induction synchronous motor does not require a starter or brushes, so it has a simple structure and configuration, and it can be started with the same torque characteristics as a conventional induction motor, so it can be started with a heavy load applied. Synchronous operation is possible. By the way, since the two-stator induction synchronous motor of the present invention has the torque characteristics of both an induction motor and a synchronous motor,
It can be used with either motor's torque characteristics. This means that even if the motor loses synchronization for some reason while operating at synchronous speed, it is possible to switch from the synchronous motor torque characteristic to the induction motor torque characteristic, so the motor will not suddenly stop like a general synchronous motor. There is no. As described above, since there are no brushes and no complicated configuration is required, maintenance and inspection are easy, and it has become possible to provide a synchronous motor with a large starting torque and a large synchronous torque.

[Brief Description of the Drawings] Fig. 1 is a simple configuration diagram of the stator winding side and rotor side of the present invention, Fig. 2 is a sectional view of the cylindrical rotor core, and Fig. 3 is a salient pole shape. A cross-sectional view of the trochanter core, Figure 4 is a cross-sectional view showing the actions of the two rotor cores and two stator cores during startup, and Figure 5 is a view showing an example of suction to synchronous speed. , FIG. 6 is a simplified cross-sectional view of two rotor cores and two stator cores at synchronous speed. DESCRIPTION OF SYMBOLS 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)

[Claims] (1) Two rotor cores arranged at an arbitrary interval on the same rotating shaft are composed of permanent magnets, and a plurality of conductors connected to the two rotor cores are arranged on the outer periphery of the rotor core. A rotor is provided, the ends of which are connected by a short-circuit ring, two stators are provided around the rotor core facing each other, and a specific stator of the two stators faces the rotor core. It is characterized by comprising a voltage phase shift device that creates a phase difference between the rotating magnetic field generated around the rotor core and the rotating magnetic field generated around the rotor core that faces other stators. 2 stator induction synchronous motor. (2) In the two-stator induction synchronous motor according to claim (1), the magnetic poles of the two rotor cores made of permanent magnets are
N poles and S poles are paired, the N pole of one rotor core and the S pole of the other rotor core are arranged at the same position, and the S pole of one rotor core and the rotation of the other rotor core are arranged in the same position. A two-stator induction synchronous motor characterized in that the N pole of the child core is located at the same position. (3) The two-stator induction electric synchronous motor according to claim (1) or (2), wherein the rotor core made of permanent magnets is cylindrical. (4) A two-stator induction synchronous motor according to claim (1) or (2), wherein the rotor core made of permanent magnets is of a salient pole type. (5) A two-stator induction synchronous motor according to any one of claims (1) to (4), in which the 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 the following. (6) The two-stator induction synchronous motor according to any one of claims (1) to (4), characterized in that the power source for exciting the stator is a single-phase AC power source or a multi-phase AC power source. A two-stator induction synchronous motor. (7) The two-stator induction synchronous motor according to any one of claims (1) to (6), wherein the voltage phase shift device periodically rotates the relative positions of the two stators. , or a two-stator induction synchronous motor characterized in that the terminals of the stator windings are connected to a power source by switching them with a switch.