JPH06335271A - Synchronous motor - Google Patents

Abstract

PURPOSE:To provide a synchronous motor as which can start like an induction motor, has a simplified DC energizing circuit fitted to a stator, and has a brushless structure. CONSTITUTION:Two pairs of stator main coils 7, 8 are provided and each coil is connected to 3-phase AC power supplies R, S, T, the main coils 7, 8 are respectively provided with auxiliary coils 9, 11 and these two auxiliary coils 9, 11 are connected in series through an ON-OFF switch S1 and a DC power supply E. Moreover, a rotor has two rotor cores and respective rotor cores are provided with the first rotor coils 3, 4 and second rotor coils 5, 6, respectively, the first rotor cores 3, 4 of two rotor core are connected in series and the second rotor coils 5, 6 are connected in the star-connection method, allowing connection of diodes D1, D2 between the terminals thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor which is self-starting as an induction motor and switches to synchronous operation.

[0002]

2. Description of the Related Art A general synchronous motor includes a starter for accelerating its rotor up to a rotational speed of a rotating magnetic field formed by a stator winding, that is, a synchronous speed, and a brush and a DC for exciting the rotor winding by direct current. Power is needed.

An induction synchronous motor is one in which the synchronous motor itself is provided with a starting torque by omitting the starter. This does not require a starter to short-circuit the rotor winding at start-up and start it as an induction motor, but does require a brush 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 released, and a DC current is passed from the external DC power source to the rotor winding through the brush to form a magnetic pole on the rotor. This magnetic pole is pulled by the rotating magnetic field created by the stator windings, and the rotor rotates at a synchronous speed. However,
Since this brushed electric motor requires maintenance and inspection, the maintenance cost is high, and a synchronous electric motor having a brushless structure and capable of self-starting is desired.

As a brushless synchronous motor having a structure having a rotor winding, there is a brushless synchronous motor with an AC exciter using an AC exciter and a rotary rectifier. However, this has a drawback that the circuit configuration is complicated and the reliability is low. is there. There is also a brushless self-excited three-phase synchronous motor that connects a diode to the rotor winding and uses the harmonic magnetic field generated by the square wave voltage of the inverter. There is a drawback that sufficient output cannot be obtained because the field magnetomotive force of the child is insufficient.

Further, in the above-mentioned inverter-driven brushless synchronous motor, a diode is connected to one phase of the three-phase stator winding.
The static magnetic field generated by the stator is superposed on the rotating magnetic field for the positive phase to induce an AC voltage due to the static magnetic field in the rotor winding rotating near the synchronous speed, and this is rectified by the diode. By doing so, there is a brushless self-excited three-phase synchronous motor that excites the rotor winding by direct current and applies a rotating magnetic field for the positive phase to generate synchronous torque.However, since this is also impossible to start the induction machine, There is a drawback that the starting torque is small due to the eddy current of the rotor core, and the synchronizing torque is also small.

The applicant of the present application has disclosed an induction synchronous motor having a plurality of stators in order to solve these drawbacks of the prior art in Japanese Patent Laid-Open No. 212143/1993.

[0007]

In this synchronous motor, rotor windings wound around a plurality of rotor cores provided on the same rotary shaft are connected in series, and the connection points of the rotor windings are connected. It is composed of a rotor in which diodes are connected in parallel, a plurality of stators in which a stator winding and a DC exciting circuit including a DC exciting winding are provided in one phase of the stator winding.

In the DC excitation circuit of this synchronous motor, an AC voltage of the fundamental wave is generally induced by the rotating magnetic field of the stator winding. This is because the AC voltage of the excitation winding, which is induced by the fundamental wave of the stator, is superimposed on the excitation winding together with the DC rectified by the diode to flow an AC current, and the AC current of this excitation winding is fixed. Since it acts so as to add to the exciting current of the child winding, there is a drawback that the alternating current of the stator winding becomes large and the capacity of the main winding becomes large. To eliminate this drawback, a large series inductance L is required in the exciting circuit. For this reason, insert a large series reactor, or, as another method, separate the excitation winding with a different number of poles from the stator and the number of poles of this excitation winding so as not to be affected by the stator winding. Had to make up the rotor.

Since such a technique not only complicates the structure of the synchronous motor but also increases the size thereof, it cannot be employed particularly in a synchronous motor capable of starting an induction machine having a plurality of stators.

From the above, a starting torque similar to that of a general induction motor can be generated, the transition from the induction machine operation to the synchronous operation can be easily performed, the synchronous torque is large, and the brushless and easy-to-maintain synchronous motor can be used. In addition to providing the DC excitation circuit of the rotor, the winding is provided in the same phase of the stator. Even with the simple configuration as before, it is a technical issue to provide a synchronous motor that does not affect other configurations or performance. .

[0011]

In order to solve the above-mentioned problems, the present applicant has two rotor cores provided on the same rotary shaft at arbitrary intervals, and the two rotor cores are provided. And a second three-phase rotor winding is provided on each of the two rotor cores, and the first three-phase rotor winding is provided on each of the two rotor cores and connected in series with each other. A rotor having a diode connected between its terminals, and two stator cores provided around the two rotor cores so as to face each other, and a stator main body is provided in each of the two stator cores. A stator in which windings are wound and connected to a three-phase power source, and an auxiliary circuit in which an auxiliary winding is provided in each of the two stators and the auxiliary winding is connected in series to a DC power source through an open / close switch. A synchronous motor was constructed by and. Further, the stator main winding, the auxiliary winding, and the first and second rotor windings have the same number of poles, so that the synchronous motor of the present invention can be realized more easily.

[0012]

The synchronous motor of the present invention is provided with two sets of stator main windings, which are connected to the three-phase AC power supplies R, S, and T, and the main windings are provided with auxiliary windings. The auxiliary windings of the two stators are connected in series via an open / close switch and a DC power supply. The rotor has two rotor cores, and the first rotor winding and the second rotor winding are respectively wound around the rotor core, and the first rotor of the two rotor cores is provided. The windings are connected in series, the second rotor windings are each star-connected and the diodes are connected between the terminals of the windings.

The operation of the synchronous motor having the above configuration will be described from the start to the operation. First, when the three-phase power supply is applied to the two stator main windings with the open / close switch of the auxiliary winding open, the rotating magnetic field generated by the two stator main windings causes the rotation of the two rotor cores. In-phase voltages are induced in the child windings, and a circulating current flows through the first rotor windings provided in the two rotor cores. In other words, starting is based on the principle of an induction motor, which is one of the features of the present invention.

At this time, since the circulating current is a short-circuit current of the first rotor winding, the voltage between the series connection points of the first rotor windings provided in the two rotor cores is zero. Next to
Therefore, since the terminal voltage of the second rotor winding also becomes zero, almost no current flows through the diode connected between the terminals. As a result, the rectified current by the diode does not flow, so that the DC magnetic flux does not occur, and even if the rotor is provided with the second rotor winding including the diode, there is no problem in starting the induction machine.

Next, the synchronous operation will be described. After the start of the induction machine, when the rotation of the rotor approaches S = 0.05 due to the slip S, the open / close switch of the stator auxiliary winding is closed. At this time, a voltage is induced in the auxiliary winding by the rotating magnetic field of the stator main winding, but since the auxiliary windings of the two stators are connected in series, the rotating magnetic field of the stator main winding is The sum of the voltages induced by is zero, no AC current flows through the auxiliary winding, and only DC current due to DC current flows through the auxiliary winding. This DC current causes the auxiliary winding to create a static magnetic field, but since the DC current flows in such a manner as to circulate through the auxiliary winding, the direction of the current is opposite in each auxiliary winding of the two stators. Therefore, the directions of the static magnetic fields created by the auxiliary windings of the respective stators are also opposite to each other.

Now, considering the voltage induced in the first and second rotor windings of the rotor by this opposite static magnetic field, first, the directions of the static magnetic fields are opposite,
The directions of the voltages induced on the two rotor cores are also opposite. Therefore, the sum of the voltages induced in the first rotor windings mounted on the two rotor cores and connected in series becomes zero, and the current due to the static magnetic field is applied to the first rotor windings. Will not flow. On the other hand, since the second rotor winding has an independent structure in the two rotor cores, the current caused by the voltage induced in the second rotor winding by the static magnetic field of the auxiliary winding is A magnetic pole is formed in the two rotor cores by the rectified direct current flowing through the diodes respectively connected to the terminals of the rotor winding. At this time, the direction of the magnetic pole of the rotor core is determined by the polarity of the diode and is independent of the induced voltage in the rotor winding.

If the diodes provided in the second rotor windings of the two rotor cores are oriented in the same direction, the polarities of the magnetic poles generated in the rotor cores will be the same in the two cores, and two sets of stators will be provided. Torque in the same direction is generated between the two rotating magnetic fields of the same phase which are formed by the main winding. Therefore 2
The synchronous torques generated between the pair of stators and the two sets of rotor cores are added, and the output becomes the same torque as the combined torque of the two synchronous motors.

As described above, the synchronous motor according to the present invention is capable of starting the induction machine, and can be brought into the synchronous operation by applying the DC power supply to the auxiliary winding on the stator side. The structure of the present invention is characterized in that both the stator and the rotor can be realized with the same number of poles. Moreover, even if the motor is out of step, it can be an induction motor due to the action of an induction machine by the rotating magnetic field of the stator main winding and the first rotor winding of the rotor. The motor torque does not cause the motor to suddenly stop.

[0019]

Embodiments of the present invention will be described below with reference to FIG. Here, FIG. 1 shows the connection state of the winding portion of the synchronous motor according to the present invention.

First, reference numeral 1 indicates a winding state on the rotor side. The rotor side 1 has two rotor cores (not shown), and the first rotor windings 3 and 4 are wound around the respective rotor cores. The first rotor windings 3, 4 are connected in series with each other. Further, on the rotor side 1, the second rotor windings 5 and 6 are wound around the respective rotor cores.
The second rotor windings 5 and 6 are star-connected, and diodes D ₁ and D ₂ are connected between terminals of the windings, respectively. The polarities of the diodes D ₁ and D ₂ at this time are the same.

On the other hand, reference numeral 2 indicates the winding state on the stator side. The stator side 2 has two stator cores (not shown) facing the rotor core of the rotor side 1, and the stator main windings 7 and 8 are provided on the respective stator cores. It is wound and connected to a three-phase power source R, S, T via an open / close switch S ₀ . Further, on the stator side 2, auxiliary windings 9 and 10 are wound around each stator core. This auxiliary winding is DC power supply E
And the open / close switch S ₁ are connected in series to form the auxiliary circuit 11.

The number of poles of each winding configured as described above may be the same, and two types of windings having different numbers of poles are used for manufacturing each of the stator side 2 and the rotor side 1. It is not necessary to have the structure as in the case where it is provided, and the structure can be simple. By the way, the present invention is not limited to the present embodiment such as the connection of the stator main windings 7 and 8 to the three-phase power sources R, S and T and the form of the connection of the three-phase windings, and a star or delta Alternatively, either serial or parallel may be selected.

The operation of the synchronous motor having the above configuration will be described from start to operation. First, the open / close switch S ₁ of the auxiliary circuit 11 is opened, the open / close switch S ₀ is closed, and three-phase power is applied to the two sets of stator main windings 7 and 8.
When this three-phase power source R, S, T is applied, a rotating magnetic field similar to that of a general induction motor is generated in the two sets of stator main windings 7 and 8. A rotating magnetic field generated by the two sets of stator main windings 7 and 8 induces an in-phase voltage e ₁ in the first rotor windings 3 and 4 of the two sets of rotor cores to rotate them in series. The current circulating in the sub windings 3 and 4 comes to flow. This means that the induction motor is started based on the principle of the induction motor, which is a self-starting synchronous motor that does not require any other starter.

At this time, since the circulating current flowing through the first rotor windings 3 and 4 is a short-circuit current, the voltage between the series connection points where the two rotor windings 3 and 4 are connected to each other is It is zero. Therefore, the terminal voltage of the second rotor windings 5 and 6 also becomes zero, and the diode D connected between the terminals is
_A current hardly flows through ₁ and D ₂ .
That is, the diodes D ₁ , D _{2 of} the second rotor windings 5, 6
Since the rectification current due to does not flow, a DC magnetic flux is not generated. This does not form a magnetic pole on the rotor even when the rotor winding including the diode is provided on the rotor at the time of starting, and does not affect the starting on the principle of the induction machine.

Next, the synchronous operation will be described. After starting by the principle of the induction machine, the rotation of the rotor rises, and when the rotor slip S approaches S = 0.05, the stator auxiliary circuit 11
The open / close switch S ₁ is closed to connect the DC power source E to the auxiliary winding 9,
The voltage was applied to 10. Now, at this time, the auxiliary winding 9,
10 has a voltage e due to the rotating magnetic field of the stator main windings 7 and 8.
_{Although 0} is induced, the auxiliary windings 9 and 10 are connected in series, and no current flows even if the open / close switch S ₁ is closed.
This is the voltage e ₀ induced by the stator main windings 7, 8.
Is because the auxiliary circuits 11 have mutually opposite directions, and the sum of the voltages e ₀ is zero. Therefore, the auxiliary circuit 1
No AC current flows through the DC power supply 1, and the DC current I from the DC power supply E
Only the auxiliary windings 9 and 10 will flow. The direct current I causes the auxiliary windings 9 and 10 to generate a static magnetic field. This static magnetic field is in the opposite directions in the two sets of auxiliary windings 9 and 10 because the direct current I flows so as to circulate in the auxiliary circuit 11.

The static magnetic fields in the opposite directions are applied to the rotor side 1
The voltages e ₂ and e ₃ are induced in the first rotor windings 3 and 4 and the second rotor windings 5 and 6, respectively. Here, looking at the voltage e ₂ induced in the first rotor winding 3 and 4, since it is induced reverse voltage e ₂ from each other by a reverse stationary magnetic field, the first rotor winding The sum of the voltages e ₂ induced in 3 and 4 becomes zero, and no current flows.

On the other hand, since the second rotor windings 5 and 6 have an independent structure, the voltage e ₃ induced by the static magnetic field of the auxiliary windings 9 and 10 causes the second rotor windings 5 and 6 to move. A rectified current flows through the diodes D ₁ and D ₂ connected to the terminals, respectively. The rectified direct current component forms magnetic poles in the two rotor core portions.

Since the direction of the magnetic pole is determined by the polarity of the diode, if the polarities of the diodes D ₁ and D ₂ are the same, the polarities of the magnetic poles generated in the rotor core will be the same in the two cores. Torque in the same direction is generated between the two stator main windings 7 and 8 and the two rotating magnetic fields having the same phase. That is, the synchronous torques generated between the two sets of stators and the two sets of rotor cores are added, and the output becomes the combined torque of the two synchronous motors.

By the way, an automatic means for the synchronous pull-in can be freely selected, for example, by connecting the open / close switch S ₁ and the speed detector of the electric motor through a control device.

[0030]

As described above, the synchronous motor of the present invention has the following structure.
Performs starting with the same torque characteristics as the conventional induction motor,
For example, the speed of the rotor shifts from the vicinity of slip S = 0.05 to the synchronous speed and the rotor is operated with the torque characteristics of the synchronous motor. Since this synchronous motor does not require a starter or brush, it not only has a simple structure and configuration, but it can be started with the same torque characteristics as conventional induction motors, so even if a heavy load is applied, it will be possible to change from start to synchronization. Can be migrated. Further, the shift from the start to the synchronization is also possible by a simple operation of closing the open / close switch S ₁ so that a direct current is passed through the auxiliary winding of the stator.

By the way, the synchronous motor of the present invention has the torque characteristics of both the induction motor and the synchronous motor.
The torque characteristics of either motor can be used. This means that even if a step out occurs for some reason during operation at synchronous speed, it is possible to operate by switching from the torque characteristics of the synchronous motor to the torque characteristics of the induction motor. Never stop.

As described above, since there is no brush and a complicated structure is not required, it is possible to provide a synchronous motor that is easy to maintain and has high reliability and has a large starting torque.

[Brief description of drawings]

FIG. 1 is a diagram showing only a winding portion of a stator and a rotor of a synchronous motor according to the present invention.

Claims (2)

[Claims] 1. A rotor having two rotor cores provided on the same rotary shaft at arbitrary intervals, and a first three-phase rotor winding being provided on each of the two rotor cores. And a rotor in which a second three-phase rotor winding is provided on each of the two rotor cores and a diode is connected between terminals of the rotor winding, A stator having two stator cores provided around the rotor core, the stator main winding being wound around each of the two stator cores and connected to a three-phase power source. A synchronous motor comprising an auxiliary circuit in which each of the two stators is provided with an auxiliary winding, and the auxiliary winding is connected in series to a DC power source through an open / close switch. 2. The synchronous motor according to claim 1, wherein the stator main winding, the auxiliary winding, and the first and second rotor windings have the same number of poles. Synchronous motor.