JPH03212142A - Two-stator induction motor - Google Patents

Abstract

PURPOSE:To continuously set a torque by wiring two stator windings of a phase shifter in series delta-connection, and coupling windings connected inphase to the windings of other phase through a variable resistor. CONSTITUTION:In order to continuously obtain intermediate characteristic of two torque characteristics, windings 10, 11 respectively wound on stators 12, 13 and connected inphase are coupled to the windings of other phase through variable resistors RA-RC. With the structure, when a power source is energized, the phase of stators is started by a serial delta winding of arbitrary phase difference A load is started by a torque curve of an arbitrary phase difference. Then, when the windings are short-circuited therebetween by setting the resistance value of the variable resistor to zero at an arbitrary rotating speed to a parallel star-connection, the phase difference is reduced, and torque characteristic and current characteristic are varied. Thus, it can be operated with a high torque and a low current at the time of driving, and operated up to the operation after driving by an arbitrary torque and current.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a single rotor and two stators, and has a rotating magnetic field generated in rotor conductors facing the two stators. The present invention relates to a two-stator induction motor that is capable of variable speed, smooth startup, and high torque from low speed to high speed by creating a phase difference between the two stators.

[Conventional technology]

For torque control and speed control of an induction motor having a plurality of stators, there is a known method of changing the phase difference between the stators.
No. 128314 is also an example. Methods for changing this phase difference include mechanical methods that create a phase difference by rotating the stator, and electrical methods that create several types of phase differences by changing the connections of the stator windings. There are a wide variety of types, including those that combine these with star-delta switching.

The above methods can be used in various ways depending on the load or application, such as when responding to the load by freely changing the torque and speed of the induction motor, and when smoothly increasing the speed at startup. Become.

[Problem to be solved by the invention]

The present invention deals with the load by providing a phase difference,
It can be said to be an electrical method if it is distinguished based on the above-mentioned conventional technology.

Now, the electrical phase shift method in the prior art is performed by switching the connections of the stator windings, and the phase difference is 0° and 60° in electrical angle.
120° and 180° are possible, but the switch required for switching is over ten sides and is expensive.

Furthermore, some general induction motors are equipped with a star-delta switching device for the purpose of improving starting performance. Although the stator is a single stator, the wiring is complicated, and torque fluctuations occur due to temporary disconnection of the load current during star-delta switching, and furthermore, the load current suddenly changes after switching. Shocks due to the increase and rapid fluctuations in generated torque were inevitable.

The present invention has torque characteristics equivalent to those at each phase difference when the above-mentioned wiring connections are switched, and is also capable of variable speed steplessly, without disconnection of load current during control, and without rapid increase in load current or rapid load torque. The present invention aims to provide an inexpensive two-stator induction motor with little fluctuation.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a rotor in which each of a plurality of conductors attached to two rotor cores provided on the same rotating shaft are connected in a continuous manner, and Two stators are placed facing each other, and one of the two stators generates a rotating magnetic field around the rotor, and the other stator faces the rotating magnetic field. In a two-stator induction motor, the two-stator induction motor has a phase shift device that generates a phase difference between the two stator windings and a rotating magnetic field generated around the stator windings, and the phase shift device connects the two stator windings in a series delta connection;
In addition, the windings of the plurality of stators connected in the same phase and the windings of the other phases were connected via a variable resistor or a variable resistor and an on/off switch.

Further, a means for solving the problem is provided in this phase shift device with a control device that controls the variable resistor or the variable resistor and the open/close switch using a signal from the speed detector.

[For production]

The stator winding of the present invention has a series delta connection. At this time, the phase difference between the stators is 180°, ■20°, 60°
, 0° are possible. Now, if we create a circuit with a series delta connection with a phase difference of 60 degrees, and short-circuit between the stator windings connected in the same phase and between the windings of the other phase, , the phase difference will be switched to 0° in parallel star connection. Therefore, at start-up, a series delta connection is established with an arbitrary phase difference, and when a short circuit occurs, the connection is switched to a parallel star connection with a different phase difference. In other words, if you switch directly from series delta connection to parallel star connection, the phase difference between them will change from 180° to 120' 120°
It can be switched from 60° to 0° and from 600° to 0°.

The above can be summarized as follows. First, when the power is turned on, the phase difference between the stators starts with the series delta connection of the arbitrary phase difference. The load is activated by a torque characteristic curve with an arbitrary phase difference. Next, when an arbitrary rotation speed is reached and the windings are short-circuited to form a parallel star connection, the phase difference decreases by 60 degrees, and the torque characteristics and current characteristics change.

In the present invention, in order to steplessly obtain an intermediate characteristic between the two torque characteristics, the windings of the two stators connected in the same phase and the windings of the other phase are Since it is connected via a variable resistor or a variable resistor and an on/off switch, it can be operated with high torque and low current at startup, and can be operated steplessly at any torque and current until operation after startup, and speed changes are also possible. It is possible.

〔Example〕

Although the present invention will mainly be described in detail as a two-stator induction motor having a squirrel-cage rotor, it goes without saying that the present invention is not limited thereto. There is also a two-stator induction motor with a wound rotor, which can also be used as a linear motor.

In addition, the torque characteristics may be further diversified by switching between star connection and delta connection of the stator windings, and the configuration between the rotor cores is also spaced.

Non-magnetic materials, magnetic materials, etc. may be used.

The present applicant has already given a detailed explanation of the structure and operation of an induction motor comprising a plurality of stators, which is a part of the structure of the present invention, in Japanese Patent Application No. 128314/1982.

An embodiment of an electric motor forming a part of the structure of the present invention will be explained with reference to FIG. Reference numeral 1 denotes a two-stator induction motor according to the present invention, and the induction motor 1 has the following configuration. Rotor cores 2.3 made of magnetic material are mounted on the rotor shaft 4 at arbitrary intervals. A non-magnetic core 5 is interposed between the rotor cores 2 and 3, or a space is provided between the rotor cores 2 and 3.

A plurality of conductors 6 installed in the rotor cores 2 and 3 are connected to each other in communication with the rotor cores 2 and 3 to form an integral rotor 7, and a plurality of conductors 6 are connected in series. Conductor 6・
Both ends of . . . are short-circuited by short-circuit rings 8, 8. Also,
In this embodiment, each conductor 6 installed on the rotor 7 is a resistive material for passing a current of an arbitrary vector difference in the non-magnetic core 5 between the rotor cores 2 and 3. It is connected via 9.

A first stator 12 and a second stator 13, each having a winding 10.11 on the outer side facing the rotor cores 2 and 3, are arranged side by side in a machine frame 14, and the first stator 12 and the second stator 13 is fixed to the machine frame 14.

In addition, the windings 10.1 of the first stator 12 and the second stator 13
As an example, the connection form No. 1 is a series delta connection with an electrical phase difference of 60°.

Next, a first embodiment of the present invention will be described with reference to FIG. 2 and subsequent figures.

What is shown in FIG. 2 is a wiring diagram of the present invention.

One terminal (Ul.

■7. W,) to the power source A via the power switchgear S.

B, C and the other terminal (x, , y
+, Z+) to one terminal (Y2,
Z2, X2) D, and the other terminal (V2, W2, Y2) of the stator winding 10 is
1. W+, Ut) are connected to the power supply in series delta connection. Also, the variable resistor RA is between xl and 22,
Between Rs HaX and X2, Rc! Connect between iZ and 22.

The operation of the above configuration will be explained. First, when the power switch S is closed when the resistance value of the variable resistor is infinite, the stator winding 10 and the stator winding 10 become series delta connections having an electrical phase difference of 60°. This can be expressed as shown in FIG. Further detailed in FIG. 4, the shared voltage E1 of the coils U, ~X1 of the stator winding 11 and the shared voltage El of the corresponding coils U2 ~ X2 of the winding 10 have an electrical phase difference of 60°. It is wired so that it has. Further, the shared voltage of each coil at this time is 172 of the power supply voltage Eab. The same applies to other phases.

Next, when the variable resistance is set to zero and the state is completely conductive, the phase difference between coils U1 to X and coils U2 to X2 becomes θ°, and ■1 to Y, v2 to Y2, and W, ~z1 and W2.
~z2 also has a phase difference of O0. Then, the wiring is connected as shown in FIG.

If E 1 is the voltage shared by the coils U, ~X, and E mb is the line voltage of the power supply, then the magnitude of El is 2713 = 1.15 times that of the series delta connection.

As described above, by varying the resistance value of the variable resistor, it is possible to provide a phase difference for starting and a phase difference for operation, and furthermore, it is possible to obtain the characteristics of the intermediate step of the side phase difference steplessly. Each torque characteristic at this time is shown in FIG. Figure 6 shows variable resistance RA.

The intermediate torque characteristic when the resistance values of RB and RC are changed from the high resistance value R7 to the low resistance value R4 is shown, and is an example of the torque characteristic at each resistance value.

Actually, since the resistance value is gradually changed from R1 to R4, the torque characteristic is also gradually changed from R1 to R4.

What is shown in FIG. 7 shows the current value for each torque characteristic in FIG.
~R4 indicates the current value of the variable resistor. From this figure, it is clear that the starting current is small and the current flowing through the variable resistor that becomes the phase shifter is even smaller than the load current. Unlike the conventional technology, the circuit through which the load current flows is not directly opened and closed, so the electric capacity of the phase shifter is It is small, so the device can also be made smaller.

Also, when the phase difference is 0°, the other side of the stator winding 11 (X+
, Y+, Zl) and one of the stator windings 10 (X2,
The phases with Y2, Z2) are in a short-circuited state, and even if a short-circuit occurs due to a failure of the variable resistor, an electrical accident such as burnout of the motor will not occur.

Furthermore, since the control of the variable resistor uses series delta connection to short circuit between lines during operation, the load current is not temporarily cut off due to switching, and the voltage between the poles is 1/2 of the power supply voltage. Because of this, it is possible to use a variable resistor with a small electrical capacity, and the phase shift device using the variable resistor can be downsized.

By the way, if a phase shifter consisting of a variable resistor is installed on the motor side as shown in Figure 2, only three wires are needed from the power supply side to the motor, which eliminates the complexity of star-delta starting found in general large motors. It is possible to create an electric motor that can be operated at high torque from low speed to high speed without requiring extensive wiring.

Next, a second embodiment of the present invention will be described with reference to FIG.

Although what is shown in FIG. 8 is a wiring diagram, only the parts different from the first embodiment will be explained, and the same parts will be omitted. The difference from the first embodiment is that the variable resistors (RA, Ra,
The point is that opening/closing switches (switches SL+S2, S3) are provided in series with Rc). In this case, the open/close switch may be provided in series or in parallel with the variable resistor.

The operation of the above configuration will be explained. The variable resistor of this embodiment is the same as that of the first embodiment, but the on/off switch Sl
l S2. Providing S3 works as follows. When an open/close switch is provided in series with a variable resistor, the variable resistor acts only when the open/close switch is closed. It is possible to instantly switch between parallel star connection operation and series delta connection operation, and after gradually accelerating by changing the variable resistance at startup, two-step speed control or Torque control becomes possible.

Furthermore, if an open/close switch is provided in parallel to the variable resistor, the variable resistor acts only when the open/close switch is open.

Next, control of the phase shift device will be explained with reference to FIG. First, in the configuration shown in FIG. 9, the induction motor 1 is connected to a three-phase power supply 22 equipped with a switching device. Further, the induction motor is integrally provided with a phase shift device 20, and a control device 21 composed of a hard logic circuit or the like is connected to the phase shift device. This is to connect the signal of the speed detector 23.

The control device may be a simple logic circuit or may include a microprocessor if desired.

Furthermore, a circuit receives the signal from the detector 23 and converts the signal as necessary, a circuit compares the converted signal with a pre-input setting value, and a circuit stores the pre-input setting value. The device is equipped with a signal output circuit, etc., which outputs a signal based on the above comparison. The phase difference of the phase shifter 20 is changed by the signal from this signal output circuit. Further, although the speed detector 23 is used as the detector here, it may be any means that detects the rotational state of the electric motor, such as one that detects the number of rotations.

With the phase switching control by the above-mentioned control device, the torque characteristic becomes as shown in FIG. 6, and compared to the conventional star-delta switching, the torque fluctuation is small and it is possible to suppress the starting current to a small value.

The set values input to the control device 21 are the load torque, GD2, and the desired operating rotation speed determined by the output of the electric motor.

In addition, as shown in Figure 10, the phase difference is set to 000 with series delta connection.
When the windings of each phase are short-circuited, the phase difference becomes 60° as shown in FIG. If the wiring is connected in this way, it will start with a parallel star connection with a phase difference of 60' as shown in Fig. 11, and the
The present invention can also be implemented by shifting to a series delta connection with a phase difference of 0° as shown in the figure. If you desire another phase difference, you can mechanically rotate and fix one stator with respect to the other. For example, in the case of 4 poles, the mechanical angle can be rotated by 10 degrees. If they are shifted, a phase difference of 20° in electrical angle will occur.

〔effect〕

As mentioned above, the torque setting of a two-stator induction motor can be set steplessly using a simple phase shift device, and these torque characteristics are such that at startup, the starting current is small and the starting torque is large, constant torque characteristics and square This is a variable speed electric motor that achieves improved startability due to reduced torque characteristics and reduced start-up time, and does not require expensive control devices such as inverters. In addition, for wiring to the motor, if a simply formed phase shift device is integrated with the motor and a three-phase power source is used, the motor only requires three wires and anyone can wire the motor.

Therefore, by diversifying the torque, the two-stator induction motor, which can generate high torque from low speed to constant rotation range, will be able to expand its applications and contribute even more to all fields that require high-torque motors. became.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a two-stator induction motor, Fig. 2 is a wiring diagram of a phase shifter, Fig. 3 is a wiring diagram using a different display method from Fig. 2, and Fig. 4 is a series connection diagram with a phase difference of 60°. A delta connection diagram, FIG. 5 is a phase difference QO1 parallel star connection diagram, and FIG. 6 is a diagram showing an example of an intermediate torque characteristic curve at each resistance value of a variable resistor.
Fig. 7 is a characteristic curve diagram of load current and short circuit current at each resistance value of the variable resistor, Fig. 8 is a wiring diagram showing another embodiment of the phase shift device, Fig. 9 is a control block diagram using a logic circuit,
FIG. 10 is a series delta connection diagram of another embodiment, and FIG. 11 is a parallel star connection diagram with a phase difference of 6 G' when the windings of FIG. 10 are short-circuited. DESCRIPTION OF SYMBOLS 1...Multiple stator induction motor, 2.3...Rotor core, 4...Rotor shaft, 5...Nonmagnetic core, 6...
・Rotor conductor, 7... Rotor, 8... Short circuit ring, 9.
...Resistance material, 10.11...Stator winding, 12...
1st stator, 13...2nd stator, 14...machine frame,
20... Phase shift device, 21... Control device, 22...
Supply power side, 23...speed detector.

Claims (3)

[Claims] (1) A rotor in which a plurality of conductors attached to two rotor cores provided on the same rotating shaft are connected in a continuous manner, and two rotors are provided around each of the rotor cores facing each other. A rotating magnetic field generated around a rotor with which one of the two stators faces the stator, and a rotating magnetic field generated around the rotor with the other stator facing it. In a two-stator induction motor, the phase shifter has two stator windings in series delta connection, and the two stator windings connected in phase. A two-stator induction motor characterized in that the windings of a stator and the windings of other phases are connected via variable resistances. (2) A rotor in which a plurality of conductors attached to two rotor cores provided on the same rotating shaft are connected in a continuous manner, and two rotors are provided around each of the rotor cores facing each other. A rotating magnetic field generated around a rotor with which one of the two stators faces the stator, and a rotating magnetic field generated around the rotor with the other stator facing it. In a two-stator induction motor, the phase shifter has two stator windings in series delta connection, and the two stator windings connected in phase. A two-stator induction motor characterized in that the windings of a stator and the windings of other phases are connected via a variable resistor and an on/off switch. (3) The two-stator induction motor according to claim (1) or (2), wherein the two-stator induction motor is provided with a speed detector, and the variable resistance of the phase shift device is adjusted according to the signal from the speed detector. A two-stator induction motor characterized by being provided with a control device that controls a variable resistor and an open/close switch.