JPH0834712B2 - Variable speed induction motor - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an induction motor capable of continuously performing speed control over a wide range.

[Prior art and its problems]

In the related art, as a method of controlling the speed of the induction motor, there is a method of changing the power supply frequency. This method is capable of continuous and wide-range speed control, on the other hand, the frequency converter required by this method is expensive, and in the process of converting alternating current into direct current and converting it into alternating current again by the frequency converting device, Generally, harmonics and radio waves are generated, which may cause malfunction such as malfunction of computers and other electric control devices or overheating of capacitors. Among them, measures against harmonic interference can be taken by installing a filter, but installation of the filter is costly. It also has a drawback that performance is generally insufficient at low speeds. Also, the method of controlling the speed by changing the number of poles of the motor is
Although the speed can be changed stepwise by changing the number of poles, there is a drawback that smooth speed control cannot be performed steplessly. Also, in the method of controlling the speed by changing the voltage of the power supply,
Although the speed control can be performed continuously, there is a drawback that the efficiency becomes poor especially in the low speed region. The method of controlling the speed by changing the secondary resistance by changing the secondary resistance in the wire-wound electric motor enables continuous speed control relatively easily, but on the other hand, the rotor is externally connected via a brush and a slip ring. The insertion of the resistance into the winding circuit requires maintenance and inspection due to wear of the brush, and the squirrel-cage induction motor has the drawback that the secondary resistance cannot be changed to control the speed.

[Object of the invention]

An object of the present invention is to improve the above-mentioned drawbacks of the prior art, to provide an induction motor which has a wide speed control range and can continuously perform the speed control, and has good torque characteristics especially in a low speed range.

[Means for solving problems]

In order to solve the above problems, there are two rotor cores axially attached to the same rotary shaft with a space or a non-magnetic core interposed, and a plurality of conductors communicating with the two rotor cores. An integral rotor, and two stator cores, each having two stator cores provided around its outer periphery facing the two rotor cores, and each having a winding wound around it. At least one of the two stators and a resistance material serving as a connecting material for short-circuiting the plurality of conductors in the space or the non-magnetic core portion provided between the two rotor cores; A stator rotating device for changing the phase shift between the rotating magnetic fields of the two stators by arranging the stator concentrically and rotatably with the rotor; and the two stator windings. Switch to delta connection or star connection for the power supply, and at the same time connect one of the two stator windings. By means of a variable speed induction motor consisting of a change-over switch control device for switching the polarity to the opposite polarity to that of the other and a control device for setting an arbitrary control value for controlling the operation of each device, means for solving the above problems, did. Further, the torque characteristic when the phase shift is 180 ° due to the delta connection and the torque characteristic when the phase shift is 0 ° (in phase) due to the star connection are matched so that the above-mentioned means operates more effectively. I decided to do it.

[Work]

With the above structure, when two stators fixed to the machine frame are energized, a rotating magnetic field is generated, a voltage is induced in the rotor, a current flows through a conductor mounted on the rotor, and the rotor rotates.
When the rotation of the stator on the rotation side relative to the stator fixed to the machine frame is set to zero, there is no phase shift between the rotating magnetic fields of both stators, and there is a space between the rotor cores or a non-magnetic material. No current flows in the resistance material that forms a connecting material with the conductor short-circuited in the core part, and shows the same torque characteristics as a general induction motor. However, when the rotating side stator is rotated, the rotating side stator The rotational speed changes in accordance with the phase shift of the rotating magnetic field generated between the rotating magnetic field and the rotating magnetic field of the stator fixed to the machine frame. When the amount of rotation of the rotating stator is increased, the voltage induced in the rotor conductor facing the stator fixed to the machine frame due to the phase shift between the rotating magnetic fields of the stator, There is a phase shift with the voltage induced in the rotor conductor facing the stator on the moving side, and due to this phase shift, a short-circuit current flows through each of the multiple conductors through the resistance material. By flowing this short-circuited current, the power factor and torque in the low speed region can be improved.
Further, when the phase shift of both stators reaches 180 °, speed control becomes a limit. In the present invention, at this point in time, the connection of the windings wound around both the stators is switched from the delta connection having a high sharing voltage to the star connection having a low sharing voltage and the connection polarity of one winding is switched by operating the switch. In addition, the stator on the rotating side is rotated to change the phase shift of the voltage. Thus, in the present invention, the shift control in the lower speed region can be performed, and not only the phase shift between the rotating magnetic fields of the stator is changed from 0 ° to 180 °, but also the winding of the stator is changed. Since the connection of the stator is changed so as to change the shared voltage applied to and the phase shift is changed, the speed control region can be expanded in a wide range.

【Example】

An embodiment of the present invention will be described with reference to FIGS. Reference numeral 1 shown in FIGS. 1 and 2 is an induction motor, and the induction motor 1 is configured as follows. The rotor cores 2 and 3 made of an iron core are mounted on the rotor shaft 4 at an arbitrary interval, and a non-magnetic core 9 is interposed between the rotor cores 2 and 3. A plurality of conductors 5 installed in communication with the rotor cores 2 and 3 are connected in series to each other to form an integral rotor 8.
Are formed, and both ends of the plurality of conductors 5 connected in series are connected to the short-circuit rings 6 and 7. The rotor cores 2, 3, 9 are connected to both side portions 10, 11 of the rotor 8 by a plurality of ventilation drums 12 ...
Are provided, and a plurality of ventilation holes 13 are formed so as to penetrate the outer peripheral portion of the rotor 8 orthogonally from the ventilation cylinder 12. As shown in FIG. 3, the rotor 8 has a non-magnetic core 9 between the rotor cores 2 and 3.
In the section, a plurality of conductors 5 ... Are short-circuited via a resistance material r ... such as a nichrome wire or carbon mixed steel as a connecting material that conducts electricity when an arbitrary voltage is applied to each other. Also a cylindrical machine frame
Bearing plates 15 and 16 provided on both sides of 14 are connected to connecting rod 17 ... Nut 1
8 ... Fasten and assemble as a unit, install cooling impellers 19 and 20 on both sides of the rotor 8, and attach both ends of the rotor shaft 4 to the bearing plate 15,
The rotor 4 is rotatably supported by the bearings 21, 21 fitted in the shaft 16. The first stator 24 and the second stator 25 having the windings 22 and 23 provided on the outer peripheral portion facing the rotor cores 2 and 3 are arranged, and the machine frame 14 and the first stator 24 and the second stator are arranged. A slide bearing 26 and a bearing 27 are installed between the slide bearing 26 and the bearing 25, and the slide bearing 26 and the bearing 27 are fixed by stop rings 28 to 31 fitted in the machine frame 14. The movement preventing ring 32 is fitted, and the second stator 25 is fixed to the machine frame 14 by bolts 34 screwed to the machine frame 14. A gear 33 is fitted on one outer peripheral surface of the first stator 24, and a worm gear 36 is attached to a pulse motor 35 fixedly mounted on the outer peripheral portion of the machine frame 14.
The worm gear 36 is inserted through the opening 37 of the machine frame 14 and engaged with the gear 33 so that the first stator 24 is concentrically rotatable with respect to the rotor 8 and the stator is rotated. Form on the device. 38 is a cover provided in the opening 37, 39 is an exhaust hole, and 40 is a plurality of ventilation holes formed in the bearing disks 15 and 16. Next, the windings wound around the first and second stators 24 and 25 and their connections will be described with reference to FIG. The switches S _{1 to} S ₇ are connected to the respective terminal portions of the winding wire 22 wound around the first stator 24, and the switches S _{1 to} S ₇ are connected to the respective terminal portions of the winding wire 23 wound around the second stator 25. _{8 to} S ₁₁ are connected, and the connection of windings 22 and 23 can be switched by switch S _{1 to} S ₁₁ to either delta connection with high winding sharing voltage or star connection with low winding sharing voltage. , Windings 22 and 23 have switches S _{1 to} S ₁₁ respectively.
It is connected to commercial three-phase power supplies A, B, and C via. By the way, when switching to a star connection in which the sharing voltage of the winding is low, the polarity of the winding 22 of the first stator 24 is opposite to the polarity of the winding 23 of the second stator 25. A switch is provided. The operation of the above configuration will be described below. Switch S _{1 to} connect the windings 22 and 23 of the first and second stators 24 and 25.
〜S ₃ , S ₈ 〜 S ₁₀ is turned on, switches S ₄ 〜 S ₇ 、 S ₁₁ are opened to make delta connection, and windings 22 and 23 are energized.
A rotating magnetic field is generated in the rotor 8, a voltage is induced in the rotor 8, a current flows through the conductors 5 of the rotor 8, and the rotor 8 rotates. Second
When the amount of rotation of the first stator 24 with respect to the stator 25 is set to zero, there is no phase difference between the rotating magnetic fields input to the windings 22 and 23 of the respective stators 24 and 25, and details thereof will be described later. As described above, since no current flows through the resistance material r ... As the coupling material, it has the same torque characteristics as a general induction motor. Next, the phase of the rotating magnetic field of the first stator 24 is rotated by θ in terms of an electrical angle with respect to the phase of the rotating magnetic field of the second stator 25 (shift).
The case will be described. First stator 24 and second stator
The phases of the magnetic fluxes φ ₁ and φ ₂ of the rotating magnetic field created by 25 are shifted by θ in electrical angle. Therefore, the voltage ₁ induced in the conductor 5 of the rotor 8 by the first stator 24 and the second stator 25 is ₁ , ₂ are also shifted by θ in electrical angle. Now, based on the voltage ₂ induced on the conductors 5 of the rotor 8 by the second stator 25, the voltage is set to ₂ = SE. Here, S is the slip and E is the induced voltage at slip 1. At this time, the first stator 24
The voltage ₁ induced in the conductor 5A by ₁ is ₁ = SEε
^jθ . (E = Induced voltage when slip 1) FIG. 5 shows the rotor 8 in the case where the resistance material r ... Short-circuiting the plurality of conductors 5 ... Is not mounted in the non-magnetic core 9. The relationship between the slip S and the active power P input to the rotor is shown. The active power P is maximum when θ = 0 °, and is smaller when 0 ° <θ <180 °. Here, assuming that the resistance and the inductance of the conductors 5 are R and L and the angular frequency of the power source is ω, the maximum of the active power P appears when S = (R / ωL). Since the effective power P is proportional to the drive torque of the induction motor 1, the speed can be continuously controlled by rotating the first stator 24. Next, the respective resistances from the short-circuit rings 6 and 7 of the conductors 5 of the rotor 8 to the connecting member are R ₁ and R ₂ , and the inductance is L ₁ and
Assuming that L ₂ is the angular frequency of the power supply, and r is the resistance of the resistance material that short-circuits each of the conductors 5, ..., The electrical equivalent circuit of the rotor 8 is as shown in FIG. ₁ , I ₂ and I ₃ represent currents flowing through the respective branch paths. Next, converting the one shown in FIG. 6 into an equivalent circuit viewed from both stators 24 and 25, it becomes as shown in FIG. 7, where R ₁ = R ₂ , L ₁
= L ₂ and electrical angle θ = 0 °, I ₃ = I ₁ −I ₂ = 0, and no current flows through the resistance material r. This means that the torque T is equal to the value without r when the electrical angle θ = 0 °. Therefore, when the electrical angle θ = 0 °, it has the same torque characteristics as the conventional induction motor. Next, when R ₁ = R ₂ and L ₁ = L ₂ , the phase shift is electrical angle θ and θ = 1
At 80 °, I ₁ = -I ₂ , I ₃ = I ₁ -I ₂ = 2I ₁ , and the resistance of the rotor conductor in the conventional induction motor is R ₁ = R ₂ = R
Then, the result is the same as that when R is increased to R + 2r. From the above results, the torque characteristics are from S = 1.0 to S =
As shown in FIG. 8 in the range of 0, when the first stator 24 is rotated to change the phase angle, the torque changes. If the reaction torque of the load connected to the rotor shaft 4 of the induction motor 1 is Tr shown in FIG. 8, the first stator 24 is rotated to shift the phase, that is, the electrical angle θ is θ. By changing from = 0 ° to θ = 180 °, the slip of the rotor 8 becomes S
It can be changed from ₁ to S ₂ , that is, the rotation speed of the rotor 8 can be changed. Further, by changing the set value of the resistance r, the speed range of the rotor 8 can be further expanded, and a large torque can be generated during low speed rotation. However, in the above state, the slip S is S =
In the range of S ₂ to S = 1.0, that is, the speed control in the hatched area in FIG. 8 is impossible. Therefore, when the reaction torque Tr of the load becomes smaller, the speed control range becomes narrower. In order to deal with the above phenomenon as when the reaction torque of the load becomes small, the switches S ₁ , S ₂ , S ₃ , S ₈ , S ₉ , S ₁₀ are opened and the switches S ₄ , S ₅ , S _6, S _7, by introducing the S ₁₁ windings 22 and 23
Switch the connection of to star connection. Further in this state, the polarity of the winding wire 22 of the first stator 24 is the winding wire of the second stator 25.
Since they are connected so as to be opposite to the polarity of 23, the phase of the exciting current flowing through the winding 22 of the first stator 24 is electrically different from the phase of the exciting current flowing through the winding 23 of the second stator 25. Θ = θ
It is supposed to be offset by 180 °. However, due to the rotation of the first stator 24 due to the delta connection before the switching, the phase shift was θ = 180 ° in electrical angle θ, so that when the star connection was switched to the first stator 24 as a result. The magnetic fluxes φ ₁ ′ and φ ₂ ′ at the magnetic velocity of the rotating magnetic field formed by the second stator 25 are in phase (the phase shift is 0 °). Below, electrical angle at delta connection θ
Based on, the phase shift is unified and expressed. Furthermore, since each of the windings 22 and 23 of the first and second stators 24 and 25 has a star connection with a low voltage sharing of the windings, the voltage applied to the windings 22 and 23 is delta connection. become. Therefore, the voltage induced in the conductors 5 of the rotor 8 by the magnetic fluxes φ ₁ ′, φ ₂ ′ is also Since the torque of the rotor 8 is proportional to the square of the voltage E, the voltage is Then, the torque becomes 1/3. Therefore, in FIG. 8, the torque when the electrical angle θ = 0 ° S = 1.0 in the delta connection is T _1, and θ = 180 °,
If the torque when S = 1.0 is T ₂ , the first and second stators 2
By changing the connection of the windings 22 and 23 of 4,25 to the star connection by the switches S _{1 to} S ₁₁ , the torque characteristics are as shown in FIG. 9, the torque at θ = 180 °, S = 1.0 T ₁ /
3, theta = 0 °, the speed uncontrollable region torque indicated by T _2/3, and the hatching in the case of S = 1.0 becomes very small.
Therefore, it designed to be T ₂ = T _1/3, first, second stator
The connection of the windings 22 and 23 of 24 and 25 is made a delta connection with a high voltage sharing of the windings by the switches S _{1 to} S ₁₁ , and the first stator 24 is rotated to cause a phase shift at an electrical angle θ of θ = After changing from 0 ° to 180 °, the connections of the windings 22 and 23 of both stators 24 and 25 are switched to star connection with a low sharing voltage by switches S _{1 to} S ₁₁ , and the first stator 24 is rotated. When the phase shift is changed from θ = 180 ° to 0 ° in electrical angle θ, wide-range speed control can be performed when the reaction torque Tr of the load is small or in response to a large change in Tr. A large torque can be secured in the low speed control region. Next, referring to FIGS. 10 and 11, the wire connection between the winding rotor and each of the windings will be described. Two rotor cores 41, 42 made of an iron core are mounted on the rotor shaft 4 so as to face the first stator 24 and the second stator 25,
The rotor cores 41 and 42 are provided with windings 43 and 44, and as shown in FIG. 11, a resistance material r is interposed in a circuit 45 which connects the windings 43 and 44 which are conductors in series. Short circuit between each winding,
In order to prevent the windings 43, 44, the resistance material r ... from being shaken out by the centrifugal action caused by the rotation of the rotor 47, a non-magnetic material cover 46 is attached to the connecting portion 45 to form the integral rotor 47. is there. The rotor cores 41, 42 are provided with a plurality of ventilation cylinders 48 ..., 49 ... Penetrating at both ends thereof, and a plurality of air exhaust holes 50. There is. The configuration other than the above is the same as that of the embodiment shown in FIGS. 1 to 3, and the connecting material for short-circuiting the circuits 45 of the windings 43 and 44 is the resistance material r ... Since they are the same, detailed description thereof will be omitted. In the description of each of the above-mentioned embodiments, only the first stator 24 is described as rotating, but the second stator 25 may be replaced by a second stator 25 instead of the second stator 24. The same action can be obtained, and rotatably forming the stator can be freely selected according to the capacity and purpose of the electric motor. Although the operation has been described by limiting the capacities of the first stator 24 and the second stator 25 to be the same, the capacity of any one of the stators may be increased. Further, it is needless to say that the star winding or the delta connection can be selected as the winding applied to the rotor core. Next, the automatic control of the induction motor will be described with reference to FIGS. 1, 2, and 12. The switches S _{1 to} S _{11 in} which the terminals of the windings 22 and 23 formed on the first stator 24 and the second stator 25 of the induction motor 1 are extended and connected from inside the machine frame 14 are related to the changeover switch control device 51. And the windings 22 and 23 are connected via the transfer switch control device 51.
It is connected to the phase commercial power supplies A, B, and C. Control value setting panel 52 for setting the speed of the induction motor 1 corresponding to the rotation speed of the load
A pulse motor for controlling the rotation of the first stator 24 and the speed detector 54 such as a tachogenerator mounted on the rotor shaft 4 of the electric motor 1 Detects the temperature inside the machine casing 14, a stator rotating device composed of 35 etc., a change-over switch control device 51, an electric motor 55 that drives a blower 57 in which a blower pipe communicates with the ventilation port 40 of the bearing panel 16, Each of the temperature detectors 56 is connected to a controller 53. With the above configuration, the speed control value of the electric motor 1, the pulse control value of the pulse motor 35 with respect to each rotation angle for rotating the first stator 24, and the switches S _{1 to} S ₁₁ for switching to either delta connection or star connection. The rotation speed reference value for activating is input to the control device 53 from the control value setting panel 52. The output signal from the control device 53 is sent to the changeover switch control device 51 to start the electric motor 1 and the switches S _{1 to} S ₁₁ are appropriately operated according to the desired rotation speed of the load to perform either delta connection or star connection. When the rotation speed of the rotor 8 is different from the input speed control value in the control device 53 that communicates the detected value by detecting the speed of the rotor 4 by the speed detector 54, The rotation angle by the first stator 24 is calculated so as to be the speed control value, the number of operating pulses of the pulse motor 35 is calculated, and the calculated value is operated by the pulse motor 35 by the output signal of the control device 53. The first stator 24 is rotated to control it at a desired rotation speed.
Then, a signal for controlling the rotation speed of the load is sent to the control value setting panel 52.
There is also a case where it is automatically input via the motor. In this case, the rotation speed control value of the electric motor 1 is automatically controlled to the desired rotation speed by the operation of the pulse motor 35 without the speed detector 54, and unmanned operation is performed. Thus, the electric motor 1 can be used efficiently. Further, the temperature detector 56 detects that the temperature in the machine casing 14 has risen above the temperature value set in the control device 53, and activates the electric motor 55 by an output signal that notifies the control device 53 of the detected value, The stator, rotor, conductors, resistance materials, etc. are cooled by the blowing action. An air cooling device may be connected to the blower 57, and the blower 54 may operate regardless of the temperature detector 56. Next, the operation as a generator will be described with reference to FIGS. 1 to 4 and 13. First, the first and second stators
24, 25 Connect the windings 22 and 23 respectively to the switches S _{1 to} S ₃ , S ₈
The to S ₁₀ were charged, in a case of the delta connection by opening the switch S ₄ ~S _7, S _11, the active component power P total entering the rotor 8 is as follows. 1 + cos θ ≧ 0, 1−cos θ ≧ 0 Therefore, when S becomes negative, the rotation speed of the rotor 8 becomes
When the rotational speed of the rotating magnetic field generated by the second stators 24 and 25 becomes higher than the synchronous speed, the following equation holds. P ≦ 0 Therefore, when the slip S becomes negative, the total effective power P entering the rotor 8 becomes negative. This means that when the rotation speed of the rotor 8 becomes higher than the synchronous speed, the induction motor can be used as an induction generator. Next, when it is illustrated as a range of S <0, the rotation angle θ of the first stator 24 is determined so that the output P of the generator is plotted on the vertical axis of FIG. 13 and the slip S is plotted on the horizontal axis. If changed, the power generation output P changes, and efficient power generation according to the slip S can be performed. Therefore, if an energy source such as a water turbine, a wind turbine, or a turbine is connected to the rotor shaft 4 and the rotor 8 is rotated at a rotation speed higher than the synchronous speed, it will function as an efficient induction generator. In addition, it is possible to generate synchronous AC power equal to the frequency of the power supply at any rotational speed higher than the synchronous speed. However, in this case, since the output in the hatched area shown in FIG. 13 cannot be output, in such a low output area, the windings 22 and 23 of the first and second stators 24 and 25 are connected by delta connection. Switch to star connection. That is, the switches S _{1 to} S ₃ and S _{8 to} S ₁₀ are opened,
When the switches S _{4 to} S ₇ , S ₁₁ are turned on and operated, it is possible to perform efficient power generation according to the slip S even at a low output. Next, the function as a brake will be described. S
When> 1, T> 0. This means that when the rotating direction of the rotor 8 is rotated in the opposite direction to the rotating direction of the rotating magnetic field created by the first and second stators 24 and 25, the induction motor 1 functions as a brake. That is, in FIG. 1, it is possible to act as a brake by connecting it to a drive device that requires braking instead of load, and braking is performed by rotating the first stator 24 and changing the phase angle θ. Can be adjusted efficiently. Further, the braking force can be efficiently adjusted in a wide range by changing the connection of the windings 22 and 23 of the first and second stators 24 and 25 to the delta connection or the star connection by operating the switches S _{1 to} S _11. You can

【The invention's effect】

As described above, according to the present invention, by rotating the stator on the rotating side with respect to the stator fixed to the machine frame to change the phase of the rotating magnetic field, the speed of the rotor can be arbitrarily set. The speed can be controlled. In addition, in the space of the rotor core or the non-magnetic core portion where each of the plurality of conductors mounted on each rotor core does not face the stator, a connection that energizes each of the plurality of conductors when an arbitrary voltage is applied. Short-circuited via a resistance material to be used as a material, and switch the windings wound on both stators to a delta connection with a high winding-sharing voltage or a star connection with a low winding-sharing voltage. Therefore, the amount of rotation of the rotating side stator is increased to greatly shift the phase of the rotating magnetic field to control in the low speed region, and the winding connection is switched to a star connection by a switch, and the stator is By rotating it, gear shifting can be controlled even in the low speed range. Further, according to the configuration of the present invention, the efficiency of the electric motor can be improved and a large torque can be obtained, and a remarkable effect can be obtained by using it as a power source that frequently repeats start, stop and shift control.

[Brief description of drawings]

1 to 13 are views showing an embodiment of the present invention. FIG. 1 is a side sectional view of an induction motor of the present invention, FIG. 2 is a side view showing a rotating mechanism of a stator, and FIG. Partially enlarged view of the rotor, Fig. 4 is a connection diagram of the windings wound on both stators, Fig. 5 is a diagram showing the relationship between the slip of the rotor and active power, and Fig. 6 is an electrical diagram of the rotor. Equivalent circuit diagram, FIG. 7 is an electrical equivalent circuit diagram seen from the side of the stator, and FIG. 8 is a diagram showing the relationship between speed and torque when a connecting material that short-circuits each of a plurality of conductors is a resistance material, FIG. 9 is a diagram showing the relationship between speed and torque when star-connected, and FIG. 10 is a partially enlarged view of a rotor of a winding type.
FIG. 11 is a diagram showing the connection of the windings in FIG. 10, FIG. 12 is a block diagram showing automatic control of the induction motor, and FIG. 13 is a diagram showing the relationship between power generation output and speed due to phase shift. . 1 ... Induction motor, 2,3 ... Rotor core, 4 ... Rotor shaft, 5 ... Conductor, 6,7 ... Short-circuit ring, 8 ... Rotor, 9 ...
… Non-magnetic core, 10,11 …… Side part, 12 …… Ventilation copper, 13 ……
Ventilation hole, 14 …… Machine frame, 15, 16 …… Bearing board, 17 …… Connecting rod, 18 …… Nut, 19,20 …… Cooling impeller, 21 …… Bearing, 22,23 …… Winding , 24 …… First stator, 25 …… Second stator, 26 …… Slide bearing, 27 …… Bearing, 28 ～ 31 …… Stop ring, 32 …… Move prevention ring, 33 …… Gear, 34… …
Bolts, 35 ... Pulse motors, 36 ... Worm gears, 37 ... Openings, 38 ... Covers, 39 ... Exhaust holes, 40 ...
… Ventilation hole, 41,42 …… Core, 43,44 …… Winding, 45 …… Coupling part, 46 …… Cover, 47 …… Rotor, 48,49 …… Wind trunk, 5
0 ... Exhaust hole, 51 ... Changeover switch control device, 52 ... Control value setting panel, 53 ... Control device, 54 ... Speed detector, 55 ...
… Electric motor, 56 …… Temperature detector, 57 …… Blower, r …… Resistance material.

Claims (2)

[Claims] 1. A rotor having two rotor cores axially mounted on the same rotary shaft with a space or a non-magnetic core interposed therebetween, and a plurality of conductors communicating with the two rotor cores are provided. And the above two rotor cores, two stator cores are provided around the outer peripheral portions facing the two rotor cores, and two stator cores are respectively wound with windings, and the two rotors. A resistance material which is a connecting material for short-circuiting the plurality of conductors in the space or the non-magnetic core portion provided between the rotor cores, and at least one stator of the two stators. A stator rotating device that is concentrically rotatable with the rotor and changes the phase shift between the rotating magnetic fields of the two stators; and the two stator windings with respect to the power source. Switch to delta connection and star connection at the same time, the connection polarity of one of the two stator windings is changed to the other. Variable speed induction motor, characterized in that it consists of a control unit which sets an arbitrary control value for operating controls the switch controller and each device for switching the polarity opposite to the Re. 2. The invention according to claim 1, wherein the torque characteristic when the phase shift is 180 ° due to the delta connection and the torque characteristic when the phase shift is 0 ° due to the star connection are matched. Variable speed induction motor.