JPH01234077A - Safety device for variable-speed induction motor - Google Patents

Abstract

PURPOSE:To improve the torque characteristic and to prevent breakdown of wire, by providing a start position detector for detecting the starting position of a rotary stator and a stopper for limiting the rotating of the rotary stator. CONSTITUTION:Rotor cores 2A, 2B are arranged on a rotor shaft 3 and a non- magnetic core section 2C is arranged between the rotor cores 2A, 2B. Stators 12A, 12B are juxtaposed on the inner wall face of a machine frame 10 while facing with respective outer circumferential faces of the rotor cores 2A, 2B. The rotary stator 12A is rotated through a motor 15 relative to a fixed stator 12B. When the motor is started, a controller 60 increases the phase difference between the rotary stator 12A and the fixed stator 12B corresponding to an output from the starting position detector 80, and subsequently decreases the phase difference. Furthermore, stoppers 85, 86 for limiting the rotation of the rotary stator 12A are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable speed induction motor with good torque characteristics and efficiency and easy speed control.

[Prior art and its problems]

One way to control the speed of an induction motor is to change the power supply frequency. Although this method allows for continuous and wide-range speed control, it requires an expensive frequency converter, and in the process of converting alternating current to direct current and then back to alternating current using the frequency converter, harmonics and Radio waves are generated, which cause computers,
This may lead to damage such as malfunction of various other electrical control equipment or overheating of capacitors. Among these, countermeasures against harmonic interference can be taken by installing filters, but installing filters is costly. The method of varying the power supply frequency also has drawbacks such as generally insufficient performance at low speeds.

The method of controlling the speed by changing the number of poles of the motor during operation has the disadvantage that although it is possible to change the speed stepwise by changing the number of poles, it cannot control the speed to any desired speed over a wide range.

Yet another method of controlling speed by varying the voltage of the power supply is
Although speed control can be performed continuously, it has the disadvantage of poor efficiency, especially in the low speed range.

For wire-wound electric motors, there is a method of controlling the speed by changing the secondary resistance and changing the slip.

Although this method allows continuous speed control with relative ease, it requires maintenance and inspection due to wear and tear on the brushes because resistance is inserted into the rotor winding circuit from the outside via the brushes and slip ring. do. Note that in squirrel cage induction motors, speed control cannot be performed by changing the secondary resistance.

Techniques to deal with the above problems include, for example, Japanese Unexamined Patent Publication No. 54-2
It is disclosed in Japanese Patent No. 9005.

This device has two sets of stators each having independent stator windings facing the two sets of rotor cores, and is installed in common across the two sets of rotor cores, and is short-circuited at both ends. It is equipped with squirrel-cage conductors that are short-circuited to each other via a ring, and a high-resistance element that short-circuits the squirrel-cage conductors to each other at the center of the squirrel-cage conductors between two sets of rotor cores. This is a twin iron core squirrel cage electric motor characterized by having the windings shifted in phase by 180° and supplying power while matching the phases during operation after startup. This electric motor increases the starting torque and improves the starting characteristics by shifting the phase of the stator windings by 180 degrees when starting, and during operation, the phase of the stator windings is aligned to achieve normal torque. It is characterized by the fact that it can be operated according to its characteristics. Therefore, in this electric motor, the phase shift of the rotating magnetic field can be limited to 0° and 180°, and although it has an effect of improving starting characteristics, it is not originally a variable speed electric motor, so it is difficult to handle loads that require speed changes. It is not suitable as a power source for

In addition, in the above-mentioned Japanese Patent Application Laid-open No. 54-29005, in order to alleviate the shock caused by sudden fluctuations in torque accompanying the transition from startup to steady operation, both stator windings are temporarily connected in series to the power supply circuit. Although providing an intermediate step for connection is described as an example, what can be achieved in this way does not necessarily enable speed change control.

Moreover, by switching to series, the voltage applied to the stator is halved, so the torque is reduced to 1/4, and this makes gear change control completely impossible, which is the main point disclosed in this publication. This is obvious from the fact that the purpose is not to change gears.

In short, although there is a description in JP-A-54-29005 as "an intermediate step of switching between series connection and parallel connection of the stator windings with respect to the power supply circuit," this series connection is intended for speed change. It is not a thing.

Furthermore, the technology proposed in Japanese Patent Application Laid-open No. 49-86807 is an asynchronous electric motor having a squirrel cage rotor and a stator equipped with polyphase windings, which includes conductive bars, short-circuit end rings, and strong electric laminated wherein the stator comprises first and second winding sections, the sections being coaxially arranged adjacent to each other and different parts of the rotor;
and is capable of being supplied with alternating current of the same frequency, and is characterized in that it is provided with means for varying the electromotive force induced in the rotor windings by means of the second winding section. Although it is possible to change the rotation speed by creating a phase difference between the two stator sections by mechanical or electrical means, it is possible to change the rotation speed when the phase angle between the two stator sections is in the same phase. It has a defect that the torque is small and the operation stops immediately when a load is applied, so it cannot be used for practical purposes at all, and it cannot be used as a power source for frequent starting and stopping when a load is connected. This left serious problems unresolved, such as the inability to do so. In addition, since the motor is not equipped with a rotation position detector to detect the rotation position of the rotating stator when starting the motor, if the rotation position of the stator at startup is inaccurate, the motor will not be able to start. However, serious problems such as damage to starting equipment remained unresolved. Furthermore, since the stopper is not provided, serious problems such as damage to the electric wires connected to the rotary stator remain unsolved.

[Purpose of the invention]

The present invention eliminates the drawbacks of the above-mentioned prior art and
4-29005 and Japanese Patent Application Laid-Open No. 49-86807, the speed control range is wide and the speed control is stepless to achieve any desired torque characteristics. To provide a variable speed induction motor that can be set to a specific speed, can be started with high torque, and has excellent torque characteristics and efficiency over the entire speed range from the starting point to the maximum rotational speed.

The variable speed induction motor of the present invention is used by being connected to a single-phase or three-phase power supply, and the rotor has a normal squirrel cage type, a double squirrel cage type, a deep (n-squirrel cage type), and a rotor type.

It can be applied to any type of special squirrel cage zero winding type. Note that the conductor used in the description of the present invention is a general term for the conductor installed in the squirrel cage rotor core and the winding wire wound around the wound rotor core.

Means for Solving Problem C] In order to achieve the above technical problem, the present invention provides an integrated rotor by connecting each of a plurality of conductors installed in each of a plurality of rotor cores. A plurality of stators are arranged in parallel on the machine frame at an outer peripheral portion facing each of the plurality of rotor cores, and the plurality of conductors are connected to resistors between the plurality of rotor cores. short-circuited by the material, and at least one stator of the plurality of stators is provided with a drive device for rotating the stator concentrically with the rotor, so that the stator is rotatably formed so as to be rotatable. In an electric motor having a stator, a starting position detector for detecting a rotational position of the rotational stator at the time of starting the electric motor is provided directly or indirectly in relation to the rotational stator, and a starting position detector is provided directly or indirectly in relation to the rotational stator. A solution is provided by providing stoppers that limit the rotation of the child within a certain range on one side and the other side of the range.

Further, another configuration of the present invention is that the driving device has a voltage between a voltage induced in a rotor conductor facing a rotatable stator and a voltage induced in a rotor conductor facing another stator. The phase shift is O.

The stopper is formed so that it can be arbitrarily set and held within a range of 180° from 0° to 180°.
A means to solve the problem is to provide the rotary stator so as to stop its rotation at or outside the range of rotation of the rotary stator that causes a phase shift of .degree.

[For production]

In the variable speed induction motor configured as described above,
Increase the phase shift during startup, or 78
By setting the angle to 0°, a sufficient current flows through the resistive material to suppress the starting current, and the torque is improved, and by appropriately setting the phase shift during starting, the magnitude of the current flowing through the resistive material is reduced. However, if the drive device or the starting position detector fails, the rotary stator will not move within a certain range. In some cases, the electric wires connected to the windings of the rotary stator may be damaged if the stator rotates beyond the specified limit, leading to electrical leakage or other accidents. provide.

Further, the phase shift between the voltage induced in the rotor conductor portion facing the rotary stator and the voltage induced in the rotor conductor portion facing the other stator is to be within the range of 0″ to 180′. In another configuration that can be set and maintained, in the case of a phase difference of 180°, in principle all the current flowing through the rotor conductor can be passed through the resistor material,
A wide range of torque characteristics can be obtained from the torque characteristic that makes the most of the action of the resistor material to the torque characteristic that occurs when no current flows through the resistor material when the phase difference is 0°, and the range of speed change can be maximized. In addition, by providing a stopper to stop the movement at the boundary or outside of the range, the high speed range can be maximized as described above, and the winding of the rotating stator can be The wires connected to the wire can be completely protected from damage.

〔Example〕

Examples will be described below with reference to the drawings.

First, the configuration of a variable speed induction motor according to the present invention will be schematically explained. On the rotor shaft 3 of the rotor 2, a rotor core 2A,
2B are installed with a certain interval between them. A non-magnetic core portion 2C is provided between rotor cores 2Δ and 2B. A plurality of rotor conductors 4 are installed in a cage shape on the rotor cores 2A and 2B in communication between their outer ends, and both ends of the rotor conductors 4 are connected to each other by a short-circuit ring 5.6. Short circuited. The rotor conductors 4 are interconnected and short-circuited by the resistance material R at the non-magnetic core portion 2C. The rotor 2 thus configured integrally is rotatable within the motor frame 1o by having its both ends pivotally supported by bearings 7.7.

Stators 12A and 12B are arranged in parallel on the inner wall surface of the machine frame 10, facing each outer peripheral surface of the rotor cores 2A and 2B. In the illustrated embodiment, the stator 12B is a fixed stator fixed to the inner wall surface of the machine frame 1o, but the stator 12A is equipped with a small motor 15 and gears 16, 17 (gear 17 is the stator core A rotation mechanism having a main component (fitted on the outer circumferential surface) allows rotation relative to the fixed stator 12B. 85 is a ball bearing. By operating this rotation mechanism, specifically by rotating the small motor 15 by an arbitrary amount, a phase difference is generated between the rotor conductor portions corresponding to each stator of the rotor.

That is, in the illustrated embodiment, this rotation mechanism is the voltage phase shifter 18.
Configure. In addition, each stator 12A.

The stator windings 13A and 13B wound around the stator winding 12B may be connected to the power source either in series or in parallel. Further, in the illustrated embodiment, a rotating mechanism is used as the voltage phase shifter, but it may also be configured by purely electrical means such as a stator winding connection switching method or an induced voltage type phase shifter. It may also be a combination of a rotation mechanism and electrical means.

Next, the specific configuration of the cooling device 40 will be explained.

The cooling device 40 consists of a blower device 50 and a control device 60. The blower device 50 includes a blower body 51 with an open top, which is fixed so as to surround an air outlet 20 opened at a proper position of the motor frame 10 (in the case of the illustrated embodiment, the upper central position), and the blower IJ.
It is composed of a fan motor 52 supported by the ji 51 and a fan 54 pivotally attached to the rotating shaft of the motor 52.

The control output of the control device 60 is connected to the fan motor 52 of the sending device 50, and the input side thereof has the following as a control information source:
A speed detector 70, such as a tacho generator, for detecting the rotational speed of the rotor 2. A starting position detector 80 (see FIG. 2) detects the phase difference adjusted and set by the voltage phase shifter 18, and a starting position detector 80 (see FIG. A moisture detector 90, such as a thermistor, which is disposed at a suitable location in the surrounding space and detects the temperature of the component or the space is connected. In addition,
The speed detector 70 is not limited to a tachometer generator, but may include a non-contact tachometer such as a strobe-type tachometer or a photoelectric tachometer to the rotor cores 2A, 2'B, and the non-magnetic core 2G.
, rotor conductor 5, and the like.

FIG. 2 shows a starting position detector 80 connected to the control device 60.
This is an example of this. This starting position detector 80 is embedded in a magnetic sensor 82 mounted on the outer peripheral surface of the rotary stator 12A to detect magnetism, and a non-magnetic plate 83 mounted on the inner peripheral surface of the machine frame 10, and has different diameters. Accordingly, a plurality of magnetic generating bodies 84 (84b to 8 in the drawings) generating different magnetic forces may be generated.
4f is shown).

The control device 60 constantly receives various information that changes during the operation of the electric motor from each of the detectors 70, 80 and 90, and controls the operation of the blower device 50 in the following manner based on the information.

The input information from the rotation detector 70 indicates high speed operation, the input information from the phase detector 80 indicates that the phase difference is small, and the input information from the temperature detector 90 indicates that the temperature is low. If so, the control device 60 determines that the condition inside the machine frame 10 does not require much forced cooling and heat dissipation, and controls the fan motor 52 of the blower device 50 to stop operation or perform deceleration control. This signal is output to perform power-saving operation.

On the contrary, if one of the above three input information is the opposite information, that is, information of low speed operation or high temperature is input to the control device 60, the machine frame 1 The control device 60 determines that the condition inside requires forced cooling heat dissipation, and outputs an on-control signal to start operation or an acceleration control signal to the fan motor 52 of the blower device 50. , to prevent quality deterioration due to heat and further thermal destruction of parts constituting the electric motor. In addition, if the operation of the induction motor itself is stopped under such conditions, a timer function provided in the control device 60 is activated as necessary, and the operation of the blower device 50 is continued for a certain period of time even after the motor has stopped. completely protects the motor from thermal damage.

The variable speed induction motor of this configuration is equipped with a starting position detector 80, which detects the phase difference at the time of starting and sends a signal to the control device to start using that phase difference. It is possible to prevent this from occurring, protect the load from destruction, and enable smooth startup, and it is also possible to suppress the starting current and reduce the size of the current equipment container.

In addition, it is also possible to provide a plurality of starting position detectors 84b to 84[ and to change the starting position as appropriate by the control device.

Next, there is a mechanical stopper as shown in FIG. That is, 87.87 is a protrusion fixed to the rotating stator side, 85.86 is a protrusion fixed to the machine frame side,
When the two come into contact, they function as a stopper.

Also, what is shown in Figure 3 is an example of an electric stopper.
Reference numerals 91 and 92 are magnetic generators, and the magnetic sensor 82 receives a signal and sends it to the control device to stop rotation. Therefore, even if the electric wire 93 connected to the rotating stator breaks down, the electric wire will not be damaged due to excessive rotation of the stator due to failure of the control wJ device 60, etc., and serious accidents such as electric leakage can be avoided. This can now be prevented.

Regarding the electrical stopper, for example, a protrusion is provided on the rotary stator, and a mechanical limit switch is provided on the other side of the machine frame, and when the protrusion contacts the limit switch, the switch It is possible to select and use as appropriate.

In addition, the present invention can be applied not only as a variable speed induction motor but also as an induction motor that improves startability by increasing the phase difference to 180° or more during startup and reducing the phase difference to 0° or smaller during operation. be. That is, at the time of starting, the power supply can be suppressed and a large torque can be obtained.

Furthermore, the variable speed induction motor of the present application can also be used as an induction generator, and if a turbine or the like is directly connected to the rotor shaft to generate electricity, an expensive governor can be omitted. In addition, when an internal combustion engine is connected as the prime mover, it can correspond to the rotational speed of the internal twisting machine for the minimum fuel consumption, and even when the power from feng shui as an energy source is weak and unstable, it can obtain its maximum output. Power can be generated based on the number of revolutions, and in hydroelectric power generation, power can be generated efficiently according to the flow velocity, and complicated and expensive variable pitch devices or phase adjusters can be omitted. In addition, if a switch is provided that connects another rotating shaft to the rotor shaft and switches the two phases on the input side of the stator winding, and the rotor shaft is made normal or reversible by the switch, the switch and the voltage By operating with a phase device, it can also be used as an electric brake, and by controlling the rotation speed with a voltage phase device, the braking force of the rotating shaft connected to the rotor shaft can be efficiently adjusted.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces effects as described below.

That is, by appropriately setting the phase difference, it is possible to control the magnitude of the current flowing through the resistive material, and to arbitrarily change the torque characteristics, allowing for good torque characteristics and highly efficient gear shifting. In addition, it is equipped with a starting position detection device, which prevents excessive current and excessive torque so that the load can be started smoothly and without damage, and the starting current can be suppressed to reduce the current equipment capacity. .

Moreover, the electric wire whose winding is connected to the rotary stator can be protected from damage by the supper, and accidents can also be prevented.

For the above reasons, the variable speed induction motor of the present invention has become extremely excellent.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a variable speed induction motor equipped with a cooling device according to the present invention, Fig. 2 is a sectional view showing an embodiment of a phase detector, and Fig. 3 is a sectional view showing an embodiment of the phase detector. It is. In the figure, 2... Rotor, 2A, 2B... Rotor core, 2C... Non-magnetic core portion, 3... Rotor shaft,
4... Rotor conductor, 5, 6... Short circuit ring, 7... Bearing, 10... Machine frame, 12A... Rotating stator, 12B
...Fixed stator, 13A, 13B...Stator winding,
15...Small motor, 16.17...Gear, 18.
... Voltage phase shift device, 2o... Air exhaust port, 40... Cooling device, 50... Air blower, 51... Air blower body, 52...
...Fan motor, 54...Fan, 60...Control device, 70...Roughness detector, 8o...Starting position detector, 82...Magnetic sensor, 83...Nonmagnetic plate , 8
4 (84b-84g)...Magnetic generating body, 85-88
... Stopper, 91-92 ... Stopper, 93
... Power supply connected to the first winding of the rotating stator, 90...
Temperature detector.

Claims (2)

[Claims] (1) A plurality of conductors installed in each of a plurality of rotor cores are connected to form an integral rotor, and in an outer peripheral portion facing each of the plurality of rotor cores. A plurality of stators are arranged in parallel on a machine frame, the plurality of conductors are short-circuited between the plurality of rotor cores via a resistive material, and at least one of the plurality of stators is fixed. In an electric motor having a rotary stator provided with a drive device for rotating the stator concentrically with the rotor so as to be rotatable, the rotary stator is rotated when the electric motor is started. A starting position detector for detecting a rotational position is provided directly or indirectly in relation to the rotational stator, and
A variable speed induction motor characterized in that stoppers for restricting rotation of the rotary stator within a certain range are provided at one boundary and the other boundary of the range. (2) The drive device eliminates a phase shift between a voltage induced in a rotor conductor facing a rotatable stator and a voltage induced in a rotor conductor facing another stator. °
The stopper is formed to be able to set and maintain the range from 0° to 180°, and the stopper is capable of setting and maintaining the range from 0° to 180°. The variable speed induction motor according to claim 1, wherein the variable speed induction motor is provided so as to stop the rotation at or outside the boundary of a rotation range of the rotary stator that causes a phase shift.