JPH03207255A - Linear induction motor - Google Patents

Abstract

PURPOSE:To generate high torque from a low speed over to a high speed by series delta-connecting two sets of primary windings and further providing a connection open/close switch, which short-circuits each line or arbitrary line, between windings of two sets of the primary windings. CONSTITUTION:Two sets of primary windings 12, 13 are series delta-connected, and the first and second connection open/close switches S1, S2 for short circulating each line or arbitrary line are provided between these windings 12, 13, so that connection is switched to series delta and parallel Y connections by selecting these first and second connection open/close switches S1, S2. Accordingly, the windings 12, 13 are unbalanced from the series delta-connection, because the lines are only partly short-circuited when the first switch S1 is closed from a position where the first and second switches S1, S2 are opened, and switched to the parallel Y-connection next when the second switch S2 is closed.

Description

[Detailed Description of the Invention] [Industrial Application Field] A linear induction motor with a primary winding and a secondary conductor developed, which has two sets of primary windings and is opposed to the two sets of primary windings. The present invention relates to a linear induction motor that can control torque or smoothly start up and generate high torque from low speed to high speed by switching the phase difference between moving magnetic fields generated around a secondary conductor.

[Conventional technology]

Linear induction motors are used in a wide range of applications, from small transport devices to linear motor power for new transportation systems. However, the drive system is the same as the conventional induction motor, and the simple one is 0N-OFF control, voltage control, frequency control, etc., and it is simply a linear version of a rotary induction motor. There was no difference from a conventional induction motor. In addition, each drive method makes extensive use of open/close switches and thyristors, and
This requires expensive equipment such as a transformer or inverter, that is, a power supply control device such as voltage control or frequency control.

By the way, trick control is easily possible in general induction motors.
One way to control the speed is to change the phase difference between the stators of a multi-stator induction motor. There are two ways to change this phase difference: mechanically, by rotating the stator, and electrically, by changing the connections of the stator windings. Furthermore, there are a wide variety of devices including those in which Y-Δ switching is combined with these devices.

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.

For example, the variable torque asynchronous squirrel cage motor disclosed in Japanese Patent Application Laid-Open No. 49-86807 changes the electromotive force induced in the bar of the first part of the motor by the second winding section of the second part. The generated torque characteristics have the same effect as voltage control of the power supply. In addition, the one in JP-A No. 61-128314 changes the phase difference between multiple stators and uses it as a high-resistance induction motor when starting.
During operation, the torque characteristics are varied in a variety of ways as a low resistance induction motor. However, while the above two cited examples enable torque control, they require a device to change the phase difference between the stators in order to diversify the torque, making them far more expensive than ordinary induction motors. It became.

Most linear induction motors are used in relatively low-speed ranges, except in the ultra-high-speed world, and therefore, like general electric motors, they are inefficient in low-speed ranges (although improvements in this point are desired).

[Problem to be solved by the invention]

In the prior art, the only driving methods for linear induction motors are voltage control or frequency control. Although the motor itself is simple and easy to handle, no other improvements could be made to it, and the only way to drive it was to change the power supply in some way before supplying it to the motor. Therefore, the device has become expensive. Therefore, the present invention provides a linear induction motor with the simplest drive device while maintaining the same power supply, and improves the torque characteristics in the low speed range to replace the inefficient linear induction motor of the conventional technology, from low speed to high speed. The aim is to supply highly efficient motors ranging from

Furthermore, the linear induction motor of the present invention responds to the load by providing several types of stepwise phase changes, and can be said to be an electrical method when distinguished from the conventional technology of the multi-stator induction motor.

Now, the electrical method in the prior art is performed by switching the connection of the primary winding, and the phase difference is 060° and 120° in electrical angle.
1110° is possible, but the switch required for the switching is over ten, making it expensive.

Furthermore, some general induction motors are equipped with a Y-△ switching device for the purpose of improving starting performance, but the wiring is complicated and the torque is increased due to the temporary disconnection of the load current when switching Y-△. In addition, shocks due to sudden increases in load current and rapid fluctuations in generated torque after switching were unavoidable. This becomes more noticeable as the size increases.

In other words, the present invention has the torque characteristics at each phase difference when switching the wiring connections as described above, but by configuring a minimum number of switches required for switching, there is no disconnection of the load current due to switching of the switch, and the load current after switching is The present invention aims to provide a linear induction motor using an inexpensive phase switching device that exhibits little increase in load torque and fluctuations in load torque.

Here, FIG. 21 shows a torque characteristic curve of a general induction motor due to Y-Δ switching.

[Means to solve the problem]

The present invention is a linear induction motor that has a primary winding and a secondary conductor, and is composed of a plurality of conductors arranged at equal intervals and a short-circuit conductor that short-circuits the conductor ends at both ends of the plurality of conductors. a secondary conductor, two sets of primary windings provided at arbitrary intervals on the secondary conductor, and a moving magnetic field generated around the secondary conductor where one of the two sets of primary windings faces the secondary conductor. and a voltage phase switching device that generates a phase difference between the moving magnetic field generated around the opposing secondary conductor and the other primary winding, and the phase switching device The above-mentioned problem was solved by providing a series delta connection and a connection switch that short-circuited each wire or any arbitrary wire between the two sets of primary windings.

Further, a connecting conductor is added to the secondary conductor to short-circuit the conductors at the center of the conductor to form a secondary conductor; The above-mentioned problem is solved by providing a control device that controls the opening and closing of a connection switch that short-circuits between lines or arbitrary lines using a signal from a timer or a speed detector.

[For production]

The linear induction motor of the present invention has a secondary conductor and two
The phase difference between the moving magnetic fields generated in each of the primary windings at the relative position of the secondary conductor facing each of the two sets of primary windings is , a phase difference occurs in the currents generated at the relative positions of the secondary conductors. Only the magnitude of this phase difference, that is, the vector difference between the currents generated in each secondary conductor, acts effectively. When the phase difference reaches 180 degrees (electrical angle), they cancel each other out and no longer generate torque. Furthermore, when the phase difference is set to 0°, the torque characteristic becomes the same as that of a general induction motor. Such a change in torque characteristics provides the same effect as when controlling the power supply voltage.

Furthermore, the linear induction motor of the present invention includes a secondary conductor formed by providing a connecting conductor that short-circuits the conductors between the conductors;
Two sets of primary windings are provided opposite to each other, and a phase difference is created between the moving magnetic fields generated in each of the primary windings at the relative positions of the secondary conductors facing the two sets of primary windings. When provided, a phase difference occurs in the currents generated at the relative positions of the secondary conductors facing each primary winding, and the phase difference causes current to flow through the connecting conductor at the center of the conductors. At this time, if the resistance value of the connecting member is set to a high value, the entire secondary conductor side becomes a high resistance type secondary conductor, and the torque characteristics at that time become similar to a high resistance induction motor with improved starting. Furthermore, when no phase difference is provided, current circulates at the relative positions of the secondary conductors, resulting in a normal induction motor. In this way, a phase difference is provided between the moving magnetic fields generated in each of the two sets of primary windings, and by changing the phase difference, a unique torque is generated in a proportional transition manner.

Next, the generation of a phase difference between the primary windings will be described. The two sets of primary windings are connected in series Δ. At this time, the phase difference between the two sets of primary windings due to the wiring is 180°, 120°, and 60°.
, 0° are possible. Between the windings connected in this manner, a connection switch is provided to short-circuit each wire or any arbitrary wire. For example, a first connection switch that short-circuits between lines and a second connection switch that short-circuits other lines are provided, and the series Δ connection and parallel Y connection are established by opening and closing the first and second connection switches. If you set it so that the first and second switches are open, then when you close the first switch, only some of the wires will be shorted, so the windings will be connected in series Δ. Then, when the second switch is closed, the connection is switched to parallel Y connection. Therefore, at startup, it is a series delta connection,
When the first switch is turned on, the series Δ connection is unbalanced, and when the second switch is turned on, the connection is changed to a parallel Y connection.

Alternatively, if the first switch is opened from the closed position of the first and second switches, the short circuit between some wires is removed and the winding becomes unbalanced from the parallel Y connection, and then Opening the second switch will switch to series delta connection. Therefore, at startup, the parallel Y lines are connected, and when the first switch is opened, the parallel Y lines are unbalanced, and when the second switch is opened, the connection is switched to series Δ connection.

Furthermore, when switching between the two examples, if the series Δ connection (or parallel Y connection) with an electrical phase difference is switched directly to the parallel Y connection (or series Δ connection), the phase difference is also changed at the same time. In other words, if you switch directly from series Δ connection (or parallel Y connection) to parallel Y connection (or series Δ connection), the phase difference between them will be 180° → 120°.
120°-60', 60°→O0.

To summarize the above, it works as follows. First, when the power is turned on, the phase difference between the primary windings starts with the series Δ connection (or parallel Y connection) with the arbitrary phase difference. The load is activated by a torque characteristic curve with an arbitrary phase difference. Next, after an arbitrary time has elapsed or when the rotational speed reaches an arbitrary number, the first switch is turned on (or opened) while the second switch remains as it is, and the torque is changed to that due to unbalance. In the unbalanced windings, the phase difference between the two sets of windings or the shared voltage of a portion thereof changes, and the torque changes by the amount of the change. Therefore, the load is further accelerated by the torque characteristics due to the unbalanced windings, and the speed of the motor increases. Finally, after an arbitrary time has passed since the first switch is turned on (or opened), or when the speed reaches an arbitrary speed and the second switch is turned on (or opened), the phase difference is θ°, 6
0° or 120°, parallel Y of general induction motor
The load is driven by the torque characteristics of the wire connection (or series Δ connection) or the torque characteristics of the parallel Y connection (or series Δ connection) with a phase difference of 600 or 120°.

In this way, the phase difference or torque characteristics can be changed in three stages simply by opening and closing the first and second two connection switches, and the number of contacts is much smaller than in the prior art. Also, as explained above, the first and second switches are always turned on (or open) by starting with a series delta connection (or parallel Y connection), so the contact capacity of the first and second switches is small. can. This is because the first and second switches short-circuit (or open) the wires, so the load current is not cut off, and the generated torque does not become zero due to wire connection switching. Furthermore, since there is a step in which both the first and second switches are turned on, even if one or both of them are turned on due to an accident with the open/close switch, such as contact welding, an electrical accident will not occur. There is no such thing as being connected to.

The same applies even if the first and second switches are short-circuited.

It goes without saying that the switching timing of the first and second switches varies depending on the load condition and the characteristics of the linear motor, but when the load is an inertial load or a constant load, the timing of switching the first and second switches changes depending on the torque characteristics of the linear motor and the above-mentioned. The timing of switching may be uniquely determined by the load. In such a case, difficult control is not necessary and can be achieved with a simple sequence circuit or logic circuit using a speed sensor or timer.

When using a timer, it is possible to regularly switch to the rated speed based on the time from startup.

This can be used when the load does not fluctuate and is always constant. In addition, when using a speed sensor, it is effective for inertial loads that have a large load at startup, but if the inertial load is constant, it is also possible to use a timer. If the load at startup changes, the speed sensor can be used to switch to the rated speed as it reaches a constant speed.

Furthermore, among the linear induction motors of the present invention, a phase difference is provided, and the generated current in the secondary conductor is passed through a connecting conductor connecting the conductors without canceling it out, thereby generating a torque specific to the phase difference. In the low speed range, the torque characteristics of the motor with high resistance and improved starting are achieved, so efficient operation can be achieved.

The number of wires required to connect the linear induction motor of the present invention to a power source and a phase switching device consisting of a first and second connection switch is three power wires in the case of a three-phase specification; The device requires six pieces, nine in total. If the phase switching device is provided on the power supply side, six wires from the motor side and three wires from the power supply side are required, making it difficult to handle on-site. By integrating the phase switching device with the electric motor, only three wires from the power supply side are sufficient. When a general electric motor becomes large, the wiring work for six wires becomes complicated due to Y-Δ starting, but the present invention changes the torque characteristics of the motor using a phase switching device using two switches, and the phase switching device Since it is integrated with the motor, only three wires are needed for the power supply.

Therefore, even if the motor becomes large in size, it is only necessary to check the three power supply wires and the direction of rotation, just as in the case of a small motor, reducing the cost of wiring materials and simplifying the work.

By the way, in the linear induction motor of the present invention, the primary winding may be provided on the track side or on the side running on the track, and when the primary winding is provided on the side running on the track,
Providing overhead wires for power supply along the track, remotely controlling the phase switching of the primary winding, installing sensors on the track, or wirelessly operating can be achieved using known conventional techniques.

Furthermore, the generated torque can be increased by providing a ferromagnetic material in the secondary conductor.

〔Example〕

The present invention will mainly be described in detail as a linear induction motor in which a squirrel-cage secondary conductor and two sets of primary windings are deployed on a track, but it goes without saying that the present invention is not limited to this. There are also linear induction motors with a wire-wound secondary conductor, and there are also cases where the primary winding is switched between star connection and delta connection to further diversify the torque characteristics.

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

The configuration of a linear induction motor forming a part of an embodiment of the present invention will be explained with reference to FIGS. 1 to 4. FIG.

First, the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. This shows a structure consisting of a short-circuit conductor and a short-circuit conductor.

Reference numeral 1 is a linear induction motor of the present invention,
On the track side 2 in FIG. 1, there are provided a plurality of conductors 6 arranged at equal intervals on the track and short-circuiting conductors 8° 8 at both ends of the plurality of conductors 6 to short-circuit the ends of the conductors. This constitutes the secondary side 4.

On the other hand, the moving side 3 is provided with a first primary winding 12 and a second primary winding 13 facing the secondary side 4 at an arbitrary interval to form a primary winding side 5.

Next, it will be explained with reference to FIG. On the track side 14 in Fig. 2,
A primary side 16 is formed by providing a first primary winding 12 and a second primary winding 13 spaced apart in the orbital direction on the track. On the other hand, the moving side 15 is provided with conductors 6 arranged at equal intervals with an arbitrary interval from the primary side 16, and short-circuiting conductors 8, 8 that short-circuit the ends of the conductor 6 at both ends of the conductor 6. side 1
7.

Next, in the third embodiment shown in FIG. 3 and the fourth embodiment shown in FIG. 4, the secondary conductor includes a connecting conductor in the center of the conductor 6 to short-circuit the conductors.

First, explanation will be given starting from FIG. On the track side 2 in FIG. 3, a plurality of conductors 6 are arranged at equal intervals on the track, and short-circuiting conductors 8, 8 are provided at both ends of the plurality of conductors 6 to short-circuit the ends of the conductors. The secondary side 4 is constructed by providing a connecting conductor 9 that short-circuits the conductors 6 at the center of the conductors 6 . On the other hand, the movable side 3 faces the secondary side 4 at an arbitrary interval, and has a first primary winding 12 and a second primary winding 1 in a part not facing the connecting conductor 9.
．． 3 to form the primary winding side 5.

Next, it will be explained with reference to FIG. On the track side 14 in Fig. 4,
A primary side 16 is formed by providing a first primary winding 12 and a second primary winding 13 spaced apart in the orbital direction on the track. - On the blade moving side 15, there are conductors 6 arranged at regular intervals with the primary side 16, and conductors 6 on both ends of the conductor 6.
The secondary sides 1 and 7 are constructed by providing a short-circuit conductor 8.8 that short-circuits the ends of the conductor 6, and a connecting conductor 9 that short-circuits the conductors 6 at the center of the conductor 6.

The moving side and the track side have an arbitrary interval between the primary winding and the secondary conductor, and this interval is generally determined using electromagnetic levitation, air levitation, etc. It is also possible to install wheels on the vehicle and run it on rails. Further, the guiding method for traveling on the track includes the above-mentioned rail traveling using wheels and a method of guiding the moving side from the side, and is not limited by the present invention.

Next, the configurations of the connections between the first primary winding 12 and the second primary winding 13 will be shown, including a series Δ connection with an electrical phase difference of 60° and a series Δ connection with an electrical phase difference of O0. are shown in FIG. 5 and FIG. 9, respectively.

First, the case of series Δ connection with an electrical phase difference of 60° will be explained with reference to FIG. To explain in three phases, primary winding 1
Connect one terminal (U, , V, , W,) of each coil of 2 to the power switchgear S. and connect the other terminal (x+, Yl, z+) to one terminal (Y2, Z2, X2) of the primary winding 13, and the other terminal of the primary winding 13. (V2, W2, Y2) are connected to the terminals (tJ+, Vl, W,) in a series Δ connection. Further, one end of the connection switch S is connected to the other terminal X1 of the primary winding 12, and the other end is connected to one terminal Z2 of the primary winding 13. The connection switch S2 is connected to the other terminal Y1 of the primary winding 12 and to one terminal X2 of the primary winding 13.

The operation of the above configuration will be explained. First, the power switchgear S. When closed, the primary winding 12 and the primary winding 13 become a series Δ connection having an electrical phase difference of 60°. This is shown in FIG. In other words, the shared voltage E of the coils U, ~X of the primary winding 12 and the corresponding coil U of the primary winding 13
The shared voltages E1' of 2 to x2 are connected to have an electrical phase difference of 60°. 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 connection on/off switch Sl (hereinafter referred to as switch S1) is closed, the terminal X1 of the primary winding 12 and the primary winding 1 are connected to each other.
Terminal Z2 of No. 3 is short-circuited, and the series Δ connection becomes unbalanced. This is shown in FIG.

When unbalanced, some of the windings (V2 to Y2, V1 to Y,) become parallel, and the obtained torque characteristic exhibits an intermediate torque characteristic between the series Δ connection and the parallel Y connection.

Moreover, in order to make the connection diagram of FIG. 7-1 easier to understand, FIG. 7-2 has been rewritten with a focus on the short circuit between the lines, that is, the switch S1.

Next, when the connection opening/closing switch S2 (hereinafter referred to as switch S2) is closed, the phase difference becomes 00 electrical degrees as described above. Further, the wiring connections at this time are shown in FIG.

The voltage shared by the coils U1 to X1 is E, and E is the line voltage of the power supply. The size of El is 2/2 in the case of series Δ connection.
(3 = 1.15 times. This voltage increase is within the allowable range of power supply voltage fluctuations and poses no problem, but this voltage increase has the advantage of improving torque characteristics.

As described above, it is possible to provide three levels of torque characteristics by using the two connection open/close switches, switch S and switch S2. For example, for starting, medium speed, and driving.

Further, when the phase difference is O0, that is, when the switch SI+82 is closed, the other side of the primary winding 12 (X,

Y+, Zt) and one of the primary windings 13 (x2.y2, Z2
) is in a short-circuit state, and even if a short-circuit occurs due to a contact failure or other ground cause, an electrical accident such as burnout of the linear motor's primary side will not occur.

Furthermore, since the opening and closing of the switches S, S2 that change the phase is a short circuit between lines during operation due to series Δ connection, the load current is not temporarily cut off due to opening and closing, and the load Since there is no interruption of current and the voltage between poles is 172% of the power supply voltage, it is possible to use a connection switch with a small electrical capacity, and switch S
, , S2 allows the phase switching device to be miniaturized.

Next, FIG. 9 shows a case of series Δ connection with an electrical phase difference of 0°.

What is shown in FIG. 9 is a connection diagram when the primary windings 12 and 13 of the linear induction motor are connected in series with an electrical phase difference O0. To explain in three phases, primary winding 1
One terminal of each coil of 2 (U+, Vl, W+)
are connected to the power supplies A, B, and C via the power switchgear So, and the other terminals (X+, Y+, Zt
) to one terminal (U2.V2.W2) of the primary winding 13, and the other terminal (X2, Y2,
Z2) is connected to the terminals (U, , Vl, W,) in a series Δ connection. Further, one side of the connection switch S1 is connected to the other side X of the primary winding 12, and the other side is connected to one terminal 2 of the primary winding 13. In addition, the connection on/off switch S2 is the other terminal Y of the primary winding 12,
and is connected to one terminal W2 of the primary winding 13.

The operation of the above configuration will be explained. First, close the wiring on/off switches S, S2 and turn on the power on/off switch S. When closed, the electrical phase difference between the primary winding 12 and the primary winding 13 is 6.
This results in a parallel Y connection with an angle of 0°. This is shown in FIG. In other words, the shared voltage E of the coils U1 to X of the primary winding 12
.

and the corresponding voltages E,' shared by the coils U2 to X2 of the primary winding 13 have an electrical phase difference of 60°.

Next, when the connection on/off switch S2 (hereinafter referred to as switch S2) is opened, the terminal X1 of the primary winding 12 and the primary winding 13 are connected to each other.
Terminal 2 is open, and the parallel Y connection becomes unbalanced. This is shown in FIG. This FIG. 11-2 is a redrawn version of the wiring diagram of FIG. 11-1, focusing on short circuits between lines, in order to make it easier to understand.

Next, when the connection opening/closing switch S (hereinafter referred to as switch S1) is opened, the phase difference becomes 0 electrical angle as described above. Further, the wiring connections at this time are shown in FIG.

As described above, it is possible to provide three levels of torque characteristics by using the two connection open/close switches, switch S and switch S2. For example, for starting, for medium speed, and for driving.

As described above, whether it is a series Δ connection with an electrical phase difference of 60° or a series Δ connection with an electrical phase difference of 0°, it is possible to switch from a series Δ connection to a parallel Y connection, or from a parallel Y connection to a series Δ connection. It is possible to obtain a similar change in phase difference by switching to wire connection.

Here, if the above-mentioned switching is implemented in Examples 1 to 4, the following torque characteristics will be obtained.

The case of Example 1.2 is shown in FIG. 13, and the case of Example 3.
The case of 4 is shown in FIG.

By the way, as shown in FIG. 5, the connection on/off switches S, S2
By installing a phase switching device consisting of (It is possible to use a linear induction motor that can be operated with high torque from low speed to high speed.

Next, control of the phase switching device will be explained based on the third embodiment with reference to FIG. 15 and FIGS. 1-6. First of all
In the configuration shown in Figure 5, the primary side 5 is a three-phase power supply 2 equipped with a switchgear.
It is connected to 2.

Further, a phase switching device 20 is integrally provided on the primary side 5, and a control device 21 incorporating a sequence circuit consisting of a timer is connected to the phase switching device. Next, the configuration shown in FIG. 16 will be explained. The primary side 5 is connected to a three-phase power supply 22 with a switchgear. Further, a phase switching device 20 is integrally provided on the primary side 5, and a control device 23 composed of a hard logic circuit or the like is connected to the phase switching device. This is the connection of the signal of the speed detector 24 that performs the operation.

By the way, for the connection between the three-phase power supply 22 and the primary side 5, it is possible to install a power supply overhead wire along the track or to extend the power supply overhead wire for short-distance movement. Detailed explanation will be omitted in the example.

Furthermore, the speed detector 24 can be implemented in various ways, such as by detecting the speed by optical or electromagnetic pulse counting between the moving side and the track side, or by installing it directly on the running wheels, and it goes without saying that any method can be used. Therefore, detailed explanation will be omitted.

The above effects will be explained. Each control device 21.23
This is to control the opening/closing of the above-mentioned connection switch of the phase switching device 20 according to a time limit by a timer or a signal from the detector 24.

For example, in the case of the control device 21, since a general Y-Δ start typically switches in about 10 seconds, it starts with a phase difference of 600 and switches to steady operation with a phase difference of O0 as follows. For example, set the time to start with a phase difference of 60' and switch to the next unbalanced load to 4 to 5 seconds after startup, and the time to switch from the unbalanced load to 00 to 4 to 5 seconds after switching to the unbalanced load. , sequentially from 60° to 0 by the phase switching device 20.
It can be switched in 3 steps up to 3 degrees. Needless to say, the above-mentioned time limit should be changed depending on the load.

In the case of the control device 23, the control device may be a simple logic circuit or may include a microprocessor as necessary. This is based on the current state of technology. Furthermore, a circuit that receives the signal from the detector 24 and converts the signal as necessary, a circuit that compares the converted signal with a predetermined reference value, and a circuit that stores the predetermined reference value. It is equipped with a signal output circuit, etc. that outputs a signal based on the above comparison. The phase switching device 20 is sequentially switched using the signal from this signal output circuit to change the phase difference.

Although the detector is here the speed detector 24, means for detecting the state of the motor, such as one for detecting speed, is used.

The torque characteristics under control of the phase switching device by the above control device are as shown in FIG.
4 is shown in FIG.

Compared to conventional Y-Δ switching, the torque fluctuation is small and the starting current can be kept small.

By the way, the time limit of the control device 21 and the predetermined reference value of the control device 23 are determined by the load torque, GD2, and the output of the electric motor. In addition, each control device is a simple device that only controls the opening and closing of two connection on/off switches, and is used as a control device for a linear induction motor with a three-stage phase difference. It is also possible to incorporate it into the configuration.

Now, in the above embodiment, the connection on/off switch was shown as having a simple on/off contact, but as shown in FIG. This includes semiconductor devices such as thyristors and triacs.

If such an open/close switch is used and the series Δ connection is gradually shifted to an unbalanced state, the small torque fluctuations at the time of switching, as shown in Fig. 18, will disappear and the torque characteristic will have the level difference shown in Fig. 20. It is something that can be done.

Furthermore, although the three-stage phase difference has been the focus of the examples so far, it goes without saying that it is also possible to short-circuit all of the lines at the same time using an open/close switch, depending on the load condition. Unlike Δ switching, there is no load current interruption due to switching, and since it is composed of two sets of primary windings, the phase can be switched simultaneously and the torque characteristic can be switched from starting to running. Moreover, the switching device can be constructed simply and inexpensively, and has the same effect as the embodiment described above.

〔effect〕

As described above, the torque generated during startup and rated operation of a linear induction motor can be switched in three stages using a simple phase switching device, and the torque can be divided into three types: for startup, for medium speed, and for operation. be. These torque characteristics have a small starting current and a large starting torque at startup.The purpose of these torque characteristics is to improve starting performance with constant torque characteristics or square-law reduced torque characteristics, and to reduce startup time, except for equipment that always requires variable speed. In this case, it becomes a suitable linear induction motor and does not require an expensive control device for power supply such as an inverter.

Therefore, we aim to diversify the torque and expand the applications of linear induction motors that can generate high torque even at low speeds up to the rated speed range, and in all fields that require high torque and high efficiency linear induction motors in the low speed range. Now I can make an even bigger contribution.

[Brief explanation of drawings]

FIG. 1 is a diagram of a first embodiment of a linear induction motor of the present invention, FIG. 2 is a diagram of a second embodiment of a linear induction motor of the present invention, and FIG. 3 is a diagram of a third embodiment of a linear induction motor of the present invention. Embodiment diagram, FIG. 4 is a fourth embodiment diagram of the linear induction motor of the present invention, FIG. 5 is a connection diagram of the primary winding with a phase switching device having a series Δ connection with an electrical phase difference of 60°, Figure 6 is a wiring diagram of a primary winding connected in a series Δ connection with an electrical phase difference of 60° using a phase switching device, and Figure 7 is a wiring diagram of a primary winding that is unbalanced from a series Δ connection due to a phase switching device. , Fig. 8 is a connection diagram of the primary winding which has become a parallel Y line by the phase switching device, Fig. 9 is a connection diagram of the primary winding with a series Δ connection with an electrical phase difference of 0° and the phase switching device. Figure 10 shows an electrical phase difference of 60
0. Figure 11 is a wiring diagram of a primary winding that has been made unbalanced from a parallel Y connection by a phase switching device. Figure 12 is a connection diagram of a primary winding that has become unbalanced from a parallel Y connection by a phase switching device. The connection diagram of the primary winding, Figure 13 shows the 1st and 2nd
FIG. 14 is a diagram showing an example of torque characteristics at each connection due to phase switching in the third and fourth embodiments, and FIG. 15 is a diagram showing an example of torque characteristics at each connection due to phase switching in the third and fourth embodiments. 16 is a control block diagram of the phase switching device using a timer sequence circuit, FIG. 16 is a control block diagram of the phase switching device using a logic circuit, and FIG. 17 shows the torque when using the phase switching device in the first and second embodiments. A diagram showing an example of a characteristic curve, Figure 18 is a diagram showing an example of a torque characteristic curve when the phase switching device is used in the third and fourth embodiments, and Figure 19 is a diagram showing an example of the torque characteristic curve when the phase switching device is used in the third and fourth embodiments. FIG. 20 is a diagram showing an example of a torque characteristic curve when a thyristor is used as a connection opening/closing switch, and FIG. 21 is a diagram of a torque characteristic curve using conventional Y-Δ switching. DESCRIPTION OF SYMBOLS 1... Linear induction motor, 2... Track side, 3... Moving side, 4... Secondary side, 5... Non-magnetic core, 6... Conductor, 8... Short circuit Conductor, 9... Connection conductor, 12... First primary winding, 13... Second primary winding, 14... Track side, 15... Moving side, 16...
...Primary side, 17...Secondary side, 20...Phase switching device, 21...Control device, 22...Power supply side, 23
...Control device, 24...Speed detector.

Claims (3)

[Claims] (1) A linear induction motor with a primary winding and a secondary conductor, including a plurality of conductors arranged at equal intervals and a short-circuit conductor that shorts the conductor ends at both ends of the plurality of conductors. A secondary conductor, two sets of primary windings provided at arbitrary intervals on the secondary conductor, and movement of one of the two sets of primary windings around the opposing secondary conductor. a voltage phase switching device that creates a phase difference between a magnetic field and a moving magnetic field generated around a secondary conductor that the other primary winding faces, and the phase switching device A linear induction motor characterized in that the wires are connected in series Δ, and a connection switch is provided between the windings of the two sets of primary windings to short-circuit each wire or between any wires. (2) A linear induction motor with a primary winding and a secondary conductor, including a plurality of conductors arranged at equal intervals, a short-circuit conductor that shorts the conductor ends at both ends of the plurality of conductors, and a short-circuit conductor that short-circuits the conductor ends. A secondary conductor consisting of a connecting conductor that short-circuits the conductors in the center, two sets of primary windings provided at arbitrary intervals on the secondary conductor in a part not facing the connecting conductor, and the two sets of primary windings. A voltage phase that creates a phase difference between the moving magnetic field generated around the secondary conductor facing one primary winding of the windings and the moving magnetic field generated around the secondary conductor facing the other primary winding. and a switching device, and the voltage phase switching device connects the two sets of primary windings in series,
A linear induction motor characterized in that a connection switch is provided between the windings of the two sets of primary windings to short-circuit each line or any arbitrary line. (3) The linear induction motor according to claim (1) or (2), wherein the voltage phase switching device connects the two sets of primary windings in series, and A linear induction motor characterized by being provided with a connection switch for short-circuiting each line or any arbitrary line between lines, and a control device for controlling opening and closing of the connection switch by a signal from a timer or a speed detector.