JPH0564399A - Two-stator induction motor - Google Patents

Abstract

PURPOSE:To smoothen start at phase difference switch and high torque by a method wherein an open/close switch of a voltage phase shifter which generates phase differences between rotary magnetic fields by two stators of a two-stator induction motor is constituted of a semiconductor element. CONSTITUTION:Two stator windings 10, 11 are delta-connected in series and connected to a power source via a voltage adjustor 20; the interval between the same phase series windings is connected to another phase power source via a short circuit switch 21; and a voltage adjustor 20 and a short circuit switch are constituted of a semiconductor element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a single rotor and two stators, and produces a phase difference between rotating magnetic fields generated around rotor conductors facing the two stators. Accordingly, the present invention relates to a two-stator induction motor that is capable of shifting, has a smooth start, and can generate high torque from low speed to high speed.

[0002]

BACKGROUND ART Torque control and speed control of an induction motor having a plurality of stators include a method known in the prior art for changing the phase difference between the stators. For example, Japanese Patent Application No. 61- No. 128314 is also an example. The method of changing the phase difference includes mechanically rotating the stator to provide the phase difference, and electrically changing the connection of the stator windings to provide some kind of phase difference. There are a wide variety of products, including a combination of these and star-delta switching.

The above method uses various methods depending on the load or application, such as when the torque and speed of the induction motor are freely changed to cope with the load, when the speed is increased smoothly at the time of starting, and the like. It will be. The present invention corresponds to a load by providing a phase difference, and it can be said that it is an electrical method when distinguished by the above-mentioned conventional technique.

Further, the prior art will be described in detail. In the electrical method, the phase difference that is achieved by switching the connection of the stator winding can be 0 °, 60 °, 120 ° 180 ° in terms of electrical angle.
The number of switches required for the switching was as many as ten and was expensive.

Further, there are some general induction motors provided with a star-delta switching device for the purpose of improving startability. This is due to the fact that the wiring is complicated despite a single stator, and torque fluctuations occur due to the temporary disconnection of the load current during star-delta switching, and the load current after switching changes suddenly. Shocks due to changes and sudden changes in generated torque were unavoidable.

[0006]

In view of the above-mentioned prior art, the present applicant has a torque characteristic equivalent to that in which the connection is switched to each phase difference with a minimum number of changeover switches according to Japanese Patent Application No. 1-261446. Moreover, it has been possible to provide a two-stator induction motor capable of stepless speed change, abrupt increase in load current, and abrupt change in load torque. However, as the phase difference is changed by switching the changeover switch, the wiring of the windings of the two stators switches from star connection to delta connection or from delta connection to star connection, so the shared voltage of each winding changes, and Due to the change in the shared voltage and the change in the phase difference, a shock is generated to some extent when the torque characteristics are switched. In addition, it was difficult to diversify the torque because the phase difference switching width was as small as 60 °.

The present invention is intended to provide a two-stator induction motor in which the shared voltage of the windings of the stator does not change even if the phase difference is switched as described above, and shock does not occur due to the phase difference switching. ..

Further, if the entire voltage is applied to the stator winding at the time of start-up together with the change in the phase difference, the shock for this is inevitable. For this reason, a method of gradually increasing the power supply voltage at the time of start-up is used, but the use of equipment such as slidac is accompanied by an increase in the size of the apparatus, and it becomes expensive if a large number of semiconductor elements are used for downsizing. Therefore, it is desired to reduce the size and cost of the device for adjusting the voltage.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides two rotor cores on the same rotary shaft at arbitrary intervals, and a plurality of rotor cores communicating with the two rotor cores are provided. A rotor in which two conductors are provided and both ends of the conductor are connected by a short-circuit ring, two stators provided around each rotor core, and one of the two stators. The stator has a rotating magnetic field generated around the rotor facing the rotor, and a voltage phase shifter that causes a phase difference between the rotating magnetic field generated around the rotor facing the other stator. In the two-stator induction motor, the voltage phase shifting device is configured such that windings of two stators are connected in series by delta connection and connected to a power source via a voltage adjusting device formed of a semiconductor element, and the voltage is connected to the same phase. Between the windings of the two stators and between the windings, and the power supply of the other phase, It was constructed in contact through the short-circuit switch that is.

Further, the voltage regulator is constructed by interposing an anti-parallel circuit of a diode and a thyristor in each phase of the power supply.

[0011]

[Operation] The two-stator induction motor of the present invention has two stator windings connected in series to form a delta connection. At this time, the phase difference of the rotating magnetic field between the two stators is 180 °, 120
Either °, 60 °, or 0 ° is possible. Here 2
Phase difference between rotating magnetic fields of two stators 0 °
The operation will be described for the case of the serial delta connection of.

In a circuit connected to a power supply as a series delta connection with a phase difference of 0 °, a short-circuit switch is provided between the windings of two stators connected in the same phase and between the windings and the power supply of another phase. When the two stators are short-circuited, the windings of the two stators become parallel delta connection, and the phase difference of the rotating magnetic fields of the two stators is 120 ° at the same time.
Will be switched to.

From the above, at the time of start-up, the windings of the stator connected in the same phase and between the windings and the power supply of the other phase are short-circuited by the short-circuiting switch, and in this case, the torque characteristic of the phase difference 120 ° After that, the short-circuit switch is opened to set the phase difference to 0 °, and it is possible to operate with the same torque characteristics as a general-purpose induction motor. At this time, if the above-mentioned operation from short circuit to open is performed by a simple open / close switch, the torque characteristic with a phase difference of 120 ° changes rapidly to the torque characteristic with a phase difference of 0 °, so a shock to the equipment cannot be avoided. Therefore, in the present invention, the operation from short circuit to open is performed by using the semiconductor element. In other words, if a short-circuit switch is made up of a semiconductor, the switching element of the semiconductor can continuously control the conduction from 0 to 1 by adjusting the firing angle (180 ° → 0 °), so that it can be connected to the windings of the stator connected in the same phase. By connecting between the windings and the power supply of the other phase via the short-circuit switch consisting of semiconductor elements,
The phase shift of the phase difference from 120 ° to 0 °, that is, the change from the short circuit to the open, becomes gradual, and it is possible to eliminate the shock to the equipment even if the torque characteristics change due to the change in the phase difference. became.

Further, in the present invention, the windings of the two stators are connected in series by a delta connection and are connected to the power supply via a voltage regulator comprising semiconductor elements. This is because when switching the phase difference, the two stator windings are connected in parallel delta connection (phase difference 120 °) and series delta connection (phase difference).
0 °), but the shared voltage of each winding of each stator is the whole line voltage in the parallel delta connection, and half of the line voltage in the series delta connection. It will be like this. Therefore, since the torque is proportional to the square of the voltage, the torque of the series delta connection is 1/4 of that of the parallel delta connection.
It becomes the torque of. In order to eliminate this difference in the shared voltage, in the present invention, a voltage adjusting device is provided between the power supply and the stator winding. That is, the voltage adjustment device drops the voltage during parallel delta connection so that the shared voltage of each winding during parallel delta connection has the same value as the shared voltage of each winding during series delta connection.

If the short-circuit switch and the voltage adjusting device are composed of semiconductor switching elements such as thyristors and triacs, the adjustment can be performed steplessly, so that the change in the phase difference and the change in the voltage of the winding become gentle, and as a whole. The change in the torque characteristic from the phase difference of 120 ° to the phase difference of 0 ° is gentle and the operation can be performed without abrupt changes. By the way, the short-circuit switch and the voltage regulator use the semiconductor firing angle (δ °) of the voltage regulator so that the voltage shared by the windings in the parallel delta connection has the same value as the voltage shared by the windings in the series delta connection. If is known, adjust the firing angle of the short-circuit switch (0 ° → 180
The adjustment becomes easier if both the angle) and the adjustment of the firing angle of the voltage adjusting device (δ ° → 0 °) are mechanically or electrically reached at the same time.

Although the phase difference of 0 ° has been mainly described in the series delta connection, it is possible to set the phase difference to 0 ° in the parallel delta connection. In this case, the firing angle of the semiconductor of the short-circuit switch is set.
By changing from 180 ° to 0 °, the series delta connection is short-circuited between the windings and between the windings and the power supply of the other phase to change to the parallel delta connection, and the phase difference also changes from 120 ° to 0 °. It will be. As a matter of course, the firing angle of the semiconductor switch of the voltage regulator is also adjusted from 0 ° to δ ° so that the shared voltage of the series delta connection and the shared voltage of the parallel delta connection have the same value.

The configuration of the voltage regulator can be made inexpensive and compact by providing an anti-parallel circuit of a diode and a thyristor in each phase between the stator winding and the power supply. Normally, the voltage regulator using such a semiconductor element is an antiparallel circuit of a thyristor as the simplest configuration, but it is also a thyristor used for the power supply part, and its allowable amount and two antiparallel circuits are used for each phase. It was hard to say that it was cheap because of the number of devices. Therefore, in the present invention, in the case of three-phase alternating current, by replacing the six thyristors with three thyristors and three diodes, the voltage regulator can reduce the price because the diodes are inexpensive.

[0018]

The present invention will be described in detail mainly as a two-stator induction motor having a squirrel-cage rotor, but it goes without saying that the invention is not limited to this. In some cases, it is a two-stator induction motor having a wound rotor, and it can be applied as a linear motor. In some cases, the torque characteristics may be made more diversified by switching the star connection and delta connection of the stator windings, and the configuration between the rotor cores may use a non-magnetic material or a magnetic material.

The present application has already been filed in Japanese Patent Application No. 61-12831.
As No. 4, a detailed description will be given of the structure and operation of an induction motor having a plurality of stators, which is a part of the structure of the present invention.

An embodiment of an electric motor forming a part of the structure of the present invention will be described with reference to FIG. Reference numeral 1 is a two-stator induction motor according to the present invention, and the induction motor 1 has the following configuration. The rotor cores 2 and 3 made of a magnetic material are mounted on the rotor shaft 4 with an arbitrary interval. Rotor core 2,
A non-magnetic core 5 is provided between the three or spaces. Each of the plurality of conductors 6 mounted on the rotor cores 2 and 3 is connected to the rotor cores 2 and 3 so as to communicate therewith to form an integral rotor 7, and the plurality of conductors 6 connected in series. Both ends of are short-circuited by the short-circuit rings 8, 8. Further, in this embodiment, each conductor 6 mounted on the rotor 7 has a resistance material 9 for flowing a current having an arbitrary vector difference in the non-magnetic core 5 portion between the rotor cores 2 and 3. It is connected through.

The first stator 12 and the second stator 13 having the windings 10 and 11 formed on the outer side thereof, which are opposed to the rotor cores 2 and 3, are arranged side by side on the machine frame 14, and the first stator 12 and The second stator 13 is fixed to the machine frame 14. Further, as a form of connection of the windings 10 and 11 of the first stator 12 and the second stator 13, a series delta connection having an electrical phase difference of 0 ° is used as an example.

Next, an embodiment of the present invention will be shown in FIG. 2 shows the voltage phase shifter 15 and the stator windings 10 and 1.
It is a connection diagram of 1.

The case where the stator windings 10 and 11 have three phases will be described below. The winding of each phase of the stator winding 10 is U2-
Let X2, V2-Y2, W2-Z2 be windings of each phase of the stator winding 11 be U1-X1, V1-Y1, W1-Z1. The respective phases of the stator windings 10 and 11 are mechanically arranged at the same position, that is, U1-X1 and U2-X2 are arranged at the same position.

Next, the connection will be described. First, the terminals U1, V1 and W1 of the stator winding 11 are respectively connected to the three-phase AC power supplies R, S and T via the voltage regulator 20 composed of semiconductor elements and fixed. Terminals X1 and U of the child windings 10 and 11
2, Y1 and V2, Z1 and W2 are connected, and the terminal X2 of the stator winding 10 is connected to V1, Y2 to W1 and Z2 to U1. In this state, the two sets of stator windings are connected in series by delta connection and are connected to the power supply via the voltage regulator 20.

Further, between the winding U1-X1 and the winding U2-X2, the T phase (W1) of the other phase is connected via the short-circuit switch 21 made of a semiconductor, and the same applies to the winding V1-Y1.
And winding V2-Y2 and other phase R phase (U1), winding W1
The -Z1 and the winding W2-Z2 and the S phase (V1) of the other phase are connected via the short-circuit switch 21, respectively. The connection of FIG. 2 is shown in FIG. 3 for easier understanding. Here, the semiconductor firing angle of the short-circuit switch 21 is 180 °, that is, OFF, and the semiconductor firing angle of the voltage regulator 20 is 0 °, that is, O.
If N, then the shared voltages E1, E of the stator windings 10, 11
1'is as shown in FIG. Stator winding 10 in this case,
The magnitude of each of the shared voltages of 11 becomes 1/2 of the line voltage, and there is no phase difference between E1 and E1 ', and a phase difference of 0 ° is generated. A phase difference of 0 ° is generated in the same way for the other windings.
The torque characteristic in this case is the same as that of a general-purpose induction motor. This is the operating torque characteristic in the rated rotation range.

Next, the ignition angle of the semiconductor of the short-circuit switch 21 is
If 0 °, that is, it is turned on, the winding U1-X1 and the winding U2-X
2 and the power supply T of the other phase are short-circuited, and similarly, the connection point of the other two windings and the power supply are also short-circuited, and this short-circuited state is shown in FIG. In this case, the magnitude of the shared voltage of each of the stator windings 10 and 11 is the line voltage of the power source, and E1 'and E1 generate a phase difference of 120 °. Similar phase differences are generated in other windings. By the way, the shared voltage of each winding in this case is the line voltage itself, which is twice the shared voltage when the phase difference is 0 °. Since the torque changes in proportion to the square of the voltage, in order to eliminate the influence of the voltage, the ignition angle of the semiconductor of the voltage regulator 20 is changed from 0 ° to an arbitrary ignition angle δ °, and the phase difference of the phase sharing voltage of the winding. It should be half of the line voltage as 0 °.
This adjusts the firing angle of the semiconductor of the voltage regulator 20 at the same time as the firing angle of the short-circuit switch 21. In this case, the phase difference is 0
A torque characteristic with a phase difference of 120 ° adjusted to the same shared voltage as the ° shared voltage is used as the starting torque characteristic. That is, since the voltage applied to the stator winding is the same as the phase difference 0 ° and the phase difference 120 °, the characteristics of the two-stator induction motor according to the present invention have a high power factor and a large torque start. Become.

The adjustment from startup to operation with the above configuration will be described. First, set the firing angle of the short-circuit switch 21 to 0 °.
(ON), the shared voltage of the stator winding is 1
The ignition angle of the voltage regulator 20 is 180 ° (O
FF) is gradually changed to δ °. By doing so, the electric motor generates a phase difference of 120 ° between the two stators as shown in FIG. 4, and starts with this torque characteristic. At this time, the voltage supplied by the voltage adjusting device 20 gradually increases, so that the start is a soft start. Next, after starting with a phase difference of 120 °, the ignition angle of the short-circuit switch 21 is gradually changed from 0 ° (ON) to 180 ° (OFF), and at the same time, the ignition angle of the voltage regulator 20 is changed to δ. The firing angle is gradually changed from 0 ° to 0 °. With this arrangement, the phase difference becomes 0 ° between the two stators of the electric motor as shown in FIG. 3, and the torque characteristic is switched to that of a so-called general-purpose motor. Since the adjustment is done in this way, unlike the opening and closing of the switch, there is no interruption of the load current, so there is no sudden change in the characteristics of torque and current, and it is possible to start up smoothly and operate with continuous changes overall. became. Moreover, the phase difference between the two stators can be switched over a wide range from 120 ° to 0 °, and the shared voltage of the windings is always kept constant, so that the torque characteristics can be changed ideally. It is possible to start from torque characteristics that have high torque in a low rotation range with a phase difference of 120 °, which is close to a proportional transition. An example of these torque characteristics is shown in FIG.

Next, the voltage regulator 20 will be described with reference to FIGS. 6 and 7.
Will be described with reference to. The circuit shown in FIG. 6 shows a basic three-phase control circuit and is a prior art. This uses two thyristors in antiparallel to each phase of the power supply and uses a total of six thyristors.

Here, from the terminal R to T, the thyristor CR2
2 and thyristor CR27, considering the instant when current i flows, thyristor CR2
2 and two thyristors, CR27. Here, since this control is possible with either one of the thyristor CR22 and the thyristor CR27, the remaining 1
It is conceivable that diodes can be used instead of the thyristor. Considering the circuit in this way, the thyristor CR23 and the thyristor CR in FIG.
25, the thyristor CR27 is a diode D31, 32,
There is no problem even if it is replaced with 33. That is, FIG.
Even if the anti-parallel circuit of the thyristors CR22 and CR23 is replaced with the anti-parallel circuit of the diode D31 and the thyristor CR28 as described above, the three-phase AC power control function has the thyristor 6
It is similar to the case of using individual pieces. In this way, the diode D is less expensive than the thyristor CR, and therefore the circuit of FIG. 7 is less expensive than the conventional example of FIG.

By the way, the voltage phase shifter 15 and a sensor for detecting the rotation speed or the load current or the voltage shared by the windings are connected via a control device, and the firing angle of the semiconductor element is controlled by the signal of the sensor. Can also be considered.

It should be noted that the present invention can be implemented even when starting in the series delta and shifting to the parallel delta. It is also possible to set the phase difference between the two stators to 180 ° when starting.

[0032]

As described above, the torque of the two-stator induction motor can be set steplessly by the voltage phase shifter of the present invention, and these torque characteristics have a small starting current and a large starting torque at the time of starting. The variable speed electric motor achieves improved startability of low torque characteristics and square reduction torque characteristics and reduced starting time, and does not require an expensive control device such as an inverter. Therefore, it is possible to diversify the torque and expand the applications of the two-stator induction motor that can generate high torque from low speed to the rated rotation range, and further contribute to all fields that require high torque at the time of starting.

[Brief description of drawings]

FIG. 1 is a side sectional view of a two-stator induction motor according to the present invention.

FIG. 2 is a wiring diagram of a voltage phase shifter for a two-stator induction motor, showing an embodiment of the present invention.

FIG. 3 is a connection diagram in which FIG. 2 is rewritten, showing a series delta connection.

FIG. 4 shows a parallel delta connection and the phase difference of the embodiment.
It is a wiring diagram of 120 degrees.

[Fig. 5] Fig. 5 shows a phase difference of 120 ° at startup and a phase difference at operation.
It is a figure which shows an example of a torque characteristic curve of 0 degree.

FIG. 6 is a basic three-phase control circuit in which two thyristors are antiparallel circuits.

FIG. 7 is a three-phase control circuit diagram including an anti-parallel circuit including a thyristor and a diode.

[Explanation of symbols]

 1 2 Stator induction motor 2 Rotor core 3 Rotor core 4 Rotor shaft 5 Non-magnetic core 6 Rotor conductor 7 Rotor 8 Short circuit ring 9 Resistor material 10 Stator winding 11 Stator winding 12 First fixed Child 13 Second stator 14 Machine frame 15 Voltage phase shifter 20 Voltage regulator 21 Short circuit switch 22 Thyristor CR 23 Thyristor CR 24 Thyristor CR 25 Thyristor CR 26 Thyristor CR 27 Thyristor CR 28 Thyristor CR 29 Thyristor CR 30 Thyristor CR 31 D 32 diode D 33 diode D

Claims (2)

[Claims] 1. Two rotor cores are provided on the same rotary shaft at arbitrary intervals, a plurality of conductors are provided in communication with the two rotor cores, and both ends of the conductors are connected by a short-circuit ring. Rotor, two stators provided around each rotor core, respectively, and one of the two stators has a rotating magnetic field generated around the rotor facing the rotor. And a voltage phase shift device that causes a phase difference between the other stator and a rotating magnetic field generated around the rotor facing the other stator, in the two stator induction motor, the voltage phase shift device is Between the windings of the two stators, which are connected in phase with each other, are connected to a power supply via a voltage regulator made of semiconductor elements in a delta connection of the stators in series. Characterized by connecting to the power supply of the other phase via a short-circuit switch consisting of semiconductor elements And two stator induction motors. 2. The two-stator induction motor according to claim 1, wherein the voltage regulator comprises an anti-parallel circuit of a diode and a thyristor interposed in each phase of the power supply. Induction motor.