WO2010131355A1

WO2010131355A1 - Uninterruptible variable voltage device

Info

Publication number: WO2010131355A1
Application number: PCT/JP2009/059060
Authority: WO
Inventors: 和郎河辺
Original assignee: 電光株式会社
Priority date: 2009-05-15
Filing date: 2009-05-15
Publication date: 2010-11-18
Also published as: CN102428421A

Abstract

Provided is an uninterruptible variable voltage device capable of varying voltage uninterruptibly and continuously or uninterruptibly in multistage by preventing spark from occurring upon startup or operation change and capable of, for example, correcting voltage drop due to the startup of a large capacity motor, the temperature adjustment of an electric heater furnace, and the increase and decrease of the load in a distribution line by preventing the situations such as wasteful energy consumption and the difficulty in the control of electric motor startup current. A main coil comprises an intermediate tap connected to a load driven by a three-phase power supply and is provided for each phase of the three-phase power supply while having one terminal connected through a first switch to one phase of the three-phase power supply and the other terminal connected to the neutral of the three-phase power supply. A current control means is connected in parallel between the intermediate tap of the mail coil and the first switch and controls the flowing current to control the current flowing between the intermediate tap and the first switch. A control circuit controls the current control means. Using the main coil, the current control means, and the control circuit, the current flowing between the intermediate tap and the first switch is controlled.

Description

Uninterruptible voltage variable device

The present invention relates to an uninterruptible voltage variable device, and more particularly, a voltage drop due to start-up of a saddle type three-phase induction motor, energy saving control during light load operation, temperature adjustment of an electric heater furnace, and increase or decrease of load on a distribution line. The present invention relates to an uninterruptible voltage variable device that can be used for correction, etc., and can vary the voltage continuously without interruption or in multiple stages without interruption.

For example, when starting a vertical three-phase induction motor, the starting current has an excessive characteristic, and the electric heater furnace has a low resistance in a cold state, and an excessive current flows when the power is turned on. However, when the number of rotations of the induction motor increases, the flowing current decreases, and when the electric heater furnace or the like warms, the resistance increases and the current decreases. In addition, there are demands such as temperature adjustment in electric heater furnaces and correction of voltage drop due to load increase and decrease in distribution lines.

Therefore, for example, when starting a vertical three-phase induction motor, a star delta starter, a start compensator, a reactor starter, etc. are generally used. These starter determinations are determined in consideration of the motor rating, load type, start-up frequency, etc., but the start-up current is small, acceleration is smooth, and automatic control is possible. In consideration of other conditions, reactor starters are widely used.

Although the reactor starter has excellent performance as described above, it requires an expensive reactor short-circuit switch having the same performance as the power switch, and this reactor short-circuit switch generates a spark when starting or switching operation. The contacts are severely damaged. Therefore, when the activation frequency is high, there is a drawback that the lifetime is remarkably short. In particular, this disadvantage becomes a very serious problem for a high-current high-voltage circuit. This also applies to a load in which the current flowing with time changes, such as temperature adjustment of an electric heater furnace using high power, correction of a voltage drop due to increase / decrease of load on a distribution line, and the like.

For this reason, in Patent Document 1, a supplementary coasting wire having the number of amperes opposite to the number of amperes of the main circuit winding is applied to the same magnetic path as the magnetic circuit subjected to the main circuit winding. The inrush current is suppressed by the self-reactance of the main circuit winding, and when the current becomes small, the circuit of the auxiliary conventional winding is closed, and the number of reverse amperes is used to limit the magnetic flux to be generated in the magnetic path by the main circuit winding. An AC motor starter is shown.

In the circuit shown in Patent Document 1, the voltage can be stepped up at an appropriate timing without shutting off the power supply to the AC device. Therefore, the fluctuation range of the inrush current and torque generated at the time of the boosting is small. There is an advantage that the impact on the AC device can be reduced. However, since a current always flows through the reactor and Joule heating (resistance heating) is generated by this current, there is a problem that energy is consumed more than necessary.

For this reason, in the voltage regulator for an AC device disclosed in Patent Document 2, the first reactor L1 and the magnetic flux generated in the primary winding T2 are canceled in the primary winding T2 by turning on the first switch SW2. A circuit in which a second reactor L2 having a secondary winding T22 is connected in series, and a circuit in which a second switch SW4 is connected in parallel with the reactor series circuit is connected in series to the AC device 2. Has been proposed. In this circuit, the first switch SW2 is turned on to reduce the reactance of the first reactor L1 to be applied to the AC device 2 at a predetermined time after the low voltage application through the reactor series circuit to the AC device 2. Then, the second switch SW4 is turned on. In this way, by short-circuiting the reactor series circuit, applying the entire voltage and shifting to the operating state, the reactor series circuit is short-circuited in the operating state, so that it is possible to save energy in the reactor series circuit.

However, the circuit of Patent Document 2 is not suitable for starting a large-capacity motor because the reactor is directly short-circuited by a short-circuit switch. Therefore, in Patent Document 3, the primary winding connected to the power terminal of the motor, the power switch connected in series to the power supply side of the primary winding, and the secondary wound around the iron core common to the primary winding. An electromagnetic that changes the length of the tertiary winding by connecting the winding, the tertiary winding with a plurality of intermediate taps wound around different iron cores, and the end of the tertiary winding provided on each of the intermediate taps A variable reactor circuit comprising a contactor and a tap selection device for selecting the electromagnetic contactor; a starter with a variable reactor circuit comprising: a primary winding having an intermediate tap connected to a power supply terminal of a motor; , A power switch and a ground switch provided on the power supply side and the ground side of the primary winding, a secondary winding wound around a common iron core with the primary winding, and “wrapped around a different iron core” in paragraph 0029 In claim 4, the primary winding and the secondary A tertiary winding with an intermediate tap that is said to be “wound on a common iron core”, an electromagnetic contactor that changes the length of the tertiary winding, and a tap selection device that selects the electromagnetic contactor A variable reactor circuit and a starter with a variable reactor circuit are shown.

In the starter with a variable reactor circuit of Patent Document 3, when the motor is started, all the magnetic contactors of the tap selection device are turned off and the power switch is turned on to reduce the voltage by the reactance of the primary winding, and the starting current is reduced. It is suppressed. When the number of revolutions increases after starting, the starting torque increases and the starting current decreases. Therefore, the magnetic contactor is sequentially turned on by the tap selection device, and the secondary winding current matches the reactance of the tertiary winding. As a current, a part of the reactance of the primary winding is canceled out, so that the reactor is apparently decreased sequentially, so that a voltage that increases stepwise can be applied to the motor.

Japanese Patent Publication No.46-25045 JP 2005-202861 A JP 2006-271060 A

However, as described above, the AC motor starter shown in Patent Document 1 has a problem that current constantly flows through the reactor, and Joule heating (resistance heating) is caused by this current to consume more energy than necessary. The circuit of Patent Document 2 is not suitable for starting a large-capacity motor because the reactor is directly short-circuited by a short-circuit switch.

In the starter with a variable reactor circuit shown in Patent Document 3, as in Patent Document 1, a current always flows through the primary winding, and Joule heat (resistance heat generation) is generated by this current, so energy is more than necessary. There is a problem of consumption. Further, when any of the magnetic contactors indicated by 58-1 to 3 in the circuit of FIG. 5 is inserted, and any of the electromagnetic contactors indicated by 69-1 to 3 in the circuit of FIG. In this case, a part of the mutual induction between the variable reactor circuit and the primary winding is canceled by the secondary winding, which increases the excitation current of the primary winding and makes it difficult to control the motor starting current. The problem that occurs.

Therefore, in the present invention, it is possible to change the voltage continuously without interruption or in multiple stages without interruption so as not to cause a problem that a spark is generated at the time of start-up or operation switching and damage of the contact occurs. Without losing energy or controlling the motor starting current, making it possible to start up a large-capacity motor, adjust the temperature of the electric heater furnace, correct the voltage drop by increasing or decreasing the load on the distribution line, etc. It is a problem to provide an uninterruptible voltage varying device that can also be used.

In order to solve the above problems, the uninterruptible voltage variable device according to the present invention is:
An intermediate tap connected to a load driven by a three-phase power source, one end connected to one phase in the three-phase power source via the first switch, and the other end connected to the neutral of the three-phase power source A main coil provided for each phase of the power source, and connected in parallel between the intermediate tap and the first switch in the main coil, and controls a current flowing to control a current flowing between the intermediate tap and the first switch. A current control means for controlling, and a control circuit for controlling the current control means,
The control circuit controls the current control means in response to a current flowing through the load in a state where the first switch is closed, and controls a current flowing between an intermediate tap in the main coil and the first switch. It is characterized by being comprised.

By configuring the uninterruptible voltage variable device in this way, if the current flowing between the intermediate tap in the main coil and the first switch is controlled by the current control means after the first switch is closed, the current is initially For example, 50% of the power supply voltage can be applied to the load by using a voltage drop corresponding to the reactor between the intermediate tap and the first switch in the main coil, with the current flowing through the control means being zero. When the current flowing through the load decreases, the current flowing through the current control means is gradually increased, the voltage drop between the intermediate tap in the main coil and the first switch is decreased, and finally the intermediate tap in the main coil and the first The voltage drop between the switches can be, for example, about 80% of the power supply voltage or 100%.

Therefore, in the present invention, the load and the power source are not cut off, and there is no problem that the contact is damaged due to the occurrence of a spark when starting or switching the operation. Also, if the resistance of the current control means can be reduced to zero, there will be no current flowing between the intermediate tap and the first switch in the main coil, and there will be no voltage drop. Can be driven and energy is not wasted.

The current control means is formed of a magnetic path independent of the main coil and connected in series, and a plurality of independent magnetic path reactors connected in parallel between the intermediate tap and the first switch in the main coil. And a second switch connected in parallel corresponding to each of the plurality of independent magnetic path reactors, and the control circuit is configured to convert the current flowing through the load with the first switch closed. Correspondingly, the second switch is sequentially closed, and the current flowing between the intermediate tap and the first switch in the main coil is controlled, so that the independent magnetic path reactor is sequentially turned to 0 by the second switch. Since resistance can be achieved, when the plurality of second switches are all closed, the intermediate tap and the first switch are brought into conduction by the second switch. Therefore, as in the case of Patent Document 3, a part of the mutual induction action with the primary winding is canceled by the secondary winding, and the motor starting current such as an increase in the excitation current of the primary winding is reduced. There is no problem that control becomes difficult.

Further, the current control means is a variable resistor whose resistance value is controlled by an actuator, and the control circuit controls the actuator in accordance with a current flowing through the load in a state where the first switch is closed. , The resistance value of the variable resistor is controlled to control the current flowing between the intermediate tap and the first switch in the main coil, or the current control means is a current control element, and the control circuit In the state where the first switch is closed, the current control element is controlled in accordance with the current flowing through the load, and the current flowing between the intermediate tap and the first switch in the main coil is controlled. Therefore, the variable resistance can be changed from the maximum resistance to 0 resistance, and the current control elements such as triacs and thyristors are similarly changed from 0 to the maximum. Since the current can be freely controlled up to the current, the current flowing between the intermediate tap in the main coil and the first switch can be freely controlled, and there is no problem that it becomes difficult to control the motor starting current, and the large capacity motor It is possible to provide an uninterruptible voltage variable device that can be used for various purposes, such as starting the power supply, adjusting the temperature of the electric heater furnace, and correcting the voltage drop due to the increase or decrease of the load on the distribution line.

The current control means has a third switch that is closed by the control circuit and connects the power source and the load with a voltage drop between the intermediate tap and the first switch in the main coil reduced. As a result, the current flowing between the intermediate tap and the first switch in the main coil can be completely eliminated, and energy is not wasted.

As described above, the uninterruptible voltage variable device according to the present invention does not disconnect the load and the power source after the power is turned on, and if the current control means is set to 0 resistance, There is no current flowing between the switches, and there is no problem that sparks are generated at the time of start-up or operation switching, resulting in damage to the contacts, and energy is not wasted.

The current control means is formed of a magnetic path independent from the main coil, connected in series, and a plurality of independent magnetic path reactors connected in parallel between the intermediate tap and the first switch in the main coil, By configuring the second switch connected in parallel corresponding to each of the independent magnetic path reactors, if the second switch is sequentially closed according to the current flowing through the load, the independent magnetic path reactor is The resistance can be reduced to 0 with the switch. Therefore, if the intermediate tap and the first switch are brought into a non-resistance conduction state when all of the plurality of second switches are closed, as in the case of Patent Document 3, the mutual induction action with the primary winding is performed. Since a part of the current is canceled by the secondary winding, there is no problem that it becomes difficult to control the motor starting current, such as an increase in the excitation current of the primary winding.

Furthermore, the current control means is a sliding resistance whose resistance value is controlled by a pilot motor, or a current control element such as a triac or thyristor, so that the sliding resistance can vary from the maximum resistance to 0 resistance. Similarly, a current control element such as a thyristor can also freely control the current from 0 to the maximum current, so that it is difficult to control the motor start current without starting up a large-capacity motor, the electric heater furnace It is possible to provide an uninterruptible voltage variable device that can be used for various purposes such as temperature adjustment, correction of voltage drop caused by increase / decrease of load on the distribution line, and the like.

It is a schematic block diagram of the control circuit of the three-phase induction motor provided with Example 1 in the uninterruptible voltage variable device according to the present invention. It is a schematic block diagram of the other structural example of Example 1 in the uninterruptible voltage variable apparatus which becomes this invention. It is a schematic block diagram of Example 2 in the uninterruptible voltage varying apparatus which becomes this invention. It is a schematic block diagram of the other structural example of Example 2 in the uninterruptible voltage variable apparatus which becomes this invention. It is a schematic block diagram of Example 3 in the uninterruptible voltage varying device according to the present invention. It is a schematic block diagram of the other structural example of Example 3 in the uninterruptible voltage variable apparatus which becomes this invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Absent.

An uninterruptible voltage variable device according to the present invention is connected to a load driven by a three-phase power source, has an intermediate tap, one end is set to one phase in the three-phase power source via a first switch, and the other end is A main coil provided for each phase of the three-phase power supply by connecting to the neutral of the three-phase power supply directly or via a switch, and connected in parallel between the intermediate tap and the first switch in the main coil, A reactor circuit comprising: current control means for controlling current flowing to substantially control current between the intermediate tap and the first switch; and a control circuit for controlling current flow by controlling the current control means. The voltage variable device used.

Among these, as the current control means, for example, a plurality of independent magnetic paths formed in a magnetic path independent from the main coil and connected in series, and connected in parallel between the intermediate tap and the first switch in the main coil. The reactor and the second switch connected in parallel corresponding to each of the plurality of independent magnetic path reactors can change the voltage in multiple stages without instantaneous interruption (hereinafter, this configuration is referred to as the first switch). Variable resistance for controlling the resistance value by an actuator such as a solenoid actuator, a servo motor, a pilot motor (hereinafter referred to as a second configuration), for example, a current control element such as a triac or a thyristor (hereinafter referred to as a configuration). This configuration is referred to as a third configuration).

The control circuit closes the first switch when the switch is provided between the main coil and the neutral of the three-phase power supply, and closes the first switch when the switch is not provided. And a power supply to the load through a reactor between the first switch and the first switch. At this time, in the case of the first configuration using the independent magnetic path reactor as the current control means, by opening all the second switches, the reactor between the intermediate tap and the first switch in the main coil, and the parallel A voltage drop occurs due to the independent magnetic path reactor connected to, and the voltage with the voltage drop is applied to the load. In the case of the second configuration using a variable resistor, the variable resistor is set to the maximum resistance value, and in the case of the third configuration using a current control element such as a triac or thyristor, the current control element is set to a state in which no current flows. Similarly, the voltage dropped by the reactor between the intermediate tap and the first switch in the main coil can be supplied to the load.

For example, when the load is an induction motor, the starting torque increases and the starting current decreases when the rotational speed increases. Therefore, the control circuit detects this, and the first configuration using an independent magnetic path reactor as the current control means In the case of, one of the second switches connected in parallel to the independent magnetic path reactor is closed. Then, since there is no single independent magnetic path reactor, the voltage supplied to the load increases accordingly. In the case of the second or third configuration, the resistance value of the variable resistor is decreased or the value of the current flowing through the current control element is increased according to the current value detected by the control circuit. The voltage to be increased can be increased.

The second switch connected in parallel to the independent magnetic path reactor is sequentially closed, or the resistance value of the variable resistor is sequentially reduced to 0, the current value flowing through the current control element is sequentially maximized, and so on. By increasing the voltage applied to the induction motor continuously or continuously, and finally applying the power supply voltage of 100%, the induction motor is started in a state where the current is suppressed at a low voltage at the start, and the rotation speed As the voltage increases and the current decreases, the applied voltage can be increased sequentially. Therefore, it is not necessary to prepare a power supply corresponding to a large starting current generated when a power supply voltage is directly applied. Further, since the load and the power source are not cut off, there is no problem that a spark is generated at the time of start-up or switching of operation and the contact is damaged. Furthermore, if the resistance of the current control means is set to 0, there is no voltage drop and energy is not wasted.

FIG. 1 is a schematic block diagram of a control circuit of a three-phase induction motor having Example 1 as the first configuration described in the outline in an uninterruptible voltage varying device according to the present invention. In FIG. 1, reference numeral 10 denotes an uninterruptible voltage variable device according to the present invention.

Reference numerals

12 and 14 denote intermediate phase taps 16 connected to an induction motor 18 as a load, and one end of a three-phase power source via a first switch SW1. 20 is a main coil provided for each phase of the three-phase power source, with the other end connected to the neutral 22 of the three-phase power source via the fourth switch SW4. Reference numerals 24 ₁ and 24 ₂ are formed of magnetic paths independent of the main coil and connected in series, and a plurality of independent magnetic path reactors connected in parallel to the main coil 12, SW 2 ₁ and SW 2 ₁ are independent magnetic paths. A second switch SW3 provided corresponding to the reactors 24 ₁ and 24 ₂ is a switch for directly connecting each phase of the three-phase power source 20 to the induction motor 18 as a load. 26 is a control circuit that controls the uninterruptible voltage variable device, 28 is a current detector that detects the current flowing through the coil of the

induction motor

18, 30 is a voltage detector that detects the voltage of the three-

phase power source

20, and 32 is induction. It is a rotation speed detector that detects the rotation speed of the motor 18. In the uninterruptible voltage varying device according to the first embodiment shown in FIG. 1, the case where two independent magnetic path reactors 24 and two second switches SW2 are provided is shown. It is obvious that it is good, and in that case, the voltage applied to the induction motor 18 can be controlled more finely. Further, each of the switches SW1 to SW4 may be constituted by a relay or a semiconductor switch.

In the first embodiment of the uninterruptible voltage varying device according to the present invention configured as described above, the independent magnetic path reactors 24 ₁ and 24 ₂ connected in series and connected in parallel to the main coil 12 and the main coil 12, lowering the voltage of the three-phase power source 20, for example, about 50%, about 80% when the independent magnetic paths reactor 24 ₁ is short-circuited by closing the second switch SW2 _1, second switch SW2 ₂ also when short-circuit _{is also} independent magnetic path reactor 24 is closed, i.e. in the state in which the main coil 12 was also short-circuited, the main coil 12 as 100% of the voltage applied to the induction motor 18, independent magnetic paths reactor 24 _1, to select the 24 value of _2.

Then, when starting the induction motor 18, the control circuit 26 first opens the second switch SW2 and the third switch SW3 (OFF state), and first, the neutral 22 of the three-phase power source 20 in the

main coils

12, 14. The fourth switch SW4 on the side is closed (ON), and then the first switch SW1 on the power supply 20 side is closed. Then, the induction motor 18 is started in a state in which a voltage of about 50% of the three-phase power source 20 is applied and the current is suppressed by the independent magnetic path reactors 24 ₁ and 24 ₂ connected in parallel with the main coil 12. The

When the rotational speed of the induction motor 18 increases, the starting torque increases and the starting current decreases. Therefore, the control circuit 26 detects this with the rotational speed detector 32 and the current detector 28 to obtain a predetermined current. when, or when the load of the induction motor 18 which also has passed predetermined time if known beforehand, the second switch SW2 ₁ Close. Then the short-circuited independently magnetic path reactor 24 _1, the induction motor 18 from correspondingly reactor is reduced, 80% of the voltage of the voltage of three-phase power supply 20 as described above is applied.

As a result, the induction motor 18 is accelerated and the torque increases, but the current flowing therewith decreases. Therefore, the control circuit 26 detects this with the rotation speed detector 32 and the current detector 28, and determines the predetermined number. After a two current values, or induction time when the load of the motor 18 is known in advance that the second time period has elapsed also a predetermined, second switch SW2 ₂ Close. Then independent magnetic path reactor 24 ₂ are short-circuited, at the same time from the main coil 12 is also short-circuited, the voltage of the three-phase power supply 20 as described above to the induction motor 18 is directly (i.e. 100% of the voltage) applied.

Therefore, the control circuit 26 opens the fourth switch SW4 to disconnect between the main coil 14 and the neutral 22 of the three-phase power supply, and then closes the third switch SW3 and opens the first switch SW1. That is, the rated voltage is applied to the induction motor 18 by the three-phase power source 20, thereby operating the induction motor 18 at a rated operation.

As described above, in the first embodiment of the uninterruptible voltage varying device according to the present invention, the independent magnetic path reactors 24 ₁ and 24 ₂ connected in series and connected in parallel to the main coil 12 and the main coil 12 are used as induction motors. 18 at the start of lowering the voltage of the three-phase power source 20, for example, about 50% to sequentially close is an independent magnetic path reactors ₂₄ 1, 24 ₂ of the second switch _SW2 provided in parallel in correspondence to 1, SW2 ₂ For example, the voltage can be increased sequentially without cutting off the load and the power source in accordance with the current flowing through the induction motor 18. Therefore, there is no problem that a spark is generated at the time of start-up or operation switching and the contact is damaged. If all the second switches SW2 are closed, the main coil 12 is also short-circuited, and the load can be driven with 100% of the power supply voltage, so that energy is not wasted.

In FIG. 1, the case where the uninterruptible voltage varying device according to the present invention is used for the control circuit of the three-phase induction motor has been described. However, when the three-phase induction motor is driven at the rated voltage, it is continuously driven thereafter. In many cases, the third switch SW3 is connected directly to the three-phase power source 20. However, when it is used for energy saving control during light load operation, temperature adjustment of the electric heater furnace, correction of voltage drop due to increase or decrease of distribution line load, etc., the

main coils

12, 14 and the independent magnetic path reactor 24 are removed from the load. Without being completely separated, the independent magnetic path reactors 24 ₁ and 24 ₂ can be re-introduced according to the situation so that the adjustment can be performed.

FIG. 2 is a schematic block diagram of another configuration example of the first embodiment, which is the first configuration of the uninterruptible voltage variable device according to the present invention configured according to such a concept. FIG. 2 shows only a block for one phase in the uninterruptible voltage varying device according to the present invention, and the control circuit 26 in FIG. 1 is omitted. Reference numeral 40 denotes a power connection end, and reference numeral 42 denotes a load connection end. Further, there is no wiring from the third switch SW3 in FIG. 1 and the power connection terminal 40 to the connection terminal 42 to the load, and the connection terminal 42 to the load is provided from the main coil 12 via the intermediate tap 16. . Furthermore, there is no fourth switch SW4, and the main coil 14 is directly connected to the neutral 22 of the three-phase power source. Other configurations are the same as those in FIG.

In the circuit of FIG. 2, the control circuit 26 closes the first switch SW1 on the power supply 40 side with the second switch SW2 opened (OFF state). Then, the independent magnetic path reactors 24 ₁ and 24 ₂ connected in parallel with the main coil 12 are applied to the load connection end 42 with a voltage of, for example, about 50% of a three-phase power source (not shown) to suppress the current. It is started in the state.

The electric heater furnace has a low resistance when it is cold, and when it is warmed, the resistance becomes high and the current decreases. Therefore, the control circuit (not shown) detects the current with a current detector (not shown) and determines it in advance. when turned current was, or when it even has elapsed predetermined time is when the load is known in advance, the second switch SW2 ₁ Close. Then the short-circuited independently magnetic path reactor 24 _1, the load connection terminal 42 from correspondingly reactor is reduced, for example, 80% of the voltage of the voltage of three-phase power supply 20 is applied.

Therefore, a high voltage is applied to the load (not shown), and the electric heater furnace and the like are further heated. However, the current flowing therewith decreases, so the control circuit (not shown) has its current / current detector 28. in detecting, when turned to a second current value determined in advance, or when if the load is known in advance that the second time period has elapsed also a predetermined, second switch SW2 ₂ Close. Then the independent magnetic path reactor 24 ₂ short, at the same time because the main coil 12 is also short-circuited, as with said load connection terminal 42, the voltage of the three-phase power supply which is not shown as it is (i.e. 100% of the voltage) applied Is done.

In this state, for example when it is desired to lower the voltage applied like electric heater furnace, opening the second switch SW2 _2. Then, since the independent magnetic path reactor 24 ₂ and the main coil 12 are inserted into the circuit and the reactor is restored, the voltage at the load connection end 42 is lowered, and the current flowing through the load (not shown) is also lowered accordingly. Therefore, for example, the temperature of an electric heater furnace or the like can be controlled according to the situation without disconnecting the load and the power source.

In this way, the independent magnetic path reactor 24 ₁ can also be used for energy saving control during light load operation, temperature adjustment of the electric heater furnace, and correction of voltage drop due to increase / decrease of load on the distribution line. , it can be allowed to be re-charged with 24 _2, as adjustment is possible.

FIG. 3 is a schematic block diagram of the second embodiment, which is a second configuration of the uninterruptible voltage variable device according to the present invention, and FIG. 4 is a schematic block diagram of another configuration example of the second embodiment. 3 is a circuit corresponding to FIG. 1 of the first embodiment and FIG. 4 is also a circuit corresponding to FIG. 2. As described in FIGS. 1 and 2, FIG. In the case of voltage operation, FIG. 4 is a circuit used for energy saving control during light load operation, temperature adjustment of the electric heater furnace, correction of voltage drop due to increase or decrease of load on the distribution line, and the like.

In the first embodiment shown in FIGS. 1 and 2, the current control means described in the outline of the present invention is formed by a magnetic path independent from the main coil 12 and connected in series. A plurality of independent magnetic path reactors 24 ₁ and 24 ₂ connected in parallel between the intermediate tap 16 and the first switch SW1, and a _second connected in parallel corresponding to each of the plurality of independent magnetic path reactors. With the switch SW2, the voltage can be varied in multiple stages without interruption.

The second embodiment of the present invention shown in FIG. 3 and FIG. 4 and the third embodiment of the present invention shown in FIG. 5 and FIG. First, in the second embodiment of the present invention shown in FIGS. 3 and 4, the resistance value can be changed by an actuator such as a solenoid actuator, a servo motor, or a pilot motor as the current control means described in the outline of the present invention. The current is controlled by the variable resistor 46.

In the following description (FIGS. 3, 4, 5, and 6), as in FIG. 2, only the block for one phase in the uninterruptible voltage variable device according to the present invention is shown. The control circuit 26 is omitted. 40 is a power connection end and 42 is a load connection end, which are the same as those in FIG. 2. In FIGS. 3 and 5, the third switch SW 3 in FIG. 1 is connected to the load connection end 42 from the power connection end 40. In FIG. 4 and FIG. 6, there is no wiring from the third switch SW3, the power connection terminal 40 to the connection terminal 42 to the load, and from the main coil 12 to the load via the intermediate tap 16. The connection end 42 is provided. 3 and 5, the fourth switch SW4 in FIG. 1 is present, and the main coil 14 is connected to the neutral 22 of the three-phase power source via the fourth switch SW4. Then, the fourth switch SW3 does not exist, and the main coil 14 is directly connected to the neutral 22 of the three-phase power source.

First, in the second embodiment shown in FIG. 3, a control circuit (not shown) changes the resistance value of the variable resistor 46 by an actuator such as a solenoid actuator, a servo motor, or a pilot motor as described above. The other operations are the same as those in the first embodiment shown in FIG. 1. For example, when starting an induction motor (not shown) as a load, the control circuit 26 sets the variable resistor 46 to the maximum resistance. Then, the fourth switch SW4 on the neutral 22 side of the three-phase power supply 20 in the

main coils

12 and 14 is closed (ON), and then the first switch SW1 on the power connection end 40 side is closed. Then, the load connection end 42 is activated in a state in which a voltage of, for example, about 50% of the three-phase power source is applied and the current is suppressed by the variable resistor 46 connected in parallel with the main coil 12.

A control circuit (not shown) detects that the current has dropped by a current detector (not shown), and a solenoid actuator, servo motor, pilot motor, etc. that changes the resistance value of the variable resistor 46 according to the current value. The actuator is driven, the resistance value of the variable resistor 46 is gradually decreased to increase the flowing current, and this is continued until the resistance value of the variable resistor 46 becomes zero. Therefore, a voltage corresponding to the voltage appears at the load connection end 42, and the load (not shown) is finally driven at the rated voltage without causing a large amount of current to flow.

For this reason, the control circuit (not shown) opens the fourth switch SW4 in this state, disconnects between the main coil 14 and the neutral 22 of the three-phase power source, and then closes the third switch SW3 and turns on the first switch SW1. open. That is, a rated voltage is applied to the load by a three-phase power source, and thereby the load is rated.

This is the same in the case of the schematic block diagram of another configuration example of the second embodiment, which is the second configuration of the uninterruptible voltage varying device according to the present invention shown in FIG. In the circuit of FIG. 4, a control circuit (not shown) closes the first switch SW <b> 1 at the power connection terminal 40 with the variable resistor 46 as the maximum resistance. Then, for example, a voltage of about 50% of a three-phase power source (not shown) is applied to the load connection end 42 by the variable resistor 46 connected in parallel with the main coil 12 and the current is suppressed. .

Then, a control circuit (not shown) detects that the current is decreasing by a current detector (not shown), and the resistance value of the variable resistor 46 is gradually decreased so as to correspond to the current. Controls actuators such as solenoid actuators, servo motors and pilot motors not shown. When the resistance value of the variable resistor 46 becomes 0, the corresponding power supply voltage appears at the load connection end 42. Therefore, the load (not shown) does not flow a large amount of current due to the voltage, and finally reaches the rated voltage. Driven.

In this state, for example, when it is desired to decrease the voltage applied to the electric heater furnace, the actuator such as a solenoid actuator, servo motor, pilot motor, etc. (not shown) is controlled and the resistance value of the variable resistor 46 is increased. Since the main coil 12 is also inserted into the circuit and the reactor is restored, the voltage at the load connection end 42 is lowered, and accordingly, the current flowing through the load (not shown) is also lowered. Therefore, for example, the temperature of an electric heater furnace or the like can be controlled according to the situation without disconnecting the load and the power source.

This is also the case with the third embodiment of the present invention shown in FIGS. 5 and 6. In this third embodiment, the variable resistor 46 in the second embodiment is used as a current control element 48 such as a triac or thyristor. Is. Therefore, a control circuit (not shown) controls the current flowing by controlling these current control elements 48, and controls the voltage at the load connection end 42. Except for this point, the operation is the same as in the second embodiment. The description is omitted because it is exactly the same.

According to the second and third embodiments, the current flowing through the main coil 12 can be continuously and freely controlled steplessly, without causing a problem that it is difficult to control the motor starting current. It is possible to provide an uninterruptible voltage variable device that can be used for various purposes such as starting a motor with a capacity, adjusting the temperature of an electric heater furnace, and correcting a voltage drop caused by an increase or decrease in load on a distribution line.

As described above, the uninterruptible voltage variable device according to the present invention does not cause a problem that a spark occurs at the time of start-up or operation switching and damage of the contact occurs. The voltage can be varied at the same time, energy consumption is unnecessarily consumed, and it is difficult to control the motor start current, without starting up a large-capacity motor, adjusting the temperature of the electric heater furnace, and adjusting the load on the distribution line. It can also be used for correction of voltage drop due to increase / decrease, etc., and brings about a great effect.

The present invention solves various problems such as starting a large-capacity motor, adjusting the temperature of an electric heater furnace, and correcting a voltage drop due to an increase or decrease in load on a distribution line. It can be carried out continuously without interruption and in multiple stages without interruption.

DESCRIPTION OF SYMBOLS 10 Uninterruptible voltage

variable apparatus

12, 14 Main coil 16 Middle tap 18 Induction motor 20 Three-phase power supply 22 Neutral of three-phase power supply 24 Independent magnetic circuit reactor 26 Control circuit 28 Current detector 30 Voltage detector 32 Rotation speed detector 40 Power connection end 42 Load connection end 46 Variable resistor 48 Current control element

Claims

An intermediate tap connected to a load driven by a three-phase power source, one end connected to one phase in the three-phase power source via the first switch, and the other end connected to the neutral of the three-phase power source A main coil provided for each phase of the power supply;
Current control means connected in parallel between the intermediate tap and the first switch in the main coil and controlling a current flowing to control a current flowing between the intermediate tap and the first switch;
A control circuit for controlling the current control means,
The control circuit controls the current control means in correspondence with the current flowing through the load in a state where the first switch is closed, and controls the current flowing between the intermediate tap and the first switch in the main coil. An uninterruptible voltage variable device, characterized in that the device is configured to perform.
The current control means is formed of a magnetic path independent of the main coil and connected in series, and a plurality of independent magnetic path reactors connected in parallel between the intermediate tap and the first switch in the main coil,
A second switch connected in parallel corresponding to each of the plurality of independent magnetic path reactors,
The control circuit sequentially closes the second switch in response to the current flowing through the load in a state where the first switch is closed, and generates a current flowing between the intermediate tap and the first switch in the main coil. The uninterruptible voltage varying device according to claim 1, which is configured to control.
The current control means is a variable resistance whose resistance value is controlled by an actuator,
The control circuit controls the actuator in response to a current flowing through the load in a state in which the first switch is closed, and controls a resistance value of the variable resistor to control an intermediate tap and a first in the main coil. 2. The uninterruptible voltage varying device according to claim 1, wherein a current flowing between the switches is controlled.
The current control means is a current control element;
The control circuit controls the current control element in response to a current flowing through the load in a state where the first switch is closed, and controls a current flowing between an intermediate tap in the main coil and the first switch. The uninterruptible voltage varying device according to claim 1, wherein the uninterruptible voltage varying device is configured.
A third switch that is closed by the control circuit and connects the power source and the load in a state in which no current flows between the intermediate tap and the first switch in the main coil by the current control means; The uninterruptible voltage varying device according to any one of claims 1 to 4.