JP4425004B2 - Voltage regulator for AC equipment - Google Patents

Description

  The present invention relates to a voltage regulator for an AC device that adjusts a voltage applied when the AC device is started.

  In an AC device whose main component is reactance, for example, an induction motor, as shown in FIG. 4, the starting current decreases as the rotational speed increases, and the reduction rate increases as the rotational speed approaches 100% during operation. On the other hand, the torque has a starting characteristic that rapidly increases as the rotational speed approaches 100% during operation, as shown in FIG. As understood from the starting characteristic curves shown in FIG. 4 and FIG. 5, when a voltage of 100% of the rated voltage is applied from the beginning when the AC device is started, an excessive current flows and an excessive torque is generated. May be adversely affected on machines that use a power source.

  In order to avoid such adverse effects, when starting AC equipment, a starting method is adopted in which a voltage lower than the initially rated voltage is applied and the voltage is increased in order. Devices, start compensators, reactor starters and the like are known.

FIG. 6 shows an example of the configuration of a voltage regulator for an AC device using a reactor starter. Reference numeral 1 denotes an iron core that forms a closed magnetic circuit, and three upper, middle, and lower yokes are arranged in parallel. Two leg bars are juxtaposed to each other to form a closed-loop magnetic circuit. The first primary winding T ₁ is wound on one leg of which is located between the upper yoke and the middle yoke, the first secondary winding T ₁₁ is wound around the other leg of. The second primary winding T ₂ is wound on one leg of which is located between the middle yoke and the lower yoke, the second secondary winding T ₂₂ is wound around the other leg of .

First secondary winding T ₁₁ is wound around the first primary winding T ₁ and opposite, the first primary winding T ₁ and connected in parallel via the switch SW ₁ such as an electromagnetic contactor Has been. The second secondary winding T ₂₂ Similarly, wound in a second primary winding T ₂ and opposite, a second primary winding T ₂ via the switching element SW ₂ such as an electromagnetic contactor Connected in parallel. The first primary winding T ₁ and the second primary winding T ₂ is connected in series, one end of the series circuit of a primary winding connected in series to the AC power source through a switch SW such as an electromagnetic contactor The other end is connected to an AC device 2 such as an induction motor.

When operating the AC device 2 with the voltage regulator configured as described above, the switching element SW is turned on with the switches SW ₁ and SW ₂ opened. By this charging, power is supplied to the AC device 2 through a series circuit of the primary windings T ₁ and T ₂ . That is, a low voltage of, for example, 50% of the rated voltage dropped in the series circuit of the primary windings T ₁ and T ₂ with respect to the power supply voltage is applied to the AC device 2, and the current flowing through the AC device 2 as shown in FIG. As shown in FIG. 5, the torque generated by the AC device 2 is suppressed. The applied current flowing through the AC device 2 turns on the switch SW ₂ at the timing of rapid decrease. Magnetic flux this turned a current flows through the second secondary winding T _22, generated by the current, to cancel the magnetic flux that is generated in the second primary winding T _2, the second primary winding T ₂ and the reactance extinguished the second secondary winding T _22, to reduce the divided voltage drop, the voltage applied to the AC device 2 is increased to 70% of the rated voltage, as shown in FIG.

With this voltage rise, the current of the AC device 2 increases according to the characteristics when a voltage of 70% of the rated voltage is applied as shown in FIG. 4, and the torque also increases as shown in FIG. The current and torque are reduced according to the characteristics when a voltage of 70% of the rated voltage is applied. At a predetermined timing during the increase in torque in decrease of the current turning on the switching element SW _1. The charged at a current flows through the first secondary winding T _11, the magnetic flux generated by the current, to cancel the magnetic flux that is generated in the first primary winding T _1, the first primary winding T ₁ and the reactance extinguished the first secondary winding T _11, to reduce the divided voltage drop further, raising the voltage applied to the AC device 2 to 100% of the supply voltage of the rated voltage.

As the voltage rises, the current of the AC device 2 increases in accordance with the characteristics when 100% of the rated voltage is applied as shown in FIG. 4, and the torque also increases as shown in FIG. Then, according to the characteristics when 100% of the rated voltage is applied, the current and torque decrease, and the operation state is shifted. In addition, although the above description is a case where the voltage applied to AC apparatus 2 is adjusted in three steps, for example, 50%, 70%, and 100% of the rated voltage, a plurality of reactor starters are provided and adjusted in multiple steps. You can also.
Japanese Patent Publication No. 44-29503

  In the voltage adjustment by the reactor starter as described above, it is possible to step up the voltage step by step at an appropriate timing without interrupting the power supply to the AC device. There is an advantage that the impact applied to the AC device can be reduced. However, there is a problem that current always flows through the reactor, and this current generates dew heat (resistance heat generation), which may consume more energy than necessary.

  The problem to be solved by the present invention is to reduce the energy consumed in such a voltage regulator using a reactor starter and to solve such a problem.

  A second aspect of the present invention is a voltage regulator for an AC device, comprising: a first reactor; a primary winding; and a secondary winding that cancels the magnetic flux generated in the primary winding via the first switch. The first reactor and the primary winding of the second reactor are connected in series to form a reactor series circuit, and one end of the reactor series circuit is used as a power source and the other end is AC. A magnetic flux generated in the primary winding by connecting the device and providing a second switch in parallel with the reactor series circuit and turning on the first switch at a predetermined timing after voltage application to the AC device. And the reactor series circuit is short-circuited by turning on the second switch at a predetermined timing after the cancellation.

  The voltage regulator for an AC device according to the present invention, when operating the AC device, uses one end of a reactor series circuit in which a first reactor and a primary winding of a second reactor are connected in series to the AC device as a power source, etc. With the end connected to the AC device and the first and second switches open, apply a low voltage, for example, about 50% lower than the power supply voltage to the AC device, and then turn on the first switch. Then, the reactance of the second reactor is extinguished and the voltage applied to the AC device is increased to, for example, 70% of the rated voltage, and then the second switch is turned on to short-circuit the reactor series circuit and supply the AC device with the power supply voltage. The voltage of 100% is applied to shift to the operating state of the AC device.

  Therefore, the voltage can be boosted step by step at an appropriate timing without interrupting the power supply to the AC device, so that the fluctuation range of the inrush current and torque generated at the time of the voltage boost is small, and the impact on the AC device is reduced. In addition, in the operating state, the winding series is short-circuited, and there is no dew heat (resistance heat generation) generated in the reactor series circuit, so that energy saving can be achieved.

  In a voltage regulator that adjusts the voltage applied to the AC device by reducing the reactance step by step, the reactor connected to the AC device is short-circuited when the AC device is moved to the operating state for the purpose of reducing energy consumption. It was realized.

  FIG. 1 is a circuit configuration diagram of an AC device voltage regulator according to an embodiment of the present invention, and FIG. 2 is a timing chart of the AC device voltage regulator shown in FIG. The AC device shown in this embodiment is an induction motor having characteristics along the characteristic curves shown in FIGS. 4 and 5, and has a rated voltage of 50 as in the conventional voltage regulator for AC devices shown in FIG. 6. It is a case where it adjusts in 3 steps,% (or 60%), 70%, and 100%.

In Figure 1, L ₁ is constituted by a first reactor, in the present embodiment is omitted first secondary winding T ₁₁ shown in FIG. 6, only the first of the primary winding T _1. L ₂ is a second reactor, which has a primary winding T ₂ and a secondary winding T _22, and is similar to the second primary winding T ₂ and the second secondary winding T ₂₂ shown in FIG. wound around the closed magnetic circuit iron core, the secondary winding T ₂₂ is wound around the primary winding T ₂ and opposite, are connected in parallel with the primary winding T ₂ via the switch SW ₂ such as an electromagnetic contactor ing. SW is a switch such as an electromagnetic contactor for power-on, SW ₃ is changeover switch, SW4 is a switch such as an electromagnetic contactor, 2 AC devices (squirrel-cage induction motor in this example).

The first reactor L ₁ and the primary winding T ₁ of the second reactor L ₂ are connected in series, one end of the series circuit is connected to an AC power supply via the switch SW ₃ and switch SW of the power supply is turned on The other end is connected to the AC device 2. Switch SW ₄ is connected in parallel with the circuit consisting of the series circuit and the changeover switch SW ₃ of the reactor. The first reactor L ₁ has a tap for setting the voltage initially applied to the AC device 2 to 50% or 60% of the power supply voltage, and the changeover switch SW ₃ switches the tap to connect to the power source. Is.

When operating thus constituted a voltage regulator AC device 2 connects the switch SW ₃ in the first 50% of the tap of the reactor L ₁ at 50% of the applied power supply voltage, switch SW _2, SW ₄ in the open state, the switch SW is turned as shown by t ₁ in FIG. The turned in through the first reactor L ₁ and second reactor the series circuit of the primary winding T ₂ of the reactor L ₂ into AC device 2 power is supplied. That is, a low voltage of 50% of the power supply voltage dropped in the reactor series circuit with respect to the power supply voltage is applied to the AC device 2, and the current flowing through the AC device 2 as shown in FIG. 4 and the AC device as shown in FIG. 2 suppresses the torque generated.

Thereafter, before the timing when the current flowing through the AC device 2 rapidly decreases, turning on the switch SW ₂ as shown in t ₂ of FIG. The charged at a current flows through the second reactor of the secondary winding T _22, the magnetic flux generated by the current, to cancel the magnetic flux that is generated in the primary winding T _2, to eliminate the reactance of the second reactor Accordingly, the voltage drop is reduced, and the voltage applied to the AC device 2 is increased to 70% of the rated voltage as shown in FIG.

With this voltage rise, the current of the AC device 2 increases according to the characteristics when a voltage of 70% of the rated voltage is applied as shown in FIG. 4, and the torque also increases as shown in FIG. The current and torque are reduced according to the characteristics when a voltage of 70% of the rated voltage is applied. At a predetermined timing during the increase in torque in decrease of the current, turning on the switch SW ₄ as indicated by t ₃ in Figure 2. The circuit consisting of a reactor the series circuit and the changeover switch SW ₃ in turned on short, 100% of the power supply voltage into an AC device 2 is applied, the process proceeds to the operating state. When stopping the operation, the switching elements SW, SW ₂ and SW ₄ are opened as indicated by t ₄ in FIG. 2, and the system waits until the next operation starts in this state. The basic operation is the same even when operating the AC device 2 connects the switch SW ₃ in the first 60% of the tap of the reactor L ₁ to 60% of the applied power supply voltage. Moreover, the reactor shown in FIG. 6 can be added and the voltage applied to AC apparatus 2 can also be adjusted in multistage.

FIG. 3 is a circuit configuration diagram of an AC device voltage regulator suitable for an AC device operating at a high voltage. The difference from the circuit configuration of the voltage regulator shown in FIG. 1 is that the secondary winding T of the second reactor L ₂ is different. ₂₂ not connected to the primary winding _{T 2} of the second reactor _{L 2,} grounding the intermediate secondary winding _{T 22,} the provided switch SW ₅ for short-circuiting between both ends, Fig. 1 the switch SW ₅ in that power up in the same timing as the switch SW ₂ of the circuit configuration of the voltage regulator shown in, but with enhanced insulation between the windings. Thus the introduction of the switch SW ₅ be constituted, cancel the magnetic flux that is generated in the primary winding T _2, it is possible to eliminate the second reactance of the reactor L _2. The overall operation of this embodiment is the same as that of the voltage regulator shown in FIG. 1, and therefore detailed description thereof is omitted here.

The above is described by taking an induction motor as an example, but an AC device is not limited to an induction motor, and can be applied as reactance adjustment means for various AC devices such as an induction coil of an electric induction furnace.

It is a circuit block diagram of the voltage regulator for alternating current devices which concerns on the Example of this invention. Example 1 It is a timing chart which shows operation | movement of the voltage regulator for alternating current devices shown in FIG. It is a circuit block diagram of the voltage regulator for alternating current devices which concerns on the other Example of this invention. (Example 2) It is a starting current characteristic curve figure of AC apparatus. It is a starting torque characteristic curve figure of AC apparatus. It is a circuit block diagram of the conventional voltage regulator for alternating current devices.

Explanation of symbols

1 core 2 AC devices L ₁ first reactor L ₂ second reactor T ₂ second primary winding T ₂₂ second reactor of the reactor of the secondary winding SW running switch _{SW 2,} SW 4, SW ₅ Switch SW ₃ selector switch

Claims (3)

  A first reactor, and a second reactor comprising a primary winding and a secondary winding that cancels the magnetic flux generated in the primary winding via a first switch, and the first reactor And a primary winding of the second reactor are connected in series to form a reactor series circuit, one end of the reactor series circuit is connected to a power source, the other end is connected to an AC device, and in parallel with the reactor series circuit The second switch is provided, and the first switch is turned on at a predetermined timing after voltage application to the AC device to cancel the magnetic flux generated in the primary winding, and at the predetermined timing after the cancellation A voltage regulator for AC equipment, wherein a second switch is turned on to short-circuit the reactor series circuit.   The secondary winding of the second reactor is connected in parallel with the primary winding through a switch, and the magnetic flux generated in the primary winding is canceled by turning on the switching element. Item 2. The voltage regulator for an AC device according to Item 1.   A plurality of the second reactors are provided, and the primary windings of the respective second reactors are connected in series, and the secondary windings of the first reactor are sequentially inserted at a predetermined timing so that the primary windings The voltage regulator for an AC device according to claim 1 or 2, wherein the generated magnetic flux is sequentially canceled.

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