Voltage regulator

Abstract

To provide a voltage regulator with a small maximum effective value of an AC current flowing through a switching device.SOLUTION: In a voltage regulator 1, two series transformers 3u and 3v each having a primary winding 31 and a secondary winding 32 are arranged. Each of the two secondary windings 32 is placed halfway between two power distribution lines U and V. An effective value of an AC voltage between two of three taps T1, T2, and T3 is adjusted according to an effective value of an AC voltage between the two power distribution lines U and V. A switching device 50a switches the tap to which first and second terminals of the primary winding 31 of the series transformer 3u are electrically connected, among the three taps T1, T2, and T3. A switching device 50b switches the tap to which first and second terminals of the primary winding 31 of the series transformer 3v are electrically connected, among the three taps T1, T2, and T3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a voltage regulator.

Background Art

[0002] Patent Document 1 discloses a voltage regulator that adjusts the effective value of an AC voltage between two distribution lines. In this voltage regulator, a tapped winding to which a plurality of taps are connected is arranged. Two transformers having a primary winding and a secondary winding are arranged. Each of the two secondary windings is arranged midway between the two distribution lines. The switcher switches the tap to which at least one of the four terminals of the two primary windings is electrically connected among the plurality of taps.

[0003] An AC voltage is applied to the primary winding of each of the two transformers from two taps among the plurality of taps connected to the tapped winding via the switcher. As a result, the effective value of the AC voltage between the two distribution lines increases or decreases. When the switcher switches the tap to which at least one of the aforementioned four terminals is electrically connected, the AC voltage applied to the two primary windings is changed. As a result, the AC voltage output to the outside is changed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 states that, regarding the AC current flowing through a changeover switch, the upper limit of the allowable effective value must be greater than or equal to the maximum effective value of the AC current output from the two taps connected to the tap winding. Changeover switches with a large upper limit are expensive. If it is not possible to manufacture or procure a changeover switch with an upper limit that slightly exceeds the maximum effective value, an expensive changeover switch with a significantly larger upper limit will be used, increasing the manufacturing cost of the voltage regulator.

[0006] This disclosure has been made in view of the above circumstances, and its purpose is to provide a voltage regulator that has a small maximum effective value of the alternating current flowing through the switch. [Means for solving the problem]

[0007] A voltage regulator according to one aspect of the present disclosure is a voltage regulator for adjusting the effective value of an AC voltage, comprising: a tap winding to which a plurality of taps are connected; a plurality of transformers having a primary winding and a secondary winding; and a plurality of switches for switching the tap to which a specific terminal of the primary winding is electrically connected among the plurality of taps, wherein the effective value of the AC voltage between two taps among the plurality of taps is adjusted according to the effective value of the AC voltage between two distribution lines, each of the plurality of secondary windings of the plurality of transformers is located in the middle of the plurality of distribution lines, and the specific terminal corresponding to each switch is different from the specific terminal corresponding to the remaining switches. [Effects of the Invention]

[0008] According to the above embodiment, the maximum effective value of the alternating current flowing through the switch is small. [Brief explanation of the drawing]

[0009] [Figure 1] This is a circuit diagram of the voltage regulator in Embodiment 1. [Figure 2] This is a block diagram showing the main components of a switch. [Figure 3] This is a diagram illustrating the operation of two series transformers. [Figure 4]This is the circuit diagram for the upper switch circuit. [Figure 5] This is a circuit diagram of the voltage regulator in Embodiment 2. [Figure 6] This is a circuit diagram of the voltage regulator in Embodiment 3. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below with reference to the drawings illustrating its embodiments. (Embodiment 1) Figure 1 is a circuit diagram of the voltage regulator 1 in Embodiment 1. An AC power source 2 is connected between two power lines U and V. The AC power source 2 is, for example, a substation, and outputs an AC voltage to the voltage regulator 1 via the two power lines U and V. The voltage regulator 1 outputs an AC voltage via the two power lines U and V and a neutral line Q. The voltage regulator 1 adjusts the effective value of the AC voltage between the power lines U and V on the output side based on the effective value of the AC voltage between the power lines U and V on the input side.

[0011] Voltage regulator 1 comprises two series transformers 3u and 3v, a regulating transformer 4, and a switching device 5. In each of the series transformers 3u and 3v, a primary winding 31 and a secondary winding 32 are wound around an iron core (not shown). In the regulating transformer 4, a single winding 40 is wound around an iron core (not shown). The iron core is magnetic. Three taps T1, T2, and T3 are connected to the single winding 40. Taps T1 and T3 are connected to each of the two terminals of the single winding 40. Tap T2 is connected in the middle of the single winding 40. The number of turns of the single winding 40 between taps T1 and T2 is different from the number of turns of the single winding 40 between taps T2 and T3. The single winding 40 functions as a tap winding.

[0012] One terminal of each of the two secondary windings 32 is connected to the input distribution lines U and V. The other terminal of each of the two secondary windings 32 is connected to the output distribution lines U and V. A single winding 40 is connected between the output distribution lines U and V. Taps T1 and T3 are located on the distribution line U and V sides, respectively. One terminal of the neutral wire Q is connected to the middle of the single winding 40. With respect to the single winding 40, the number of turns between distribution line U and neutral wire Q is the same as the number of turns between distribution line V and neutral wire Q.

[0013] The switching device 5 has two switches 50a and 50b and a control unit 51. Figure 2 is a block diagram showing the main components of the switches 50a and 50b. Switch 50a has three upper switch circuits A1, A2, and A3, three lower switch circuits B1, B2, and B3, a tangle switch circuit C, and a tangle resistor R.

[0014] One terminal each of the upper switch circuits A1, A2, and A3 is connected to taps T1, T2, and T3. One terminal each of the lower switch circuits B1, B2, and B3 is connected to taps T1, T2, and T3. The other terminals of the upper switch circuits A1, A2, and A3 are connected to the first terminal of the primary winding 31 of the series transformer 3u. The other terminals of the lower switch circuits B1, B2, and B3 are connected to the second terminal of the primary winding 31 of the series transformer 3u. In Figures 1 and 2, the first and second terminals are located on the right and left sides, respectively. The entanglement switch circuit C is connected in series with the entanglement resistor R. The series circuit including the entanglement switch circuit C and the entanglement resistor R is connected between the first and second terminals of the primary winding 31 of the series transformer 3u.

[0015] The changeover switch 50b is configured similarly to the changeover switch 50a. Regarding the changeover switch 50b, one terminal each of the upper switch circuits A1, A2, and A3 is connected to taps T1, T2, and T3. One terminal each of the lower switch circuits B1, B2, and B3 is connected to taps T1, T2, and T3. The other terminals of the upper switch circuits A1, A2, and A3 of the changeover switch 50b are connected to the first terminal of the primary winding 31 of the series transformer 3v. The other terminals of the lower switch circuits B1, B2, and B3 of the switch 50b are connected to the second terminal of the primary winding 31 of the series transformer 3v. In FIGS. 1 and 2, the first terminal and the second terminal are located on the right side and the left side, respectively. A series circuit including the coupling switch circuit C and the coupling resistor R is connected between the first terminal and the second terminal of the primary winding 31 of the series transformer 3v.

[0016] The control unit 51 switches the states of the six upper switch circuits A1, A2, A3, the six lower switch circuits B1, B2, B3, and the two coupling switch circuits C of the switches 50a and 50b to a conducting state in which current can flow or a blocking state in which current flow is blocked. Each of the upper switch circuits A1, A2, A3 functions as a first switch circuit. Each of the lower switch circuits B1, B2, B3 functions as a second switch circuit.

[0017] In each of the switches 50a and 50b, usually, the state of one of the three upper switch circuits A1, A2, A3 is the conducting state, and the states of the remaining upper switch circuits are the blocking state. Similarly, in each of the switches 50a and 50b, usually, the state of one of the three lower switch circuits B1, B2, B3 is the conducting state, and the states of the remaining lower switch circuits are the blocking state.

[0018] In the two switches 50a and 50b, the states of the two upper switch circuits connected to the common tap are the same, and the states of the two lower switch circuits connected to the common tap are also the same. The common tap is one of the three taps T1, T2, and T3. The two upper switch circuits A1 of the switches 50a and 50b are connected to the tap T1. For example, when the state of the upper switch circuit A1 of the switch 50a is the conducting state, the state of the upper switch circuit A1 of the switch 50b is also the conducting state. The operation performed by the control unit 51 for the switch 50a is the same as the operation performed by the control unit 51 for the switch 50b.

[0019] The first terminal of the primary winding 31 of the in-line transformer 3u is electrically connected to the tap among the three taps T1, T2, and T3 that is connected to the upper switch circuit in the current-carrying state of the switch 50a. The second terminal of the primary winding 31 of the in-line transformer 3u is electrically connected to the tap among the three taps T1, T2, and T3 that is connected to the lower switch circuit in the current-carrying state of the switch 50a.

[0020] Similarly, the first terminal of the primary winding 31 of the in-line transformer 3v is electrically connected to the tap among the three taps T1, T2, and T3 that is connected to the upper switch circuit in the current-carrying state of the switch 50b. The second terminal of the primary winding 31 of the in-line transformer 3v is electrically connected to the tap among the three taps T1, T2, and T3 that is connected to the lower switch circuit in the current-carrying state of the switch 50b.

[0021] As described above, each of the upper switch circuit and the lower switch circuit in the current-carrying state of the switch 50a is common to the upper switch circuit and the lower switch circuit in the current-carrying state of the switch 50b. For this reason, the first terminals of the two primary windings 31 are electrically connected to a common tap. The second terminals of the two primary windings 31 are electrically connected to a common tap.

[0022] The control unit 51 changes the upper switch circuit in the current-carrying state in the switch 50a. Thereby, the switch 50a switches the tap to which the first terminal of the primary winding 31 of the in-line transformer 3u is electrically connected among the three taps T1, T2, and T3. Similarly, the control unit 51 changes the lower switch circuit in the current-carrying state in the switch 50a. Thereby, the switch 50a switches the tap to which the second terminal of the primary winding 31 of the in-line transformer 3u is electrically connected among the three taps T1, T2, and T3.

[0023] Similarly, the control unit 51 changes the upper switch circuit of the current-passing state in the changeover 50b. As a result, the changeover 50b switches the tap among the three taps T1, T2, and T3 to which the first terminal of the primary winding 31 of the series transformer 3v is electrically connected. Similarly, the control unit 51 changes the lower switch circuit of the current-passing state in the changeover 50b. As a result, the changeover 50b switches the tap among the three taps T1, T2, and T3 to which the second terminal of the primary winding 31 of the series transformer 3v is electrically connected.

[0024] The first and second terminals of the two primary windings 31 each function as specific terminals. The first terminal functions as the first specific terminal. The second terminal functions as the second specific terminal. The two specific terminals corresponding to switch 50a are different from the two specific terminals corresponding to switch 50b.

[0025] The AC voltage between the output distribution lines U and V is applied to both ends of the single winding 40. The single winding 40 applies a common AC voltage to the two primary windings 31 from two of its three taps T1, T2, and T3. The effective value of the AC voltage between two of the three taps T1, T2, and T3 is expressed as the product of the effective value of the AC voltage between the output distribution lines U and V and the turns ratio. The turns ratio is obtained by dividing the total number of turns of the single winding 40 by the number of turns of the single winding 40 between the two taps. Therefore, the effective value of the AC voltage between two of the three taps T1, T2, and T3 is adjusted according to the effective value of the AC voltage between the output distribution lines U and V. In each of the changeover devices 50a and 50b, if the flow state of the upper or lower switch circuit is changed, the effective value or phase of the AC voltage applied by the single winding 40 to the two primary windings 31 is changed.

[0026] When an AC voltage is applied to the two primary windings 31, the two secondary windings 32 increase or decrease the effective value of the AC voltage between the input distribution lines U and V. The AC voltage whose effective value has increased or decreased is output to the outside as the AC voltage between the output distribution lines U and V.

[0027] Figure 3 is a diagram illustrating the operation of two series transformers 3u and 3v. When the combination of the upper and lower switch circuits in the current-passing state is (upper switch circuit A1, lower switch circuit B3), (upper switch circuit A2, lower switch circuit B3), or (upper switch circuit A1, lower switch circuit B2), the two secondary windings 32 increase the effective value of the AC voltage between the input distribution lines U and V.

[0028] In Figures 1 and 2, when the combination of the upper and lower switch circuits in a flowing state is (upper switch circuit A1, lower switch circuit B3), the direction of the current when the polarity of the voltage of the distribution line U relative to the potential of the distribution line V is positive is indicated by the dashed arrow. As shown in Figures 1 and 2, in each primary winding 31, the current flows from the first terminal (right side) to the second terminal (left side). In a similar case, when the polarity of the voltage of the distribution line U relative to the potential of the distribution line V is negative, the direction of the current is opposite to the direction of the dashed arrow shown in Figures 1 and 2.

[0029] When the combination of the upper and lower switch circuits in the current-passing state is (upper switch circuit A2, lower switch circuit B3) or (upper switch circuit A1, lower switch circuit B2), the direction of the current flowing through each primary winding 31 is the same as the direction of the current flowing through each primary winding 31 when the combination of the upper and lower switch circuits in the current-passing state is (upper switch circuit A1, lower switch circuit B3).

[0030] The increase in the effective value of the AC voltage is greater the greater the effective value of the AC voltage that the single winding 40 applies to the two primary windings 31. The effective value of the AC voltage that the single winding 40 applies to the primary windings 31 is Among the three taps T1, T2, and T3, the larger the number of turns between the two taps that electrically connect to the first and second terminals of the primary winding 31, the larger the value.

[0031] In the following, any integer k is denoted by k. The integer k may be 1, 2, or 3. When the combination of the upper and lower switch circuits in the current-passing state is (upper switch circuit Ak, lower switch circuit Bk), both the first and second terminals of each primary winding 31 are electrically connected to tap Tk. Therefore, the voltage between the first and second terminals is 0V.

[0032] When the combination of the upper and lower switch circuits in the current-passing state is (upper switch circuit A2, lower switch circuit B1), (upper switch circuit A3, lower switch circuit B2), or (upper switch circuit A3, lower switch circuit B1), the two secondary windings 32 reduce the effective value of the AC voltage between the input distribution lines U and V.

[0033] Assume that the combination of the upper and lower switch circuits in the current-passing state is (upper switch circuit A2, lower switch circuit B1), (upper switch circuit A3, lower switch circuit B2), or (upper switch circuit A3, lower switch circuit B1). In this case, when the polarity of the voltage of distribution line U relative to the potential of distribution line V is positive, the current flows from the second terminal (left side) to the first terminal (right side). In the same case, when the polarity of the voltage of distribution line U relative to the potential of distribution line V is negative, the current flows from the first terminal (right side) to the second terminal (left side). The decrease in the effective value of the AC voltage is greater the larger the effective value of the AC voltage that the single winding 40 applies to the two primary windings 31.

[0034] The control unit 51 adjusts the effective value of the AC voltage between the two output distribution lines U and V by changing the combination of the upper and lower switch circuits in the current flow state.

[0035] Normally, the state of the interlocking switch circuit C is the closed state. With respect to the interlocking switch circuit C, in the process of changing the state of the upper switch circuit or the lower switch circuit that is in the flow state, in order to prevent the opening of the first terminal or the second terminal of the primary winding 31, a transition from the closed state to the flow state and a transition from the flow state to the closed state are performed sequentially. For example, when changing the upper switch circuit that is in the flow state from upper switch circuit A1 to upper switch circuit A2, the control unit 51 changes the state of the interlocking switch circuit C from the closed state to the flow state and changes the state of the upper switch circuit A1 from the flow state to the closed state. Since the state of the interlocking switch circuit C is in the flow state, the opening of the first terminal of the primary winding 31 is prevented.

[0036] The control unit 51 changes the state of the upper switch circuit A1 to the off state, and then changes the state of the upper switch circuit A2 from the off state to the flow state. Next, the control unit 51 changes the state of the interfering switch circuit C from the flow state to the off state. This completes the process of changing the flow state of the upper switch circuits.

[0037] Figure 4 is the circuit diagram of the upper switch circuit A1. The configurations of the upper switch circuits A2 and A3, the lower switch circuits B1, B2, and B3, and the interlocking switch circuit C are the same as those of the upper switch circuit A1.

[0038] Each of the upper switch circuits A1, A2, A3, the lower switch circuits B1, B2, B3, and the interlocking switch circuit C has a first thyristor G1 and a second thyristor G2. The anode of the first thyristor G1 is connected to the cathode of the second thyristor G2. The cathode of the first thyristor G1 is connected to the anode of the second thyristor G2. The gates of the first thyristor G1 and the second thyristor G2 are connected to the control unit 51.

[0039] In the following, the connection node between the anode of the first thyristor G1 and the cathode of the second thyristor G2 will be referred to as the left node. The connection node between the cathode of the second thyristor G2 and the anode of the second thyristor G2 will be referred to as the right node. The left nodes of each of the upper switch circuits A1, A2, and A3 are connected to the first terminal of the primary winding 31. The right nodes of each of the upper switch circuits A1, A2, and A3 are connected to taps T1, T2, and T3. The left nodes of each of the lower switch circuits B1, B2, and B3 are connected to the second terminal of the primary winding 31. The right nodes of each of the lower switch circuits B1, B2, and B3 are connected to taps T1, T2, and T3.

[0040] The left and right nodes of the interference switch circuit C are connected to the first terminal of the primary winding 31 and one terminal of the interference resistor R, respectively. The other terminal of the interference resistor R is connected to the second terminal of the primary winding 31. Alternatively, the left and right nodes of the interference switch circuit C may be connected to one terminal of the interference resistor R and the second terminal of the primary winding 31. In this case, the other terminal of the interference resistor R is connected to the first terminal of the primary winding 31.

[0041] For each of the upper switch circuits A1, A2, A3, the lower switch circuits B1, B2, B3, and the interlocking switch circuit C, the control unit 51 switches the state between a current-through state and an interrupted state by adjusting the gate voltages of the first thyristor G1 and the second thyristor G2.

[0042] When the upper switch circuit A1 is in the current-passing state, alternating current can flow. The current from the first terminal of the primary winding 31 to tap T1 flows through the first thyristor G1, as indicated by the solid arrow. The current from tap T1 to the first terminal of the primary winding 31 flows through the second thyristor G2, as indicated by the dashed arrow. When the upper switch circuit A1 is in the interrupted state, no current flows through the first thyristor G1 and the second thyristor G2.

[0043] The current-related effects of the upper switch circuits A2 and A3, the lower switch circuits B1, B2, and B3, and the interfering switch circuit C are the same as those of the upper switch circuit A1. Therefore, when the state is current-passing, the current flowing from the left node to the right node flows through the first thyristor G1. Similarly, in the same case, the current flowing from the right node to the left node flows through the second thyristor G2. When the state is interrupted, no current flows through the first thyristor G1 and the second thyristor G2.

[0044] The upper switch circuits A1, A2, A3, the lower switch circuits B1, B2, B3, and the interfering switch circuit C are not limited to circuits using the first thyristor G1 and the second thyristor G2, but may also be circuits using semiconductor switches other than thyristors, for example. In the upper switch circuits A1, A2, A3, the lower switch circuits B1, B2, B3, and the interfering switch circuit C, for example, triacs may be used. A triac has three terminals and operates similarly to a circuit in which the first thyristor G1 is composed of a second thyristor G2.

[0045] Furthermore, two IGBTs (Insulated Gate Bipolar Transistors) and two diodes may be used in each of the upper switch circuits A1, A2, and A3, the lower switch circuits B1, B2, and B3, and the interfering switch circuit C. The collector and emitter of the IGBTs are connected to the cathode and anode of the diodes, respectively. The gates of the two IGBTs are connected to the control unit 51.

[0046] As a first example, the emitter of one IGBT is connected to the emitter of the other IGBT. In this case, the collectors of the two IGBTs act as the left node and the right node, respectively. As a second example, the collector of one IGBT is connected to the collector of the other IGBT. In this case, the emitters of the two IGBTs function as the left node and the right node. For each of the upper switch circuits A1, A2, A3, the lower switch circuits B1, B2, B3, and the interfering switch circuit C, the control unit 51 switches the state between a current-through state and an interrupted state by adjusting the voltage of the gates of the two IGBTs.

[0047] Furthermore, a FET (Field Effect Transistor) may be used instead of an IGBT. In this case, the drain and source correspond to the collector and emitter, respectively. When a FET is used, the parasitic diode of the FET can be used as the diode connected between the drain and source.

[0048] Voltage regulator 1 is compared with a conventional voltage regulator. In a conventional voltage regulator, the first terminal of the primary winding of one series transformer is connected to the first terminal of the primary winding of the other series transformer. Similarly, the second terminal of the primary winding of one series transformer is connected to the second terminal of the primary winding of the other series transformer. A single switch is connected separately to the connection node between the two first terminals and to the connection node between the two second terminals.

[0049] Voltage regulator 1 has two switches 50a and 50b. Therefore, when voltage regulator 1 and a conventional voltage regulator adjust the effective value of the AC voltage between the output distribution lines U and V in the same way, the maximum effective value of the AC current flowing through switches 50a and 50b is half the maximum effective value of the AC current flowing through the switches of a conventional voltage regulator.

[0050] Regarding the alternating current flowing through the switch, the upper limit of the allowable effective value must be greater than or equal to the maximum effective value of the alternating current output from two of the three taps T1, T2, and T3. Switches with a large upper limit are expensive. In the case of conventional voltage regulators, if it is not possible to manufacture or procure a switch with an upper limit that slightly exceeds the maximum effective value, an expensive switch with a significantly larger upper limit is used, increasing manufacturing costs. On the other hand, with respect to voltage regulator 1, it may be possible to achieve inexpensive manufacturing by using two switches with upper limits that slightly exceed the maximum effective value.

[0051] (Embodiment 2) In Embodiment 1, the voltage regulator 1 has two series transformers. However, the number of series transformers in the voltage regulator 1 is not limited to two. The following describes the differences between Embodiment 2 and Embodiment 1. Except for the configuration described later, the other configurations are the same as those in Embodiment 1; therefore, the same reference numerals are used for the components common to Embodiment 1, and their descriptions are omitted.

[0052] Figure 5 is a circuit diagram of the voltage regulator 1 in Embodiment 2. When Embodiment 2 is compared with Embodiment 1, the number of series transformers 3u and 3v is different. The voltage regulator 1 in Embodiment 2 has two series transformers 3u and two series transformers 3v. Two secondary windings 32 of the two series transformers 3u are located in the middle of the distribution line U. These secondary windings 32 are connected in series. Two secondary windings 32 of the two series transformers 3v are located in the middle of the distribution line V. These secondary windings 32 are connected in series. Distribution line U functions as the first distribution line. Distribution line V functions as the second distribution line.

[0053] In Figure 5, the series transformers 3u and 3v positioned first from the left will be referred to as the first series transformer 3u and the first series transformer 3v, respectively. The series transformers 3u and 3v positioned second from the left will be referred to as the second series transformer 3u and the second series transformer 3v, respectively. The first and second terminals of the primary winding 31 of the first series transformer 3u are connected to the first and second terminals of the primary winding 31 of the first series transformer 3v. The series is continued. The first and second terminals of the primary winding 31 of the second series transformer 3u are connected to the first and second terminals of the primary winding 31 of the second series transformer 3v.

[0054] The connection node between the first terminals of the two primary windings 31 of the first series transformer 3u,3v is connected to the three upper switch circuits A1, A2, and A3 of the changeover switch 50a. The connection node between the second terminals of the two primary windings 31 of the first series transformer 3u,3v is connected to the three lower switch circuits B1, B2, and B3 of the changeover switch 50a.

[0055] Similarly, the connection node between the first terminals of the two primary windings 31 of the second series transformers 3u,3v is connected to the three upper switch circuits A1, A2, and A3 of the changeover switch 50b. The connection node between the second terminals of the two primary windings 31 of the second series transformers 3u,3v is connected to the three lower switch circuits B1, B2, and B3 of the changeover switch 50b.

[0056] The changeover switch 50a switches the taps T1, T2, and T3 to which the first and second terminals of the two primary windings 31 of the first series transformers 3u and 3v are electrically connected. The specific terminals of the changeover switch 50a are the first and second terminals of the two primary windings 31 of the first series transformers 3u and 3v.

[0057] Similarly, the changeover switch 50b switches the taps T1, T2, and T3 to which the first and second terminals of the two primary windings 31 of the second series transformers 3u and 3v are electrically connected. The specific terminals of the changeover switch 50b are the first and second terminals of the two primary windings 31 of the second series transformers 3u and 3v.

[0058] The control unit 51 in Embodiment 2 operates in the same manner as the control unit 51 in Embodiment 1. With respect to the switches 50a and 50b, the state of the upper switch circuit connected to the common tap is the same, and the state of the lower switch circuit connected to the common tap is also the same. Therefore, the AC voltage applied by the single winding 40 to the four primary windings 31 is the same. As a result, the four secondary windings 32 operate in the same manner.

[0059] The voltage regulator 1 in Embodiment 2 is compared with the conventional voltage regulator described in the description of Embodiment 1. The voltage regulator 1 has two switches 50a and 50b. Therefore, when the voltage regulator 1 and the conventional voltage regulator adjust the effective value of the AC voltage between the output distribution lines U and V in the same way, the maximum effective value of the AC current flowing through switches 50a and 50b is half the maximum effective value of the AC current flowing through the switches of the conventional voltage regulator. For this reason, similar to Embodiment 1, it is possible to manufacture the voltage regulator 1 at low cost.

[0060] In Embodiment 2, the number of series transformers in the voltage regulator 1 may be (2·n), where n is an integer greater than or equal to 2. The "·" indicates multiplication. Therefore, the number of series transformers in the voltage regulator 1 in Embodiment 2 may exceed 4. In this case, the secondary windings 32 of n series transformers 3u are located in the middle of the distribution line U, and the secondary windings 32 of n series transformers 3v are located in the middle of the distribution line V. The switching device 5 has n switches. Each switch switches the taps to which the first and second terminals of the two primary windings 31 of the series transformers 3u and 3v are electrically connected. The maximum effective value of the AC current flowing through each switch is 1 / n of the maximum effective value of the AC current flowing through the switches of a conventional voltage regulator.

[0061] (Embodiment 3) In Embodiment 2, each of the (2·n) primary windings 31 is the same as in Embodiment 1. It may be connected to a single switch. The following describes the differences between Embodiment 3 and Embodiment 2. Except for the configuration described later, the other configurations are the same as those in Embodiment 2; therefore, the same reference numerals are used for the components common to Embodiment 2, and their descriptions are omitted.

[0062] Figure 6 is a circuit diagram of the voltage regulator 1 in Embodiment 3. Figure 6 shows an example where there are four series transformers. The four secondary windings 32 are arranged in the same way as in Embodiment 2. Switch 50a is connected to the primary winding 31 of the first series transformer 3u. The connection between switch 50a and the primary winding 31 of the first series transformer 3u is the same as the connection between switch 50a and the primary winding 31 of the series transformer 3u in Embodiment 1. Switch 50b is connected to the primary winding 31 of the first series transformer 3v. The connection between switch 50b and the primary winding 31 of the first series transformer 3v is the same as the connection between switch 50b and the primary winding 31 of the series transformer 3v in Embodiment 1.

[0063] The changeover switch 50c is connected to the primary winding 31 of the second series transformer 3u. The connection between the changeover switch 50c and the primary winding 31 of the second series transformer 3u is the same as the connection between the changeover switch 50a and the primary winding 31 of the series transformer 3u in Embodiment 1. The changeover switch 50d is connected to the primary winding 31 of the second series transformer 3v. The connection between the changeover switch 50d and the primary winding 31 of the second series transformer 3v is the same as the connection between the changeover switch 50b and the primary winding 31 of the series transformer 3v in Embodiment 1.

[0064] The changeover 50a switches the taps T1, T2, and T3 to which the first and second terminals of the primary winding 31 of the first series transformer 3u are electrically connected, in the same manner as in Embodiment 1. The changeover 50b switches the taps T1, T2, and T3 to which the first and second terminals of the primary winding 31 of the first series transformer 3v are electrically connected, in the same manner as in Embodiment 1.

[0065] Similar to switcher 50a, changer 50c switches the taps T1, T2, and T3 to which the first and second terminals of the primary winding 31 of the second series transformer 3u are electrically connected. Similar to switcher 50b, changer 50d switches the taps T1, T2, and T3 to which the first and second terminals of the primary winding 31 of the second series transformer 3v are electrically connected.

[0066] The control unit 51 in Embodiment 3 operates in the same manner as the control unit 51 in Embodiment 1. With respect to the switches 50a, 50b, 50c, and 50d, the state of the upper switch circuit connected to the common tap is the same, and the state of the lower switch circuit connected to the common tap is also the same. Therefore, the AC voltage applied by the single winding 40 to the four primary windings 31 is the same. As a result, the four secondary windings 32 operate similarly.

[0067] The voltage regulator 1 in Embodiment 3 is compared with the conventional voltage regulator described in the description of Embodiment 1. The voltage regulator 1 has four switches 50a, 50b, 50c, and 50d. Therefore, when the voltage regulator 1 and the conventional voltage regulator adjust the effective value of the AC voltage between the output distribution lines U and V in the same way, the maximum effective value of the AC current flowing through each of the switches 50a, 50b, 50c, and 50d is one-quarter of the maximum effective value of the AC current flowing through the switches of the conventional voltage regulator. For this reason, similar to Embodiment 1, it is possible to achieve inexpensive manufacturing of the voltage regulator 1.

[0068] In Embodiment 3, if the number of series transformers in the voltage regulator 1 exceeds 4, the secondary windings 32 of n series transformers 3u are placed in the middle of the distribution line U, and the secondary windings 32 of n series transformers 3v are placed in the middle of the distribution line V, similar to Embodiment 2. Device 5 has (2·n) switches. Each switch switches the taps to which the first and second terminals of the primary winding 31 of the series transformer 3u or series transformer 3v are electrically connected. The maximum effective value of the AC current flowing through each switch is obtained by dividing the maximum effective value of the AC current flowing through the switches of a conventional voltage regulator by (2·n).

[0069] In embodiments 1 to 3, the number of taps provided on the single winding 40 is not limited to 3, but may be 2 or 4 or more. For each changeover, the number of upper switch circuits is the same as the number of taps connected to the single winding 40. The number of lower switch circuits is also the same as the number of taps connected to the single winding 40.

[0070] The technical features (constituent elements) described in Embodiments 1 to 3 are combinable with each other, and by combining them, new technical features can be formed. The disclosed embodiments 1 to 3 should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, not in the sense described above, and all modifications are intended to be in the sense and scope equivalent to the claims. [Explanation of Symbols]

[0071] 1 Voltage regulator, 3u, 3v series transformer, 31 Primary winding, 32 Secondary winding, 40 Single winding (tap winding), 50a, 50b, 50c, 50d changeover, A1, A2, A3 upper switch circuit (first switch circuit), B1, B2, B3 lower switch circuit (second switch circuit), T1, T2, T3 tap

Claims

1. A voltage regulator that adjusts the effective value of an AC voltage, A tap winding to which multiple taps are connected, Multiple transformers having primary and secondary windings, Among the aforementioned multiple taps, a plurality of switches that switch the tap to which a specific terminal of the primary winding is electrically connected, and Equipped with, The effective value of the AC voltage between two of the aforementioned taps is adjusted according to the effective value of the AC voltage between the two distribution lines. Each of the multiple secondary windings of the multiple transformers is positioned in the middle of the two distribution lines. The specific terminals corresponding to each switch are different from the specific terminals corresponding to the remaining switches. The wires extending from the aforementioned tap to multiple switches are branched according to the number of switches. Each of the branched wires is connected to a switch, Each switch is, Multiple first switch circuits that switch between a current-passing state where current can flow and a current-blocking state where current flow is blocked, A plurality of second switch circuits that switch between a current-passing state and a blocked state, It has, Each of the plurality of first switch circuits in each changeover is connected to the plurality of taps, Each of the plurality of second switch circuits in each changeover is connected to the plurality of taps, The plurality of first switch circuits are connected to one of the plurality of specific terminals, The plurality of second switch circuits are connected to one of the plurality of specific terminals, In the aforementioned multiple switches, the state of the multiple first switch circuits connected to a common tap is the same, and the state of the multiple second switch circuits connected to a common tap is also the same. Voltage regulator.

2. The specific terminals of each switch are the two terminals of a single primary winding. The voltage regulator according to claim 1.

3. Multiple secondary windings are arranged in the middle of the first distribution line, which is included in the two distribution lines mentioned above. Multiple secondary windings are arranged in the middle of the second distribution line, which is included in the two distribution lines mentioned above. The specific terminals of each switch are the two terminals of the primary winding of a series transformer whose secondary winding is located in the middle of the first distribution line, and the two terminals of the primary winding of a series transformer whose secondary winding is located in the middle of the second distribution line. The voltage regulator according to claim 1.

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