JP3530879B2 - Voltage regulator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage regulator using a load tap change transformer. 2. Description of the Related Art A conventional voltage regulator using a load tap switching transformer will be described with reference to FIG. The voltage regulator 50 includes a series winding 54 (number of windings Ns) inserted in series in an AC line 52, and a plurality of taps 56a to 56a.
Voltage adjustment winding 58 provided with 56d (four in this example)
Are formed, and switch means 62a to 62d for switching the taps 56a to 56d.
Further, a manual switching switch is used for the switch means 62a to 62d. As an example, the voltage adjustment winding 58 is connected to the output side of the AC line 52, but may be configured to be connected to the input side. Incidentally, reference numeral 64 denotes an AC power supply connected to the input side of the AC line 52,
66 is a load such as an electric device connected to the output side of the AC line 52. Each of the taps 56a to 56d is switched such that one of the taps is in a connected state and the other taps are in a disconnected state. Thereby, the voltage adjustment winding 5
8, the number of windings Np changes, and the number of windings Ns, the number of windings Np, and the input voltage Vi determine the AC line 52 determined by the following equation.
Can be varied in a stepwise manner on the output terminal side Vo. Vo = Vi × Np / (Ns + Np) In recent years, the AC line 52
In order to keep the voltage Vo on the output terminal side of the switch circuit 62 substantially constant, a semiconductor switch element such as a thyristor is used for the switch means 62a to 62d, and the output terminal voltage Vo of the AC line 52 is detected to switch the switch means 62a to 62d. Some voltage regulators include a control circuit that determines an optimal switch means from among 62d and switches the taps 56a to 56d of the voltage regulating winding 58. [0004] However, the conventional voltage regulator has the following problems. When an abnormal current flows through the switch for selectively connecting the taps, the switch and the voltage adjustment winding between the taps connected by the switch are overheated and damaged. Further, when the input voltage rises abnormally, the voltage is also applied to the switch means, so that the switch means may be broken. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-mentioned problems, and an object of the present invention is to provide a voltage adjusting device capable of protecting a switch means and a winding of a transformer. [0005] To achieve the above object, the present invention has the following arrangement. That is, a transformer having a series winding inserted in series with the AC line, and a voltage adjustment winding provided with a plurality of taps ,
A voltage detection unit for detecting an output voltage; first switch means for switching the plurality of taps; and a voltage detection unit.
Input voltage of the AC line based on the output voltage
Should be adjusted so that the output voltage is almost constant regardless of
And a control circuit for performing switching control of the first switch means, wherein a second switch means is provided between the AC line and the voltage adjustment winding,
The voltage adjustment winding is provided with short-circuit means for short-circuiting the voltage adjustment winding, and the first switch means and / or
Alternatively, the transformer is provided with a temperature sensor, and the control circuit is provided with a first switch which detects the temperature via the temperature sensor.
The temperature of the stage and / or the transformer
If the temperature exceeds the quasi-temperature and the input voltage fluctuates,
Output voltage exceeds the reference voltage range or
The voltage falls below the voltage range.
Indicates that the output voltage cannot be adjusted to a substantially constant value.
In this case, it is characterized in that the second switch means is operated to disconnect the voltage adjustment winding from the AC line, and the short-circuit means is operated to short-circuit the voltage adjustment winding. By this configuration, an overvoltage or overcurrent
In the case of a current, the control circuit operates the second switch means and the short-circuit means to disconnect the voltage adjustment winding and the first switch means and the voltage adjustment winding connected to the voltage adjustment winding from the AC line. The first switch
Means and protection of the voltage adjustment winding can be performed. In addition, the input voltage
Output voltage is changed by tap change of the voltage adjustment winding.
Even if the voltage becomes uncorrectable, the voltage adjustment winding is disconnected from the AC line, so that the input voltage is approximately
Output with pressure. The operation will now be described. When the second switch means provided between the AC line and the voltage adjustment winding is operated and opened, the voltage adjustment winding can be separated from the AC line. Also, by activating the short-circuit means,
It is possible to prevent the induced voltage of the series winding generated in the separated voltage adjustment winding from becoming high. Preferred embodiments of a voltage regulator according to the present invention will be described in detail below with reference to the accompanying drawings. The same components as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. First, the configuration of an embodiment of the voltage regulator 10 will be described with reference to FIG. Reference numerals 12a to 12d denote first switch means disposed between the taps 56a to 56d (four in this example) of the voltage adjustment winding 58. First switch means 1
Thyristor modules are used for 2a to 12d. Reference numeral 14 denotes a connection relay, which uses a reversible relay. The connection relay 14 includes three contact circuits as an example, and one contact circuit 14a operates so that the contact state is always reversed with the other contact circuits 14b and 14c. The connection relay 14 has the other contact circuits 14b and 14c in the connected state when energized, and is disconnected when not energized. One contact circuit 14a is in the opposite state. In this connection relay 14, the other contact circuits 14b and 14c serve as second switch means, and the other contact circuits constitute part of a control circuit. Reference numeral 16 denotes a short-circuit relay as short-circuit means, which is configured using a reversible relay similar to the connection relay 14. The short circuit relay 16 has four contact circuits.
The circuit is built in, and the contact state of one contact circuit 16a is always reversed with the other contact circuits 16b to 16d. The short-circuit relay 16 has one contact circuit 16a disconnected when energized, and connected when non-energized. Other contact circuit 1
6b to 16d are in the opposite state. In this short-circuit relay 16, of the three other contact circuits, a contact circuit 16 disposed between both ends of the voltage adjustment winding 58 as described later.
b and 16c are short-circuiting means, and the others constitute a part of the control circuit. Reference numeral 18 denotes a first relay which constitutes a part of a control circuit. The first relay 18 has two contact circuits.
a and 18b are built in. Reference numeral 20 denotes a timer relay constituting a part of the control circuit, which is connected between the AC lines 52 and has one built-in contact circuit 20a. Timer relay 2
0 has a function of temporarily switching from the initial state before energization to another state for a certain period of time after energization, and then switching back to the original initial state. Reference numeral 22 denotes a voltage detection unit which constitutes a part of the control circuit, detects an output voltage (an average voltage within a predetermined time) of the AC line 52, and detects one of the first switch means 12a to 12d according to the detected voltage value. Of the voltage adjusting winding 58 to selectively connect only one of the taps 56a to 56d to adjust the output voltage. Reference numeral 24 denotes a second power supply provided in the voltage detector 22.
It is a relay, and includes one contact circuit 24a and constitutes a part of a control circuit. In the voltage detection unit 22, for example, an A / D converter, a comparator, a microcomputer, and the like are provided, and the microcomputer outputs an output from the contact circuits 24a and 20a via the A / D converter and the comparator. The voltage is constantly monitored, and the second relay 24 is activated when the output voltage rises or exceeds the reference voltage range set in advance. Reference numeral 26 denotes a temperature protection circuit which constitutes a part of the control circuit, and includes a temperature sensor (not shown) attached to each of the first switch means 12a to 12d, and a temperature detected by the temperature sensor set to a predetermined reference temperature. In this case, the contact circuits 26a to 26d which are connected in the above case are incorporated. Reference numeral 28 denotes a pilot lamp which is turned on when an abnormality occurs. Note that a buzzer or the like may be used instead of the lamp 28. 30 is a through switch,
The voltage adjustment winding 58 of the transformer 60 is forcibly connected to the AC line 52.
, And short-circuited to output an input voltage to the output terminal of the AC line 52. The through switch 30 is normally urged by a built-in spring so as to be in a disconnected state, and is turned on when pressed. 32
Is a reset switch for returning the voltage adjustment winding 58 once disconnected from the AC line 52 and short-circuited to the initial state. The reset switch 32 is normally urged by a built-in spring to be in a connected state, and is turned off when pressed. Next, connection of the above-described components will be described. Between the AC line 52 and the voltage adjustment winding 58, the contact circuit 1 of the connection relay 14 as the second switch means
4b and 14c are arranged. The voltage adjustment winding 58
Tap 56a and contact circuit 14 of connection relay 14
Contact circuits 16b and 16c of the short-circuit relay 16 are connected between the contacts b and 14c on the voltage adjustment winding 58 side (between both ends of the voltage adjustment winding 58). A common terminal of one contact circuit 18a of the first relay 18 is connected to an AC line 52, and a contact circuit of the connection relay 14 is provided between the terminal a and a middle point (hereinafter, "middle point") of the AC line 52. 14a and the short-circuit relay 16 are connected in series. A contact circuit 16a of the short-circuit relay 16 and the connection relay 14 are connected in series between the terminal b and the middle point. The common terminal of the contact circuit 24a of the second relay 24 is connected to the AC line 52, and the voltage detecting section 22 is connected between the terminal a and the middle point. The terminal b of the contact circuit 24a is connected to the terminal a of the other contact circuit 18b of the first relay 18 and the contact circuit 2 of the temperature protection circuit 26.
One of the terminals 6a to 26d, one terminal of the through switch 30, and one terminal of the reset switch 32 are connected. The first relay 18 is connected between the other terminal of the reset switch 32 and the middle point. The common terminal of the contact circuit 20a of the timer relay 20 is connected to the AC line 52, and the terminal b is connected to the second relay 2
4 is connected to the terminal a of the contact circuit 24a, and the terminal a of the contact circuit 20a is a common terminal of the contact circuit 18b of the first relay 18, and each of the contact circuits 26a to 26 of the temperature protection circuit 26.
The other terminal of d and one terminal of the through switch 30 are connected. The contact circuit 16d of the short-circuit relay 16 and the pilot lamp 28 are connected in series between the AC line 52 and the middle point. Next, the operation will be described. First, when an AC voltage is input to the input end of the AC line 52, the timer relay 20 is energized, and the contact circuit 20 a of the timer relay 20 is switched to the terminal b to supply the voltage to the voltage detection unit 22. Then, the detection operation is started. Then, one of the first switch means 12a to 12d is selected according to the detected voltage, and the tap of the voltage adjustment winding 58 is switched. The connection relay 14 is also energized via the terminal b of the contact circuit 18a of the first relay 18 and the contact circuit 16a of the short-circuit relay 16, so that the contact circuits 14b and 14c of the connection relay 14 are connected. Therefore, a voltage is also applied to the voltage adjustment winding 58 via the series winding 54, and the output end of the AC line 52 is connected to the voltage adjustment winding 58.
An AC voltage corresponding to the tap position is output. The short-circuit relay 16 is not energized, so that the contact circuits 16b and 16c of the short-circuit relay 16 are disconnected, and the voltage adjustment winding 58 is not short-circuited. When the microcomputer provided in the voltage detector 22 detects that the output voltage is within the reference voltage range, it activates the second relay 24 to switch the contact circuit 24a to the terminal a. . Therefore, even if the timer relay 20 switches from the terminal “b” to the terminal “a” again after a certain time, the AC voltage is supplied to the voltage detection unit 22 via the contact circuit 24a of the second relay 24. Also,
When the input voltage fluctuates, the voltage detection unit 22 outputs the first switch means 12 a to
One is selected from 12d, the tap of the voltage adjustment winding 58 is switched, and the output voltage is controlled so as to be substantially constant regardless of the fluctuation of the input voltage. Next, the case where the input voltage fluctuates and the output voltage exceeds the reference voltage range which cannot be corrected by the tap switching of the voltage adjustment winding 58 will be described. In this case, the microcomputer operates the second relay 24 to connect the terminal b of the contact circuit 24a. As a result, the first relay 18 is energized via the reset switch 32, and the contact circuit 18a of the first relay 18 is turned on.
Terminal a is connected. Therefore, the connection relay 14
Is stopped, and the contact circuit 14b of the connection relay 14
14c is disconnected, the contact circuit 14a is connected,
The voltage adjustment winding 58 is disconnected from the AC line 52. Further, the short-circuit relay 16 is energized, the contact circuit 16a of the short-circuit relay 16 is disconnected, the contact circuits 16b to 16d are connected, and the voltage adjusting winding 58 disconnected from the AC line 52 is further short-circuited. At the output end of the line 52, the input voltage is output at substantially the same voltage via the series winding 54 of the transformer 60. Thereby, protection of the first switch means 12a to 12d by overvoltage can be performed. In addition, by not only disconnecting the voltage adjustment winding 58 but also short-circuiting,
It is also possible to reduce the induced voltage of the voltage adjustment winding 58. When the contact circuit 16d of the short-circuit relay 16 is connected, the pilot lamp 28
Lights up. The same applies to a case where the input voltage fluctuates and the output voltage falls below the reference voltage range that cannot be corrected by tap switching of the voltage adjustment winding 58, and the microcomputer operates the second relay 24 to operate the second relay 24. By connecting the terminal b of the contact circuit 24a to the connection state, the voltage adjusting winding 58 is disconnected from the AC line 52 and short-circuited.
The input voltage is output at approximately that voltage via the zero series winding 54. Subsequently, first switch means (thyristor modules) 12a-1 for connecting the taps 56a-56d
A case where an overcurrent flows in 2d and the first switch means is overheated will be described. As an example, the first switch means 12a
Is overheated, a temperature sensor (not shown) of the temperature protection circuit 26 attached to the first switch means 12a operates, and a contact circuit (first switch) corresponding to the temperature sensor among the contact circuits 26a to 26d is operated. Since the means 12a is overheated, the contact circuit 26a) becomes connected. This allows
The first relay 18 is energized from the terminal a of the timer relay 20 via the contact circuit 26a and the reset switch 32, and the voltage adjustment winding 58 is disconnected from the AC line 52 in the same manner as in the case where the overvoltage is detected. In addition, the current to the first switch means 12a that has been short-circuited and overheated is stopped and protected. Similarly, when the other first switch means is overheated, the voltage adjustment winding 58 is separated from the AC line 52 and short-circuited to protect the first switch means 12b to 12d. Further, once the voltage adjustment winding 58 is
2 and short-circuited, the reset switch 32 is depressed to temporarily stop energizing the first relay 18, and thereby the terminal b of the contact circuit 18 a of the first relay 18 is turned off.
Is in the connected state, the short-circuit relay 16 is in the non-conductive state, the contact circuit 16a of the short-circuit relay 16 is in the connected state,
The contact circuits 16b to 16d are disconnected. Therefore, the pilot lamp 28 goes out and the connection relay 1
4 is energized and the contact circuits 14b, 1
4c is in the connected state, the contact circuit 14a is in the disconnected state, and the voltage adjustment winding 58 is connected to the AC line 52 to be in the normal connected state. It is also possible to increase the number of temperature sensors and contact circuits of the temperature protection circuit 26 as described above, arrange a temperature sensor in the transformer 60, and connect the contact circuits in parallel with the contact circuits 26a to 26d. . With this configuration, even when an overcurrent flows through the voltage adjustment winding 58 and the transformer 60 generates heat, the voltage adjustment winding 58 is similarly cut off from the AC line 52 and short-circuited, so that the voltage adjustment winding 58 Can protect the transformer 60. When the voltage adjusting winding 58 is forcibly cut off from the AC line 52, the through switch 32 is depressed.
As in the case of the overheating of 2a to 12d, the first relay 18 is energized, and the voltage adjustment winding 58 can be disconnected from the AC line 52 and short-circuited. Although the preferred embodiments of the present invention have been described in various ways, the present invention is not limited to the above-described embodiments. Other circuit configurations may be employed. The AC line may have a single phase. In this case, the series winding and the voltage adjustment winding become one, and the first switch means for switching each tap of the voltage adjustment winding includes a tap and a single-phase return. It goes without saying that many modifications can be made without departing from the spirit of the invention, such as by arranging it between the side lines. With the use of the voltage regulator according to the present invention,
Even when the input voltage of the AC line becomes abnormally high or when the first switch for switching the tap of the voltage adjustment winding is overheated, the voltage adjustment winding can be disconnected from the AC line and short-circuited. This has a significant effect that protection of the first switch means and further protection of the voltage adjustment winding can be performed. In addition, the output voltage is adjusted by the fluctuation of the input voltage.
If the voltage cannot be corrected by switching the winding tap,
In both cases, the voltage adjustment winding is disconnected from the AC line, so output
On the side, the input voltage is output at approximately that voltage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a configuration of an embodiment of a voltage regulator according to the present invention. FIG. 2 is a circuit diagram showing a configuration of an example of a conventional voltage regulator. Reference Signs List 10 Voltage regulators 12a to 12d First switch means 14 Connecting relays 14b, 14c Contact circuit 16 as second switch means Short-circuit relays 16b, 16c Contact circuit 18 as short-circuit means 18 First relay 20 Timer relay 22 Voltage detector 24 Second relay 26 Temperature protection circuit 52 AC line 54 Series windings 56a to 56d Tap 58 Voltage adjustment winding 60 Transformer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05F 1/24 H02H 3/08

Claims (1)

(57) [Claim 1] A series winding inserted in series into an AC line,
And a transformer having a plurality of taps the voltage regulating winding provided is formed, a voltage detecting unit for detecting an output voltage of the AC line, a first switching means for switching the plurality of taps, the voltage Based on the output voltage detected by the detector
Therefore, the output voltage is almost constant regardless of the fluctuation of the input voltage of the AC line.
And a control circuit for performing switching control of the first switch means so as to adjust the voltage to be constant . A second switch means is provided between the AC line and the voltage adjustment winding. The voltage adjustment winding is provided with short-circuiting means for short-circuiting the voltage adjustment winding, and the first switch means and / or the transformer is provided with a short circuit.
A temperature sensor, and the control circuit includes a first switch means and a first switch means detected through the temperature sensor.
And / or a reference temperature at which the temperature of the transformer is set in advance
If the value exceeds, and the input voltage varies, the output voltage group with it
Exceeding the reference voltage range or below the reference voltage range,
Output voltage is almost constant when switching the tap of the voltage adjustment winding.
If adjustment is no longer possible, the second switch means can be operated to disconnect the voltage adjustment winding from the AC line, and the short-circuit means can be operated to short-circuit the voltage adjustment winding. A voltage regulator characterized by the above.