JP5177438B2 - Voltage drop protection device for DC power supply - Google Patents

Description

  According to the present invention, in a DC power supply that converts commercial AC power into DC power and supplies it to a device such as a switching power supply unit, the input AC voltage temporarily decreases (instantaneously or continuously for a certain period of time). The present invention relates to a voltage drop protection device for a DC power supply that continues to supply DC power to equipment even at times.

  In production sites such as factories, switching power supply units are frequently used to supply power to industrial robots, control devices, measuring devices, and the like. AC power such as AC100V or AC200V supplied from a commercial AC power supply is input to such a switching power supply unit. When the voltage of the commercial AC power drops for a short time due to an instantaneous drop or the like, the switching power supply It is not preferable that the supply of power from the unit to the load is interrupted. In order to avoid this, a voltage drop protection device is usually used.

  Conventionally, the voltage drop protection device widely used is an AC / DC converter that converts AC power supplied from a commercial AC power source and stores it in a capacitor. When the input AC voltage drops, the electrical energy stored in the capacitor is stored. Is converted into DC / AC by an inverter and output instead of commercial AC power. However, since the circuit becomes complicated in order to perform AC / DC conversion-DC / AC conversion in this way, it is generally expensive, and the above-described voltage drop protection device is provided for each switching power supply unit. Is difficult in terms of cost.

  In addition to the switching power supply unit described above, many servo motor driver devices, inverter devices, and the like can accept not only AC power input but also DC power input. Therefore, as such a voltage drop protection device for various units and devices, it is not a voltage drop protection device for an AC power source that outputs AC power when the commercial AC voltage drops, but a DC voltage when the commercial AC voltage drops. It is also possible to use a voltage drop protection device for a DC power supply that outputs electric power. As such a voltage drop protection device for a DC power supply, for example, the one described in Patent Document 1 is known. FIG. 2 is a schematic block diagram of the voltage drop protection device described in this document.

  The voltage drop protection device 30 backs up the input DC power of the switching power supply unit 3 and is inserted between the commercial AC power supply 2 and the switching power supply unit 3. The voltage drop protection device 30 includes a rectifying unit 10 that rectifies an AC input voltage Vacin applied to the input terminal 11 from the commercial AC power supply 2 and converts it into a DC voltage, an electrolytic capacitor 18, a choke coil 32, a power MOSFET, and the like. The charging unit 31 that is a step-up chopper circuit composed of the switching element 33 and the diode 34, the charging control unit 37 that controls on / off of the switching element 33 in order to charge the electrolytic capacitor 18, and the AC input voltage Vacin is A voltage sag / power failure detection unit 36 that detects that the voltage has dropped below a predetermined value, and a switching element 35 that is turned on in response to an instruction from the voltage sag / power failure detection unit 36 when the voltage is reduced are output from the output terminal 19. A DC output voltage Vdcot is applied to the switching power supply unit 3.

  The basic operation of the voltage drop protection device 30 is as follows. When the AC input voltage Vacin from the commercial AC power supply 2 is normal, that is, when the AC input voltage Vacin exceeds a predetermined value set in the instantaneous voltage drop / power failure detection unit 36, the switching element 35 is turned off. The DC voltage that has been AC / DC converted by the rectifier 10 is output to the output terminal 19 as the DC output voltage Vdcot. The DC voltage is input to the charging unit 31, boosted by the on / off operation of the switching element 33, and charged to the electrolytic capacitor 18. For example, the charging unit 31 charges the electrolytic capacitor 18 until the terminal voltage VB becomes DC 360V.

  When the AC input voltage Vacin drops below a predetermined value set in the voltage sag / power failure detection unit 36 due to the occurrence of a power failure or the like, the switching element 35 is turned on by an instruction signal from the voltage sag / power failure detection unit 36. Then, one end of the electrolytic capacitor 18 is connected to the output terminal 19. As a result, the terminal voltage VB (DC 360 V) of the electrolytic capacitor 18 is applied from the output terminal 19 to the switching power supply unit 3, and DC power is supplied to the switching power supply unit 3 by the electric energy held in the electrolytic capacitor 18.

  In the voltage drop protection device 30 described above, since the discharge of the electrolytic capacitor 18 is started from the time when the switching element 35 is turned on, the voltage output from the output terminal 19 is the terminal voltage as time elapses from that time. It gradually decreases from DC 360V which is VB. The rate of this reduction depends on the current consumption of the load that is the power supply destination of the switching power supply unit 3. For example, when the DC input voltage range of the switching power supply unit 3 is DC 120 to 360 V, the time until the voltage output from the output terminal 19 drops to 120 V is a time that can be protected by the voltage drop protection device 30.

  As described above, the terminal voltage VB of the electrolytic capacitor 18 appears at the output terminal 19 of the voltage drop protection device 30 immediately after the occurrence of a power failure or instantaneous drop. Therefore, there are the following problems.

  The DC input voltage range of devices such as switching power supply units varies depending on the model. For example, if the DC input voltage range is a wide input type having a DC120V to DC360V, the voltage drop protection device 30 having the above-described configuration can be used to provide appropriate protection immediately after the occurrence of a voltage sag or power failure, and the time that can be protected also Relatively long. However, when the DC input voltage range is DC240V to DC360V, although appropriate protection is possible immediately after the occurrence of a voltage sag or a power failure, the output DC voltage Vdcot output from the output terminal 19 drops below 240V. In such a case, sufficient driving cannot be performed, so that the protection time is relatively short. On the other hand, when the DC input voltage range is DC120V to DC180V, such a device cannot be connected because the DC output voltage Vdcot is too high immediately after the occurrence of a sag or power failure. That is, the voltage drop protection device 30 needs to be designed according to the DC input voltage range of the equipment connected to the output terminal 19.

JP 2005-269653 A

  The present invention has been made in view of the above problems, and the object of the present invention is to widen the DC input voltage range of equipment connectable to the output terminal, to increase the efficiency of backup, extend the protection time, and to perform electrolysis. An object of the present invention is to provide a DC power supply voltage drop protection device capable of reducing the capacity of power storage means such as a capacitor.

The present invention made to solve the above problems comprises an input terminal connected to an external commercial AC power supply, and an output terminal that outputs DC power to a load that requires DC power supply power , A voltage drop protection device for a DC power supply corresponding to a load having a different DC input voltage range ,
a) AC / DC converting means for converting AC voltage supplied to the input terminal into DC voltage;
b) power storage means for storing electrical energy;
c) Voltage for the user to set the value of the second DC voltage that is within the DC input voltage range of the load connected to the output terminal and the value of the first DC voltage that is higher than the second DC voltage. A setting section;
The DC voltage obtained by d) the AC / DC converting means, a charging operation for charging the power storage unit temperature pressure and to the first DC voltage set by the voltage setting unit, are stored in said storage means a bidirectional transformation means for performing a DC voltage by electric energy, wherein the discharge operation that later push up the second DC voltage set by the voltage setting unit, selectively a
e) Detecting a decrease in the AC voltage supplied to the input terminal, and performing a charging operation while outputting the DC voltage obtained by the AC / DC converting means from the output terminal when there is no decrease in the AC voltage. the control bidirectional converter, an AC voltage for controlling the bidirectional converter as during abnormality lowered to output a second DC voltage obtained thereby I discharge operation line from the output terminal Control means;
It is characterized by having.

  The power storage means is typically an electrolytic capacitor, but other than that, an electric double layer capacitor, a lithium ion capacitor, a secondary battery such as a lithium ion battery, or the like can be used.

As the bidirectional conversion means, for example, a chopper type DC / DC converter or the like can be used. When the power storage means is an electrolytic capacitor, the power storage means can be charged with a high DC voltage corresponding to the breakdown voltage of the electrolytic capacitor .

  In the voltage drop protection device for a DC power supply according to the present invention, when AC power from a commercial AC power supply is normally supplied, the DC voltage converted by the AC / DC converter is output from the output terminal to an external load. The Further, the bidirectional conversion means boosts this voltage to an appropriately high first DC voltage and charges the power storage means under the control of the control means. The first DC voltage at this time, that is, the charging voltage may be determined appropriately according to the withstand voltage of the power storage means, for example. However, since the energy efficiency is proportional to the square of the voltage, it is better to set the charging voltage as high as possible. This is advantageous in terms of energy efficiency.

  When the commercial AC power supply voltage suddenly drops due to an instantaneous drop or a power failure, the control means detects this voltage drop and switches the operation of the bidirectional conversion means from the charging operation to the discharging operation. Then, the direct current voltage by the electric energy held in the power storage means until immediately before is stepped down to the second direct current voltage by the bidirectional conversion means and output to the output terminal. The second DC voltage at this time may be appropriately determined in advance according to the operating DC input voltage range of the device connected to the output terminal.

  During the discharging operation, the operation of the bidirectional conversion means is controlled so as to maintain the second DC voltage substantially constant. When the commercial AC power supply voltage recovers, the voltage appearing at the input terminal rises. Therefore, the control means detects this and switches the bidirectional conversion means from the discharging operation to the charging operation again. In this way, the commercial AC power supply can be backed up immediately or during a power failure for a time corresponding to the amount of electrical energy held in the power storage means.

As described above, the first DC voltage is preferably determined as appropriate according to the withstand voltage of the storage means, and the second DC voltage is determined as appropriate according to the operating DC input voltage range of the equipment connected to the output terminal. I can decide. In the chopper type DC / DC converter, the voltage value of the step-up / step-down is determined by the on / off time of the switching element for turning on / off the current. Therefore, the first and second DC voltages are easily determined only by switching the control program. it is possible.

  According to the voltage drop protection device for DC power supply according to the present invention, the value of the charging voltage when charging the power storage means and the value of the DC voltage output from the output terminal when the commercial AC power supply voltage drops are independently determined. I can decide. In addition, the value of the DC voltage output from the output terminal at the time of voltage drop, that is, the second DC voltage does not decrease with the passage of time as in the prior art, but is a desired value over an appropriate time that can be backed up. Is maintained almost constant. Therefore, by appropriately setting the second DC voltage in accordance with the operating DC input voltage range of the device connected to the output terminal, the commercial AC power supply voltage can be reduced for devices having various operating DC input voltage ranges. A backup voltage can be applied in place of the voltage immediately after.

In particular, since it is possible to set the second DC voltage by the voltage setting unit, a second DC voltage according to the operating DC input voltage range of the device to be connected to the output terminal can be appropriately set to a, the operating DC input voltage range Versatility for different devices is widened.

  Further, as described above, since the voltage during charging is independent of the DC voltage output to the output terminal when the voltage drops, the charging voltage is made as high as possible according to the withstand voltage of the storage means such as an electrolytic capacitor, and energy efficiency is increased. Can be increased. Thereby, the capacity of the power storage means can be reduced if the same backup time as in the prior art is realized, and the backup time can be extended if the capacity of the power storage means is the same as that in the prior art.

1 is a schematic block diagram of a DC power supply voltage drop protection device according to an embodiment of the present invention. The schematic block diagram of the conventional voltage drop protective device for DC power supplies.

  An embodiment of a DC power supply voltage drop protection device according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic block diagram of a voltage drop protection device for a DC power supply according to this embodiment.

  This voltage drop protection device 1 is inserted between the commercial AC power supply 2 and the switching power supply unit 3 in the same manner as the conventional voltage drop protection device 30 shown in FIG. It protects this. 1, the same components as those of the conventional voltage drop protection device 30 shown in FIG.

  The voltage drop protection device 1 of the present embodiment includes an electrolytic capacitor 18 as a power storage unit in the present invention, a capacitor 13, choke coils 14 and 15 as a bidirectional conversion unit in the present invention, and a first switching element connected in series. 16 and a second switching element 17, a bidirectional DC / DC converter 12, a voltage sag / power failure detection unit 20 for detecting that the AC input voltage Vacin has dropped below a predetermined value, and a first and a second switching element. Switching control unit 21 for controlling on and off of 16 and 17, respectively, and detecting the voltage after boosting (that is, the terminal voltage VB of the electrolytic capacitor) and the voltage after dropping (that is, the output voltage Vdcot when the voltage drops). A voltage monitoring unit 22 to be monitored and a voltage setting unit 23 for setting these voltages from the outside are included.

  The bi-directional DC / DC converter 12 is a chopper type DC / DC converter, and the first switching element 16 is turned on and the second switching element 17 is turned on / off to boost the voltage in the right direction in FIG. . Further, the second switching element 17 is turned on, and the first switching element 16 is turned on / off, whereby the voltage is stepped down in the left direction in FIG. The step-up mode for boosting is a charging mode for charging the electrolytic capacitor 18, and the step-down mode for stepping down is a discharge mode for discharging the electrolytic capacitor 18. The switching control unit 21 controls switching of the step-up / step-down (that is, charging / discharging) and execution / stop of the step-up / step-down operation.

  The input voltage range of the input terminal 11 is, for example, AC 85V to 264V. The DC voltage Vdcot output from the output terminal 19 at the time of voltage drop is arbitrarily set within the range of, for example, 120 to 360 VDC, that is, the user can freely determine and set the value determined appropriately in the voltage setting unit 23 in advance. To do. The charging voltage of the electrolytic capacitor 18, that is, the terminal voltage VB can be arbitrarily determined under the restriction of the rated withstand voltage of the electrolytic capacitor 18. For example, when the withstand voltage is 500V, the charging voltage is determined to be DC420V and the voltage is set. Set in section 23.

  When the commercial AC voltage from the commercial AC power supply 2 is normally supplied, the DC voltage that is AC / DC converted by the rectifier 10 is output to the output terminal 19 as the DC output voltage Vdcot. The DC voltage is input to the bidirectional DC / DC converter 12, and the DC voltage is increased to 420V by the operation of the first and second switching elements 16 and 17 driven as described above under the switching control unit 21. Then, the electrolytic capacitor 18 is charged. When the terminal voltage VB of the electrolytic capacitor 18 detected by the voltage monitor unit 22 reaches 420 V, the switching control unit 21 controls the operations of the first and second switching elements 16 and 17 so as to maintain this.

  When the AC voltage from the commercial AC power supply 1 temporarily decreases due to a power failure or the like, and the voltage sag / power failure detection unit 20 detects that the voltage has dropped below a predetermined value, the switching control unit that has received this detection signal 21 switches the operation of the switching elements 16 and 17 to operate the bidirectional DC / DC converter 12 in the discharge mode. Then, the electric energy stored in the electrolytic capacitor 18 is supplied to the bidirectional DC / DC converter 12, and the DC voltage set in the voltage setting unit 23, for example, stepped down to about 120V, is converted into the bidirectional DC / DC converter. 12 is output. This DC voltage is output to the switching power supply unit 3 through the output terminal 19.

  The voltage value after step-down by the bidirectional DC / DC converter 12 is detected by the voltage monitor unit 22 and fed back to the switching control unit 21 so that the DC voltage after step-down is maintained at about 120V. The chopper of the bidirectional DC / DC converter 12 (that is, the switching operation of the switching elements 16 and 17) is controlled. Although the electric energy held in the electrolytic capacitor 18 decreases with the discharge, a DC voltage of about 120 V is continuously output from the output terminal 19 until the charging voltage drops to near 120V. For example, when driving a wide input type switching power supply unit 3 of DC120V to 360V, the DC 120V DC voltage is output from the output terminal 19 from the backup start time immediately after the voltage drop, so that the electric energy held in the electrolytic capacitor 18 can be obtained. Since it can be used effectively without being wasted, backup time can be extended.

  As described above, in the DC power supply voltage drop protection device 1 according to the present embodiment, even when the power supply is temporarily shut off by the commercial AC power supply 2, DC power is replaced with the switching power supply unit 3 instead. Can be supplied to. As a result, the load connected to the switching power supply unit 3 can continue to operate without being affected by a sag or power failure.

  When the switching power supply unit 3 connected to the output terminal 19 or another device capable of inputting DC voltage is replaced with one having a different operating DC input voltage range, a voltage setting unit is set according to the operating DC input voltage range. It is only necessary to appropriately change the DC voltage Vdcot set to 2.

  In the above embodiment, the electrolytic capacitor 18 is used as the power storage means, but instead of this, a secondary battery such as a battery can be used in addition to an electric double layer capacitor, a lithium ion capacitor, or the like.

  Further, the above-described embodiment is an example of the present invention, and it is obvious that any modification, correction, and addition as appropriate within the scope of the present invention are included in the scope of the claims of the present application.

DESCRIPTION OF SYMBOLS 1 ... Voltage drop protection device 2 ... Commercial alternating current power supply 3 ... Switching power supply unit 10 ... Rectification part 11 ... Input terminal 12 ... Bidirectional DC / DC converter 13 ... Capacitor 14, 15 ... Choke coil 16 ... 1st switching element 17 ... 1st 2 switching element 18 ... electrolytic capacitor 19 ... output terminal 20 ... voltage drop / power failure detection unit 21 ... switching control unit 22 ... voltage monitoring unit 23 ... voltage setting unit

Claims (2)

DC power supply voltage that has an input terminal connected to an external commercial AC power supply and an output terminal that outputs DC power to a load that requires DC power supply, and that supports loads with different DC input voltage ranges A drop protection device,
a) AC / DC converting means for converting AC voltage supplied to the input terminal into DC voltage;
b) power storage means for storing electrical energy;
c) Voltage for the user to set the value of the second DC voltage that is within the DC input voltage range of the load connected to the output terminal and the value of the first DC voltage that is higher than the second DC voltage. A setting section;
The DC voltage obtained by d) the AC / DC converting means, a charging operation for charging the power storage unit temperature pressure and to the first DC voltage set by the voltage setting unit, are stored in said storage means a bidirectional transformation means for performing a DC voltage by electric energy, wherein the discharge operation that later push up the second DC voltage set by the voltage setting unit, selectively a
e) Detecting a decrease in the AC voltage supplied to the input terminal, and performing a charging operation while outputting the DC voltage obtained by the AC / DC converting means from the output terminal when there is no decrease in the AC voltage. the control bidirectional converter, an AC voltage for controlling the bidirectional converter as during abnormality lowered to output a second DC voltage obtained thereby I discharge operation line from the output terminal Control means;
A voltage drop protection device for a DC power supply, comprising: The voltage drop protection device for a DC power supply according to claim 1 ,
It said storage means is a DC power supply voltage protection device comprising an electrolyte capacitor der Turkey.

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