JPH05146092A - Charge control circuit for multiple charger standby redundant operation system uninterruptible power supply - Google Patents

Abstract

PURPOSE:To prevent an AC power supply from bearing an excessive current by employing a value, obtained by dividing the rated current of charger by the number of chargers, as a droop current set value for each charger. CONSTITUTION:A rated current setter 17, having rated value equal to the output current from charger No.1 10, is additionally provided with a droop current setter 31. A switch 32 functions to select the droop current setter 31 upon recovery of an AC power supply 2 from power interruption. At that time, a value obtained by dividing the rated current of charger No.1 10 by the number of chargers is set in the droop current setter 31. Consequently, total output current from chargers can be limited to a value of single charger. According to the invention, AC power supply 2 can be protected against its entering into overcurrent state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of standby redundant operation type uninterruptible power supply units capable of preventing an excessive current from flowing into this unit when the AC power supply recovers from a power failure. The present invention relates to a charging control circuit of a stand-by redundant operation system uninterruptible power supply.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram showing a conventional example of a charge control circuit of a multiple standby redundant operation type uninterruptible power supply system, showing a case where two sets of uninterruptible power supply systems perform standby redundant operation. ing. In FIG. 4, a first uninterruptible power supply device for converting AC power from the AC power supply 2 into AC power having a constant voltage and a constant frequency by the No. 1 charger 10 and the No. 1 inverter 12, and the AC power from the AC power supply 2. There is a second uninterruptible power supply device for converting the AC power of No. 2 charger 20 and No. 2 inverter 22 into AC power of constant voltage / constant frequency, and by switching the AC switch 4 composed of a semiconductor switch element such as a thyristor, No. 1 inverter 12 or No. 2 inverter 22
Supplies AC power to the load 5. Further, since the battery 3 is connected to the circuit in which the DC output of the No. 1 charger 10 and the DC output of the No. 2 charger 20 are commonly connected,
If the AC power supply 2 fails, the battery 3 supplies power to the load 5 through either the No. 1 inverter 12 or the No. 2 inverter 22, so that the load 5 can be prevented from failing.

The No. 1 charger 10 supplies charging power to the battery 3 and the load 5 via the No. 1 inverter 12
In order to supply electric power to the voltage regulator 14, the voltage regulator 14 performs an adjustment operation so that the charger output voltage matches the voltage command value from the voltage setter 13, and the phase shifter 15 operates the voltage regulator 14
The No. 1 charger 10 is controlled in response to the signal from. Here, the current detector 11 detects the output current of the No. 1 charger 10, and if the value reaches the value set by the rated current setting device 17 (generally 100% of the rated current), the signal from the droop command circuit 16 Is supplied to the phase shifter 15 to droop the output current of the No. 1 charger 10, so that the No. 1 charger 10 does not become an overcurrent state. Similarly, the No. 2 charger 20 also has a current detector 21, a voltage setter 23, a voltage regulator 24, and a phase shifter 2.
5, the drooping command circuit 26 and the rated current setting device 27 are provided, and the operation thereof is the same as that of the No. 1 charger 10.

When the No. 1 uninterruptible power supply system including the No. 1 charger 10 and the No. 1 inverter 12 is supplying power to the load 5, the No. 2 charger 20 and the No. 2 inverter 22 are provided. Since the uninterruptible power supply is in the standby state, it does not supply power to the load 5, but if the inverter 1 of 12 fails, the AC switch 4 immediately switches to the inverter 2 of 2
2 supplies AC power to the load 5. If the AC power supply 2 fails during power supply by the No. 1 uninterruptible power supply, the No. 1 inverter 12 converts the DC power from the battery 3 into AC power and continues to supply power to the load 5.

[0005]

When the power failure of the AC power supply 2 is restored, the power supply by the No. 1 uninterruptible power supply is restarted, but this battery is discharged by the discharge of the battery 3 during the power failure of the AC power supply 2. The voltage is dropping. If the power failure of the AC power supply 2 is eliminated, the No. 1 charger 10 supplies the charging current to the battery 3 together with the current to the No. 1 inverter 12, but at the same time, the No. 2 charger 20 also supplies the charging current to the battery 3. At this time, the output current of the No. 1 charger 10 does not exceed the value set by the rated current setting unit 17 due to the action of the drooping command circuit 16, and the output current of the No. 2 charger 20 is also set by the rated current setting unit 27. Since it does not exceed the specified value, there is no risk of overcurrent. However, the AC power source 2 is the rated current of the first charger 10 and the second charger 20.
Since the total value of the rated current is output, the AC power supply 2 will trip again due to overcurrent, or a voltage drop due to an excessive current will cause this AC power supply 2 to trip even if it does not trip.
It will adversely affect other loads connected to.
If the number of uninterruptible power supply units on standby is large, the overcurrent from the AC power supply 2 is further increased.

Therefore, an object of the present invention is to cause an excessive charging current to flow from the AC power supply to the battery when the AC power supply supplying the power to the plural standby redundant operation type uninterruptible power supply recovers from the power failure. Is to prevent.

[0007]

In order to achieve the above-mentioned object, a charging control circuit of the present invention comprises a plurality of charging means which are connected to an alternating current power source and convert alternating current into direct current, and direct current outputs of these charging means. Rated current setting means for separately setting the current to a rated value, a battery to which the DC output of each of these charging means is connected in common, and a battery connected to each of these charging means separately to convert DC to AC An inverter to
In a plurality of standby redundant operation type uninterruptible power supply devices equipped with an AC switch for switching the AC output of each of these inverters to supply it to the load, the rated current of the charging means is divided by the number of installed charging means. Each charging means is separately provided with a drooping current setting means to be set and a selecting means for selecting one of the drooping current setting means and the rated current setting means, and the selecting means when the AC power supply recovers from a power failure. Is to select the drooping current setting means, each charging means is provided with a first logic circuit which outputs a logic signal when all the charging means are operating and the charging means other than itself are normal. It is assumed that the first logic circuit gives an operation signal to the selecting means. Alternatively, an output cut-off means for cutting off the output of the charging means, and a second output means for outputting a logical signal when the charging means other than itself are in operation and normal.
And the above logic circuit are separately provided for each charging means, and the output cutoff means is operated in response to the output signal of the second logic circuit when the AC power supply recovers from a power failure. Alternatively, a total charging current detecting means for detecting a total output current of each of the charging means, a first current upper limit value setting means for setting a first current upper limit value, and a first current upper limit value smaller than the first current upper limit value. The second current upper limit value setting means for setting the second current upper limit value, and the remaining charging means excluding the specific charging means in each of the charging means if the total charging current detection value exceeds the first current upper limit value. And a third logic circuit that stops the operation and outputs an operation restart signal to the remaining charging means when the total charging current detection value becomes equal to or less than the second current upper limit value.

[0008]

[Function] When there are multiple standby redundant operation type uninterruptible power supply units, conventionally, each uninterruptible power supply unit charges the batteries simultaneously with their rated current when the AC power supply is restored from the power failure. In the present invention, the total value of the battery charging current is equal to that of one charging means even if there are a plurality of standby redundant operation type uninterruptible power supply devices. By suppressing it, the AC power supply does not bear an excessive current, and the value obtained by dividing the rated current of the charging means by the number of installed charging means is set as the drooping current set value of each charging means. Therefore, the total value of the charging current is limited to one. Or 1 battery charge when AC power supply is restored from power failure
If the total charging current exceeds the first upper limit current setting value by limiting all the charging means or operating all the charging means, only the specific charging means continues the operation and the remaining charging means interrupts the operation. By doing so, the AC power supply does not bear an excessive current.

[0009]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. The first embodiment circuit shown in FIG. 1 is the same as the conventional circuit described in FIG. Setting device 31, changeover switch 32 as selecting means, and drooping current setting device 41
Except that a changeover switch 42 as a selection means is added, and the other parts are all the same, so the description of the same parts will be omitted.

In this first embodiment circuit, No. 1 charger 10
Rated current setter 17 that sets the output current of the
Further, a drooping current setting device 31 is further added, and when the AC power supply 2 recovers from a power failure, the changeover switch 32 is switched so as to select the drooping current setting device 31. At this time, the set value of the drooping current setting device 31 is a value obtained by dividing the rated current of the No. 1 charger 10 by the number of installed chargers (2 in the case of FIG. 1). The set value of the drooping current setting device 41 is also the drooping current setting device 3.
The same value as 1, and when the AC power supply 2 recovers from a power failure, the changeover switch 42 selects the drooping current setting device 41.
Thereby, the total value of the output currents of the No. 1 charger 10 and the No. 2 charger 20 can be limited to the value for one charger.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention. The second embodiment circuit shown in FIG.
The difference is that a logical product element 33 as a first logic circuit and a logical product element 43 as a first logic circuit are added to the circuit of the first embodiment described above with reference to FIG. Are all the same, the description of the same parts will be omitted.

In the second embodiment circuit, when the AC power supply 2 is restored from a power failure, the operating states of a plurality of chargers and the presence / absence of a failure are input to the logical product element 33 or the logical product element 43, and the logical product thereof is input. The switching position of the changeover switch 32 or the changeover switch 42 is selected based on the calculation result. That is, all the chargers in the No. 1 charger 10 (No. 1 charger 10 in FIG. 2).
And No. 2 charger 20) are operating, and the other charger (No. 2 charger 20 in FIG. 2) is normal, the logical product element 33
Issues a changeover command to the changeover switch 32 so as to select the drooping current setting device 31. Similarly, the AND element 43 issues a changeover command to the changeover switch 42 so as to select the drooping current setting device 41.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention. The circuit of the third embodiment shown in FIG.
In the conventional example circuit described above with reference to FIG.
5, and a logical product element 36 as a second logic circuit, a contact 45 as an output cutoff means, and a logical product element 46 as a second logic circuit are added.
Since the other parts are the same, the description of the same parts will be omitted.

In the circuit of the third embodiment, a normally-closed contact 35 is provided on the output side of the phase shifter 15 and a normally-closed contact 45 is provided on the output side of the phase shifter 25. The contact 35 is an AND element 36. When driven, the contact 45 is driven by the logical product element 46. Here, the logical product element 36 is the other charger (see FIG. 3).
Then, when the No. 2 charger 20) is operating normally and the contact 35 is opened, the output of the No. 1 charger is cut off,
Only the No. 2 charger 20 supplies the charging current to the battery 3. Further, the logical product element 46 also opens the contact 45 when the other charger (No. 1 charger 10 in FIG. 3) is operating normally, so that the output of the No. 2 charger is cut off at this time. 1
Only the No. charger 10 supplies the charging current to the battery 3. That is, only one of the plurality of chargers charges the battery 3 with the rated current.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention. The fourth embodiment circuit shown in FIG. 5 is as follows.
In the conventional circuit described above with reference to FIG. 4, an adder 51 as a total charging current detecting means, a comparator 52 with hysteresis as a third logic circuit, an upper limit current setting device 53 as a first current upper limit value setting means, and a second current. The difference is that a hysteresis setter 54 as an upper limit value setting means and an operation interruption contact 55 are added, and the other circuit configuration is the same as the conventional example circuit of FIG. Is omitted.

In the fourth embodiment circuit, the current detector 11
Output current of No. 1 charger 10 detected by and current detector 2
The output current of the No. 2 charger 20 detected by 1 is added to the adder 51.
Then, the total value of the charging current is detected, and the current value set by the upper limit current setting unit 53 and this total charging current detection value are compared by the comparator with hysteresis 52. Here, the upper limit current setting value is the rated current value for one charger or a value slightly larger than the rated current value (for example, 120% of the rated current).
%). While the AC power supply 2 is out of power, the battery 3 serves as a power source and continues to supply AC power to the load 5 via each inverter. Is often decreasing. Therefore, if all the chargers start the charging operation all at once with the restoration of the power failure, the total charging current detection value becomes a large value and exceeds the upper limit current setting value.
The comparator with hysteresis 52 detects that the total charging current detection value exceeds the upper limit current setting value and sends an open signal to the operation interruption contact 55 to interrupt the operation of the No. 2 charger 20. (Of course, if there is another charger, the operation of the charger is also interrupted.) As a result, the No. 1 charger 10
Only continues to operate (all remaining chargers can be interrupted by the operation interruption contact, so only one No. 1 charger operates), but the charging of battery 3 is completed and the total charging current When the detected value is lower than the second current upper limit value set below the first upper limit current value, the hysteresis-equipped comparator 52 sends a closing signal to the operation interruption contact 55, and all chargers are turned on. The operation will be restarted. Here, the hysteresis setter 54 sets a hysteresis value that is a difference between the first upper limit current value and the second upper limit current value.

FIG. 6 is a time chart showing the operation of each part of the circuit of the fourth embodiment already described in FIG. 5. FIG. 6 shows the voltage change of the AC power supply 2, and FIG. 6 shows the output of the No. 1 charger 10. Voltage change, FIG. 6 shows output voltage change of No. 2 charger 20, FIG.
Is the voltage change of the battery 3, and FIG.
6 shows the output current change of the No. 2 charger 20, FIG. 6 shows the total charge current change, and FIG. 6 shows the operation of the operation interruption contact 55.

In FIG. 6, t ₁ is a time point when the power supply starts a power failure, t ₂ is a time point when the power failure is restored, t ₃ is a time point when the operation interruption contact 55 starts to operate (that is, is opened), and t ₄ is a battery 3 It is the time when the charging of is completed. That is, since the battery is discharged and its voltage is lowered with the start of the power failure, all the chargers supply the charging current when the power failure is restored, and the total charging current becomes excessive and the power source becomes an overcurrent. Therefore, when the problem of this total charging current is detected, t
At time ₃ , the operation interruption contact 55 opens and interrupts the output of the No. 2 charger 20, so that only the No. 1 charger has the battery 3
Is charged, and at the time point t ₄ when the charging is completed, the operation interrupting contact 55 is closed again to return to the original state.

FIG. 7 shows an application circuit of the fourth embodiment circuit described above with reference to FIG. In the circuit shown in FIG. 7, output sides of a plurality of chargers are commonly connected by a bus bar, and a plurality of inverters are configured as a main circuit so as to receive DC power from the bus bar. Therefore, in the application circuit shown in FIG. 7, since the total charging current detector 60 may be installed on the bus and the detected current may be sent to the comparator with hysteresis 52, the adder 51 can be omitted. Note that, except for the total charging current detector 60, all the operations have already been described with reference to FIG.

[0020]

According to the present invention, when a standby redundant operation system is composed of a plurality of uninterruptible power supply units, when the AC power supply recovers from a power outage and charges a consumed battery, By setting the output current of the charger to the value obtained by dividing the rated current of the charger by the number of installed units, the total output current of each charger is limited to one unit, so the AC power supply is in an overcurrent state. Can be avoided. Alternatively, when the power failure is restored, the circuit is configured so that all the chargers do not start the charging operation all at once, but operate only one of the chargers to charge the battery. I am configuring. As a result, in either case, the AC power supply only needs to carry the current for one charger, so by simultaneously carrying the charging currents of multiple chargers, the power supply becomes overcurrent and trips, or this overcurrent occurs. Due to the voltage drop caused by
It is possible to avoid the inconvenience that other loads connected to the power source are adversely affected.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional example of a charging control circuit of a multiple stand-by redundant operation type uninterruptible power supply system.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 6 is a time chart showing the operation of each part of the circuit of the fourth embodiment described above in FIG.

FIG. 7 is an application circuit diagram of the fourth embodiment circuit described above with reference to FIG.

[Explanation of symbols]

2 AC power supply 3 Battery 4 AC switch 5 Load 10 No. 1 charger 11 Current detector 12 No. 1 inverter 16 Drooping command circuit 17 Rated current setting device 20 No. 2 charger 21 Current detector 22 No. 2 inverter 26 Drooping command circuit 27 Rated current setting device 31 Drooping current setting device 32 Changeover switch as selection means 33 ANDing device as first logic circuit 35 Contact as output cutting means 36 ANDing device as second logic circuit 41 Drooping current setting device 42 Selection Changeover switch as means 43 AND element as first logic circuit 45 Contact as output shutoff means 46 AND element as second logic circuit 51 Adder as total charging current detection means 52 Hysteresis as third logic circuit With comparator 53 Upper limit current setting as first current upper limit value setting means Vessel 54 second current upper limit value setting hysteresis setter 55 operates interruption contacts 60 total charging current detector as a means

Claims (5)

[Claims] 1. A plurality of charging means connected to an AC power source to convert alternating current into direct current, rated current setting means for separately setting the direct current output current of each of these charging means to a rated value, and each of these charging means. A battery connected in common to the DC output, an inverter that is separately connected to each of these charging means to convert DC into AC, and an AC switch that switches the AC output of each inverter to supply to the load. In a multiple standby redundant operation type uninterruptible power supply device having a drooping current setting means for setting the rated current of the charging means to a value divided by the number of installed charging means, the drooping current setting means and the rating. Each charging means is separately provided with a selection means for selecting one of the current setting means, and the selection means sets the drooping current when the AC power supply recovers from a power failure. A charging control circuit for a plurality of standby redundant operation type uninterruptible power supply devices characterized by selecting means. 2. A plurality of charging means connected to an AC power source to convert AC into DC, rated current setting means for setting the DC output current of each of these charging means to a rated value separately, and each of these charging means. A battery connected in common to the DC output, an inverter that is separately connected to each of these charging means to convert DC into AC, and an AC switch that switches the AC output of each inverter to supply to the load. In a multiple standby redundant operation type uninterruptible power supply device having a drooping current setting means for setting the rated current of the charging means to a value divided by the number of installed charging means, the drooping current setting means and the rating. A selection means for selecting any one of the current setting means and a first logic circuit for outputting a logic signal when all the charging means are in operation and the charging means other than itself are normal. A plurality of standby units, characterized in that each charging unit is provided separately, and the selecting unit selects the drooping current setting unit in response to the output signal of the first logic circuit when the AC power supply recovers from a power failure. Charge control circuit for redundant operation type UPS. 3. A plurality of charging means for connecting to an alternating current power source to convert alternating current into direct current, a rated current setting means for separately setting a direct current output current of each of these charging means to a rated value, and a charging means for these charging means. A battery connected in common to the DC output, an inverter that is separately connected to each of these charging means to convert DC into AC, and an AC switch that switches the AC output of each inverter to supply to the load. In a multiple standby redundant operation type uninterruptible power supply device comprising: a second output means for cutting off the output of the charging means, and a logic signal when the charging means other than itself is in operation and is normal. And a logic circuit of the second logic circuit are separately provided for each charging means, and the output cutoff means is operated in response to the output signal of the second logic circuit when the AC power supply recovers from a power failure. Charging control circuit for multiple uninterruptible power supply system with redundant operation. 4. A plurality of charging means for connecting to an AC power source to convert AC into DC, rated current setting means for separately setting the DC output current of each of these charging means to a rated value, and each of these charging means. A battery connected in common to the DC output, an inverter that is separately connected to each of these charging means to convert DC into AC, and an AC switch that switches the AC output of each inverter to supply to the load. In a multiple standby redundant operation type uninterruptible power supply device including: a total charging current detection unit that detects a total output current of each charging unit; and a first current upper limit value setting unit that sets a first current upper limit value. A second current upper limit value setting means for setting a second current upper limit value that is less than the first current upper limit value; and if the total charging current detection value exceeds the first current upper limit value, The operation of the remaining charging means excluding the specific charging means in each charging means is stopped, and when the total charging current detection value becomes equal to or less than the second current upper limit value, an operation restart signal is sent to the remaining charging means. A charging control circuit for a plurality of standby redundant operation type uninterruptible power supply units, comprising a third logic circuit for outputting. 5. The plural standby redundant operation system uninterruptible power supply device according to claim 4, wherein the third logic circuit is the first
A charge control circuit for a multiple stand-by redundant operation type uninterruptible power supply device, comprising a comparator with hysteresis having a difference between a current upper limit value and a second current upper limit value as an operation hysteresis.