JPH0836429A - Dc power source system - Google Patents

Abstract

PURPOSE:To use a storage battery up to the utmost of its capability at the time of service interruption. CONSTITUTION:A transistor TR 21 and a diode 22 are inserted in series to a feeder 14 and in the forward direction of a storage battery 13 in the vicinity of a load 16. Input terminals 26 and 27 of a DC power source (DC-DC converter) 25 are connected to feeders 14 and 15, and output terminals 28 and 29 of the DC power source 25 are connected to both ends of the series circuit of the TR 21 and the diode 22, and the output voltage is added to the voltage of the storage battery 13. The load voltage is detected by a control circuit 19, and a switch 31 is turned on to operate the DC power source 25 if it tries to fall below its allowable range, and thus, the DC of the voltage in the allowable range is always applied to the load 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, as an operating power supply for a communication device, converts commercial AC current into DC power and supplies it to a load, charges a storage battery, and supplies DC power from the storage battery to the load during a power failure. The present invention relates to a highly reliable DC power supply system.

[0002]

2. Description of the Related Art As a DC power supply system for supplying stable DC power to a communication device, generally, a commercial AC power is received,
A DC power supply that outputs DC power of 48V or 21V is used. A storage battery is provided on the output side of the DC power supply to supply the DC power to the communication device even when the commercial AC power that is the input of the DC power supply fails. This storage battery is generally used by connecting a plurality of cells in series in order to obtain a voltage required on the communication device side.

FIG. 2 shows a conventional DC power supply system. The commercial AC power supply 11 is connected to the input side of the DC power supply 12, and the storage battery 13 is connected in parallel to the output side of the first DC power supply 12. The AC power from the commercial AC power supply 11 is the DC power supply 12
Is converted into DC power by the DC power, the storage battery 13 is charged with the DC power, and at both ends of the storage battery 13,
Load 16 connected through the second power supply lines 14 and 15
Then, the DC power from the DC power supply 12 is supplied. When the commercial AC power supply 11 fails, the DC power supply 12 stops operating, so the storage battery 13 to the first and second power supply lines 14,
DC power is supplied to the load 16 via 15.

When the voltage of the storage battery 13 exceeds the allowable voltage range of the load 16, a series circuit 17 of one or more voltage adjusting diodes (hereinafter referred to as a diode string)
Is connected in series with one of the power supply lines 14, and the diode array 17
By causing a voltage drop at and adjusting the voltage, the load 16 operates to be held within the allowable voltage range. When the storage battery 13 discharges, the voltage drops, and when it becomes lower than the voltage drop of the diode string 17 from the upper limit of the allowable voltage range of the load 16, the diode string 17 is short-circuited by the switch 18 to reduce the loss. The switch 18 was controlled by. The value obtained by subtracting the voltage drop due to the power supply lines 14 and 15 from the voltage of the storage battery 13 is the load 16
If the lower limit of the allowable voltage range is broken down, the communication device of the load 16 system downs. When the power supply lines 14 and 15 become long, the loss due to the power supply lines 14 and 15 increases, and the energy that can be supplied from the storage battery 13 to the load 16 at the time of power failure further decreases.

[0005]

Energy remains in the storage battery 13 even when the load 16 reaches the minimum allowable voltage. However, the conventional technique shown in FIG. 2 can effectively utilize this residual energy. Instead, there was the problem of leaving a relatively large amount of energy. An object of the present invention is to provide a highly reliable DC power supply system that can maximize the use of energy in a storage battery during a commercial AC power failure and compensate for a voltage drop in a power supply line to supply stable DC power.

[0006]

According to a first aspect of the invention, a series circuit of a voltage adjusting semiconductor element and a diode, which is in the forward direction with respect to a storage battery, is connected in series to the first power supply line, and The pair of input terminals of the second DC power source is connected to the first and second power supply lines, and the pair of output terminals of the second DC power source are connected to each other so that the DC output is added to the output of the storage battery. Connected to both ends of the series circuit via switches,
A control circuit detects a load voltage to control the semiconductor element, adjusts an output voltage of the second DC power supply, and controls ON / OFF of the switch.

According to the second aspect of the invention, the voltage adjusting semiconductor element is connected in series with one of the first and second power supply lines and is in the forward direction with respect to the storage battery. The pair of input terminals of the second DC power supply is connected to the power supply line, and the pair of output terminals of the second DC power supply are connected to the first and second output terminals so that the DC output is added to the series output of the storage battery. Is connected in series to one of the power supply lines, the load voltage is detected by the control circuit, the semiconductor element is controlled, and the output voltage of the second DC power supply is adjusted.

In any of the first and second aspects of the invention, it is preferable that the second DC power source, the voltage adjusting semiconductor element and the control circuit are provided as close to the load as possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows an embodiment of the invention of claim 1, and the same reference numerals are given to the portions corresponding to those of FIG. In the present invention, the transistor 21 as the voltage adjusting semiconductor element and the diode 2 connected in series in the forward direction with the transistor 21.
Two series circuits 23 are connected in series with one power supply line, in this example the first power supply line 14, and in the forward direction with the storage battery 13. In addition, in this example, one end of the series circuit 23 is connected to one end of the load 16, that is, it is connected in the immediate vicinity of the load 16.

The control circuit 19 detects the voltage across the load 16 and controls the resistance value of the transistor 21 so as not to exceed the upper limit of the allowable voltage of the load 16. Diode 2
Reference numeral 2 is for preventing the reverse voltage from being applied to the transistor 21. Further, the input terminals 26 and 27 of the second DC power supply 25 are connected to the first and second power supply lines 14 and 15, respectively, and the output terminals 28 and 2 of the second DC power supply 25 are connected.
9 are connected to both ends of the DC circuit 23, respectively. The second DC power supply 25 is a DC-DC converter that outputs an input DC voltage as a DC voltage in accordance with the control of the control circuit 19 and has a polarity such that this DC voltage is added to the DC voltage of the storage battery 13. Connected by. A switch 31 is inserted in series between one of the output terminals 28 and 29 of the second DC power supply 25, 29 in this example, and the series circuit 23.
In this example, like the series circuit 23, the second DC power supply 25
Is provided near the load 16. The control circuit 19 controls the adjustment of the output voltage of the second DC power supply 25 and the ON / OFF of the switch 31 according to the detected load voltage of the control circuit 19.

The operation of this configuration will be described. When the AC power supply 11 is normal, the first DC power supply 12 charges the storage battery 13 and also supplies the load 16 via the first and second power supply lines 14 and 15. Supply stable DC power. Storage battery 1
When 3 is a small sealed lead acid battery of 24 pieces, the output voltage of the first DC power supply 12 is 54.5V (2.27V / charge voltage).
ceLL × 24 ceLL = 54.5V), and when the voltage drop of the first and second power supply lines 14 and 15 is small, the voltage exceeds the allowable voltage range (43V to 53V) of the load 16, so the control circuit 19 switches the switch 31. It is opened and the voltage is dropped by the transistor 21 to supply the load 16 with DC power in the allowable voltage range.

When the AC power supply 11 fails, the first DC power supply 12 stops its operation, and therefore the storage battery 1 is connected to the load 16.
Power is supplied from 3. When the voltage of the storage battery 13 drops and the storage battery voltage falls below the upper limit of the allowable voltage of the load 16, the switch 31 is short-circuited to eliminate the voltage drop in the transistor 21 and the output voltage of the second DC power supply 25 is added. Then, the DC power is supplied to the load 16. The second DC power supply 25 receives the voltage supplied from the storage battery 13 via the power supply lines 14 and 15, and inputs the voltage of the storage battery 13 and the power supply lines 14 and 15.
The control circuit 19 controls so that the voltage obtained by adding the voltage drop of 15 and the output voltage of the second DC power supply 25 becomes constant. It should be noted that even if the switch 31 is turned on, the second DC power supply 25 does not immediately reach the ideal state, and it takes some time to reach the steady state. During this period, the DC power of the storage battery 13 is supplied to the load 16 through the output of the second DC power supply 25. Therefore, even if the voltage of the storage battery 13 becomes equal to or lower than the minimum allowable voltage 43V of the load 16, the output voltage of the second DC power supply 25 is added, so that the voltage of the load 16 is 43V.
It is maintained at a voltage higher than V 2. The storage of the storage battery 13 is performed by selecting the voltage of the second DC power supply 25 as the voltage obtained by subtracting the minimum operating voltage of the storage battery 13 from the voltage obtained by adding the minimum allowable voltage of the load 16 and the voltage drop of the power supply lines 14 and 15. It is possible to make maximum use of energy. In addition,
Diode 22 connected in series with transistor 21
Is for preventing a reverse voltage from being applied to the transistor 21 when the second DC power supply 25 is operating, and is, for example, a Schottky diode having a voltage drop as small as possible.

When the AC power supply 11 recovers from the power failure, the first DC power supply 12 operates to charge the storage battery 13, whereby energy is stored in the storage battery 13, and the storage battery 1
The voltage of 3 gradually increases. Its charging voltage is 54.
When the voltage drops to 5V and the voltage drop of the power supply lines 14 and 15 is 1.5V or less, the upper limit value 53V of the allowable voltage of the load 16 is exceeded. Therefore, when the voltage of the load 16 becomes 53V, the switch 3
Open 1 and insert transistor 21 in series with the circuit,
By using the voltage drop of the transistor 21 to cause a voltage drop of 1.5 V or more, the voltage applied to the load 16 becomes 1
It is controlled by the control circuit 19 so as to be within the allowable voltage range of 6.

FIG. 1B shows an embodiment of the invention of claim 2,
Portions corresponding to those in the embodiment of FIG. 1A are designated by the same reference numerals. In this embodiment, the transistor 21 and the output terminals 28 and 29 of the second DC power supply 25 are connected in series, and the diode 22 is omitted. The second DC power supply 25 is always in operation regardless of whether the commercial AC power supply 11 is normal or a power failure. When the control circuit 19 detects the voltage of the load 16 and tries to make it higher than the allowable voltage range of the load 16, the control circuit 19 causes the voltage to drop in the transistor 21, and when the voltage of the load 16 becomes lower than the allowable voltage range, the second The output voltage of the DC power supply 25 is increased.

Also in the embodiment shown in FIG. 1B, the control circuit 19, the transistor 21, and the second DC power supply 25 are provided near the load 16. However, in both FIG. 1A and FIG. 1B,
Transistor 21, second DC power supply 25, control circuit 19
Need not be provided near the load 16. In that case, the load voltage detection line 20 connecting the control circuit 19 and the load 16 is simply lengthened. Instead of the transistor 21, M
You may use semiconductor elements, such as OSFET and SIT.

[0016]

As described above, according to the present invention, the stored energy of the storage battery 13 can be utilized to the maximum extent, and the storage battery 13 can be made compact and lightweight. For example, load 16
The allowable voltage range is 43 to 53 V, the load current is 1000 A, and the storage battery 13 is a set of 24 and the holding time of the storage battery 13 is 1
The case where the voltage drop of the power supply lines 14 and 15 is 2V for 0 minutes will be compared with the conventional DC power supply system.

In the conventional system, the voltage of the single cell when the load 16 reaches the minimum allowable voltage is 1.88V ((43 + 2)
V / 24ceLL = 1.88V), and the storage battery capacity required in this case is 680AH. On the other hand, in the system of the present invention, assuming that the storage battery discharge end voltage is 1.6V, the maximum output voltage of the DC power supply 12 is 6.6V (45V- (1.6V
By setting /ceLL)×24ceLL=6.6V), the discharge end voltage of the storage battery 13 can be used. In this case, since the storage battery capacity is 470 AH, the storage battery 13 can be downsized by about 30% as compared with the conventional equipment, and can be made economical.

Further, the abrupt voltage change which has been caused by the on / off operation of the conventional switch can be eliminated by slowly changing the resistance value change of the voltage adjusting semiconductor element such as the transistor 21. Power lines 14 and 15
Is long and the second DC power supply 25 is provided near the load 16, the output voltage range of the second DC power supply 25 can be widened to increase the voltage drop due to the power supply lines 14 and 15. By using a power supply line with a small diameter, the cost of the power supply line can be significantly reduced.

Further, in the conventional system in which the load voltage detection line 20 laid in parallel with the power supply lines 14 and 15 is thin and long, the detection line 20 is easily broken and the system is easily brought down. However, in the present invention, the control circuit 1
When the voltage adjusting semiconductor element 21, the second DC power supply 25, etc. are provided near the load 16, the load voltage detection line 20 becomes shorter, and the load voltage detection line 20 is not cut off.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional DC power supply system.

Claims (2)

[Claims] 1. A commercial AC power is input, a DC power is output from a first DC power supply, a storage battery connected in parallel to the output side of the first DC power supply is charged, and both ends of the storage battery are charged. In a DC power supply system for supplying DC power to a load via first and second power supply lines, a voltage adjustment semiconductor element connected in series to the first power supply line and in a forward direction with respect to the storage battery. A series circuit of a diode and a pair of input terminals connected to the first and second power supply lines,
A second DC power supply having a pair of output terminals connected to both ends of the series circuit so as to input DC power, output DC power, and add the DC output power to the output of the storage battery; A switch connected between the output terminal of the second DC power supply and the series circuit, a function of detecting the voltage of the load and controlling the semiconductor element, and adjusting the output voltage of the second DC power supply. A DC power supply system comprising: a control circuit having a function and a function of controlling ON / OFF of the switch. 2. A commercial AC power is input and a DC power is output from a first DC power supply, a storage battery connected in parallel to the output side of the first DC power supply is charged, and both ends of the storage battery are charged. In a DC power supply system for supplying DC power to a load via first and second power supply lines, the DC power supply system is connected in series to one of the first and second power supply lines and is in a forward direction with respect to the storage battery. A voltage adjusting semiconductor element, and a pair of input terminals connected to the first and second power supply lines,
A second output having a pair of output terminals connected in series to one of the first and second power supply lines so that direct current power is input, direct current power is output, and the direct current output is added to the output of the storage battery. And a control circuit having a function of detecting the voltage of the load and controlling the semiconductor element, and a function of adjusting the output voltage of the second DC power supply. DC power supply system.