JPH08308143A - Power supply device for communication equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] In a power supply device for a communication device equipped with a backup storage battery, a switch for disconnecting the storage battery from the load is necessary in order to prevent system down due to over discharge of the storage battery. This switch is electronic and improves reliability. [Structure] A storage battery 5 for backup and a FET 7 as a disconnection switch are connected in series, and a power supply device 3 is connected to both ends of these circuits. The voltage maintaining circuit 17 turns off the gate voltage of the FET 7 when the output voltage is insufficient. The current limiting circuit 19 short-circuits the gate and the source when the voltage (corresponding to the current value) between the drain and the source of the FET 7 is higher than the set value. The drive detection circuit 21 generates a signal when the gate-source voltage of the FET 7 is lower than a predetermined value. The monitoring circuit 23 also generates a signal when there is an open circuit failure between the drain and source of the FET 7. The alarm circuit 8 operates for all these failure modes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for a communication device, and more specifically, in a power supply device for a communication device provided with a storage battery for backup, an electronic storage battery disconnection switch and its failure detection. Related to those including circuits.

[0002]

2. Description of the Related Art Since a power supply for a communication device is required to have a high reliability for always supplying electric power stably and continuously, a power supply from a commercial power supply and a storage battery for backup are arranged in parallel, Be prepared for a power outage. However, when the voltage drops below a predetermined value due to overdischarge of the storage battery,
In order to protect the storage battery, it is necessary to disconnect the storage battery. In general, a switch having an electric contact is used as the switch for disconnecting the storage battery. In order to find the operation failure of the switch, a method of sending a failure signal as a switch failure when a disconnection or the like of the coil of the switch driving relay is confirmed and there is disconnection or the like is performed.

[0003]

However, if the switch for disconnecting the storage battery is a mechanical contact, the life is finite, so it is desirable to use an electronic switch.
However, in the case of using an electronic switch such as a semiconductor, there is a problem that it is more vulnerable than a mechanical switch with respect to problems such as input voltage fluctuation, load fluctuation, and terminal connection error.

According to the present invention, a backup storage battery and a power supply device for a communication device equipped with a switch for disconnecting the storage battery from a load in order to prevent the system from being down due to over-discharge of the storage battery are electrically connected to the disconnection switch.
An object of the present invention is to improve reliability by providing a means for detecting a failure in any mode of an electronic switch.

[0005]

In order to solve this problem, the present invention proposes the following means. A backup storage battery and a disconnecting switch FET are connected in series, and the power supply device is connected by connecting both ends of these series circuits as a power supply plus line and a power supply minus line to form a communication device power supply device. When the voltage between the power supply plus line and the power supply minus line is equal to or higher than a predetermined value, F
A voltage maintaining circuit for turning on the ET gate voltage is provided.
Further, a current limiting circuit is provided which short-circuits the gate and source of the FET when the voltage between the drain and source of the FET is higher than the set value. Further, a drive detection circuit for generating an alarm signal when the gate-source voltage of the FET is lower than a predetermined value is provided. Then, a monitoring circuit is provided which generates an alarm signal when there is an open circuit failure between the drain and source of the FET.

Regarding the configuration of the voltage maintaining circuit, the power supply plus line and the power supply minus line are used as operating power supplies, and an ON signal is generated when the voltage of the operating power supplies is equal to or higher than a predetermined value.

Regarding the configuration of the current limiting circuit, the gate-source voltage of the FET and the drain-source voltage are used as operating power supplies, and when the drain-source voltage is equal to or higher than a predetermined value, an ON signal between the gate and source of the FET. Will disappear.

With respect to the structure of the drive detection circuit, the power supply plus line and the gate-source voltage of the FET are used as the operating power supply, and an alarm signal is generated when the gate-source voltage is below a predetermined value.

With respect to the configuration of the monitoring circuit, the power source plus line and the drain-source voltage of the FET are used as operating power sources, and an alarm signal is generated when the drain-source voltage has a predetermined polarity and a predetermined value or more. is there.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply device for a communication device according to the present invention will be described with reference to FIG. In the figure, the power supply device 3 generates a DC voltage converted from a commercial AC power supply (not shown).
The power source plus line P of the power source device 3 is connected to the plus electrode of the backup storage battery 5 and the output terminal 11. The negative electrode of the storage battery 5 is connected to the source of the FET 7 as a switch. And FET
The drain of 7 is connected to the negative line N of the power supply device 3. Since the voltage drop between the drain and the source of the FET 7 is extremely low when the FET 7 is turned on, the terminal voltage of the storage battery 5 is almost equal to the voltage of the power supply device 3.
Therefore, when the FET 7 is on, the storage battery 5
Is charged in the power supply device 3 and becomes a terminal voltage slightly higher than its own electromotive force. This higher voltage is applied to the dropper 9 connected in series between the power source minus line N and the output terminal 13.
The desired output voltage, which is subtracted by, can be applied to the load 15 via the output terminals 11 and 13. A snubber resistor 74 and capacitor are placed between the drain and source of the FET7.
75 and are connected.

In order to provide the FET 7 with a function of applying a necessary bias voltage and a function of protection, a voltage maintaining circuit 17, a current limiting circuit 19, a drive detecting circuit 21 and a monitoring circuit 23 are provided.
It has four circuits. The configuration of each circuit will be described in detail below.

The voltage maintaining circuit 17 is connected to three potential points of the power source plus line P, the power source minus line N and the gate line G of the FET 7, and the power source plus line P and the power source minus line N are used as the power source of the circuit itself. When the voltage between the power source plus line P and the power source minus line N is equal to or higher than a predetermined value, a drive voltage is applied to the gate line G. On the contrary, when the voltage between the power source plus line P and the power source minus line N does not reach the predetermined value, the gate drive voltage disappears, the FET 7 is turned off, and the storage battery 5 is disconnected from the line. Explaining in detail the configuration of the voltage maintaining circuit 17,
A terminal 177 connected to the power supply plus line P, a terminal 178 connected to the power supply minus line N, and a gate line G.
It is composed of three terminals, a terminal 179 and a resistor 180 connected to the terminal 179. Between terminals 177 and 178 are resistors 173 and arms of resistors 174, and Zener diode 172 and resistors.
A bridge circuit consisting of 175 arms is connected. The emitter / base of the PNP transistor 170 is connected between the midpoints a and b of this bridge circuit. The transistor 170 is turned on when the potential at the point a becomes higher than the potential at the point b, and is turned off when the potential relationship is opposite. Since the Zener diode 181 is connected, an excessive voltage is not applied between the gate and source of the FET 7.

The current limiting circuit 19 will be described. In the normal ON state of the FET 7, current flows from the drain to the source. The value of the forward current is almost proportional to the drain-source voltage due to the ohmic characteristics of the FET.
By utilizing this property, if the drain current proportional value detected by the resistor 192 and the resistor 193 connected between the drain and source is larger than a predetermined value, the transistor 190 with the base and emitter connected at this point is turned on. . When the transistor 190 is turned on, the gate-source voltage of the FET 7 is reduced and the conductivity of the FET 7 is reduced.

The drive detection circuit 21 has a terminal 216 connected to the power source plus line P and a terminal 219 connected to the gate line of the FET 7 and a terminal connected to the source line S as well.
218 and the alarm output terminal 217. First, F
When a normal drive voltage is applied between the gate and source of ET7, that voltage appears between terminals 219 and 218,
The transistor 210 is turned on via the Zener diode 215 and the resistor 214. The collector of the transistor 210 is connected to the terminal 216 via the resistor 212, and when the transistor 210 is turned on, the potential of the power source plus line P changes to the source potential of the FET 7. Then, due to this potential change, the transistor 211 is turned off and the terminal 217 is opened. Next, when the gate-source voltage of the FET 7 is zero or insufficient, the transistor 210 is turned off, the transistor 211 is turned on, and the terminals 217 and 218 are turned on.

The monitoring circuit 23 uses the alarm output terminal 234 and the FE
A terminal 236 connected to the source line S of T7 and a terminal 235 connected to the power source minus line N are provided. The monitoring circuit 23 includes a transistor 230, a resistor 231, a diode 232 and a resistor 233. Transistor
230 collector at terminal 234, emitter at terminal 235,
The base is connected to terminal 236 via resistor 233. A resistor 231 and a diode 232 connected in parallel between the base and emitter of the transistor 230 are for bias stabilization and protection from reverse voltage, respectively.

Regarding the operation of this monitoring circuit 23,
When 7 is normal, transistor 230 is off and F
The alarm signal is issued when the source-drain of ET7 is opened. When the source-drain of the FET 7 is opened due to a disconnection or the like, the storage battery 5 is disconnected from the power supply device 3 and falls to a self-opening voltage lower than that during charging. A voltage which is the difference between the lowered self-opening voltage of the storage battery 5 and the voltage of the storage battery 5 from the voltage of the power supply device 3 is generated at the terminal 236 of the monitoring circuit 23 with a positive polarity and at the terminal 235 with a negative polarity. Due to this potential relationship, the transistor 230
Turns on and turns on the alarm signal at terminal 234.

The alarm signals of the drive detection circuit 21 and the monitoring circuit 23 are logically added by the diodes 82 and 83 and the resistor 81 to activate the alarm circuit 8. The alarm circuit 8 links with related systems.

The present invention is not limited to the embodiment described above, and can be easily modified to have the same operation. For example, the FET 7 of the disconnection switch can be replaced with an IGBT. The electrode emitter of the IGBT is connected to the source of the FET, the gate is connected to the gate, and the collector is connected to the drain. However, in order to correct the current detection signal, it is necessary to insert a resistor having a low resistance value in the current path. Moreover, it is naturally possible to switch the polarities of the respective constituent elements.

[0019]

EFFECTS OF THE INVENTION Since the present invention has the characteristics as described above, in a power supply device for a communication device using an electronic switch such as a FET for a storage battery and a storage battery disconnecting switch,
It is possible to self-protect against load fluctuations and incorrect connection of terminals. Or, in the unlikely event that the FET malfunctions, an alarm is issued to help recovery of the communication system. Further, since the operating power supplies for the voltage maintaining circuit, the current limiting circuit, the drive detecting circuit, and the monitoring circuit are supplied in the power supply device for a communication device, they are highly reliable and economical.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a power supply device for a communication device according to the present invention.

[Explanation of symbols]

1 ... Power supply device for communication device 3 ... Power supply device 5 ... Storage battery 7 ... FET 8 ... Alarm circuit 9 ... Dropper 11, 13 ... Output terminal
15 ... Load 17 ... Voltage maintaining circuit 19 ... Current limiting circuit 21 ... Drive detection circuit 23 ... Monitoring circuit P ... Power supply plus line N ... Power supply minus line S ...
Source line G ... Gate line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Suzuki ▲ Noboru 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Takayuki Uno 1-1-1 Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nippon Telegraph and Telephone Corporation

Claims (6)

[Claims] 1. A power supply for a communication device, which is configured by connecting a backup storage battery and a disconnection switch FET in series, and connecting a power supply device with both ends of these series circuits as a power supply plus line and a power supply minus line. A voltage maintaining circuit for turning on the gate voltage of the FET when the voltage between the power source plus line and the power source minus line is a predetermined value or more, and a voltage between the drain and source of the FET is a set value. A current limiting circuit that short-circuits the gate and source of the FET when higher, a drive detection circuit that generates an alarm signal when the gate-source voltage of the FET is lower than a predetermined value, and a drain-source of the FET A power supply device for a communication device, comprising: a monitoring circuit that generates an alarm signal when there is an open circuit failure. 2. The configuration of the voltage maintaining circuit is characterized in that the power supply plus line and the power supply minus line are used as operating power supplies, and an ON signal is generated when the voltage of the operating power supplies is equal to or higher than a predetermined value. The power supply device for a communication device according to claim 1. 3. The current limiting circuit is configured such that the gate-source voltage and the drain-source voltage of the FET are used as operating power supplies, and the gate of the FET is when the drain-source voltage is a predetermined value or more. The power supply device for a communication device according to claim 1 or 2, wherein an ON signal is lost between the sources. 4. The drive detection circuit is configured so that the gate-source voltage of the power source plus line and the FET is used as an operating power source, and an alarm signal is generated when the gate-source voltage is below a predetermined value. The power supply device for a communication device according to any one of claims 1 to 3, characterized in that. 5. An alarm signal when the drain-source voltage of the power supply plus line and the FET is used as an operating power source and the drain-source voltage has a predetermined polarity and a predetermined value or more. The power supply device for a communication device according to any one of claims 1 to 4, characterized in that: 6. An IGBT in place of the FET, the source of which is connected to the emitter, the gate of which is connected to the gate, and the drain of which is connected to the collector, according to any one of claims 1 to 5. Power supply device for communication equipment.