JPS63294233A - Backup device for power supply - Google Patents

Abstract

PURPOSE:To prevent abnormal discharge from a backup power circuit and the shortening of a lifetime by connecting a switch in series with the backup power circuit and turning the switch ON only when the voltage of an AC power drops. CONSTITUTION:An AC power detecting means 22 is connected to an AC rectifying power circuit 21, and the signal of output or non-output of power from the power circuit 21 is input to a control means 28. Voltage-level detecting means 23 and 24 are connected between power output lines while a backup power circuit 25 is connected through a switch section 26. When the stoppage of an output from an AC power 29 is detected by the AC power detecting means 22, a signal is emitted from the control means 28 by an output from the voltage-level detecting means 23, the switch section 26 is turned ON through a switch drive means 27 by the signal, and power is extracted from the backup power circuit 25.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a power supply used in electronic equipment, in which when AC power is not input, a backup power circuit such as a battery is used as the power supply, and when AC power is input, When you are
The present invention relates to a power backup device that uses a rectifier power circuit as a power source.

2. Description of the Related Art A conventional power backup device will be described below with reference to FIG. In FIG. 5, 1 is an AC power source.

2 is a rectifier power supply circuit, which steps down the AC power supply 1 with a transformer 8, rectifies it with a diode bridge 4 and an electrolytic capacitor 5, and includes a diode 6, a Zener diode 7, a transistor 8, a current limiting resistor 9, and an electrolytic capacitor 10.
A predetermined DC power supply voltage is obtained and applied to the main circuit 11. 12 is a backup power supply circuit, which includes a negative battery 13, a current limiting resistor 14, and a reverse charge prevention diode 1.
5 and 16, and are connected to the main circuit 11 in parallel with the rectifying power supply circuit 2.

The operation of the conventional power backup device configured as described above will be described below.

First, when the AC power supply 1 is input, the rectification power supply circuit 2 supplies the power supply voltage to the main circuit 11 . At this time, when the power supply voltage obtained by the backup power supply circuit 12 is lower than the power supply voltage obtained by the rectification power supply circuit 2, the negative battery 18 is connected to the reverse charging prevention diode 15,
It is charged by the leakage current from 16. Conversely, when the power supply voltage obtained by the backup power supply circuit 12 is higher than the power supply voltage obtained by the rectification power supply circuit 2, the negative battery 13 is connected to the current limiting resistor 14 and the reverse charging prevention diode 1.
5 and 16. When the AC power supply 1 is not input, a power supply voltage is supplied to the main circuit 11 by the backup power supply circuit 12.

The problem that the invention aims to solve In such traditional power backup equipment.

AC power supply 1 is input, and backup power supply circuit 1
When the power supply voltage obtained by 2 is lower than the power supply voltage obtained by the rectifying power supply circuit 2, the primary battery 18 is charged by leakage current from the reverse charge prevention diodes 15 and 16, and the life of the negative battery 18 is shortened. Also, when the AC power supply 1 is input and the power supply voltage obtained by the backup power supply circuit 12 is higher than the power supply voltage obtained by the rectification power supply circuit 2, the negative battery 18 is reversely charged with the current limiting resistor 14. Since abnormal discharge occurs through the prevention diodes 15 and 16, there is a problem in that the life of the secondary battery 18 is shortened.

The present invention solves the above conventional problems by preventing the battery from being reversely charged or abnormally discharged when AC power is input.

The object of the present invention is to provide a power backup device that can extend the life of a battery and operate a backup power supply circuit for a long period of time.

Means for Solving the Problems In order to solve the above problems, the present invention provides a rectifying power supply circuit that rectifies an AC power source to produce a DC power source, and an AC power detection means that detects that AC power is input. , a first voltage level detection means for detecting the voltage level of the DC power supply, @2 voltage rep/I/@output means for detecting a voltage level different from the first voltage level detection means, and a rectification power supply. A backup power supply circuit comprising a battery and connected in parallel with the rectification power supply circuit through the circuit and the switch section.

, the output signals of the switch driving means for opening and closing the switch section, the AC power supply detecting means, the first voltage level V detecting means, and the second voltage level V output means are inputted, and the output signals of the switch driving means are inputted. When AC power is input, the switch section is opened and the rectifying power supply circuit is used as a power source, and when AC power is not input, the switch section is closed and the backup power supply circuit is used as a power source. It is equipped with a control means.

Effect With the above configuration, when AC power is input, the switch is opened, the backup power circuit is cut off, and the luxury power circuit is used as the power source, preventing the battery from being reversely charged or abnormally discharged. The life of the backup power supply circuit can be extended and the backup power supply circuit can be operated for a long period of time, and when AC power is not input, the backup power supply circuit can be operated by closing the switch section.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a power backup device according to an embodiment of the present invention. 21 is a rectifier power supply circuit that rectifies the AC power source to convert it into a DC power source. Reference numeral 22 is an AC power detection means that detects that AC power is input. Reference numeral 28 denotes a first voltage level output means for outputting the voltage level of the DC power supply. A second voltage level detecting means 24 detects a voltage level different from that of the first voltage level detecting means 28. 2
Reference numeral 5 denotes a backup power supply circuit, which has a built-in battery and is connected to a control means 28, which will be described later, through a switch section 26 so as to be parallel to the rectification power supply circuit 21. Reference numeral 27 denotes a switch driving means for opening and closing the switch section 26. Reference numeral 28 denotes a control means built into the main circuit, which receives the output signals of the AC power supply detection means z2, the first voltage V/I/level detection means z3, and the second voltage level detection means 24 as input.

The switch driving means 27 is controlled by the input, and when AC power is input, the switch unit 26 is opened to use the rectifier power supply circuit 21 as a power source, and when AC power is not input, the switch unit 26 is closed. The configuration is such that the backup power supply circuit 25 is used as a power supply.

FIG. 2 is a circuit diagram showing a specific configuration of this embodiment.

The rectifier power supply circuit 21 steps down the voltage of the AC power supply 29 through a track 80, and connects a diode bridge 31 and an electrolytic capacitor 8.
2, rectified by diode 38. zener diode 34
, Transinuta 85. A predetermined DC power supply voltage is created by a current limiting resistor 86 and an electrolytic capacitor 87.

The AC power supply detection means 22 connects the AC power supply 29 to a resistor 88 ,
89, and a noise prevention capacitor 40 and clamp diodes 41 and 42 generate a rectangular wave when AC power is input, and a low level when AC power is not input.

The first voltage level detection means 23 is composed of a voltage detector ICI, and sets the output to a level of 1 when the voltage reaches 5 VRI or more (FIG. 4(a)) during the start-up process of the DC power supply.

This is an IC that outputs a low level when the voltage becomes less than VR2 (broken line curve in FIG. 4(c)) during the falling process.

The second voltage level detection means 24 is composed of a heavy pressure detector IC2, and in the falling process of DC, the voltage force s Vl > vR
2. When the value is 1 or less (FIG. 4(C)), the output becomes low level. 1< The pull-up power supply circuit 25 consists of a battery 43, a current limiting resistor 44, and reverse charge prevention diodes 45 and 46, and the forward voltage characteristics of the reverse charge prevention diodes 45 and 46 and 1wL are determined from the voltage of the battery 43.
By subtracting the voltage drop across the current limiting resistor 44, the voltage T becomes the pull-up power supply voltage. The ground of the battery 48 is connected to the ground of the rectifier power supply circuit 21, and the cathode of the reverse charge prevention diode 46 is connected to the current level μ side 9 of the rectification power supply circuit 21 via the relay contact NC of the switch unit 26. The output drive means 27 for driving the relay LY of the switch section 26 is composed of resistors 47 and 48, a switching transistor 49, and a back electromotive force prevention diode 50. The control means 28 is composed of a microcomputer, and includes a human power section 28a, a storage section 281), and an arithmetic control section 28c.
, an output section 28d, an AC power supply detection means 2z and a first
The output signals of the voltage level detection means 28 and the second voltage level detection means 24 are taken into the input section 28a,
Corresponding to the output of a, the arithmetic control section 28c controls the output section 28d based on the program stored in the storage section 28b,
This output section 28d gives a signal to the switch driving means 27, and when AC power is input, the switch section 26
The relay contact NC is opened to turn the rectifier power supply circuit 21 into a power source, and when no AC power is input, the switch part 26
The relay contact NC is closed and the backup power supply circuit 25 is used as a power source.

Next, its operation will be explained. FIG. 8 shows the main part of a flowchart under the control of the control means z8. The operation when the user inputs AC power will be explained based on the flowchart of FIG. 3(a). First, the backup power supply circuit 25
Considering the case where the control means 28 is not connected, when AC power is input, it is determined in step 51 whether the reset state of the control means 28 has been released. Specifically, it is determined whether the output of the ICI of the first voltage level detection means 28 has reached a high level. The output of the ICI of the first voltage level detection means 28 becomes HIGH REPE when the DC power supply voltage becomes equal to or higher than the VRI. Here, when the reset state of the control means 28 is released and the control means 28 becomes operable, the process proceeds to the next step 52, where AC power is input,
If a rectangular wave is output from the AC power supply detection means 22, the process proceeds to the first step 58. Step 58 is.

This is a step of waiting for 11 seconds until the reset state of the control means 28 is released and sufficient DC power is available. When the DC power supply is completely completed, the process proceeds to % step 54, where the control means z8 gives a signal of /% ELEPEL from the output section 28d to the switch driving means z7, turns on the transistor 49, and drives the relay LY of the switch section 26. .

to open the V-contact NC. Next, the process proceeds to step 55, and the relay contact NC becomes completely open 12 seconds after the /XVbeμ signal is applied to the switch driving means 27. The above operation shows the operation when the backup power supply circuit 25 is not connected, and this operation is shown in terms of the relationship between time and DC power supply voltage.

The result will be as shown in FIG. 4(a).

Next, when the backup power supply circuit 25 is connected and the backup operation is enabled, when AC power is input, the output of the first voltage level detection means 2B is already at a high level due to the DC voltage from the backup power supply circuit 25. Since the control means 28 has been released from the reset state, the process immediately proceeds from step 51 to step 52, where it is determined whether a rectangular wave is output from the output of the AC power supply detection means 22, and it is determined that AC power has been input. Then step 53
Then, wait t1 seconds until the DC power supply is sufficiently generated, and in the next step 64, a high level signal is applied from the output section 28d to the switch driving means 27, turning on the transistor 49 and driving the relay LY of the switch section 26. , relay contact N
Open C. Next, the process proceeds to step 55, and the relay contact NC becomes completely open t2 seconds after the high level signal is applied to the switch driving means 27.

In this state, the backup power supply circuit 25 is turned off, and this operation is shown in FIG. 4(b) in terms of the relationship between time and DC power supply voltage.

Next, the operation when the backup power supply 25 is connected and the AC power is input, and then the AC power is turned off will be described with reference to the flowchart in FIG. 8(b). As described above, when AC power is input, the backup power supply circuit 25 is not operating because the relay contact NC of the switch section z6 is in an open state. next,
When the input of the AC power supply disappears, the DC power supply voltage by the rectifier power supply circuit 21 decreases. In step 56, when the voltage becomes less than v1, the second voltage Vbeμ detection means 24
When the output of IC2 becomes high level and the signal is input to the input section 28a, the process proceeds to step 57, where the arithmetic control section 28c supplies a low level signal to the switch driving means 27 from the output section 28d to turn off the transistor 49.

Next, in step 58, the relay LY of the switch 26 is no longer driven, the relay contact NC is closed after t3 seconds, and the backup power supply circuit 25 is connected. Next, the ICI of the first voltage level detection means 28 outputs a low level when the DC power supply voltage becomes less than VR2, causing the control means 28 to be in a reset state, so that the value of %v1 satisfies vl>vl2. And, with respect to the time t3 when the relay contact NC of the switch unit 26 is completely closed after the V signal is applied to the switch drive amniotic membrane zr, the period from when the DC power supply voltage becomes less than ■1 until it becomes VR2 is vl and vl2 are set so that time t is sufficiently long. This operation is shown in terms of the relationship between time and DC power supply voltage as shown by the solid line in FIG. 4(C). Further, the first voltage level detection means 23
, and the low level of the output voltage of IC2 of the second voltage level detection means 24.

The high level may be either high level (the point is, it is sufficient that the control means Z8 microcomputer can detect a predetermined DC power supply voltage).

According to the embodiment described above, the switch section 26 is connected in series with the backup power supply circuit z5, and the AC power supply detection means 22 detects the presence or absence of AC power input and the first voltage level detection means detects the level of the DC power supply voltage. means 23 and second voltage level μ detection means 24.

By controlling the switch driving means using these detection signals, it is possible to turn off the backup power supply circuit 25 when AC power is input, thereby preventing the battery from being reversely charged or abnormally discharged. This can extend battery life. Furthermore, when AC power is not input, the backup power circuit can be reliably operated.

Effects of the Invention According to the present invention, when AC power is input, the switch section is opened and the rectifier power circuit is used as the power source,
When AC power is not input, the switch part is closed and the backup power circuit is used as a power source, so the battery in the backup power circuit will not be reversely charged or abnormally discharged when AC power is input, and the battery life will be extended. For a long time,
An excellent effect can be obtained that allows the backup power supply circuit to operate for a long period of time.

[Brief explanation of drawings]

fa1 is a block diagram showing a power backup device according to an embodiment of the present invention, FIG. 2 is a specific circuit diagram of the same power backup device, FIG. 3 is a flowchart of the main parts thereof, and FIGS. (C) is a characteristic diagram illustrating changes in DC power supply voltage with respect to time, and FIG. 5 is a circuit diagram of a conventional power supply backup device. 21... Rectifier power supply circuit, 22... AC power supply detection means, 28° 24... First and second voltage level detection means, 25...-Backup power supply circuit, 26... Switch section, 27 . . . switch driving means, 28 . . . control means.

Claims (1)

[Claims] 1. A rectifying power supply circuit that rectifies an AC power source to produce a DC power source, an AC power source detection means that detects that the AC power source is input, and a first voltage level detection means that detects the voltage level of the DC power source; second voltage level detection means for detecting a voltage level different from the first voltage level detection means;
a backup power supply circuit connected in parallel with the rectification power supply circuit through a switch section and containing a battery;
The switch driving means for opening and closing the switch section, the output signals of the AC power supply detecting means, the first voltage level detecting means, and the second voltage level detecting means are input, and the switch driving means is controlled by the inputs. , a control means that opens the switch section and uses the rectifying power circuit as a power source when AC power is input, and closes the switch section and uses the backup power circuit as a power source when AC power is not input; Equipped with power backup device.