JPH0446530A - Battery malfunction detecting circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Summary) Regarding an abnormality detection circuit for a battery in which a plurality of cells are connected in series, the purpose of this invention is to be able to correctly detect -1 abnormalities even during charging, and to In a Panteri abnormality detection circuit in which cells are connected in series, a battery is set as an intermediate terminal that outputs the potential between the It consists of a resistor voltage divider circuit connected to the battery, and a comparator that compares the potential at the intermediate terminal of the battery and the divided voltage output potential of the resistor voltage divider circuit. The voltage division ratio of the resistor voltage divider circuit is determined so that the voltage division output potential of the voltage divider is approximately equal to the voltage output voltage of the voltage divider, and a battery abnormality is determined when the comparator detects an input voltage difference of a certain value or more.

(Industrial Application Field) The present invention relates to an abnormality detection circuit for a battery in which a plurality of cells are connected in series.

The conventional Panteri abnormality detection circuit detects a battery abnormality by extracting a detected voltage from a resistive voltage divider circuit connected to the battery and comparing it with a fixed reference voltage determined by a Zener diode or the like.

However, when charging the battery, charging 1t1! The voltage on the source side is applied to the resistor voltage divider circuit, and
Since the charging power source is a constant voltage or constant current, even if the battery is abnormal and the voltage drops, the detected voltage will be a value determined by the voltage on the charging power source side. Therefore, it was not possible to determine whether the battery voltage was abnormal during charging.

The present invention provides a battery abnormality detection circuit that can detect battery abnormalities during charging as well as during discharging.

[Conventional technology]

FIG. 3 shows a conventional panteri abnormality detection circuit.

In the figure, 50 is a battery in which a plurality of cells are stacked;
1.52 is the resistance value R1 of each resistor voltage divider circuit
and R2 are for taking out the divided voltage V, and 53 is a reference voltage V for detecting battery abnormality.
raf; 54 is a comparator that compares the detection voltage V of the voltage dividing circuit with the reference potential of the reference voltage source 53 and outputs a different signal depending on whether or not there is an abnormality in the battery 50; 55 is connected to the battery; The load 56 is a switch for switching the power source of the load to the battery 50 in an emergency.

The operation of the illustrated circuit will now be described.

A normal power source such as a commercial power source is normally used as the power supply for the load, and at the same time, the battery 50 is charged by the charging power source.

When the normal power supply fails, the changeover switch 56 is connected to the battery 50 side, and the pantry 50 is used as the power supply for the load 55.

The operation of detecting an abnormality in the pantry 50 by the comparator 54 is as follows.

The divided voltage V determined by the voltage dividing resistors R and R2 of the resistance voltage dividing circuit and the reference voltages vt and f determined by the reference battery 53 are input to the comparator 54.

When the voltage output by the battery 50 is normal, the detected voltage also becomes higher than the base voltage Vraf, and the comparator 54 outputs a signal indicating that the battery is normal.

However, the voltage of the battery 50 decreases, and the detected voltage V,
becomes smaller and becomes lower than the reference voltage, comparator 5
4 inverts the output and outputs a signal indicating that the battery 50 is abnormal.

[Problem to be solved by the invention]

As mentioned above, in the conventional battery detection circuit, the detection voltage V during charging is determined by the voltage on the charging power source side, and even if the battery voltage drops, it is not possible to detect the voltage abnormality.

Additionally, in order to extend the battery's lifespan, batteries are usually configured to vary the charging voltage depending on the temperature of the battery.

Furthermore, the voltage when charging, the voltage when opening, and the voltage when discharging are different. Alternatively, the ambient temperature 3
The voltage of the panteri is constantly fluctuating due to variations among products.

Therefore, by comparing the detected voltage with a fixed reference voltage as in the past, it was not possible to perform accurate determination.

In addition, since an abnormality could only be detected during discharging, in a battery normally used as a backup in the event of a TA failure, an abnormality would only be detected during backup, and the battery would not function as a bank amplifier until the original one. There were times when the function was not working.

SUMMARY OF THE INVENTION An object of the present invention is to provide a battery detection circuit that can correctly detect battery abnormalities even during charging, and to provide a battery abnormality detection circuit that can make highly accurate determinations.

[Means to solve the problem]

The present invention detects a bridge output consisting of the intermediate terminal of the voltage dividing resistor of a resistive voltage dividing circuit and the intermediate terminal of the battery, and accurately detects battery abnormalities regardless of differences in temperature changes in the battery, product variations, etc. This makes it possible to accurately detect battery abnormalities even during charging.

FIG. 1 shows the principle of the present invention.

In the figure, 1 is a battery in which a plurality of cells are connected in series, 2 is a cell which is a battery unit, and 3.4 is a voltage dividing resistor forming a resistive voltage dividing circuit, each having a resistance value of R, R1.
, 5 is the detected voltage V of intermediate terminal A of battery 1
11 and a reference voltage ■, which is the divided output voltage at the intermediate terminal B of the resistor of the resistor voltage divider circuit. This is a comparator that inputs , compares the two, determines whether there is a battery abnormality, and outputs a different signal depending on the determination result.

In the present invention, the ratio of the values of the resistors 3 and 4 is determined so that when the battery is normal, the detected voltage 1 at the intermediate terminal A of the battery and the bridge output due to the reference voltage V raf of the resistor voltage divider circuit are balanced. .

For example, if the total number of cells is n and the intermediate terminal is A, then
Assuming the connection point between the th cell and the x+1 th cell, the ratio of the value of resistor R1 to the value of resistor R1 is R:R1=x: (
n-x).

[Effect]

The operation of the principle of the present invention shown in FIG. 1 will be explained.

For resistors R3 and R2, RI = xR, Rz = (n-
x) R (R is arbitrary), RI :Rz=x: (n
−x).

In a normal battery consisting of cells connected in series, there is little variation in the voltage between each cell, and the voltage V between the Xth and X11th cells is , v,'iVm · (n-x)/n (V).

For the reference voltage V ref, V, -t = V m ・R, / (l ma, +12
□)=V, ・(n-x)/n(V).

Therefore, by setting the voltage division ratio of resistor 3 and resistor 4 as shown in 1, it becomes vl-■r, and the intermediate terminals A and B
The output is balanced.

According to this method of setting the reference voltage V rat, even if ■ changes due to changes in battery temperature, ■ and V rat will change at the same rate J
Therefore, the relationship vI - V raf is always maintained.

Therefore, it is assumed that the x-th cell is short-circuited.

At this time, the voltage of the entire battery changes from ■ to ■.

Suppose that it becomes .

At this time, the detection voltage is v, ' = V * ' / (n-x-1) (V)
becomes.

Also, V,, + ' = Va ' - R, / (R,
+Rz)=V, ・(l-χ)/n[V), and ,1≠Vraf゛.

The bridge voltage, which is vI-Vr@l when the battery is normal, is unbalanced, and the comparator 5 detects the difference, thereby making it possible to detect an abnormality in the battery.

Also, even if one cell in battery l has an open failure, the reference voltage ■1. ．． It is possible to detect an abnormality if the bridge balance between the detection voltage and the voltage and voltage is not balanced.

According to the present invention, the reference voltage also fluctuates as the voltage of the pantry 1 itself fluctuates, and the bridge balance is automatically set.

Further, since the reference voltage Vrer and the detected voltage V= from the battery are always compared and determined even during charging, battery abnormality can be correctly detected even during charging.

〔Example〕

The present invention will be explained in detail with reference to FIG.

In the figure, 20 is a battery in which n cells are connected in series, and has an intermediate terminal A from which a detected voltage V is taken out, and 21 and 22 are voltage dividing resistors constituting a voltage dividing resistor circuit, each having a resistance value. are R1 and R2, which take out the divided voltage at the intermediate terminal B as the reference voltage V raf , and 24 is a window comparator, which connects the upper limit voltage V, which determines the upper limit of the normal range of the input voltage, and the normal range. Lower limit voltage ■, which determines the lower limit, is set, and if the input voltage is between upper limit voltage ■ and lower limit voltage ■, a signal indicating that the battery is normal is output, and the upper limit voltage is higher than ■. 26 is a load, 27 is a switch l for switching between the normal power supply and the battery 20, and 28 is a switch for preventing battery discharge during rest. This is switch 2.

Next, the operation of the illustrated circuit will be explained.

In the illustrated circuit, a bridge is formed by a resistor R6, a resistor Rz, and cells 1 to x1 and cells x+1 to n.

Therefore, for resistance R, and resistance R1, R,=xR,R
t = (n-x)R (By setting R as desired, the bridge can be balanced, and the reference voltage V rat and the detected voltage vS can be made approximately equal when the battery is normal.

For the window comparator, an upper limit voltage (8) and a lower limit voltage (2) are determined in advance.

And, for example, the input voltage of the window comparator is ■, and ■. When it is between, the window comparator outputs a high level (H) signal and the upper limit
. When a higher voltage or a voltage lower than lower limit (1) is input, a low level (L) signal is output.

In the circuit shown in the figure, when the pantry is normal, V
rat and V are approximately balanced, the output of the differential amplifier is approximately O, and the window comparator 24 outputs a normal signal 11.

For example, if one of the Panteli cells fails and short-circuits, the bridge balance between the reference voltage ■ rat and the detection voltage V will be disrupted, and a voltage proportional to the difference between V raf and v6 will be output between intermediate terminals A and B. be done.

The voltage difference is input to the window comparator 24, and if the difference is greater than the upper limit voltage V of the window comparator or smaller than the lower limit voltage V, it outputs L indicating a battery abnormality signal.

■ If the voltage of each cell is slightly uneven. ,
−■, is the upper limit voltage of the window comparator■. The window comparator outputs a signal 11 indicating that the battery is normal because V, , V, are set in advance to be in the range between V1 and lower limit voltage V1.

Further, even when a cell in the battery has an oven failure, the bridge balance of Vral=V1 between the reference voltage V rat and the detection voltage v6 is similarly disrupted, and a battery abnormality can be detected.

〔Effect of the invention〕

According to the present invention, voltage V rat
is determined from the battery's own voltage based on a normal battery, so even if the battery's own voltage fluctuates due to temperature characteristics, etc., or there are variations due to product opening, etc., It is possible to accurately determine the presence or absence of battery abnormality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention. FIG. 2 is a diagram showing an embodiment of the present invention. FIG. 3 is a diagram showing a conventional battery voltage abnormality detection circuit. In the figure, 1: battery, 2: cell, 3: resistor R1, 4: resistor R2, 5: comparator.

Claims (3)

[Claims] (1) A battery with n cells (n>2) connected in series (
In the abnormality detection circuit of 1), the intermediate terminal (A) that outputs the potential between the xth and x+1th cells with x (1<x<n) as an arbitrary value is connected to the set battery and the battery. It consists of a resistive voltage divider circuit (3, 4), which is connected to a normal battery, and a comparator (5) that compares the potential at the intermediate terminal of the battery with the divided voltage output potential of the resistive voltage divider circuit. The voltage division ratio of the resistor voltage divider circuit is determined so that the potential of A) and the divided output voltage of the resistor voltage divider circuit (3, 4) are almost equal, and when the comparator detects an input potential difference of more than a certain value, the battery A battery abnormality detection circuit characterized by determining an abnormality. (2) The battery abnormality detection circuit according to claim 1, wherein the value x is an integer closest to n/2. (3) The battery abnormality detection circuit according to claim 1, wherein the comparator is a window comparator.