JPH06319226A - Battery voltage detector - Google Patents

Abstract

PURPOSE:To provide a battery voltage detector capable of determining defective connection when defective connection is generated in a connecting line up to the connection midpoint of a battery. CONSTITUTION:Since a constant current circuit I is connected in parallel on every other voltage detector to voltage detectors V1-V3 for a battery voltage detector V detecting voltage at every battery single cell, a defective fact or a defective place can be determined easily from overvoltage appearing in the voltage detector V1 or V3 even when defective connection is generated in a connecting terminal S2 or S3 reaching the connection midpoints of batteries B1-B3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage detecting circuit useful for a DC power source constructed by connecting a plurality of batteries in series.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional voltage detecting circuit of this kind. In the same figure, B is a DC power source consisting of two batteries B1 and B2 connected in series, V is a voltage detection circuit having the same number of voltage detectors V1 and V2 as the batteries B1 and B2, and each voltage The input ends of the detectors V1 and V2 are connected to the end points and the connection midpoints of the batteries B1 and B2 via connection terminals S1 to S3. The voltage detection circuit V can detect the voltage of each battery single cell in each of the voltage detectors V1 and V2 in the connection state shown in the figure.

[0003]

By the way, in the above-mentioned conventional voltage detection circuit V, the central connection terminal S is used for voltage detection.
Even if the connection failure occurs in 2, the fact that the connection is defective is detected by the voltage detector V1,
There are difficulties that cannot be captured on V2.

That is, the upper and lower connection terminals S1 or S
When the connection failure occurs in No. 3, since the voltage value of the voltage detector V1 or V2 on the failure side becomes zero, the fact and the location of the failure can be grasped from the value, but the central connection terminal S
If a connection failure occurs in No. 2, both voltage detectors V1, V2
Since the voltage value corresponding to the internal impedance appears in the above, it is impossible to grasp the fact and the defective portion from these values.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery voltage detection circuit capable of grasping the occurrence of connection failure in a connection line extending to a battery connection midpoint. To do.

[0006]

In order to achieve the above object, in the present invention, the same number of voltage detectors as the series-connected batteries to be detected are provided in series, and each voltage detector is provided for each battery single cell. In a battery voltage detection circuit capable of detecting a voltage, a constant current circuit is connected in parallel to every other voltage detector.

[0007]

In the voltage detection circuit of the present invention, when connection failure occurs in the connection line that reaches the middle connection point of the battery, a current flows in series with the constant current circuit corresponding to the connection line and the voltage detector adjacent thereto. The sum of the two battery voltages appears at the voltage detector. That is, if over-discharge appears in the voltage detector with the constant current circuit and over-voltage appears in the voltage detector adjacent thereto, it can be understood that the connection line on the over-voltage side has a connection failure.

[0008]

1 is a diagram showing a voltage detection circuit to which the present invention is applied, and the same reference numerals are used for the parts having the same configurations as those of the conventional example shown in FIG. In the figure, B is a direct current power source composed of three batteries B1 to B3 connected in series, for example, a rechargeable battery pack containing a lithium battery or the like.

V is a voltage detection circuit provided with the same number of voltage detectors V1 to V3 as the batteries B1 to B3 in series. Each voltage detector V1 to V3 has its input end connected to the battery via connection terminals S1 to S4. It is connected to the end points of B1 to B3 and the connection midpoint. Incidentally, the internal impedance of each of the voltage detectors V1 to V3 is 10 MΩ.

Reference numeral I denotes a constant current circuit connected in parallel to the central voltage detector V2, which is constructed by connecting the gate and source of an N-channel junction type field effect transistor (FET) Q through a resistor R, and FETQ The drain and source are connected to the input terminal of the central voltage detector V2. As the resistor R, one having a resistance of 1 MΩ, which is lower than the internal impedance of the voltage detectors V1 to V3, is used.

The voltage detecting operation of the above voltage detecting circuit V will be described below. All connection terminals S1 to S
4 is connected without any defect, each battery B1 ~ B
The voltage of 3 is applied to the corresponding voltage detectors V1 to V3, and the voltage of each battery single cell appears in each of the voltage detectors V1 to V3.

If a connection failure occurs at one of the connection terminals S2 of the batteries B1 to B3 that reaches the connection midpoint during voltage detection, the sum voltage of the two batteries B1 and B2 is the voltage detectors V1 and V2 and the constant current circuit. Is applied to the series circuit of I, which increases the gate voltage defined by the resistance R of the constant current circuit I, and F
The impedance of ETQ becomes lower than that of the voltage detector V2, and a current flows from the voltage detector V1 to the constant current circuit I in a substantially conductive state. As a result, the sum of the voltages of the two batteries B1 and B2 appears in the voltage detector V1, and the voltage detector V2
The voltage value of becomes zero.

That is, the voltage detector V2 with the constant current circuit I
If the over-discharge occurs and the over-voltage appears in the voltage detector V1 adjacent thereto, it can be understood that the connection terminal S2 on the over-voltage side has a connection failure.

When a connection failure occurs in the connection terminal S1 or S4 other than the above-mentioned connection terminal, the voltage value of the voltage detector V1 or V3 on the failure side becomes zero. It can be seen that a poor connection has occurred.

As described above, according to the voltage detection circuit V described above, even if a connection failure occurs in the connection terminal S2 or S3 reaching the midpoint of connection of the batteries B1 to B3, the overvoltage appearing in the voltage detector V1 or V3 causes There is an advantage that the defect fact and the defective portion can be easily grasped, and the connection defect that may occur at the time of voltage detection can be surely caught to properly detect the voltage.

In the above embodiment, three voltage detectors are used as the voltage detection circuit, but even if the number of voltage detectors is increased according to the number of batteries to be detected, the same as in the embodiment. Similarly, if a constant current circuit is connected in parallel to every other voltage detector, the same defect detection can be performed.

[0017]

As described in detail above, according to the present invention,
Even if a connection failure occurs in the connection line to the middle point of the battery connection, the fact of failure and the location of the failure can be easily grasped from the overvoltage appearing on the voltage detector, and the connection failure that may occur during voltage detection is ensured. It is possible to properly detect and detect the voltage.

[Brief description of drawings]

FIG. 1 is a diagram showing a voltage detection circuit to which the present invention is applied.

FIG. 2 is a diagram showing a conventional voltage detection circuit.

[Explanation of symbols]

B ... DC power supply, B1 to B3 ... battery, V ... voltage detection circuit,
V1 to V3 ... Voltage detector, I ... Constant current circuit.

Claims (1)

[Claims] 1. A battery voltage detection circuit, comprising the same number of voltage detectors as the number of batteries connected in series to be detected in series, each voltage detector being capable of detecting the voltage of each single battery cell. A battery voltage detection circuit characterized in that a constant current circuit is connected in parallel to every other one.