JPS5923268A - Monitoring apparatus of battery - Google Patents

Abstract

PURPOSE:To monitor exactly a remaining capacity of a battery also during charging and discharging, by connecting stably an open voltage through a capacitor and a high resistance and storing said capacity to a capacitor connected to an operational amplifier. CONSTITUTION:A capacitor 5 connected to a reverse current preventing element 6 is charged by a circuit 4 generating a voltage obtained by subtracting a prescribed value from the open voltage of a battery 1 and the voltage proportional to the battery capacity is stored. A capacitor 8 connected parallelly through the capacitor 5 and a high resistance 9 and connected to the operational amplifier 12 converting voltage to impedance delays and stores the open voltage. During discharging the battery 1, the capacitor 8 discharges through the resistor 9, the amplifier 12, etc., the stored voltage varies with the decrease of the open voltage. During charging, even if the charging voltage of the capacitor 5 is raised suddenly through the resistor 9, the stored voltage doesn't respond to this. Thus, the voltage of the capacitor 8 attains to the peak value of normally stable open voltage, monitor of the remaining capacity of battery can be performed during charging and discharging.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a storage battery monitoring device that displays the remaining capacity of a storage battery using a meter or digitally. It is related to.

When monitoring the capacity of a storage battery, the most common method is to measure the specific gravity of the electrolyte and then estimate the battery capacity from the measured specific gravity of the electrolyte, and this method is still considered the most accurate method. There is.

Conventionally, the electrolyte specific gravity was electrically measured and a sensor made of a float or the like was inserted directly into the electrolyte to display the electrolyte specific gravity value as is or by converting the electrolyte specific gravity value into a capacity. A method has been considered in which the displacement of the float is converted into an electrical signal, amplified, and displayed as the electrolyte specific gravity value or capacity. However, with this method, converting the displacement of the float into an electrical signal is complicated, and as the temperature rises, dissolved oxygen forms bubbles and adheres to the surface of the float.
There are problems in that it causes errors, requires temperature conversion, and is unsuitable for mobile storage batteries that are subject to vibration. A method that uses the refractive index of the electrolyte has also been considered, but this method also has the problems of dirty prisms, large errors due to changes in the light intensity of the light source, and the need for an amplification device, making the device itself quite complex. be. As described above, many problems remain with any of the conventionally devised methods.

The present invention provides a storage battery monitoring device that solves the conventional problems as described above, that is, a circuit connected to both ends of a storage battery to obtain a voltage obtained by subtracting a constant voltage from the open circuit voltage of the storage battery.
A first capacitor connected in parallel to the circuit through a backflow prevention element and a high resistance connected in parallel and charged with the voltage obtained in the circuit; and a first capacitor connected in parallel to the first capacitor through a high resistance. a first capacitor connected to the second capacitor, an amplifier such as an operational amplifier connected to the second capacitor for impedance conversion of the voltage of the second capacitor, and a meter etc. connected to the output of the amplifier. The present invention provides a storage battery monitoring device equipped with a display device.

That is, in the present invention, in a storage battery that is discharged intermittently, such as a storage battery for an electric car or an electric vehicle, the stable peak voltage of the open circuit voltage (no-load voltage) during rest is determined by the capacity of the storage battery or the specific gravity of the electrolyte. has a theoretically proportional relationship with the value,
Focusing on the fact that the voltage value at the peak portion also decreases as the capacity decreases or the electrolyte specific gravity value decreases, the voltage at the stable peak portion of the open circuit voltage during rest is stored in the first capacitor. By connecting a second capacitor in parallel with the first capacitor through an ultra-high resistance,
The voltage is delayed and stored in the second capacitor, and the voltage of this second capacitor is discharged through an impedance inside an amplifier such as an operational amplifier to convert the impedance and create a virtual discharge curve. The storage battery status is displayed by displaying a virtual discharge curve on a display such as a meter.

In addition, the voltage when a storage battery is discharged varies widely depending on the magnitude of the discharge current, so it is not possible to monitor the capacity etc. based on the voltage at the time of discharge. This also allows the capacity of storage batteries to be monitored. Furthermore, when the hibernation state occurs again, the first and second capacitors are charged again with the stable peak voltage of the open circuit voltage during the hibernation, and the virtual discharge curve is corrected as much as possible. This allows for accurate monitoring.

In this way, the storage battery monitoring device of the present invention does not require the insertion of a sensor for measuring specific gravity into the storage battery, unlike conventional methods.
In addition, unlike conventional Ah meters, there is no need to insert a shunt for current detection into the main circuit, and the capacity of the storage battery as well as the specific gravity of the electrolyte can be monitored by simply connecting it to the terminal of the storage battery. be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The storage battery monitoring device of the present invention will be specifically described below using an embodiment shown in the drawings.

FIG. 1 shows an embodiment of the storage battery monitoring device of the present invention, in which (1) indicates a storage battery to be monitored (hereinafter simply referred to as a storage battery);
(2) is a load, and (3) is a load-on switch. (4
) is a circuit for obtaining the open circuit voltage of the storage battery (1), that is, the voltage obtained by subtracting a constant voltage from the storage battery voltage when the load (2) is not connected to the storage battery (1).
connected to both ends of the Various circuit configurations can be considered for the circuit (4), but for example, it is constructed from a series circuit of a constant voltage diode and a resistor, and a constant voltage is subtracted by the constant voltage diode, and the remaining voltage is obtained from both ends of the resistor. It may be configured as follows. Furthermore, the circuit (4) is provided because, for example, when a 24-cell storage battery (1) is used, the open circuit voltage of this storage battery changes in actual use from approximately 51V to 47V.
This is because a display device such as a meter, which will be described later, is operated at full scale in the vicinity of this voltage change width. (5) is a first capacitor that is charged with the voltage obtained in circuit (4), and the first capacitor is a backflow prevention element (6) such as a silicon diode and a high resistance (7) connected in parallel. It is connected in parallel to the circuit (4) through the

Therefore, the first capacitor (5) is charged with the stable peak voltage remaining after subtracting a constant voltage from the open circuit voltage of the storage battery obtained in the circuit (4), and the load (
2) If the voltage obtained by the circuit (4) is lower than the voltage at the time of charging the first capacitor due to a decrease in the terminal voltage due to the connection, the electric charge charged in the first capacitor (5) will have a high resistance (7). discharge through. (8) is the second capacitor, which connects to the first capacitor (5) through the high resistance (9).
are connected in parallel. Since the second capacitor (8) is connected through a high resistance (9), it is charged to the same potential as the first capacitor (5) in a stable state for a long time. (10) and (11) are capacitors that constitute a filter circuit that absorbs pulse voltage when a voltage higher than the no-load voltage is generated at the terminal of the storage battery (1) due to regenerative braking or chopper control in the load (2). and resistance. (12) is an amplifier device using an operational amplifier or the like, and is connected to the second capacitor (8). (13) is a meter connected to the amplifier (12).
As for 13), a pointer display type or a digital display type using an LED or the like is used.

In this embodiment of the present invention, when the device is connected to both terminals A and B of the storage battery (1), a voltage of approximately 51.5V is obtained when the storage battery (1) has 24 cells and is fully charged. It will be done. This no-load voltage is 51.5V when fully charged.
, there is only a small change of about 4 to 5V, which is about 47V when fully discharged. In order to accurately detect this small change, a circuit (
4) Subtract the constant voltage and get the voltage of , that is, C of this circuit.
, D, the first capacitor (5) is charged through the filter resistor (11) and capacitor (10). Charging of the first capacitor (5) takes place rapidly through the anti-backflow element (6) if the voltage between C and D rises above the voltage of the first capacitor (5), for example.

On the other hand, if the voltage between C and D is, for example, the first capacitor (5)
, the charge stored in the first capacitor (5) is discharged through the high resistance (7). In this way, the first capacitor (5) is always charged to the peak value at the recovery voltage, so it exhibits a voltage value that is approximately close to the open circuit voltage of the storage battery (1). The second capacitor (8) has a high resistance (9
), it has the same potential as the first capacitor (5) in a long-term stable state. That is, the second capacitor (8) also exhibits approximately the open circuit voltage value of the storage battery (1).

When the storage battery (1) is discharged, when the voltage between C and D decreases,
The second capacitor (8) discharges through the high resistances (9), (11) and at the same time discharges through the internal impedance of the amplifier (12), and the voltage of the second capacitor (8) also increases from that of the accumulator (1). It decreases in proportion to the decrease in open circuit voltage.

Therefore, the output of the amplifier (12) is also connected to the second capacitor (
A current proportional to the voltage of the second capacitor (8) is obtained, and when the meter (13) is operated by this current, an indication proportional to the voltage of the second capacitor (8) is obtained on the meter (13). Therefore, if the discharge of the second capacitor (8) is adjusted to approximate the discharge of the storage battery (1), a value approximate to the discharge state of the storage battery (1) will be obtained on the meter (13).

The second capacitor (8
The loss voltage of ) is corrected the next time the storage battery (1) stops discharging, for example, for a long time, by being charged again using the open circuit voltage at this time.

Furthermore, when charging the storage battery (1), the voltage of the first capacitor (5) rises rapidly due to the voltage rise between C and D, but the voltage of the second capacitor (8) is controlled by the high resistance (9). By adjusting the resistance value of the resistor (9), the second capacitor (8) can be charged at almost the same speed as the charging progress speed. Therefore, the output of the amplifying device approximates the open circuit voltage of the storage battery (1) in any state of charging, discharging, or leaving it alone.

In addition, the open circuit voltage of the storage battery (1) is E=0.84+SG
(electrolyte specific gravity value), there is a proportional relationship with the electrolyte specific gravity and capacity, and detecting the voltage of the second capacitor (8) is based on the capacity of the storage battery (1) or the electrolyte solution. The specific gravity will be detected.

Furthermore, in this embodiment, the capacity range of the storage battery required for display is displayed in the full case on the meter (13), making it easy to read, and therefore, the state of the storage battery (1) can be accurately monitored.

In this way, in the embodiment of the present invention, the present device is equipped with a storage battery (
1), the discharge state (remaining capacity) of the storage battery (1) can be detected, and by setting the temperature coefficient of the circuit (4) and amplifier (12) to zero, the voltage obtained from the circuit (4) can be detected. Since the change indicates the characteristics of the storage battery (1) itself, the value displayed on the meter (13) is obtained by correcting the temperature of the storage battery (1). In addition, the power consumption of this device is several mA.
It has the great feature of being able to accurately display information whether it is being discharged or left unused.

As described above, the storage battery monitoring device of the present invention does not require the insertion of a sensor for measuring specific gravity into the storage battery as in the conventional case, nor does it require the insertion of a shunt in the main circuit as in the conventional Ah meter. This device has the excellent advantage that by simply connecting to the terminals of the storage battery, the capacity of the storage battery and the specific gravity of the electrolyte can be accurately monitored while the storage battery is being left unused, discharging, or charging.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the monitoring device of the present invention. (1)...Monitored storage battery, (2)...Load, (4)
...Circuit for obtaining the remaining voltage after subtracting a certain voltage from the circuit voltage of the storage battery, (5)...First capacitor, (6)...Backflow prevention element, (7)...High resistance,(
8)...Second capacitor, (9)...High resistance, (
12)... Amplifier, (13)... Meter.

Claims (1)

[Claims] A circuit connected to both ends of the storage battery for obtaining a voltage obtained by subtracting a constant voltage from the open circuit voltage of the storage battery, and a backflow prevention element and a high resistance connected in parallel to the circuit, and a first capacitor charged with the obtained voltage, a second capacitor connected in parallel to the first capacitor via a high resistance, and a capacitor for impedance converting the voltage of the second capacitor. A storage battery monitoring device comprising an amplifier such as an operational amplifier connected to a second capacitor and a display such as a meter connected to the output of the amplifier.