JPH0410029B2 - - Google Patents

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, for this purpose, the specific gravity of the electrolyte was measured electrically,
To display the electrolyte specific gravity value as is or by converting the electrolyte specific gravity value into capacity, a sensor consisting of a float or the like is inserted directly into the electrolyte, converting the displacement of the float into an electrical signal, amplifying it, and displaying the electrolyte solution. Methods of displaying it as a specific gravity value or capacity have been considered. However, with this method, converting the displacement of the float into an electrical signal is complicated, and when the temperature rises, dissolved oxygen becomes bubbles and adheres to the float surface, causing errors, and temperature conversion. However, there are problems in that it is unsuitable for mobile storage batteries that are subject to vibrations. 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. There is. 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, namely, a circuit connected to both ends of a storage battery to obtain a voltage obtained by subtracting a certain voltage from the open circuit voltage of the storage battery, and a backflow prevention element in the circuit. and a first capacitor connected in parallel through a high resistance 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 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 an indicator such as a meter connected to the output of the amplifier. The present invention provides a storage battery monitoring device comprising:

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. By focusing on the fact that the voltage value at the peak part is theoretically proportional to the value, and the voltage value at the peak part decreases as the capacity decreases or the electrolyte specific gravity value decreases, we calculated the stable peak part of the open circuit voltage at rest. A voltage is stored in a first capacitor, and by connecting a second capacitor in parallel with this first capacitor via an ultra-high resistance, the voltage is also stored in the second capacitor with a delay, and this By discharging the voltage of the second capacitor through the internal impedance of an amplifier such as an operational amplifier, impedance conversion is performed to create a virtual discharge curve, and this virtual discharge curve is displayed on a display such as a meter. It is designed to display the status.
In addition, the voltage when a storage battery is discharged varies widely depending on the size of the discharge current, so it is not possible to monitor the capacity etc. based on the voltage during discharge, but the hypothetical discharge curve described above can be used to This allows the capacity of the storage battery to be monitored even when the battery is being discharged. Furthermore, when the hibernation state is entered 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;
This is to enable monitoring to be as accurate as possible.

In this way, the storage battery monitoring device of the present invention does not require the insertion of a sensor for measuring specific gravity inside the storage battery as in the conventional case, nor does it require the insertion of a shunt for current detection in the main circuit as in the conventional Ah meter. Without,
Simply by connecting to the terminals of the storage battery, the capacity of the storage battery and the specific gravity of the electrolyte can be monitored.

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 is a storage battery to be monitored (hereinafter simply referred to as a storage battery), 2 is a load, and 3 is a load input switch. 4 is a circuit connected to both ends of the storage battery 1 to obtain 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. Various circuit configurations can be considered for the circuit 4, but for example, it is configured by a series circuit of a constant voltage diode and a resistor,
It may be configured such that a constant voltage is subtracted by a constant voltage diode and the remaining voltage is obtained from both ends of the resistor.
Further, the circuit 4 is provided, for example, as a storage battery 1.
When using a 24-cell battery, the change in the open circuit voltage of this storage battery in actual use is small, about 51V to 47V, and this is because indicators such as meters, which will be described later, are operated at full scale around this voltage change range. 5 is the first capacitor charged with the voltage obtained in circuit 4;
The first capacitor is connected in parallel to the circuit 4 via a backflow prevention element 6 such as a silicon diode and a high resistance 7 connected in parallel.

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 1 obtained in the circuit 4, and due to the drop in terminal voltage due to the connection of the load 2 of the voltage battery 1. When the voltage obtained by the circuit 4 is lower than the voltage at the time of charging the first capacitor, the charge charged in the first capacitor 5 is discharged through the high resistance 7. 8
is a second capacitor, which is connected in parallel to the first capacitor 5 via a high resistance 9. 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 storage batteries 1
A capacitor and a resistor constitute a filter circuit that absorbs a pulse voltage when a voltage higher than the no-load voltage is generated at the terminal of the load 2 due to regenerative braking or chopper control. 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 the meter 13, one with a pointer display type or one with 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, if the storage battery 1 has 24 cells and is fully charged, the voltage will be approximately 51.5V.
voltage can be obtained. This no-load voltage is 51.5V when fully charged and about 47V when fully discharged, so there is only a small change of about 4 to 5V. In order to accurately detect this small change, a constant voltage is subtracted in the circuit 4, and the first capacitor 5 is charged with the remaining voltage, that is, the voltage between C and D of this circuit, through the filter resistor 11 and the capacitor 10. Ru. The first capacitor 5 is charged by the backflow prevention element 6 when the voltage between C and D rises above the voltage of the first capacitor 5, for example.
It is carried out rapidly through. On the other hand, when the voltage between C and D becomes lower than the voltage of the first capacitor 5, for example, the electric charge charged 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 approximately approximate to the open circuit voltage of the storage battery 1. Since the second capacitor 8 is connected via 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 is discharged through the high resistances 9 and 11, and at the same time, it is discharged through the internal impedance of the amplifier 12, and the voltage of the second capacitor 8 decreases. also decreases in proportion to the decrease in the open circuit voltage of the storage battery 1. Therefore, the output of the amplifier 12 is also connected to the second capacitor 8.
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 can be obtained on the meter 13.

The loss voltage of the second capacitor 8 caused by the above-mentioned discharge is corrected by being charged again by the open circuit voltage at this time, for example, the next time the storage battery 1 stops discharging for a long 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 rises rapidly because of the high resistance 9 provided. In addition, by adjusting the resistance value of the resistor 9, the second capacitor 8 can be charged at a speed almost equal to the charging progress speed, so the output of the amplifier device can be charged, discharged, or left unused. The voltage is close to the open circuit voltage of the storage battery 1 in any state.

In addition, the open circuit voltage of storage battery 1 is E=0.84+SG
As expressed by the approximate formula of (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
The capacity or specific gravity of the electrolyte will be detected.

Further, in this embodiment, since the capacity range of the storage battery required for display is displayed in full on the meter 13, it is 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 discharge state (remaining capacity) of the storage battery 1 can be detected simply by connecting this device to the storage battery 1, and the circuit 4 and the amplifier 12 can detect the discharge state (remaining capacity) of the storage battery 1.
When the temperature coefficient of is set to zero, the voltage change obtained from the circuit 4 indicates the characteristics of the storage battery 1 itself, so that the value displayed on the meter 13 is obtained by correcting the temperature of the storage battery 1. In addition, this device has the great feature of consuming only a few mA of power and 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 shaft into the main circuit as in the conventional Ah meter. This device has an excellent advantage in that the capacity of the storage battery and the specific gravity of the electrolyte can be accurately monitored even when the storage battery is left unused, discharged, or charged by simply connecting it to the terminals of the storage battery.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the monitoring device of the present invention. DESCRIPTION OF SYMBOLS 1...Storage battery to be monitored, 2...Load, 4...Circuit for obtaining the remaining voltage after subtracting a constant 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 ... Amplifying device,
13...Meter.

Claims (1)

[Claims] 1. 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 circuit connected in parallel to the circuit through a circuit in which a backflow prevention element and a high resistance are connected in parallel. a first capacitor charged with the voltage obtained at
a second capacitor connected in parallel to the first capacitor via a high resistance; and an amplifier device such as an operational amplifier connected to the second capacitor for impedance conversion of the voltage of the second capacitor. A storage battery monitoring device comprising an indicator such as a meter connected to the output of the amplifier.