JPH03180783A - Battery remaining amount calculation device - 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 [Industrial Field of Application] The present invention relates to a battery remaining amount calculation device that estimates the remaining battery amount, that is, the degree of charging and discharging of the battery, by calculation.

[Prior Art] Conventionally, in devices that use batteries as a power source, methods for detecting the remaining battery power include monitoring the discharge voltage of the battery, and calculating power consumption by integrating the discharge time from a fully charged state. There is a configuration that estimates the remaining battery capacity by accumulating the amount of power remaining, and in the case of a charging device, there is a configuration that monitors changes in the charging voltage.

[Problem to be solved by the invention] However, in the conventional configuration that uses the terminal voltage of the battery,
Due to variations in individual batteries, it is extremely difficult to quantitatively display the remaining capacity in terms of time, and it can only be used as a guide to when the battery capacity is running out. Also,
Even when charging, it is not possible to quantitatively determine how much the battery has been charged.

Further, in the configuration in which the discharge time and/or discharge current are integrated, the integration must be started after starting use from a fully charged state, and cannot be applied to a half-charged battery. Furthermore, it is not possible to adapt to unexpected changes in usage conditions, and the determination value becomes an unreliable value.

Therefore, an object of the present invention is to provide a battery remaining amount calculation device that does not have such drawbacks.

[Means for Solving the Problems] A battery remaining amount calculation device according to the present invention includes a data holding means for holding data of open circuit voltage of a battery versus remaining battery amount, and a data holding means that detects the open circuit voltage of the battery and holds the data. It is characterized in that the remaining battery capacity of the battery is determined by comparing it with data held by the means.

[Operation] The open circuit voltage of the battery has little variation from battery to battery, and can be used as an indicator for determining the remaining battery capacity. By applying the open-circuit voltage (internal electromotive voltage) to the open-circuit voltage versus remaining battery capacity data using the above means, the remaining battery capacity and usage amount can be quantitatively and more accurately estimated.

[Example code] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention. 1
0 is the battery to be measured, which consists of a series circuit of an ideal battery part with an open circuit voltage E0 and an internal resistance with a resistance value r0. 12.14 is a resistor with a known resistance value,
It is selectively connected to battery 10 by switch 16 . 18 is an ammeter that measures the current flowing through the resistor 12.14 when the resistor 12.14 is connected to the battery 10 and outputs it as a voltage signal; 20 is an A/D converter that digitizes the current value measured by the ammeter 18; , 22 is an arithmetic circuit consisting of a microcomputer that controls the switch 16 and determines the degree of charge and discharge of the battery 10 from the measured current value, 24 is a display device that displays the determination result of the arithmetic circuit 22, and 26 is a battery This is a memory that stores data necessary for determining the degree of charge and discharge.

FIG. 2 shows the discharge characteristics when a predetermined load is connected to the battery 10 and the battery is discharged. The vertical axis shows the discharge voltage. The horizontal axis shows the remaining battery power in time.

That is, when the lowest voltage at which the equipment in use can operate is V, when the discharge voltage reaches v8, the remaining power time becomes O. Even if the battery is of the same type, there is a large variation among individual batteries. Therefore, even if the discharge voltage is V, for example, the remaining capacity time will show a value of T to T2 depending on the battery being measured.

On the other hand, FIG. 3 shows a characteristic curve of remaining power time versus open circuit voltage. The vertical axis is the open circuit voltage, and the horizontal axis is the remaining power time, which is the same as in FIG. In terms of open circuit voltage, batteries of the same type exhibit quantitatively almost the same discharge characteristics with little variation. The fact that there is little variation in discharge characteristics in terms of open circuit voltage is basically the same whether it is a secondary battery or a secondary battery.

Therefore, in this embodiment, the discharge characteristics due to the open circuit voltage as shown in FIG. 3 are converted into data and stored in the memory 26, and the degree of charge and discharge of the battery 10 is determined quantitatively. Methods for converting the discharge characteristics shown in Figure 3 into data include using the remaining amount of time as an approximate function of the open circuit voltage, and creating a table and interpolating data for the open circuit voltage that approximates the obtained open circuit voltage value. and so on.

FIG. 4 shows an operation flowchart of the arithmetic circuit 22. The arithmetic circuit 22 first connects the switch 16 to the a contact point S.
l) and the current flowing through the resistor 2 are measured and read using the ammeter 18. Calculate the voltage V between the terminals of the battery 10 from the resistance value R1 of the resistor 12 and the measured current value ■1 (S
l). Next, connect the switch 16 to the b contact (S3)
, reads the current I2 caused by the resistor 14, and calculates the voltage v2 between the terminals of the battery 10 (S4).

Accordingly, I got 4 points! +, 1. , V, , calculate the open circuit voltage E0 from V, (S5).

Eo” L +1,・r.

=V, +t, .ro = (I2L-1,V2)/(1,-11) In the following formula, ro= (v+-vz)/(b-■1).

The open circuit voltage E0 thus obtained is applied to the relationship data of open circuit voltage E versus remaining battery time T stored in the memory 26 (Fig. 3) to determine the remaining battery time T0 corresponding to the open circuit voltage E0. (S6). And when it should be displayed (
S7), the remaining battery time T0 is displayed in a predetermined manner on the display device 24 (S8).

By performing the above operations cyclically, the battery 10
You can quantitatively know the remaining battery time.

FIG. 5 shows a block diagram of another embodiment.

30, like the battery 10, has an internal resistance r0 and a voltage E,
32 is a load resistor with a resistance value R5, 34 is an ammeter that measures the current flowing through the load resistor 32, 36 is an AC signal generation circuit that generates AC of a predetermined amplitude, 38 is a capacitor with a large capacity C1 that allows the AC signal's actance to be ignored; 40 is the output impedance of the AC signal generation circuit; 42 is a capacitor for cutting DC; 44 is a low-pass filter for cutting AC; This is a capacitor for DC cut.

48 is the voltage V between the terminals of the battery 30 (output of the low-pass filter 44), the load resistance 32 in the AC signal, and the voltage drop V of the battery 30. (amplitude value of the AC signal from the capacitor 46), amplitude Vs of the AC signal output from the AC signal generation circuit 36 (amplitude of the AC signal from the capacitor 42), and current value of the load resistor 32 measured by the ammeter. 52 is an A/D converter for digitizing; 50 is an arithmetic circuit consisting of a microcomputer that calculates the remaining battery time of the battery 10 from the output data of the A/D converter 48;
54 is a display device that displays the obtained battery remaining time, and 54 is a memory that stores discharge characteristic data of the battery 10, similar to the memory 26.

FIG. 6 shows an operation flowchart of FIG. 5.

The AC signal Vs output by the AC signal generation circuit 36 is applied to the battery 30 (and load resistance 32) via the output impedance 40 and the capacitor 38, and the voltage drop across the internal resistance ro of the battery 30 (and the load resistance 32) is vo
Then, the internal resistance r0 can be found by the following formula.

5RL ro = RL (vs/vo-1) - Rs On the other hand, in terms of direct current, the resistance value RL between the terminals of the battery 30
When the resistor 32 is connected, the DC current flowing through the resistor is (2), and the voltage between the terminals of the battery 30 is V, the open circuit voltage E0 of the battery 30 is determined by the following formula.

E,=V+Ir.

becomes.

These vo.

vs.

■.

■A/D converter The data is digitized at 48 and input to the arithmetic circuit 50.

The arithmetic circuit 50 reads these (SIO) and calculates the open circuit voltage E0 (5ll), and similarly to the case 86 in FIG. Find the remaining amount time T0 (S12),
Then, when it is necessary to display it (S13), it is displayed on the display device 52 (514).

Although the case of a secondary battery has been described as an example, the present invention can of course also be applied to the case of obtaining the remaining battery power of a secondary battery.

[Effects of the Invention] As can be easily understood from the above explanation, according to the present invention, electric power? It becomes possible to quantitatively grasp the remaining amount of Ih.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the configuration of an embodiment of the present invention, Fig. 2 is a characteristic diagram of battery discharge voltage versus remaining current time, Fig. 3 is a characteristic diagram of open circuit voltage versus remaining battery time, and Fig. 4 1 is an operation flowchart of FIG. 1, FIG. 5 is a block diagram of the configuration of the second embodiment, and FIG. 6 is an operation flowchart of FIG.

Claims (1)

[Claims] A data holding means for holding data on the open circuit voltage of the battery versus the remaining battery capacity, and a method for determining the remaining battery capacity of the battery by detecting the open circuit voltage of the battery and comparing it with data held by the data holding means. Characteristic remaining battery power calculation device.