JPH11136877A - Charging controller of rechargeable battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain desirable charge completion under various conditions by discriminating maximum value of a differential signal between a reference voltage signal and a battery voltage signal, and then discriminating it as charging completion if a difference between the maximum value and the differential signal is higher than a prescribed discriminating value. SOLUTION: Battery voltage rises sharply while charging is being started. A charging controller discriminates that value of A/D voltage at this time is higher than a discriminating upper limit, and increase a reference signal value from a D/A converter by a prescribed value (set D/A MOVE at 1). Then it compares a predetermined discriminating value with voltage decrease amount if the battery voltage drops to V1-V2 inclusive. The value of A/D voltage at this time is equal to the maximum value of A/D voltage within the period. Therefore, this controller discriminates that voltage decrease amount is lower than the discriminating voltage value to initialize D/A MOVE. The battery voltage at the time of full charging becomes maximum, the value of A/D voltage at this time is subtracted from the maximum value of A/D voltage, and the voltage decrease amount of voltage is discriminated as a lower one than the discriminating voltage value to initialize D/A MOVE.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control device for charging a rechargeable battery.

[0002]

2. Description of the Related Art When a rechargeable battery such as Ni-Cd, Ni-MH or the like is rapidly charged, as shown in FIG. It gradually increases over time. The magnitude of this battery voltage becomes maximum when fully charged, and thereafter, as the charging time elapses, the battery voltage gradually decreases. Therefore, the conventional charging completion determination method monitors the amount of voltage decrease, which is the difference between the maximum battery voltage value at full charge and the battery voltage value after full charge, and determines a predetermined fixed determination voltage. When the voltage decrease becomes larger than the value,
It is determined that charging is completed.

On the other hand, the above-mentioned amount of decrease in battery voltage is as follows:
For example, when a rechargeable battery with a battery voltage of 24 (V) is charged, the amount is as small as 50 (mV). Therefore, the battery voltage is converted to an A / D signal having a coarse resolution such as an 8-bit resolution.
When the amount of voltage decrease is measured using a converter,
Since a minute change in voltage cannot be detected, there has been a problem that it is not possible to accurately determine the timing of completion of charging. In order to solve this inconvenience, conventionally, as shown in FIG. 1, the input voltage range of the A / D converter is shifted by an offset voltage value as shown in FIG. Was provided and the battery voltage was measured to determine the completion of charging. This bias voltage value is a fixed value determined by the setting value of the adjustment circuit in the charging circuit, for example, the value of the variable resistor. In this conventional charging device, when the number of rechargeable batteries is changed, As described above, when charging the rechargeable battery by changing the charging condition, it is necessary to change the setting value of the adjustment circuit to change the bias voltage value, and it is difficult to easily use the rechargeable battery charging device. Met.

[0004]

In the conventional charging control device, as described above, when the charging conditions such as the number of rechargeable batteries are changed, it is necessary to change the set value of the adjustment circuit. It has been difficult to easily use rechargeable batteries. The need for rechargeable battery charge control is increasing for passenger cars,
This is not limited to rechargeable batteries for vehicles such as electric bicycles, and the same applies to rechargeable batteries used in portable electric products used under various charging conditions.

In view of the above circumstances, an object of the present invention is to provide a rechargeable battery charge control device capable of completing preferable charging under various charging conditions.

[0006]

A power output control means for controlling a power output supplied from a power source to a rechargeable battery, and a battery voltage signal representing a battery voltage between a positive electrode and a negative electrode of the rechargeable battery. A battery voltage signal generating means for controlling the power supply output control means based on the battery voltage signal, wherein the charge control apparatus for a rechargeable battery includes a reference voltage signal that rises in accordance with the rise of the battery voltage signal. Reference voltage signal generating means for generating, a difference signal generating means for generating a difference signal having a value representing a difference between the value of the battery voltage signal and the value of the reference voltage signal, and a value in which the value of the difference signal is within a predetermined central range. And a center range determining means for fixing the reference voltage signal as long as it falls within, and after determining occurrence of a maximum value of the difference signal, a difference between the maximum value and the difference signal is larger than a predetermined determination value. Charge completion determining means for determining the completion of charging of the rechargeable battery when it becomes crisp, and instructing means for issuing a charge stop command signal to the power output control means in response to a completion determination signal issued from the charge completion determining means, It is characterized by consisting of.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing an apparatus for controlling charging of a rechargeable battery according to a first embodiment of the present invention. The rechargeable battery 21 housed in the battery case 20 is connected to the power supply 11 via a power output control circuit 62 composed of, for example, a relay switch and the resistor 12. The positive electrode of the rechargeable battery 21 is connected to the non-inverting input terminal of the operational amplifier 33 via the resistors 31 and 32, while the negative electrode of the rechargeable battery 21 is grounded. The output terminal of the buffer amplifier 43 is connected to the inverting input terminal of the operational amplifier 33 via the resistor 35. Further, the output terminal of the operational amplifier 33 is connected to the inverting input terminal of the operational amplifier 33 via the resistor 34. This operational amplifier 3
3, a differential amplifier circuit 3 from the resistors 31, 32, 34 and 35
0, and the amplification factors are resistances 31, 32, 34 and 35.
Is determined by The output terminal of the operational amplifier 33 is A / D
Connected to converter 51.

The A / D converter 51 is connected to a CPU 54 via an input / output bus 53. The input / output bus 53 inputs and outputs a data signal or an address signal to / from the CPU 54. In the CPU 54, a determination process according to a flowchart described later is performed. Further, a D / A converter 52 is connected to the input / output bus 53, and emits a predetermined voltage signal in response to a command from the CPU 54. The output terminal of the D / A converter 52 is connected to a constant voltage power supply (not shown) via the resistor 13. Further, the output terminal of the D / A converter 52 is connected to the inverting input terminal of the operational amplifier 33 via a low-pass filter including a resistor 41 and a capacitor 42, a buffer amplifier 43, and a resistor 35.

Further, the input / output bus 53 has an RO
The drive circuit 61 of the M55, the RAM 56, and the power output control circuit 62 are connected to each other. Further, the ROM 55 stores a program for executing a determination process according to the flowcharts described in FIGS. 4, 5, 6, 9, and 10. The above-described drive circuit 61 and power supply output control circuit 62 function as power supply output control means, the resistors 31 and 32 function as battery voltage signal generation means, and the differential amplifier circuit 30 functions as difference signal generation means. The CPU 54, the ROM 55, the RAM 56, the D / A converter 52, the resistor 13, the resistor 41, the capacitor 42, and the buffer amplifier 43 function as reference voltage signal generating means. , A function as a center range determining means and a digital value generating means.

FIG. 3 shows a voltage value of a difference signal supplied to an A / D converter used in an apparatus for controlling charging of a rechargeable battery according to an embodiment of the present invention, an output value emitted from the A / D converter, and discrimination. 5 is a schematic diagram illustrating a relationship between values. In FIG. 3, the A / D converter has, for example, an input voltage range of 0 to 5 (V) and a resolution of 10 bits. Therefore, the lower limit of the measurement limit of the A / D converter is an input voltage value of 0 (V), the output value from the A / D converter corresponding to this is 0000 in hexadecimal notation, and the upper limit of the measurement limit is 5 ( V), the corresponding output value from the A / D converter is 03FF in hexadecimal notation. Further, in a flowchart described later, a discrimination upper limit value V _UL , a discrimination lower limit value V _LL , a discrimination center upper limit value V1 and a discrimination center lower limit value V2 used when discriminating charging completion of the rechargeable battery are 02E0 in hexadecimal notation, 00E0, 0170 and 0
190. In the following description, an output value of a signal generated from the A / D converter is referred to as an A / D voltage value.

FIG. 4 is a flowchart showing a subroutine for controlling charging of a rechargeable battery according to the present invention. This subroutine is executed, for example, by the CPU at a predetermined timing.
The processing is executed by interrupting the main routine 54. In this subroutine, first, it is determined whether or not a charging request is present from input means (not shown) such as a keyboard (step S41). As long as the charge request is present, a charge command is issued to the power supply output control circuit 62 (step S42), variables used for a charge completion determination process described later are initialized (step S43), and the charge completion determination process is executed. (Step S44), this subroutine ends.

FIG. 5 and FIG. 6 show a subroutine of a charge completion judging process as a first embodiment of the present invention. Hereinafter, a description will be given using FIGS. 5 and 6 and a graph showing the relationship between the charging time and the battery voltage of the rechargeable battery shown in FIG. In a period from immediately after the charging is started until the A / D voltage value falls to the determination center range determined by V1 and V2, that is, in the first determination processing cycle of period 1 shown in FIG. The current value of the A / D voltage, which is a digital value representing the current value, is sampled and captured (step S50)
1). Next, it is determined whether D / A_MOVE is 1 (step S502). This D / A_MOVE is a voltage value (hereinafter, referred to as a reference voltage signal) of the reference voltage signal generated from the D / A converter 52.
(Referred to as a reference voltage value) in the previous determination processing cycle. In the first cycle, it is determined that the voltage value of the reference voltage signal has not been changed (step S502), and it is determined whether the current value of the A / D voltage is equal to or more than the determination upper limit value V _UL (step S503). . In the period 1 in which the charging is started, the battery voltage of the rechargeable battery rapidly increases as shown in FIG. 7, so that the current value of the A / D voltage is determined to be equal to or more than the determination upper limit value V _UL . Therefore, in order to increase the value of the reference voltage signal generated from the D / A converter 52 by a predetermined value,
A reference voltage digital value (hereinafter, referred to as a D / A voltage value) supplied from the CPU 54 to the D / A converter 52 is increased by a predetermined value ΔV, for example, 1 in hexadecimal notation (step S508), and D / A_MOVE is set to 1 (Step S50)
9) Return to the beginning of this subroutine.

In the next cycle in period 1,
First, after fetching the current value of the A / D voltage (step S5
01), it is determined whether the flag D / A_MOVE is 1 (step S502). Since D / A_MOVE has been set to 1 in the previous cycle, the maximum A / D voltage value is set to an initial value V ₀ , for example, 0 (step S50).
5) It is determined whether the current value of the A / D voltage fetched in step S501 falls within the range of V1 to V2 (step S506). In period 1, the current value of the A / D voltage is larger than V2 (step S50).
7), the D / A voltage value is increased by a predetermined value ΔV (step S508), and D / A_MOVE is set to 1 (step S5).
09), returning to the head of this subroutine. Subsequent period 1
In the remaining period, the D / A voltage value is changed to a predetermined value ΔV
The cycle as described above is repeated while increasing the number only.

Next, when the battery voltage value falls to the center range of determination between V1 and V2, that is, during the period 2 shown in FIG.
In the first cycle, first, A / D
After fetching the current voltage value (step S501), D / A_
MOVE is determined to be 1 (step S502), and maximum A
/ D voltage value is initialized to V ₀ (step S505),
It is determined that the current value of the / D voltage is in the range from V1 to V2 (step S506). Then, the process proceeds to the process of the flowchart shown in FIG.
A comparison with the D voltage value is performed (step S601). Since the maximum A / D voltage value is initialized in step S505, the current A / D voltage value is determined to be equal to or greater than the maximum A / D voltage value, and the current A / D voltage value is set as the maximum A / D voltage value ( Step S602). Next, the current A / D voltage value is subtracted from the maximum A / D voltage value to obtain a voltage decrease amount (step S60).
3), this value is stored in the RAM 56 (step S6).
04). Next, a predetermined discrimination voltage value is compared with the voltage decrease amount (step S605). In the first discrimination processing cycle in period 2, the current A / D voltage value is equal to the maximum A / D voltage value.
The voltage decrease amount is determined to be smaller than the determination voltage value, and D / A_MO
VE is initialized (step S606), and the process returns to the head of this subroutine.

In the next cycle in period 2,
A / D voltage current value is acquired (step S501), and D / A_
MOVE is determined to be 0 (step S502), and A / D
After determining the voltage current value is smaller than the determination limit V _UL (step S503), A / D voltage current value is determined to be greater than the determination limit value V _LL (step S504).
In the period 2, since the A / D voltage current value is constantly increasing, it is determined that the A / D voltage current value is equal to or greater than the maximum A / D voltage value (step S601). Next, as described above, steps S602, S603, and S6
04, it is determined that the amount of voltage decrease is smaller than the determination voltage value, and D / A_MOVE is initialized (step S
606), returning to the beginning of this subroutine. In the subsequent period 2, since the current value of the A / D voltage is constantly increasing, the D / A voltage value is increased by the predetermined value ΔV while repeating the above-described determination.

Next, in the first cycle in the period 3, when the battery is fully charged, the value of the battery voltage of the rechargeable battery becomes maximum. Therefore, after performing the determination processing of steps S501 to S504 and step S601 in the same manner as the determination processing in period 2 described above, the current A / D voltage value corresponding to the maximum battery voltage value is set as the maximum A / D voltage value. (Step S602), the current A / D voltage value is subtracted from the maximum A / D voltage value to obtain a voltage decrease amount (Step S603),
This maximum A / D voltage value is stored (step S604),
It is determined that the voltage decrease amount is smaller than the determination voltage value (step S605), and D / A_MOVE is initialized (step S60).
6) Return to the beginning of this subroutine.

In the next cycle in period 3,
Since the battery voltage has begun to decrease, step S50 is performed again.
After performing the determination processing from 1 to step S504, A /
The D voltage current value is determined to be smaller than the maximum A / D voltage value (step S601), and the voltage decrease amount is obtained (step S601).
603), and stores the maximum A / D voltage value (step S60).
4) It is determined that the voltage decrease amount is smaller than the determination voltage value (step S605). This determination processing is repeated until the amount of voltage decrease becomes equal to or greater than the determination voltage value. When the battery voltage of the rechargeable battery further decreases and the amount of voltage decrease becomes equal to or greater than the determination voltage value, the processing from steps S501 to S504 and steps S601 to S604 is performed, and then the amount of voltage decrease is determined. It is determined that the voltage has become equal to or higher than the voltage value (step S605), and the present subroutine ends.
Thereafter, a charge stop command is supplied to the power output control circuit 62 via the drive circuit 61, and the power output control circuit 62 stops supplying the power output to be supplied to the rechargeable battery 21 (not shown). .

In step S504, A / D
If it is determined that the current voltage value is equal to or less than the lower limit value _VLL, it is determined that some trouble has occurred during charging,
The D / A voltage value of the D / A converter is set to an initial value, for example, 0 (step S510), and the discrimination processing cycle is executed again. By performing such a determination process, it is possible to reliably generate a reference voltage signal that increases or decreases according to the current increase or decrease in the battery voltage. Step S504 constitutes initialization means.

FIG. 8 is a block diagram showing an apparatus for controlling charging of a rechargeable battery according to a second embodiment of the present invention.
In this device, a battery voltage signal generated from the positive electrode of the rechargeable battery 21, a differential signal generated from the differential amplifier circuit 30, and a reference voltage signal generated from the D / A converter 52 are supplied to the MPX 57. This MPX57
The A / D converter 51 selectively selects any one of the above-described battery voltage signal, difference signal, and reference voltage signal in accordance with a command issued from the CPU 54 at a predetermined timing.
This is the switch that supplies the power.

FIGS. 9 and 10 are flow charts showing a subroutine for determining charging of a rechargeable battery according to a second embodiment of the present invention. Step S9 in FIG.
04 to step S908 correspond to step S5 in FIG.
02 to Step S510. First, a first A / D voltage value that is a digital value representing a difference signal is captured (step S901), and a second A / D voltage value that is a digital value representing a battery voltage signal is captured (step S902).

Next, it is determined whether D / A_MOVE is 1 (step S903). If it is determined that D / A_MOVE is 1, the maximum A / D voltage value is initialized (step S904). Next, when the first A / D voltage value is V1 or more and V2
It is determined whether it is the following (step S905). If it is determined that the first A / D voltage value is smaller than V1 or larger than V2, the second A / D voltage value is set so that the first A / D voltage value becomes a desired value, for example, a center value between V1 and V2. The value of the reference voltage signal is calculated from the value (step S906), the D / A voltage value corresponding to the reference voltage signal value is set (step S907), and D / A_MOVE is set to 1 (step S906).
908). If it is determined in step S905 that the first A / D voltage value is equal to or higher than V1 and equal to or lower than V2, the process proceeds to step S905.
The process proceeds to the process shown in the flowchart of FIG. The first A / D voltage value used in the determination processing of FIG. 10 is the same as the current A / D voltage value in FIGS. 5 and 6, and steps S1001 to S1006 in FIG. The same determination processing as in step S606 is performed.

By setting the reference signal voltage value using the second A / D voltage value in this manner, the value of the reference voltage signal can be reliably changed even when some trouble occurs during charging. It is.

[0023]

As described above, according to the rechargeable battery charging control apparatus of the present invention, it is possible to complete a preferable charging under computer control under various charging conditions.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a charging time of a rechargeable battery and a battery voltage between positive and negative electrodes of the rechargeable battery.

FIG. 2 is a block diagram showing an apparatus for controlling charging of a rechargeable battery according to a first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a relationship among an input voltage value, an output voltage value, and a determination value of an A / D converter used in an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a determination processing subroutine for controlling charging of a rechargeable battery according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a first half of a subroutine of a determination process for determining completion of charging of the rechargeable battery according to the first embodiment of the present invention.

FIG. 6 is a flowchart illustrating a latter half of a subroutine of a determination process for determining completion of charging of the rechargeable battery according to the first embodiment of the present invention.

FIG. 7 is a graph showing a manner in which a determination center range is changed according to a change in a battery voltage of a rechargeable battery.

FIG. 8 is a block diagram showing an apparatus for controlling charging of a rechargeable battery according to a second embodiment of the present invention.

FIG. 9 is a flowchart illustrating a first half of a subroutine of a determination process for determining completion of charging of a rechargeable battery according to a second embodiment of the present invention.

FIG. 10 is a flowchart illustrating a second half of a subroutine of a determination process for determining completion of charging of a rechargeable battery according to a second embodiment of the present invention.

[Description of Signs of Main Parts]

 Reference Signs List 11 power supply 21 rechargeable battery 30 differential amplifier circuit 51 A / D converter 52 D / A converter 54 CPU 55 ROM 56 RAM 62 power supply output control means

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[Procedure amendment]

[Submission date] October 23, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

FIG. 3 shows a voltage value of a difference signal supplied to an A / D converter used in an apparatus for controlling charging of a rechargeable battery according to an embodiment of the present invention, an output value emitted from the A / D converter, and discrimination. 5 is a schematic diagram illustrating a relationship between values. In FIG. 3, the A / D converter has, for example, an input voltage range of 0 to 5 (V) and a resolution of 10 bits. Therefore, the lower limit of the measurement limit of the A / D converter is an input voltage value of 0 (V), the output value from the A / D converter corresponding to this is 0000 in hexadecimal notation, and the upper limit of the measurement limit is 5 ( V), the corresponding output value from the A / D converter is 03FF in hexadecimal notation. Further, in a flowchart described later, a determination upper limit value V _UL , a determination lower limit value V _LL , a determination center upper limit value V 2, and a determination center lower limit value V used when determining the completion of charging of the rechargeable battery.
1 is a 02E0,00E0,01 9 0 and 01 7 0 at each hexadecimal notation. In the following description, A /
The output value of the signal emitted from the D converter is called an A / D voltage value.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

In the next cycle in period 3,
Since the battery voltage has begun to decrease, step S50 is performed again.
After performing the determination processing from 1 to step S504, A /
The D voltage current value is determined to be smaller than the maximum A / D voltage value (step S601), and the voltage decrease amount is obtained (step S601).
603), and stores the maximum A / D voltage value (step S60).
4) It is determined that the voltage decrease amount is smaller than the determination voltage value (step S605). This determination processing is repeated until the amount of voltage decrease becomes equal to or greater than the determination voltage value. Further decrease the battery voltage of the rechargeable battery, when the voltage decrease amount becomes equal to or higher than the determination voltage value, after executing the processing from step S501 from step S 504 and step S601 to step S604, the voltage reduction amount It is determined that the voltage has become equal to or greater than the determination voltage value (step S605), and the present subroutine ends. Thereafter, a charge stop command is supplied to the power supply output control circuit 62 via the drive circuit 61, and the power supply output control circuit 62
Stops supply of power output to be supplied to the rechargeable battery 21 (not shown).

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

Next, D / A It is determined whether MOVE is 1 (step S903). D / A If it is determined that MOVE is 1, the maximum A / D voltage value is initialized (step S904). Next, it is determined whether the first A / D voltage value is not less than V1 and not more than V2 (step S905). The first A / D voltage value is smaller than V1 or V2
If it is determined to be larger, the first A / D voltage value is determined from the second A / D voltage value and the amplification factor of the differential amplifier circuit 30 so that the first A / D voltage value becomes a desired value, for example, a center value between V1 and V2. The value of the reference voltage signal is calculated (step S906), and the D / A voltage value according to the reference voltage signal value is set (step S906).
907), D / A MOVE is set to 1 (step S908). If it is determined in step S905 that the first A / D voltage value is equal to or higher than V1 and equal to or lower than V2, the process proceeds to a process illustrated in a flowchart of FIG. The first A / D voltage value used in the determination processing of FIG. 10 is the same as the current A / D voltage value in FIGS. 5 and 6, and steps S1001 to S1006 in FIG. The same determination processing as in step S606 is performed.

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9

Claims (4)

[Claims] 1. A power output control means for controlling power output supplied from a power source to a rechargeable battery, and a battery voltage signal generating a battery voltage signal representing a battery voltage between a positive electrode and a negative electrode of the rechargeable battery. Means for controlling the power supply output control means based on the battery voltage signal, comprising: a reference voltage signal for generating a reference voltage signal that increases in accordance with an increase in the battery voltage signal. Generating means, a difference signal generating means for generating a difference signal having a value representing a difference between the value of the battery voltage signal and the value of the reference voltage signal, and the value of the difference signal falls within a predetermined central range. A center range determining means for fixing the reference voltage signal as long as possible, and after determining occurrence of a maximum value of the difference signal, a difference between the maximum value and the difference signal is larger than a predetermined determination value. Charge completion determination means for determining the completion of charging of the rechargeable battery; andinstruction means for issuing a charge stop command signal to the power output control means in response to a completion determination signal issued from the charge completion determination means. A charge control device for a rechargeable battery. 2. The charge control device for a rechargeable battery according to claim 1, wherein said difference signal generating means comprises a differential amplifier circuit. 3. The reference voltage signal generating means includes: a digital value generating means for generating a reference voltage digital value having a magnitude corresponding to the magnitude of the battery voltage signal or the difference signal; 2. The rechargeable battery charge control device according to claim 1, further comprising a D / A converter for performing an A / A conversion. 4. The rechargeable battery according to claim 1, further comprising initialization means for setting the value of the reference voltage signal to an initial value when the value of the difference signal becomes smaller than a predetermined value. Charge control device.