JP2003079066A - Battery charging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging method which surely discriminates full charge, by eliminating a short state of charge due to premature charging operation stop, even if temperature rise value becomes high immediately after start of charging caused by a temperature gradient between the battery temperature and the ambient one, when the ambient temperature is higher than the battery temperature. SOLUTION: The charging method comprises a battery temperature detection means 2A; a map which calculates and memorizes a temperature rise value ΔT for each predetermined period based on an output of the battery temperature detection means 2A, and allows mapping of a charging-current-allowable value which allows charging while suppressing temperature rise value of a battery pack 2 based on the battery temperature T and the temperature rise value ΔT; a charging completion discrimination means which discriminates charging completion, based on whether the frequency belonging to a region at the charging terminal stage in the map is high or not; and a microcomputer 50 having a counting means to count the lapsed time from the start of charging. Setting of the charging completion discrimination means is changed, when the lapsed time from the start of charging is within a predetermined time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for charging a secondary battery such as a nickel-cadmium battery (hereinafter referred to as a nicad battery) or a nickel-hydrogen battery (hereinafter referred to as a nickel-hydrogen battery).

[0002]

2. Description of the Related Art As one of the methods for charging a nickel cadmium battery or a nickel hydride battery used as a power source for an electric tool or the like, as disclosed in Japanese Patent Laid-Open No. 11-355971, the battery temperature and temperature during charging are set. When the rise value is high (low), charge with a small (large) charge current to suppress the rise in battery temperature and set the allowable charge current that can be charged rapidly as the battery temperature value and the battery temperature rise value. Based on the detected and calculated battery temperature and battery temperature rise value, the charging current permissible value is stored for each constant cycle by storing a plurality of maps mapped based on the temperature difference between the ambient temperature and the battery temperature. The battery is searched and charged according to the retrieved charging current allowable value, and the battery temperature and the battery temperature rising value are in a region where the temperature rising value is large in the map or the battery temperature is high. Charging apparatus frequently degrees rise value belongs to the final stage of charging region is a moderate area determines the full charge based on whether high or not have been proposed.

[0003]

However, in such a charging device, when the ambient temperature is higher than the battery temperature, the temperature rise value becomes high immediately after the start of charging due to the temperature gradient between the battery temperature and the ambient temperature. In a map that does not assume such a phenomenon, the battery is frequently charged in a region indicating the end of charge, and there is a risk that the battery is ill-charged with almost no charge, resulting in insufficient charge.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to enable charging without causing insufficient charging due to premature charge even when the ambient temperature is higher than the battery temperature by a predetermined value or more. It is also necessary to ensure that the full charge can be determined.

[0005]

Means for Solving the Problems The above-mentioned object is to judge whether charging is completed by the charging completion judging means, and if the elapsed time from the start of charging is continuously within a predetermined time based on the output of the counter means, charge in the map. Change the setting of the charging completion judgment means that judges the completion of charging based on whether the frequency indicating the end period is high or not, and search the allowable charging current value in the map again according to the battery temperature and the battery temperature rise value. ,
This is achieved by continuing the charging based on the retrieved allowable charging current value and determining the charging completion, that is, the full charging by the charging completion determining unit whose setting is changed.

[0006]

1 is a circuit diagram showing an embodiment of the present invention. Reference numeral 1 is an AC power source, and 2 is a battery group in which a plurality of unit cells are connected in series, and a battery temperature detecting means 2A including a thermistor or the like for detecting a battery temperature in contact with or in proximity to the unit cells is incorporated. 3 is a current detecting means for detecting a charging current flowing in the battery set 2, 4 is a charging control signal transmitting means for transmitting a signal for controlling the start and stop of charging, and 5 is a charging for feeding back the signal of the charging current to the PWM control IC 23. It is a current signal transmission means. The charging control transmission signal means 4 and the charging current signal transmission means 5 are photocouplers or the like. Reference numeral 10 is a rectifying / smoothing circuit including a full-wave rectifying circuit 11 and a smoothing capacitor 12, and 20 is a high-frequency transformer 21, MO.
It is a switching circuit including an SFET 22 and a PWM control IC 23. The PWM control IC 23 is the MOSFET 22
Is a switching power supply IC that adjusts the output voltage of the rectifying and smoothing circuit 20 by changing the drive pulse width of. Reference numeral 30 is a rectifying / smoothing circuit including diodes 31, 32, choke coil 33, and smoothing capacitor 34, and 40 is a battery voltage detecting means including resistors 41 and 42, which divides the terminal voltage of the battery set 2. 50 is a calculation means (CPU) 51, ROM 52, RA
The microcomputer includes an M53, a counter 54, an A / D converter 55, an output port 56, and a reset input port 57. Reference numeral 60 is a charging current control means including operational amplifiers 61 and 62 and resistors 63 to 66, and 70 is a constant voltage power supply including a power transformer 71, a full-wave rectifier circuit 72, smoothing capacitors 73 and 74, a three-terminal regulator 75, and a reset IC 76. , The microcomputer 50, the charging current control means 60, etc. The reset IC 76 outputs a reset signal to the reset input port 57 to initialize the microcomputer 50. Reference numeral 80 is a charging current setting means for setting a charging current, which changes the voltage value applied to the inverting input terminal of the operational amplifier 62 in response to the signal from the output port 56a.

FIG. 2 shows the battery temperature T and the battery temperature rise value ΔT.
The allowable values I11 to I66 of the charging current searched according to the above are shown, and the shaded area shows the area searched at the end of charging.
That is, in the region where the battery temperature rise value ΔT is large (I51 to I
66) or a region where the battery temperature T is high and the battery temperature increase value ΔT is medium (I45, I46) is a region searched at the end of charging. It should be noted that it is possible to perform better full-charge detection if the maps are provided according to the battery type and the battery voltage (the number of unit cells).

Next, the circuit diagram of FIG. 1, the map of FIG. 2 and the circuit diagram of FIG.
The operation of the charging method of the present invention will be described with reference to the flowchart of FIG.

When the power is turned on, the microcomputer 50 initially sets the output port 56 and the early charging flag, and the battery group 2 is in a connection standby state (step 101). When the battery set 2 is connected, charging is started (step 102), and the counter 54 that continuously counts the time from the start of charging
Is started (step 103). Next, the battery temperature T during charging is detected and calculated from the output of the battery temperature detecting means 2A at predetermined intervals (step 1104), and the temperature increase value ΔT is obtained (step 105). The battery temperature value T and the temperature increase value ΔT are calculated. Based on the above, the microcomputer 50 searches the map to obtain a charging current allowable value that allows charging while suppressing the temperature rise (step 106).

Next, the microcomputer 50 determines whether or not the retrieved charging current allowable value is within the charging end period region shown by the shaded portion in the selected map of FIG. 2 (step 107). When it does not enter the end-of-charge region, the routine proceeds to step 113, where the charging at the allowable charging current value obtained at step 106 is continued and the routine returns to step 104. When the battery enters the end-of-charge region, it is determined whether the probability of entering the end-of-charge region is high (step 108). For example, it is determined that the probability of entering the end of charge region is high when the end of charge region is entered for three consecutive cycles. If the terminal does not enter the end-of-charge region for three consecutive cycles even if it enters the end-of-charge region, it is not determined that the probability of entering the end-of-charge region is high.
Return to 04. If you enter the end of the three-cycle continuous charging area,
It is determined that the probability of entering the end-of-charge region is high, and it is continuously determined whether or not the early charge flag is set (step 109). If Flag = 1 is not established, charging is started based on the output of the counter 54. It is determined whether or not the elapsed time from is a predetermined time or more (step 11
0). This is because the temperature rise value increases due to the temperature gradient between the battery temperature and the ambient temperature immediately after the start of charging, and as a result,
Since there is a possibility that it may be erroneously determined that charging is complete, the elapsed time from the start of charging until the influence of the temperature gradient between the battery temperature and the ambient temperature is reduced is monitored, and if the elapsed time has reached the predetermined time, the charging is performed. Upon completion, it is determined that the battery is fully charged and charging is stopped (step 114). Therefore, the predetermined time may be set to a time when the influence of the temperature gradient between the battery temperature and the ambient temperature becomes small.

If the predetermined time has not elapsed in step 110, there is a possibility that the temperature rise value becomes high immediately after the start of charging due to the temperature gradient between the battery temperature and the ambient temperature and the battery set 2 is erroneously determined to be fully charged. Therefore, in order to recheck, the setting of the probability of entering the end-of-charge region is changed (step 111). The setting can be changed, for example, in the above-mentioned 3
It was decided that the probability of entering the end-of-charge region when entering the end-of-charge region for a number of consecutive cycles is high. There are various methods for determining After the setting is changed in step 111, the temperature rise value may be increased once due to the temperature gradient between the battery temperature and the ambient temperature, which may have caused the premature charge termination. Therefore, the premature charge flag is set to 1 (step 11
2) and returns to step 104 via step 113.
In step 109, if the charge premature cut flag is set to 1, it is determined once that the charging is completed and then that the charging is completed again. At this time, it is finally determined that the battery is fully charged.
Step 110 is skipped to complete the charging.

As described above, in the above-described embodiment, when it is determined that the end of charge region is reached within the predetermined time, the temperature rise becomes high due to the temperature gradient between the battery temperature and the ambient temperature, which causes full charge. Therefore, the probability of entering the end-of-charge region again will be rechecked so that charging can be performed without causing insufficient charging due to premature charging, and full charge can be reliably determined. Is to Also, the structure of the charging device is simplified.

[0013]

As described above, according to the present invention, when the ambient temperature is higher than the battery temperature, even if the temperature rise value becomes high immediately after the start of charging due to the temperature gradient between the battery temperature and the ambient temperature, charging is performed. It eliminates the shortage of charge due to premature disconnection, and enables reliable judgment of full charge.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a charging device adopting a charging method of the present invention.

FIG. 2 is an explanatory diagram showing the contents of an example of a map.

FIG. 3 is a flowchart for explaining the operation of the charging method of the present invention.

[Explanation of symbols]

2 is a battery group, 2A is a battery temperature detecting means, and 50 is a microcomputer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 10/44 H01M 10/44 QF term (reference) 2G016 CB31 CC03 CC04 CC10 CC13 CC14 CC16 CC17 CC21 CC23 CC27 CC28 CD09 CD10 CD14 CF06 5G003 AA01 CA03 CA14 CA20 CB01 GA10 GB04 GC04 GC05 5H030 AA08 AS20 BB01 FF22 FF42 FF52

Claims (3)

[Claims] 1. A storage unit for storing a map in which an allowable value of a charging current that can be charged while suppressing a temperature rise value of a battery is mapped based on a battery temperature and an increase value of the battery temperature, and a battery for detecting the battery temperature. The temperature detection means, the battery temperature rise value detection means for calculating the rise value of the battery temperature for each predetermined cycle based on the output of the battery temperature detection means, the battery temperature detected by the battery temperature detection means and the battery temperature rise detection means The detected battery temperature rise value, the charge completion determination means for determining the completion of charging based on whether or not the frequency indicating the end of charge in the map is high, and a counter for counting the elapsed time from the start of charging. Means for searching the charge current allowable value in the map according to the battery temperature and the battery temperature rise value, and charging with the searched charge current allowable value. Charging method, characterized in that the elapsed time from the start of charging when the charge completion determining means determines that the charge completion in the charging process is finished charging and determining that full charging not less than a predetermined value. 2. A storage unit for storing a map in which an allowable value of a charging current that can be charged while suppressing a temperature rise value of the battery is mapped based on the battery temperature and an increase value of the battery temperature, and a battery for detecting the battery temperature. The temperature detection means, the battery temperature rise value detection means for calculating the rise value of the battery temperature for each predetermined cycle based on the output of the battery temperature detection means, the battery temperature detected by the battery temperature detection means and the battery temperature rise detection means The detected battery temperature rise value, the charge completion determination means for determining the completion of charging based on whether or not the frequency indicating the end of charge in the map is high, and a counter for counting the elapsed time from the start of charging. Means for searching the allowable value of the charging current in the map according to the battery temperature and the battery temperature increase value, and charging with the searched allowable charging current value. In this charging process, when the elapsed time from the start of charging when the charging completion determining means determines that the charging is completed is within a predetermined value, the charging completion determining means does not determine that the charging is complete, and the setting that the charging completion determining means determines that the charging is completed is changed. The charging method is characterized in that the charging is continued according to the allowable charging current value, and when the charging completion judging means judges that the charging is completed while the charging is continuing, the charging is judged to be full charging and the charging is terminated. 3. Storage means for storing a map in which an allowable value of a charging current that can be charged while suppressing a temperature rise value of the battery is mapped based on the battery temperature and a rise value of the battery temperature, and a battery for detecting the battery temperature. The temperature detection means, the battery temperature rise value detection means for calculating the rise value of the battery temperature for each predetermined cycle based on the output of the battery temperature detection means, the battery temperature detected by the battery temperature detection means and the battery temperature rise detection means The detected battery temperature rise value, the charging completion determination means for determining the completion of charging based on whether or not there is a high frequency of belonging to the region indicating the end of charging in the map, and a counter for counting the elapsed time from the start of charging. And a charging method comprising the following steps. a. Retrieving the charging current allowable value in the map according to the battery temperature and the battery temperature increase value. b. The step of charging with the charge current allowable value found in the above step. c. A step of judging whether or not the allowable charging current value is a value within the end-of-charge region, and returning to step a when it is not within the region. d. A step of determining whether or not the charge current allowable value is a value within the end-of-charge region, and determining that the charge current is a value within the region and that the frequency of belonging to the end-of-charge region is high is temporary. e. If it is determined in step d that provisional charging has been completed, if the elapsed time from the start of charging is less than or equal to a predetermined value, the setting that the completion of charging determination means determines completion of charging is changed, and the process returns to step a If the value exceeds a predetermined value, it is determined that the battery is fully charged. f. A step of determining that the battery is fully charged when the completion of charging is determined again in step d when the charging completion determining means continues charging after changing the setting. g. A step of stopping charging when it is determined that the battery is fully charged in steps e and f.