JP2008236972A - Charger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely achieve full charge by continuing recharging, after a battery temperature drops to a prescribed charge return temperature, when battery voltage is lower than a prescribed value, while completing charging as fully charged, when a battery voltage exceeds a prescribed value, in a charger for a nickel-hydrogen storage battery. <P>SOLUTION: After the number of times that a battery temperature reaches a prescribed charge-halt temperature becomes a prescribed specific number of times, a charger executes battery voltage determination so as to complete charging as full charge, when a battery voltage exceeds a prescribed threshold. When a battery voltage is lower than a prescribed threshold, the charger continues charging again after a battery temperature drops to a prescribed charge return temperature. Consequently, it surely makes the charger fully charged, without finishing charging in the middle of charging, even for a battery having a large battery temperature rise. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a charge control technique performed by detecting a battery temperature in a charger for a secondary battery such as a nickel metal hydride storage battery.

The conventional charger that detects the battery temperature and determines the charging completion is a method of detecting an appropriate charging completion point using the detected battery temperature. For example, Patent Document 1 describes a method of detecting an appropriate completion point based on a temperature difference between a battery temperature and an outside air temperature (see, for example, Patent Document 1).
Japanese Patent No. 3346821

  In Patent Document 1, the charging is terminated when the temperature difference between the battery temperature and the outside air temperature reaches a predetermined temperature difference. However, in a battery stored for a long time, the battery temperature rise is larger than that of a normal battery. However, as a battery, there was a problem that charging ended even though charging was not completed. The phenomenon that the battery temperature rises becomes large, especially when a battery having a high capacity in recent years becomes inactive due to long-term storage or the like.

  FIG. 6 shows a relationship diagram of the battery temperature, the outside air temperature, the battery voltage, and the charging current when the battery temperature rise is larger than that of a normal battery in the conventional method, as compared with a normal battery. In FIG. 6, Tb1 is the battery temperature when the battery temperature rise is large, Tb2 is the battery temperature when the battery temperature rise is normal, Ta is the outside air temperature, and Td is the battery temperature and outside air temperature for determining the completion of charging. A temperature difference threshold, Vb is a battery voltage, and Ich is a charging current. Further, a solid line indicates a case where the battery temperature rise is large, and a broken line indicates a case where the battery temperature rise is normal. After the start of charging, if the battery is a normal battery, the battery temperature increases slightly as shown by Tb2, and the battery temperature rapidly increases from the time when the charging is almost complete. However, a battery that has become inactive due to long-term storage or the like exhibits a larger temperature increase gradient after the start of charging as indicated by Tb1. For this reason, there is a problem that the charging is terminated because the temperature difference between the battery temperature and the outside air temperature reaches the threshold temperature difference Td even though charging is still in progress.

  In order to solve the above problems, a charger according to the present invention detects a battery voltage by a power supply unit that supplies a charging current, a current control unit that controls the charging current, an output switch that turns the charging current on and off, and a battery voltage. A battery voltage detector for detecting the battery temperature, a battery temperature detector for detecting the battery temperature, and a charge controller for performing main control of charging. After the battery starts charging, the battery temperature rises and reaches a predetermined charging suspension temperature. When the battery temperature is lowered and then the charging is continued when the battery temperature drops and reaches the predetermined charging return temperature, the number of times the battery temperature reaches the predetermined charging suspension temperature is the first specified number of times. Battery voltage is determined, and when the battery voltage detected by the battery voltage detector is greater than or equal to a predetermined threshold, the battery is fully charged and the battery voltage is less than the predetermined threshold. When the battery temperature returns to the predetermined charge After lowered to degree, it has a function to continue charging again.

When the number of times the battery temperature reaches the charging suspension temperature reaches the first specified number of times, the charger of the present invention pauses charging and determines the battery voltage, and the battery voltage detected by the battery voltage detection unit When the battery voltage is lower than the threshold value, the charging is completed, and when the battery voltage is lower than the threshold value, the charging is continued again after the battery temperature falls to a predetermined charging return temperature. As a result, in a battery with a large battery temperature rise, the battery voltage detected by the battery voltage detection unit becomes less than the threshold value and drops to a predetermined charge recovery temperature. There is an effect that the battery is surely fully charged without being terminated.

  In the present invention, since the battery voltage is less than the predetermined threshold value, the transition to the battery voltage determination and the continuation of charging are repeated many times, and the transition to the battery voltage determination reaches the second specified number of times. When the detected battery voltage is less than a predetermined threshold, adding a function to complete charging will cause the charging time to become excessively long for the user when the battery temperature rise is abnormally high. You can avoid anxiety.

  In addition, when it is determined in the battery voltage determination that the battery voltage is equal to or higher than a predetermined threshold value and charging is completed, a first trickle current is passed, and the battery voltage is less than the predetermined threshold value, but the battery voltage When charging is completed because the transition to the determination has reached the second specified number of times, the battery temperature rise becomes abnormal by flowing a second trickle current set to a current value larger than the first trickle current. Even a battery that has been fully charged without being fully charged can be made closer to full charge.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
A more specific embodiment 1 of the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 3, FIG. FIG. 1 is a circuit block diagram of Embodiment 1 of the present invention, FIG. 2 is a relationship diagram of battery temperature, battery voltage, and charging current when a normal battery is charged according to Embodiment 1, and FIG. When charging a battery that has become inactive due to long-term storage or the like and has a large battery temperature increase due to mode 1, the battery voltage, battery voltage, and charging current when the battery voltage Vb rises above the threshold Vs for battery voltage determination FIG. 4 is a relational diagram, FIG. 4 is a relational diagram of battery temperature, battery voltage, and charging current when the battery voltage Vb does not rise above the threshold value Vs for battery voltage determination when the battery is charged. FIG. 1 is a charge control flowchart of FIG.

  The structure of Embodiment 1 of this invention is demonstrated based on FIG. In the first embodiment, the power supply unit 1 supplies a charging current, and the power supply control unit 2 controls the charging current. The output switch 3 turns on and off the charging current, the battery voltage detector 4 detects the battery voltage, and the battery temperature detector 5 detects the battery temperature. Further, the main control of charging is performed by the charging control unit 6. The charging current supplied from the power supply unit 1 is made constant by the current control unit 2 and flows to the battery via the output switch 3. The battery voltage is always detected by the battery voltage detection unit 4, the battery temperature is detected by the battery temperature detection unit 5 using the temperature detection element, and the charging control unit 6 completes charging of the battery based on the battery voltage and the battery temperature. To detect.

  FIG. 2 shows a battery voltage, a charging current, and a battery temperature when a normal battery is charged with a high outside air temperature according to the first embodiment. The battery voltage is Vb, the battery temperature is Tb, the charging current is Ich, the charging suspension temperature is Ts1, the charging recovery temperature is Ts2, and the battery voltage determination threshold is Vs. Further, when the number of times the battery temperature reaches the charging suspension temperature Ts1 reaches the first specified number of times (hereinafter referred to as N1 times), charging is suspended and battery voltage determination is performed. Then, this N1 times is set to 2 times. Further, even when the transition to the battery voltage determination is repeated, when the transition to the battery voltage determination reaches the second specified number of times (hereinafter referred to as N2 times), the detected battery voltage is set to the threshold value. Charging is completed even if it is less than Vs, but in the first embodiment of the present invention, this N2 times is set to 4 times.

  In FIG. 2, after the start of charging, the battery temperature Tb gradually rises, and since the outside air temperature is high, it reaches the charging suspension temperature Ts1 during the charging, and the charging current Ich is turned off to enter the charging suspension state. Thereafter, when the battery temperature Tb falls and reaches the charge recovery temperature Ts2, the charging current is turned on again and the charging is continued. As the charging progresses, the battery temperature Tb rises and reaches the charging suspension temperature Ts1 again. In the first embodiment, since the battery voltage is determined when the battery temperature reaches the charging suspension temperature Ts1 for the second time, the battery voltage is determined at the point A in FIG. It is compared with the threshold value Vs. As a result, since battery voltage Vb is equal to or higher than threshold value Vs, it is determined that the battery is fully charged, charging is completed, and a first trickle current flows.

  Next, FIG. 3 shows the battery voltage, charging current, and battery temperature when charging a battery having a high battery temperature rise due to long-term storage or the like in a state where the outside air temperature is high according to the first embodiment. Each symbol is the same as in FIG. After the start of charging, since the battery temperature rises greatly and the outside air temperature is high, the battery temperature Tb reaches the charging suspension temperature Ts1 at an early stage, the charging current Ich is turned off, and the charging suspension state is entered. Thereafter, when the battery temperature Tb falls and reaches the charge recovery temperature Ts2, the charging current is turned on again and the charging is continued. Then, the battery temperature Tb rises and reaches the charging suspension temperature Ts1 again. In the first embodiment, since the battery voltage is determined when the battery temperature reaches the charging suspension temperature Ts1 for the second time, the battery voltage is determined at the point A in FIG. It is compared with the value Vs. As a result, since the battery voltage Vb is less than the threshold value Vs, it is not determined that the battery is fully charged. When the battery temperature Tb falls and reaches the charge recovery temperature Ts2, the charging current is turned on again and charging is continued. Thereafter, charging and rest are repeated in the same manner, and after reaching the charging suspension temperature Ts1 for the second time in each repetition, battery voltage determination is performed at points B and C in the figure. Even at the second point B as the battery voltage determination, since the battery voltage Vb is less than the threshold value Vs, charging is continued thereafter. At point C, which is the third battery voltage determination, since the battery has reached full charge, the battery voltage Vb becomes equal to or higher than the threshold value Vs, charging is completed, and the first trickle current flows. As described above, by using the embodiment according to the present invention, the battery voltage is determined, so that even if the battery becomes inactive due to long-term storage or the like and the battery temperature rises greatly, the battery is fully charged without terminating charging in the middle of charging. It becomes possible to lead to charging.

Next, in the same manner as in FIG. 3, according to the first embodiment, the battery voltage, charging current, and battery temperature when charging a battery whose battery temperature has increased due to long-term storage or the like with a high outside air temperature are shown in FIG. Although shown, FIG. 4 demonstrates the case where the battery voltage Vb does not raise more than the threshold value Vs of battery voltage determination. Each symbol is the same as in FIGS. After the start of charging, since the battery temperature rises greatly and the outside air temperature is high, the battery temperature Tb reaches the charging suspension temperature Ts1 at an early stage, the charging current Ich is turned off, and the charging suspension state is entered. Thereafter, when the battery temperature Tb falls and reaches the charge recovery temperature Ts2, the charging current is turned on again and the charging is continued. Then, the battery temperature Tb rises and reaches the charging suspension temperature Ts1 again. In the first embodiment, since the battery voltage is determined when the battery temperature reaches the charging suspension temperature Ts1 for the second time, the battery voltage is determined at the point A in FIG. It is compared with the threshold value Vs. As a result, since the battery voltage Vb is less than the threshold value Vs, it is not determined that the battery is fully charged. When the battery temperature Tb falls and reaches the charge recovery temperature Ts2, the charging current is turned on again and charging is continued. Thereafter, charging and resting are repeated in the same manner, and after reaching the charging suspension temperature Ts1 for the second time in each repetition, battery voltage determination is performed at points B, C, and D in the figure. Even at point B, which is the second battery voltage determination, the battery voltage Vb is less than the threshold value Vs, so that charging is continued thereafter. The battery voltage Vb is less than the threshold value Vs at the third point C as the battery voltage determination, and the charging is continued thereafter. The battery voltage Vb is less than the threshold value Vs at the point D, which is the fourth battery voltage determination, but in the first embodiment, the battery voltage Vb is less than the threshold value Vs in the fourth battery voltage determination. Since the charging is completed, the process proceeds to the charging completion at the point D, and thereafter, the second trickle current set larger than the first trickle current is supplied. As a result, the charging time becomes abnormally long and the user is not worried, and the shortage of charging can be compensated by a large second trickle current.

  FIG. 5 is a flowchart of charging control according to the first embodiment. In the flowchart of FIG. 5, the charging suspension temperature Ts1 is set to 60 ° C., and the charging return temperature Ts2 is set to 47 ° C. Further, the fact that the battery temperature Tb reaches the charging suspension temperature Ts1 is described as temperature protection.

  The battery voltage determination based on the comparison with the threshold value Vs is not limited to the charger for the nickel metal hydride storage battery, but can be used for other rechargeable batteries, for example, lithium ion battery chargers.

  The present invention ensures that the battery is fully charged even when it is charged in a state where the temperature of the outside air is high due to the increase in capacity in recent years due to the fact that the battery temperature rise during charging is large due to long-term storage or the like. Therefore, this technique is particularly useful for quick charging of nickel metal hydride storage batteries.

Circuit block diagram of Embodiment 1 of the present invention Relationship diagram of battery temperature, battery voltage, and charging current when charging a normal battery according to the first embodiment According to the first embodiment, when charging a battery that has become inactive due to long-term storage or the like and the battery temperature increase has increased, the battery temperature, battery voltage, battery voltage when the battery voltage Vb rises above the threshold value Vs for battery voltage determination, Relationship diagram of charging current Relationship between battery temperature, battery voltage, and charging current when battery voltage Vb does not rise above battery voltage determination threshold Vs when the battery is charged Charging control flowchart of the first embodiment Relationship between battery temperature, battery voltage, and charging current when charging a battery that has become inactive due to long-term storage, etc., due to long-term storage, etc.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply part 2 Current control part 3 Output switch 4 Battery voltage detection part 5 Battery temperature detection part 6 Charge control part Vb Battery voltage Ich Charging current Tb Battery temperature Ts1 Charging suspension temperature Ts2 Charge return temperature Vs Battery voltage determination threshold value Tb1 Battery temperature Tb2 Battery temperature Ta Outside air temperature Td Temperature difference between battery temperature and outside air temperature

Claims (3)

A power supply for supplying charging current;
A current control unit for controlling the charging current;
An output switch for turning on and off the charging current;
A battery voltage detector for detecting the battery voltage;
A battery temperature detector for detecting the battery temperature;
A charge control unit that performs main control of charge,
When repeating the phenomenon that after the battery starts charging, the battery temperature rises and reaches a predetermined charging suspension temperature, and then stops charging, and then continues charging when the battery temperature decreases and reaches a predetermined charging recovery temperature. The battery voltage is determined after the number of times the battery temperature reaches the predetermined charging suspension temperature reaches the first specified number of times, and the battery voltage detected by the battery voltage detection unit is equal to or higher than a predetermined threshold value. Is a fully charged battery, and when the battery voltage is lower than a predetermined threshold value, the battery temperature is lowered to a predetermined charging return temperature, and then the charging is continued again.   After the start of charging, after the battery temperature rises and reaches the predetermined charging suspension temperature reaches the first specified number of times, the battery voltage is determined, and when the detected battery voltage is less than the predetermined threshold After the battery temperature falls and reaches a predetermined charging return temperature, charging is continued, and then the battery temperature rises to reach the first specified number of times when the battery temperature rises and reaches the predetermined charging suspension temperature. When the phenomenon of transition is repeated, when the transition to the battery voltage determination reaches the second specified number of times, the charging is completed even if the detected battery voltage is less than a predetermined threshold value. The charger according to claim 1.   After the start of charging, when the battery voltage rises above the predetermined threshold in the battery voltage determination after the battery temperature rises and reaches the specified charging suspension temperature, the battery is charged as a full charge. And the first trickle current is applied, and the battery voltage is less than the predetermined threshold value, but the charging is completed because the transition to the battery voltage determination has reached the second specified number of times. The charger according to claim 2, wherein a second trickle current set to a current value larger than the trickle current is allowed to flow.

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