JP2008086106A - Charger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a peak timer from counting up to terminate charging when the charging capacity is not fully used in a charger for hydrogen batteries. <P>SOLUTION: The charger is so constructed that when a battery is charged to a preset capacity and a certain voltage is held, a peak timer starts counting. This prevents the following phenomenon: the peak timer is actuated during charging and charging is terminated when the battery capacity is not fully used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charger for charging a secondary battery.

In recent years, the market for portable electronic devices such as portable audio and digital still cameras has grown rapidly. Among them, rechargeable batteries for supplying power to portable electronic devices play an important role.

  Charger for rechargeable battery detects secondary battery charge, especially when charging a hydrogen battery, the phenomenon that the battery voltage that has risen falls at the end of charge (-ΔV) is detected. And control to complete charging. Further, as protection in the case of not detecting -ΔV, a charge protection timer (peak timer) that completes charging is set if the battery voltage does not change for a certain period of time. Further, trickle charging is performed after charging is completed as described above in order to increase the charging capacity.

In the charge control method, for example, Patent Document 1 has been proposed in the case of controlling the charge with a microcomputer. In this document, the temperature is detected by a microcomputer, and when the temperature becomes high, the charging is switched from rapid charging to trickle charging, and charging is completed by counting up a timer.
Japanese Patent Laid-Open No. 5-328629

  However, when charging a battery such as a hydrogen-based battery that has deteriorated due to being left in a high temperature environment for a long period of time, the battery voltage is unlikely to rise as shown in FIG. The battery voltage may hold a constant value. In this case, although the charging capacity is small, the peak timer of the charger operates and completes charging, so that it cannot be fully charged.

  In the configuration of Patent Document 1, when charging is performed in a high temperature environment or the like, switching to trickle charging is performed at an early stage of charging, and a sufficient charging capacity cannot be obtained. At this time, there may be a problem that the device cannot be used for a sufficient time.

  The present invention solves such problems, and an object of the present invention is to provide a charger that fully charges a secondary battery, particularly a hydrogen battery.

  In order to solve the above-mentioned problem, it becomes possible by improving the charging control especially in the middle of charging. The charge control method of the present invention estimates the battery capacity from the battery voltage, and when the battery voltage becomes equal to or higher than a certain battery capacity and the battery voltage becomes constant, the charge protection that completes charging if the battery voltage does not change for a certain time The timer (peak timer) starts counting. When the timer counts up, charging is completed. However, if the battery voltage changes, the peak timer count is reset. Thereby, it is possible to prevent the peak timer from counting up and completing the charging even when the battery voltage becomes constant during the charging and the charging capacity is not sufficient.

According to the present invention, it is possible to prevent the charging from being completed in spite of insufficient charging of a secondary battery, particularly a long-term battery of a hydrogen-based battery.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below specifically describes the present invention, and the present invention does not specify the charger as follows.

(Embodiment 1)
In the block diagram of FIG. 1, a charging power supply unit 1 that supplies a charging current to the secondary battery, the charging current value is switched by a pulse depending on the battery charging state, and when the secondary battery 4 is fully charged, The charge control switch 2 for stopping the supply of the charge current to the battery 4, a signal for turning on / off the charge control switch 2 in order to switch the pulse width of the charge current to the charge control switch 2, It has the charge control part 3 which detects a voltage. The charge control unit 3 detects the voltage of the secondary battery 4 being charged, estimates the battery charge capacity from the battery voltage, and peaks until the charge capacity reaches a certain value or more even if the battery voltage remains constant. Does not start the timer count. If the charge capacity becomes equal to or greater than a certain value and the voltage maintains a certain value, the charge control unit starts counting the peak timer. When the peak timer counts up, charging is completed, and the charging control switch is turned off to complete charging. FIG. 3 is a flowchart showing a series of flow of the charging control.

  The charge control unit detects the battery voltage even while the peak timer is counting, and the charge control switch when the secondary battery 4 is fully charged (for example, -ΔV is detected and other charge protection functions are activated). It also has a function of turning off and completing charging. Moreover, the charger which has this invention can also charge a some secondary battery simultaneously. A charge control switch is provided for each secondary battery so that a plurality of battery voltages can be detected, and the charge control unit 3 sequentially switches the charge control switch 2 to detect the battery voltage and count the peak timer for each secondary battery. You can also start.

  The batteries were charged by the charge control method of the embodiment of the present invention (FIG. 3) and the conventional charge control method (FIG. 4), and the discharge capacities were compared. In the present embodiment, the peak timer starts counting when the battery capacity becomes 70% or more and the battery voltage becomes constant. In the conventional charge control method, as shown in FIG. 6, the peak timer operates during the charge, and the charge is completed although the battery is not fully charged. However, in the charge control method of the present invention, the battery voltage rises in the middle of charging, but since the peak timer is not operating, charging is continued without completion of charging as shown in FIG. When the battery capacity becomes constant at the end of charging when the charging capacity is 70% or more and charging is sufficient, the peak timer is counted and the charging is completed. The discharge capacity ratio between the battery charged according to the present invention and the battery charged according to the conventional charge control method was 48% in the conventional method, but 80% in the method of the present invention. . Here, the discharge capacity ratio indicates (discharge capacity) / (nominal capacity of the battery). As can be seen from the above results, the battery charged by the charge control method of the present invention has a larger capacity.

  According to the present invention, the battery can be charged to almost full charge regardless of the state of the battery, in particular, a battery left for a long time and a new battery. And the device cannot be used for a sufficient amount of time.

Block diagram of a charger according to an embodiment of the present invention Diagram showing the charging curve of a long-term battery Charge control flowchart of an embodiment of the present invention Conventional charging control flowchart The figure which shows the charge curve by the charge control of this invention Diagram showing the charging curve by conventional charging control

Explanation of symbols

1 Charging Power Supply Unit 2 Charging Control Switch 3 Charging Control Unit 4 Secondary Battery

Claims (2)

  In a charger having a charge control unit for charging a hydrogen-based battery, a charge protection timer is operated to complete charging if the battery voltage does not change over a specified time after the battery capacity exceeds a certain reference value. A charger characterized by.   In the above charger, the battery voltage is detected from the charge control unit during charging, the battery capacity is estimated from the battery voltage, and if the battery voltage does not change for a certain time after the battery capacity reaches the reference value or more, the battery is charged. 2. The charger according to claim 1, wherein a charge protection timer for completing the operation is operated.

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