JP3042200B2 - Battery charger - Google Patents

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 a secondary battery (hereinafter referred to as a battery) such as a nickel-cadmium battery.

[0002]

2. Description of the Related Art In a charging apparatus for charging a battery with a DC power supply having a smoothing capacitor on an output side, there is a method of monitoring the terminal voltage of the smoothing capacitor to determine the presence or absence of the battery.

[0003]

THE INVENTION It is an object and you'll solve] removed from the charging device the battery was fully charged, if I charge the following battery Utosuru, it is necessary to fully charge the waiting time. That is, FIG.
As shown in FIG. 3, the charge of the smoothing capacitor is discharged based on the time constant of the capacity of the smoothing capacitor and the load resistance connected in parallel with the smoothing capacitor, and the voltage of the smoothing capacitor is changed to the battery at the point of FIG. It takes time t _B to be reduced to the presence or absence discrimination value Vth. It should be noted that the battery presence / absence determination value Vth is set to a sufficient value in consideration of variations in the battery itself, effects of temperature, and the like. Since the charging is not performed even if the next battery is connected until the time t _B has elapsed, it is necessary to connect the battery after the time t _{B has} elapsed.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art and detect the removal of a battery after charging is completed.
To reduce the charging standby time and continuously charge the next battery.
To improve the operating rate of the charging device .

[0005]

An object of the present invention is to provide a method for controlling a battery after charging is completed.
Flat terminal voltage synovial capacitor change rate i.e. the rate of descent is achieved by determining that the removal of the battery when the predetermined value or more has been performed.

[0006]

SUMMARY OF] According to the thus constructed charging apparatus as described above, it becomes possible to charge the continuous following of the battery I <br/> Do so as to detect rapidly the removal of the battery after completion of charging.

[0007]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1 is an AC power supply, 2 is a battery set composed of a plurality of rechargeable batteries, 3 is a current detecting means for detecting a charging current flowing through the battery set 2, 4 and 5 are signal transmitting means including a photocoupler, and 6 is a discharging means. A resistor 10 is a full-wave rectifier circuit 11, a smoothing capacitor 12, a high-frequency transformer 13, and a MOSFET 1.
4. DC generating means comprising a PWM control IC 15, diodes 16, 17, a choke coil 18, and a smoothing capacitor 19. PWM control IC 15 is MOSFET 14
Is a switching power supply IC that adjusts the output voltage by changing the drive pulse width of the switching power supply. Reference numeral 20 denotes voltage detecting means composed of resistors 21 and 22 for detecting the terminal voltage of the battery set 2 by dividing the voltage. After the battery set 2 is taken out, the terminal voltage of the smoothing capacitor 19 is detected. 30 is a CPU 31, RO
M32, RAM33, timer 34, A / D converter 3
5, a microcomputer comprising an output port 36, a reset input port 37, and the like. Reference numeral 40 denotes amplifying means including operational amplifiers 41 and 42 and resistors 43 to 46. Reference numeral 50 denotes a constant voltage power supply including a power transformer 51, a full-wave rectifier circuit 52, a capacitor 53, a three-terminal voltage regulator 54, and a reset IC 55, and serves as a power supply for the microcomputer 30, the amplifying means 40, and the like. The reset IC 55 outputs a reset signal to the reset input port 37 to bring the microcomputer 30 into an initial state.

Next, the operation will be described with reference to the circuit diagram of FIG. 1 and the flowchart of FIG. When the power is turned on,
The microcomputer 30 determines the connection of the battery set 2, that is, the presence or absence of the battery set 2. That is, the microcomputer 30 determines whether the voltage detecting means 2
0, it is monitored that the voltage Vc across the smoothing capacitor 19 becomes larger than the battery presence / absence determination value Vth (step 101). When the battery set 2 is connected, the voltage Vc across the smoothing capacitor 19 immediately rises to the battery voltage.
The microcomputer 30 determines the battery connection based on the signal of the voltage detecting means 20, sends a charging start signal from the output port 36 to the PWM control IC 15 via the signal transmitting means 4, and starts charging (step 102). At the start of charging, battery set 2
Is detected by the current detecting means 3, this value is amplified by the operational amplifier 41, the difference from the value Vref corresponding to the set charging current value is amplified by the operational amplifier 42, and Feedback is applied to the PWM control IC 15. That is, when the charging current is large, the pulse width is narrowed, and when the charging current is large, the pulse width is widened, and a pulse proportional to the pulse width is given to the high-frequency transformer 13, and the diodes 16 and 17, the choke coil 18, and the smoothing capacitor 19 To keep the charging current constant. That is, the current detection means 3, the amplification means 40, the signal transmission means 5, and the DC generation means 1
The constant current control for controlling the charging current to a constant value via 0 is performed.

Next, full charge detection is performed (step 10).
3). As the full charge detection method, there are a battery voltage detection method for detecting a battery voltage at the end of charging, a −ΔV detection method for detecting a drop ΔV of the battery voltage at the end of charging, and the like. When full charge is detected, the microcomputer 30 sends a charge stop signal to the PWM control IC 15 from the output port 36 via the signal transmission means 4 to stop charging (step 104). Next, it is determined that the battery set 2 is taken out. That is, the microcomputer 3
0 is applied to the smoothing capacitor 19 via the voltage detecting means 20.
(Step 105) is monitored for the change in the voltage Vc between the two terminals to become larger than the predetermined value K (point A in FIG. 3). When the battery set 2 is taken out, the charge of the smoothing capacitor 19 is discharged through the discharging resistor 6 and the voltage detecting means 20. FIG.
As shown in (2), when it is determined that there is no battery set 2 after a very short section t _G after the removal of the battery, the process returns to step 101 and waits for charging the next battery set 2.

As described above, the embodiment of the present invention utilizes the characteristic that the smoothing capacitor terminal voltage Vc is constant when the battery set 2 is connected, and gradually decreases when the battery set 2 is removed. In this case, the presence or absence of the battery set 2 is detected, so that it is possible to detect the battery set 2 quickly even after the completion of charging, and it is possible to charge a large number of battery sets 2 almost continuously. The efficiency of the device can be improved.

[0011]

As described above, according to the present invention, battery removal can be determined in a short time, so that batteries can be charged one after another without worrying about waiting time. this
As a result, the operating rate of the charging device can be improved, and the battery can be charged efficiently
become able to.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing one embodiment of the present invention.

FIG. 3 is an operation curve showing a temporal change of a terminal voltage of a smoothing capacitor.

[Description of Signs] Reference numeral 10 denotes a DC generator, reference numeral 20 denotes a voltage detector, and reference numeral 30 denotes a microcomputer including a charge controller.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J ⁷ /00-7/10 H01M 10/44-10/46 G01R 31/36

Claims (1)

(57) [Claims] 1. A battery charging device for charging a battery by an output of a DC generator having a smoothing capacitor on an output side, detecting a full charge, stopping an output of the DC generator, and stopping charging. A voltage detecting means for detecting a terminal voltage of the smoothing capacitor, and a rate of drop of the terminal voltage detected by the voltage detecting means.
A charge control method that determines that the battery has been removed
Steps so that battery removal can be detected quickly.
Charging device of the battery, characterized in that the.