JPH07143687A - Battery charger - Google Patents

Abstract

PURPOSE:To provide a battery charger which can shorten the charging time of a battery up to its full charge with electricity and, at the same time, can prevent the overcharging of the battery. CONSTITUTION:A battery 5 is charged with an electric current supplied from an external power supply 1 and PWM-controlled by means of a charging control section 3. A charging amount calculating section 8 calculates the charging amount of the battery 5 by detecting the charging time since the charging of the battery 5 is started. A discharging amount calculating section 11 calculates the discharging amount from the battery 5 by detecting the discharging time since the battery 5 starts discharge to a load 2. Then a residual capacity calculating section 12 calculates the residual capacity of the battery 5 from the charging amount and discharging amount. In addition, a charging control section 3 compares the residual capacity of the battery 5 with a prescribed value and, when the residual capacity is larger than the prescribed value, charges the battery 5 with electricity in a trickle charging mode. When the residual capacity is smaller than the prescribed value, on the contrary, the section 3 quickly charges the battery 5 in a quick charging mode.

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 storage battery that supplies power to a load with a charging current from an external power supply.

[0002]

2. Description of the Related Art Conventionally, as a charging device as described above, there is one as shown in FIG. The charging device shown in FIG. 6 performs full-wave rectification on an alternating current supplied from an external power supply 1 such as a commercial power supply by a diode bridge DB, smoothes it with a capacitor C ₂ via a diode D ₃ , and supplies the smoothed current to a load 2. There is. Further, the output-side terminal of the diode bridge DB is connected to the capacitor C ₃ and the Zener diode ZD through the resistor R _2, a diode bridge DB
Output is the above capacitor C ₃ and Zener diode ZD
The voltage is converted to a constant voltage and is supplied to the charging control unit 13.

The charging control unit 13 has its voltage output terminal V_O
Transistor Q₂The gate of the
Dista Q₂ON / OFF control. In addition,
Current output terminal I of power control unit 13_OHas a resistance R₃And photo
The phototransistor Q, which is the secondary side of the coupler PC₃Average
Column circuit and resistor R_FourAre connected in series and output current
Terminal I_OSince the potential of is kept constant, the current output terminal
I_OOutput current from the above two resistors R₃, R_FourBy
Will be decided. That is, the phototransistor Q ₃Is off
When, the current output terminal I_oFrom two resistors R₃，
R_FourAn output current determined by
Q₃Is on, one resistor R_FourOutput determined only by
Force current flows, and phototransistor Q₃When is on
Output current is phototransistor Q₃Flow when is off
Output current is larger than the output current. Furthermore, the charging control unit 1
3 voltage output terminal V_ODuty ratio of output pulse from
Is the current output terminal I_oThe larger the output current from, the smaller
It is supposed to be.

Further, the transistor Q₂Drain and die
Aether D₃The primary side of the transformer T is connected between
The charge control unit 13 turns on the transistor Q.₂PWM control
The transistor Q₂When is on
AC current supplied from the external power supply 1 to the primary side of the
Flowing. This AC current is applied to the secondary side of the transformer T.
Pressure is generated, diode D_FourAnd inductor L₁Through
Capacitor C_FourIs charged. Next, transistor Q₂
Turns off, inductor L₁The magnetic energy stored in
The energy is released and the capacitor C_FourDC voltage across both ends of
You can get it. And the capacitor C_FourTo
Is a diode D for backflow prevention_FiveAnd charging current limit resistor
Anti-R_FiveThe storage battery 5 is connected in parallel via the
Densa C _FiveOf the storage battery 5 by the DC voltage generated at both ends of
The charging current is supplied.

On the other hand, when the external power supply 1 is removed, the battery voltage of the storage battery 5 is boosted by the boosting circuit 9 to a voltage required to drive the load 2, and power is supplied from the storage battery 5 to the load 2. . Here, the storage battery 5 is charged rapidly by a relatively large charging current in order to fully charge the storage battery 5 in a short time. However, when the storage battery 5 is overcharged, gas is generated inside the storage battery 5 and the battery life is shortened. Therefore, in order to prevent such overcharge, it is common to provide a function for preventing overcharge. Is done in a regular manner. Therefore, also in the charging device shown in FIG. 6, when the storage battery 5 is fully charged, switching to trickle charging in which the storage battery 5 is charged with a small current that supplements the self-discharging current of the storage battery 5 prevents overcharging of the storage battery 5. is doing.

In the charging device shown in FIG.
Switching of the current is performed by the timer operation of the timer unit 14.
Connected to the secondary side of the transformer T in parallel with the storage battery 5.
In the external power supply detection unit 6 that is being operated, the charging device is supplied with external power.
Detects whether the source 1 is connected or not, and connects the external power source 1
If it continues, the detection signal is sent to the timer unit 14.
The timer unit 14 receives the detection signal and charges the storage battery 5.
The elapsed time (charging time) from the start of charging is measured and the product
I am calculating. Then, the storage battery 5 is continuously charged.
The total charging time, regardless of whether it is performed continuously or discontinuously.
When the time reaches a predetermined time, the timer unit 14 sends a control signal.
Send transistor Q_FourTurn on and thereby
Current flows through the light emitting diode of the coupler PC, and
Dista Q ₃Turns on. As a result, the charge controller 13
Output current terminal I_oCurrent of the charging controller 13 increases
The duty ratio of the output pulse of the
Mode switches to trickle charge mode and the storage battery 5 is charged.
The electric current is reduced.

Further, the timer unit 14 detects the battery voltage of the storage battery 5 by dividing the voltage of the storage battery 5 by the resistors R ₆ and R _7.
When the battery voltage of the storage battery 5 falls below a predetermined value due to power supply from the storage battery 5 to the load 2 or self-discharge of the storage battery 5 when is not connected, the timer unit 14 resets the integrated value of the charging time to zero. At the same time, the charge mode is switched from the trickle charge mode to the quick charge mode.

[0008]

In the configuration of the above-mentioned conventional example, when the battery voltage of the storage battery 5 drops below a predetermined value, rapid charging is performed until the integrated value of the charging time in the timer section 14 reaches a predetermined value, When the integrated value of the charging time reaches the predetermined value, the charging mode is switched to the trickle charging mode, and it is possible to prevent the storage battery 5 from being overcharged.

By the way, the predetermined value set in the timer section 14 is determined by the battery capacity of the storage battery 5 and the charging current in the quick charging mode, and the charging amount obtained as the product of the normal charging current and the charging time. Is set to a value about 1.5 times the battery capacity C _ap of the storage battery 5. Therefore, if the charging current in the rapid charging mode is Ic, the charging time t _c in the rapid charging mode set by the timer unit 14 is t _c = 1.5 × C _ap
/ Ic.

The charging time t _{c in the} above equation indicates the full charging time required for the storage battery 5 to be fully charged from an empty state, and is charged again immediately after switching from the trickle charging mode to the quick charging mode. When it is performed, the storage battery 5 is not completely discharged until it is empty, but the quick charging is performed until the timer unit 14 measures the charging time t _c shown by the above formula. Therefore, after the storage battery 5 is fully charged. However, there is a problem that the storage battery 5 is overcharged by being charged with a relatively large charging current in the rapid charging mode.

Here, the charging mode is switched between trickle charging and rapid charging by generally detecting the battery voltage of the storage battery 5 and estimating the remaining capacity of the storage battery 5 from the battery voltage to switch the charging mode. Has been adopted by. FIG. 7 shows the relationship between the remaining capacity of the storage battery 5 based on the charging time and the discharging time due to the power supply to the load 2. When the storage battery 5 is charged and discharged at a constant current, the remaining capacity of the storage battery 5 and the charging time and the discharging time are in a proportional relationship, and as shown in FIG. 7, the state of full charge (the remaining capacity is C _ap from the battery 5 in), when there was only power supplied to the load 2 time t _a, the remaining capacity of the storage battery 5 at that time becomes C _1. Time can be further power supply to the load 2 therefrom when the (storage battery remaining capacity of 5 at that time) and t _d, the charging time required to charge from that point to the opposite until the battery 5 is fully charged the t _c (see FIG. 7). Here, as described above, there is a relationship of t _c = 1.5 × t _d between the time t _c and the time t _d .

Therefore, if the level of the remaining capacity of the storage battery 5 for switching the charging mode is set to a low level, the charging mode becomes the trickle charging mode even if the remaining capacity of the storage battery 5 is very small, and the storage battery 5 is fully charged. Since it cannot be charged up to charging, it is normally set to switch with the remaining capacity C _ap2 obtained by the product of the time t _{b for} which the load 2 can be driven without trouble and the discharge current I _d2 . (See FIG. 8). Therefore, immediately after the charge mode is switched from trickle charge to quick charge, the storage battery
When the charge of is performed, in order, as shown in FIG. 8, the quick charge is always constant time t _k regardless of the remaining capacity to counting in the timer unit 14 is performed, the storage battery 5
Are overcharged, and there is a problem that the storage battery 5 deteriorates and the life is shortened.

The present invention has been made in view of the above problems, and when the remaining capacity of the storage battery is small, quick charging is performed to recover the storage battery in a short time.
An object of the present invention is to provide a charging device capable of preventing overcharge of a storage battery.

[0014]

In order to achieve the above object, a storage battery for supplying power to a load is provided.
An external power supply detection unit that detects the external power supply connected to the load, a charging control unit that controls the charging current from the external power supply to charge the storage battery only when the external power supply detection unit detects the external power supply, and a storage battery A charge amount calculation unit that calculates the charge amount of the storage battery by the charge time detected by detecting the charge time, and a discharge amount calculation unit that calculates the discharge amount of the storage battery by the discharge time detected by detecting the discharge time of the storage battery, The remaining capacity of the storage battery calculated by the remaining capacity calculation unit is provided with a remaining capacity calculation unit that calculates the remaining capacity of the storage battery from the charge amount calculated by the charge amount calculation unit and the discharge amount calculated by the discharge amount calculation unit. The charging control unit responds to the trickle charge mode in which the charging mode of the storage battery is charged with a small current close to the self-discharge current of the storage battery and the rapid charging mode in which the charging mode is charged with a current larger than the above small current. Wherein the switch to and.

According to a second aspect of the present invention, in the first aspect of the present invention, the remaining capacity of the storage battery in a state where the fully charged storage battery is supplying power to the load is compared with a predetermined threshold value,
If the remaining capacity is not smaller than the threshold value, the remaining capacity comparison unit for prohibiting switching of the charging mode is provided. According to a third aspect of the present invention, in the first aspect of the invention, the charging control unit controls the charging current so that the charging current is proportional to the difference between the remaining capacity of the storage battery and the battery capacity at the start of charging in the quick charging mode. Is characterized by.

[0016]

According to the structure of the invention of claim 1, the storage battery for supplying power to the load, the external power source detecting unit for detecting the external power source connected to the load, and the external power source only when the external power source is detected by the external power source detecting unit. A charge control unit that controls the charging current from the power supply to charge the storage battery, a charge amount calculation unit that calculates the charge amount of the storage battery by detecting the charging time of the storage battery, and a discharge time of the storage battery The remaining capacity of the storage battery is calculated from the discharge amount calculation unit that calculates the discharge amount of the storage battery based on the detected discharge time, and the charge amount calculated by the charge amount calculation unit and the discharge amount calculated by the discharge amount calculation unit. And a charge control unit that charges the storage battery charging mode with a small current close to the self-discharge current of the storage battery according to the remaining capacity of the storage battery calculated by the remaining capacity calculation unit. Since than the charging mode and the small current switched between quick charging mode for charging with a large current,
When the remaining capacity of the storage battery is less than the battery capacity of the storage battery, the charging time until the storage battery is fully charged by charging in the quick charge mode is shortened, and the remaining capacity of the storage battery is in a fully charged state close to the battery capacity of the storage battery. At times, the charge mode can be switched to the trickle charge mode to prevent overcharge of the storage battery.

In the configuration of the invention of claim 2, the remaining capacity of the storage battery in a state where the fully charged storage battery is supplying power to the load is compared with a predetermined threshold value, and the remaining capacity must be smaller than the threshold value. For example, since the remaining capacity comparison unit that prohibits switching of the charging mode is provided, the remaining capacity of the storage battery is below the threshold even when incomplete discharge and charging are repeated such that the remaining capacity of the storage battery is sufficient. Unless it is smaller, the trickle charge mode is not switched to the quick charge mode, so that the load on the storage battery can be reduced.

According to the third aspect of the invention, the charging control unit controls the charging current so that the charging current is proportional to the difference between the remaining capacity of the storage battery and the battery capacity at the start of charging in the quick charging mode. When the remaining capacity is small, the charging time is shortened by charging with a large charging current, and when the remaining capacity is large, the burden on the storage battery can be reduced by charging with a small charging current.

[0019]

EXAMPLE 1 FIG. 1 shows a schematic circuit diagram of this example. As shown in FIG. 1, a DC external power supply 1 is connected to the external power supply terminals 1a, 1a of the charging device of this embodiment. Further, the load 2 is connected to the external power supply terminal 1a via the diode D ₁ for preventing backflow, and power is supplied from the external power supply 1 to the load 2. Further, the external power source terminal 1a is the emitter of the transistor Q ₁ is connected, is connected to the charging control unit 3 to the base of the transistor Q _1, the transistor Q ₁ is controlled PWM (Pulse Width Modulation) by the charge control unit 3 It is. The transistor Q ₁ constitutes a step-down chopper circuit 4 together with the diode D ₂ , the inductor L and the capacitor C ₁ , and the charge control unit 3
Performs PWM control of the transistor Q ₁ to reduce the power supply voltage of the external power supply 1 by the step-down chopper circuit 4 to charge the storage battery 5.

A resistor R for detecting a charging current is connected in series with the storage battery 5.
₁ is connected, the magnitude of the charging current detected by the resistor R ₁ is input to the charging control unit 3, and the charging control unit 3 performs PWM control so that the charging current becomes substantially constant. . By the way, the load 2 in this embodiment can be approximated by a resistance component, and therefore, the external power supply 1
If the power supply voltage of is approximately constant, a constant current will flow through the load 2, and even when power is supplied from the storage battery 5 to the load 2, the storage battery 5 can be regarded as a substantially constant voltage source, so the storage battery 5 is completely A substantially constant discharge current flows until the battery is discharged, and the discharge characteristic of the storage battery 5 exhibits the characteristic shown in FIG.

An external power source detection unit 6 is connected in parallel with the storage battery 5 on the output side of the step-down chopper circuit 4,
It is detected whether or not the external power supply 1 is connected to the external power supply terminals 1a, 1a, and the detected output is sent to the boost control unit 7 and the charge amount calculation unit 8. External power supply 1 based on the above detection output
Is connected, the step-up control unit 7 operates the step-up circuit 9
Is stopped and the power supply from the storage battery 5 to the load 2 is cut off. On the other hand, the charge amount calculation unit 8 detects the charge time after the charging of the storage battery 5 is started when the external power supply 1 is connected, and calculates the charge amount from the product of the detected charge time and the charge current. is doing.

An over-discharge prevention circuit 10 is connected in parallel to the storage battery 5, and this over-discharge prevention circuit 10 detects the battery voltage of the storage battery 5 and if the battery voltage of the storage battery 5 drops below a predetermined value. A stop signal is sent to the boost controller 7. On the other hand, the boost control unit 7 receives the stop signal and stops the operation of the boost circuit 9 to cut off the power supply from the storage battery 5 to the load 2 to prevent the storage battery 5 from being over-discharged.
In the above case, the over-discharge prevention circuit 10 sends a reset signal to the charge amount calculation unit 8 and resets the charge time of the charge amount calculation unit 8 according to the reset signal.

Further, the booster control unit 7 includes an external power source detection unit 6
Based on the detection signal from the overdischarge prevention circuit 10 and the state of the switch SW connected to the boost control unit 7, the external power supply 1 is not connected to the external power supply terminals 1a and 1a,
Moreover, the booster circuit 9 is operated to boost the power supply from the storage battery 5 to drive the load 2 only when the overdischarge prevention circuit 10 is not operating and the switch SW is ON. Further, during operation of the booster circuit 9, the booster control unit 7
The discharge amount calculation unit 11 is operating according to the control signal from the storage battery, and the discharge amount calculation unit 11 detects the discharge time after the discharge of the storage battery 5 and calculates the storage battery from the product of the discharge time and the discharge current. The amount of discharge of No. 5 is calculated.

Further, data of the charge amount of the storage battery 5 calculated by the charge amount calculation unit 8 and the discharge amount of the storage battery 5 calculated by the discharge amount calculation unit 11 is used as the remaining capacity calculation unit 12.
The remaining capacity of the storage battery 5 at that time is calculated by the remaining capacity calculator 12 based on the charge amount and the discharge amount. Then, the calculated remaining capacity data is sent to the charging control unit 3, and the charging control unit 3 sets the transistor Q ₁ of the step-down chopper circuit 4 to P in accordance with the value of the remaining capacity.
By changing the current value of the charging current by WM control,
The charge mode for charging the storage battery 5 is switched between the trickle charge mode and the quick charge mode.

The switching of the charging mode by the charging control unit 3 will be described in more detail below. If the battery capacity of the storage battery 5 is C _ap , the charging current in the quick charge mode is Ic, and the discharge current when the power is supplied from the storage battery 5 to the load 2 is Id, the remaining capacity of the storage battery 5 is almost zero. Full charge time t until the storage battery 5 is fully charged
The relationship between _max and the battery capacity C _ap is expressed by the following equation.

The _{t max = 1.5 × C ap /} Ic ··· ( Equation 1) Thus, the charge amount C _c of the battery 5 for any charge time _{t c, C c = Ic /} 1.5 × t c It can be calculated by (Equation 2). Conversely, the discharge amount C _d of the battery 5 for an arbitrary discharge time t _d can be calculated by _{C d = Id × t d ···} ( Equation 3). Therefore, when the charging time t _c is equal to the discharging time t _d , the above (formula 2)
From (Equation 3), C _d / C _c = 1.5 × Id / Ic (Equation 4), and the discharge amount C _d is 1.5 × Id / Ic of the charge amount C _c.
Doubled.

That is, the charging time t _c and the discharging time t _d
Is detected and the difference between the charge amount C _c and the discharge amount C _d is obtained, the remaining capacity of the storage battery 5 can be calculated, and the change in the remaining capacity of the storage battery 5 is estimated to fully charge the storage battery 5. The battery is charged in the quick charge mode until it reaches the end. In the present embodiment, when the over-discharge prevention circuit 10 operates, a reset signal is sent from the boost control unit 7 to the charge amount calculation unit 8 and the discharge amount calculation unit 11, and the charge amount calculation unit 8 and the discharge amount calculation unit 1
Since the integrated value of the charging time and the discharging time detected in 1 is reset, the overdischarge prevention circuit 10
It is possible to correct the estimated value of the remaining capacity of the storage battery 5 every time the is operated. Further, since the charging of the storage battery 5 and the supply of power from the storage battery 5 to the load 2 are not performed at the same time, the detection of the charging time by the charging amount calculation unit 8 and the detection of the discharging time by the discharging amount calculation unit 11 are performed respectively. It is performed by switching.

Now, the integrated value of the charging time and the discharging time after the start of charging is set to t _r, and the integrated value t _s after further charging for Δt time is t _s = t _r + Δt (equation 5) The relationship between the integrated value t _s and accumulated value t _r of the preceding after the discharge of Delta] t time is performed by (Equation _{1), t s = t r} -1.5 × Id / Ic × Δt ... (Equation 6) That is, the integrated value t _s becomes a value proportional to the remaining capacity of the storage battery 5. Therefore, when the integrated value t _s becomes equal to the full-charge time t _max required to fully charge the storage battery 5 from the empty state, it is estimated that the storage battery 5 is in the full-charged state, and the battery is charged at that time. The control unit 3 may switch the charging mode from the quick charging mode to the trickle charging mode. After that, in the trickle charge mode, the detection of the charging time and the discharging time in the charging amount calculating unit 8 and the discharging amount calculating unit 11 is stopped and the integrated value t _s is held as the full charging time t _max . From that state, power is supplied from the storage battery 5 to the load 2 and the storage battery 5
Even when the remaining capacity decreases, the remaining capacity is estimated as described above, and when the value of the remaining capacity becomes equal to or less than the predetermined value, the charging mode is switched from the trickle charging mode to the quick charging mode. That is, the charging current Ic is equal to the discharging current I
If it is equal to d, the charge amount and the discharge amount are represented by the charge time and the discharge time, respectively. Therefore, in the remaining capacity calculation unit 12, the integrated value t of the charge time and the discharge time is calculated.
_s is calculated and the remaining capacity of the storage battery 5 is estimated.

As described above, since the charging time for performing rapid charging is determined according to the remaining capacity of the storage battery 5, the storage battery 5
When the remaining capacity of the storage battery becomes low, the storage battery 5 can be fully charged in a short time by rapid charging, and the storage battery 5 can be prevented from being overcharged by performing excessive rapid charging. Further, the above operation will be described with reference to the flowchart shown in FIG. First. The state in which the storage battery 5 is fully discharged as an initial state, the accumulated value t _s of the charging time and discharging time of the residual capacity calculation unit 12 and t _s = 0 (S1).
Next, the external power supply detection unit 6 detects whether or not the external power supply 1 is connected (S2), and if the external power supply 1 is connected, the storage battery 5 is charged by the charging current from the external power supply 1 (S3 and S4). . During charging, the integrated value t _s of the remaining capacity calculator 12 and the full charge time t of the storage battery 5 in the charge controller 3
_max is compared (S5), and the integrated value t _s is the full charge time t
when less than _max perform quick charge the charging mode as the rapid charge mode (S6), to as t _s = t _s +1 adds 1 to the integrated value t _s (S7) again detecting the external power source 1 (S2) After returning, the above steps are repeated until the storage battery 5 is fully charged or the external power source 1 is removed (S2 to S7).

When the storage battery 5 is fully charged, that is, when the integrated value t _s is equal to or longer than the full charge time t _max , the charging control unit 3 switches the charging mode to the trickle charging mode (S8), and thereafter. External power supply 1 is removed and load 2
The charging in the trickle charge mode is continued until the discharge is performed (S2 to S8). On the other hand, when the external power supply 1 is not connected, the charging control unit 3 detects the battery voltage V _B of the storage battery 5 (S9) and compares it with the threshold voltage V _{1 for} starting the operation of the over-discharge prevention circuit 10. (S1
0), when the battery voltage V _B is equal to or lower than the threshold voltage V ₁ and the overdischarge prevention circuit 10 is operating, the state returns to the initial state (S
1). On the contrary, if the battery voltage V _B is higher than the threshold voltage V ₁ , the boost control unit 7 detects the state of the switch SW (S11), and if the switch SW is on, the boost control unit 7 causes the boost circuit. 9 is operated to discharge the storage battery 5 to the load 2 (S13), and the integrated value t _{s is changed} to t _s = t _s
The value is set to −1.5 × Id / Ic (S14), and the process returns to the detection of the presence or absence of the connection of the external power source 1 (S2). When the switch SW is off, the booster control unit 7 does not operate the booster circuit 9 and enters a standby state (S15), and again detects whether or not the external power supply 1 is connected (S2).

The circuit configuration of the charging circuit for charging the storage battery 5 and the circuit configuration of the booster circuit 9 for boosting the battery voltage of the storage battery 5 to supply power to the load 2 are not limited to those of this embodiment. Instead, the circuit configuration may be such that the charging time for charging the storage battery 5 and the discharging time for discharging the storage battery 5 can be detected. Further, in the present embodiment, the battery voltage of the storage battery 5 is boosted and supplied to the load 2 by the booster circuit 9, but the battery voltage of the storage battery 5 may be directly supplied to the load 2 without being boosted. Further, the load 2 is not limited to one, and may be one that supplies power to a plurality of loads.
The technical idea of the present invention can be applied as long as it can be charged and the power is supplied from the storage battery 5 to the load 2 except during charging. Then, in the present embodiment, the boosting control unit 7 stops the power supply from the storage battery 5 to the load 2 and resets the integrated value t _s in the remaining capacity calculation unit 12 to zero by the signal from the overdischarge prevention circuit 10. However, when the integrated value t _s becomes t _s = 0 without using the over-discharge prevention circuit 10, it is considered that the storage battery 5 is over-discharged, and the power supply from the storage battery 5 to the load 2 is stopped. You may

(Embodiment 2) Since the circuit configuration of this embodiment is the same as that of the first embodiment, the description of the circuit configuration will be omitted. In the present embodiment, when the storage battery 5 is once fully charged to the battery capacity C _ap of the storage battery 5 and the storage battery 5 is discharged from the fully charged state, the charge control unit 3 determines that the remaining capacity of the storage battery 5 is a predetermined value. Compared to a threshold,
If the remaining capacity is not smaller than the threshold value, the charge control unit 3
Does not switch the charging mode from trickle charging mode to fast charging mode. That is, in the present embodiment, the charge control unit 3 also serves as the remaining capacity comparing unit that prohibits switching of the charging mode in the above case.

That is, the charging control unit 3 switches the charging mode to have a hysteresis characteristic, and the integrated value t _s representing the time during which power can be continuously supplied from the storage battery 5 to the load 2 and the load If the integrated value t _s is not smaller than the threshold value t ₁ , charge is performed by comparing the threshold value t ₁ as a guaranteed time that can continuously drive the load 2 depending on the type of 2 By setting the mode to the trickle charge mode, it is possible to drive the load 2 as usual and reduce the load on the storage battery 5.

The actual operation of this embodiment will be described with reference to the flow chart shown in FIG. However, since the basic operation is the same as that of the first embodiment, the description of the common part will be omitted. That is, the operation of this embodiment is different from that of the first embodiment in that the storage battery 5 is connected to the load 2
Integrated value t _s If you are doing a discharge to the t _s = t _s -
After setting 1.5 × Id / Ic (S14), the integrated value t
The _s in the charge control unit 3 compared with the threshold value t ₁ (S14 '), when the integrated value t _s is greater than the threshold value t ₁ is returned to the detection of the external power source 1 (S2). On the other hand, when the integrated value t _s is the threshold value t ₁ or less, the variable X is set to X = 0.
(S16).

The external battery 1 is connected to the storage battery 5
Is charged, the integrated value t_sAnd storage
Full charge time t of battery 5_maxAnd are compared (S5), and integrated
Value t _sIs the full charge time t_maxCharge when smaller than
Whether or not the value of the variable X is zero in the control unit 3
If the variable X = 0, that is, the integrated value t_sGashiki
Value t₁In the following cases, charge mode is set to quick charge mode.
Quick charging is performed (S6). Conversely, when the variable X ≠ 0,
Switch the charging mode to the trickle charging mode (S
8), set the variable X to X = 1 (S8 '), and use the external power supply.
The operation of returning to the detection of 1 (S2) is performed.

(Third Embodiment) Since the circuit configuration of this embodiment is the same as that of the first embodiment, the description of the circuit configuration will be omitted. In the present embodiment, when the storage battery 5 is charged, the charging current is adjusted by the charging control unit 3 according to the remaining capacity of the storage battery 5 at that time, and the storage battery 5 at the time when charging of the storage battery 5 is started. Regardless of the remaining capacity of the storage battery 5, the storage battery 5 can be fully charged at a constant constant rapid charging time. That is, the difference between the full charge time t _max of the storage battery 5 and the integrated value t _s when the storage battery 5 starts to be charged is divided by the predetermined constant rapid charge t _c0 ((t _max − t
By controlling the charging current so that the storage battery 5 is rapidly charged by the charging current proportional to _s ) / t _c0 ), a large charging current can be supplied when the remaining capacity of the storage battery 5 is small. The load on the storage battery 5 can be reduced by shortening the charging time until full charge and reducing the charging current when the remaining capacity is large.

The above operation will be described with reference to the flow chart shown in FIG. 5. During charging, the charge controller 3 compares the integrated value t _s with the full charge time t _max (S5), and the integrated value t _s is compared with the full charge time t _max. When it is smaller than _max , the charging control unit 3 adjusts the charging current Ic so that the charging current Ic becomes a value shown by the following equation (S6 ′). Ic = k × (t _max −t _s ) / t _c0 where k is a constant. Then, the integrated value _{t s t s = t s +} k / Ic 1 × (t max -t s) / t c0 and set (S7 '), the integrated value t _s is fully charged time t
_The rapid charging is performed with the integrated value t _s , that is, the charging current according to the remaining capacity of the storage battery 5 until it becomes equal to or more than _max (S2
~ S7 '). Note that Ic ₁ is a reference charging current.

[0038]

According to the first aspect of the present invention, a storage battery for supplying power to a load, an external power source detecting unit for detecting an external power source connected to the load, and an external power source only when the external power source is detected by the external power source detecting unit. A charge control unit that controls the charging current from the power supply to charge the storage battery, a charge amount calculation unit that calculates the charge amount of the storage battery by detecting the charging time of the storage battery, and a discharge time of the storage battery The remaining capacity of the storage battery is calculated from the discharge amount calculation unit that calculates the discharge amount of the storage battery based on the detected discharge time, and the charge amount calculated by the charge amount calculation unit and the discharge amount calculated by the discharge amount calculation unit. A trickle that includes a remaining capacity calculation unit, and the charging control unit charges the storage battery charge mode with a small current close to the self-discharge current of the storage battery according to the remaining capacity of the storage battery calculated by the remaining capacity calculation unit. The charging time is until the battery is fully charged by charging in the quick charge mode when the remaining capacity of the storage battery is less than the battery capacity of the storage battery, as it switches between the charging mode and the quick charging mode in which the battery is charged with a current larger than the above small current. There is an effect that can be shortened. Also,
When the remaining capacity of the storage battery is in a fully charged state close to the battery capacity of the storage battery, there is an effect that the charging mode is switched to the trickle charge mode to prevent overcharging of the storage battery and the life of the storage battery can be extended. .

According to a second aspect of the present invention, the remaining capacity of the storage battery in a state where the fully charged storage battery is supplying power to the load is compared with a predetermined threshold value, and if the remaining capacity is not smaller than the threshold value, the battery is charged. Since the remaining capacity comparison unit that prohibits mode switching is provided, the remaining capacity of the storage battery must be smaller than the threshold even when incomplete discharge and charging are repeated such that the remaining capacity of the storage battery is sufficient. For example, it does not switch to the quick charge mode as it is in the trickle charge mode. As a result, there is an effect that the load on the storage battery can be reduced.

According to the third aspect of the present invention, the charge control unit controls the charging current so that the charging current is proportional to the difference between the remaining capacity of the storage battery and the battery capacity at the start of charging in the quick charging mode. When the capacity is small, charging with a large charging current can shorten the charging time in the quick charging mode, and when the remaining capacity is large, charging with a small charging current can reduce the load on the storage battery. effective.

[Brief description of drawings]

FIG. 1 is a schematic circuit configuration diagram showing a first embodiment.

FIG. 2 is a voltage waveform diagram showing the relationship between the discharge time of the storage battery and the battery voltage of the same.

FIG. 3 is a flowchart for explaining the operation of the above.

FIG. 4 is a flowchart for explaining the operation of the second embodiment.

FIG. 5 is a flowchart for explaining the operation of the third embodiment.

FIG. 6 is a schematic circuit configuration diagram showing a conventional example.

FIG. 7 is a waveform diagram showing the relationship between the remaining capacity of the storage battery and the discharge time of the same.

FIG. 8 is another waveform diagram showing the relationship between the remaining capacity and the discharge time of the above storage battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 External power supply 2 Load 3 Charging control unit 5 Storage battery 6 External power supply detection unit 7 Boost control unit 8 Charge amount calculation unit 10 Overdischarge prevention circuit 11 Discharge amount calculation unit 12 Remaining capacity calculation unit

Claims (3)

[Claims] 1. A storage battery that supplies power to a load, an external power supply detection unit that detects an external power supply connected to the load, and a charging current from the external power supply is controlled only when the external power supply is detected by the external power supply detection unit. Then, the charge control unit that charges the storage battery, the charge amount calculation unit that calculates the charge amount of the storage battery by the charge time that is detected by detecting the charge time of the storage battery, and the discharge time that is detected by detecting the discharge time of the storage battery A discharge amount calculation unit that calculates the discharge amount of the storage battery, and a remaining capacity calculation unit that calculates the remaining capacity of the storage battery from the charge amount calculated by the charge amount calculation unit and the discharge amount calculated by the discharge amount calculation unit The trickle charge mode in which the charging control unit charges the storage battery charging mode with a small current close to the self-discharge current of the storage battery according to the remaining capacity of the storage battery calculated by the remaining capacity calculation unit A charging device characterized by switching to a quick charging mode in which a current larger than the current is charged. 2. The remaining capacity of the storage battery in a state where the fully charged storage battery is supplying power to the load is compared with a predetermined threshold value, and if the remaining capacity is not smaller than the threshold value, switching of the charging mode is prohibited. The charging device according to claim 1, further comprising: a remaining capacity comparing unit for performing the charging. 3. The charging control unit controls the charging current so that the charging current is proportional to the difference between the remaining capacity of the storage battery and the battery capacity at the start of charging in the quick charging mode. Charging device.