KR920009671B1 - Charging control circuit of battery - Google Patents

Abstract

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Description

Charge control circuit of storage battery

1 is a block diagram of an embodiment of the present invention.

2 is a detailed circuit diagram of the present invention.

3 is an operation explanatory diagram of the present invention.

4 is a detailed circuit diagram of another embodiment.

5 is a characteristic diagram of forward voltage rise.

6 is a battery temperature rise characteristics.

* Explanation of symbols for the main parts of the drawings

1: AC power supply 4: switching circuit

7 battery 8 voltage detection circuit

9 sensor 10 temperature detection circuit

11: R-S flip-flop 12: current setting circuit

13 output voltage regulation circuit 14 PWM control circuit

The present invention relates to a charge control circuit of a storage battery such as a Ni-Cd battery.

Background Art Conventionally, battery voltage control methods, timers, control methods, battery temperature control methods, and the like are known as charge control methods for storage batteries.

FIG. 5 shows the charge time-cell low voltage characteristics of the Ni-Cd battery, and FIG. 6 shows the charge time-cell temperature characteristics of the Ni-Cd battery.

By the way, the battery voltage control method detects an increasing battery voltage as shown in FIG. 5 when the storage battery is also charged with a predetermined current, and stops charging when the battery voltage reaches a preset value.

However, in such a battery voltage control method, the battery voltage at 100% capacity is greatly uneven due to the nonuniformity of the battery voltage of the battery and the nonuniformity of the temperature characteristic of the battery. We do not set to voltage at display (at the time of 100% charge) and must set at voltage at around 80% charge.

As a result, there was a problem that the storage battery was not fully charged in the state where charging was stopped and the capacity was often insufficient.

On the other hand, the timer control method allows a predetermined charging current to flow through the battery only for a predetermined time regardless of the remaining capacity of the battery. Therefore, when the storage battery in the fully charged state is repeatedly charged by the charging control circuit of this control method, there is a problem that overcharging is repeated and characteristics deterioration occurs.

Therefore, a battery temperature control method has been proposed as a control method for solving the above-mentioned problems, and as shown in FIG. 6, when the battery is further charged beyond 100% of the charge capacity, it has a characteristic of rapidly increasing the temperature. When the battery temperature exceeded the preset value, charging was stopped. However, even in the charge control circuit of the battery temperature control system, charging is started immediately even when the storage battery whose temperature rises immediately after the heavy load is used (mass discharge) is connected, even though the remaining capacity is reduced. There was a problem that it did not work.

As described above, the charge control circuit of a conventional battery has a problem that it cannot be fully charged in the battery voltage control system, and in the timer control system, there is a problem in that deterioration of characteristics due to overcharging occurs, in particular, battery temperature control. In the system type, there was a problem in that charging at the time of power storage could not be started until the battery temperature dropped immediately after the heavy load was used. As charge control circuits that perform charge control based on battery voltage and battery temperature, Japanese Patent Application Laid-Open No. 56-16631 and Japanese Patent Application No. 56-39135 are given, but these charge control circuits have a voltage detection circuit output and temperature. The detection circuit output is logically calculated and the charging is stopped when an arbitrary detection output is obtained. It is only to ensure the determination of the charging stop point, and to store the battery in a high temperature state immediately after using it under heavy load. Cannot be charged.

The present invention has been made in view of the above point, and its object is to charge the storage battery to a full charge state, and there is no deterioration of characteristics due to overcharging and the remaining capacity becomes smaller. It is to provide a charge control circuit of a storage battery that can immediately start charging regardless of battery temperature.

The present invention is to supply a charging current from the AC power supply to the battery, and when the high temperature detection circuit is obtained in the temperature detection circuit that detects that the temperature variable of the battery is higher than the set value, the normal charging is terminated and the end of the storage battery is switched to In the charge control circuit, a high temperature detection signal output from the temperature detection circuit when a low voltage detection signal is obtained from the voltage detection circuit while providing a voltage detection circuit for determining whether the voltage variable of the battery is lower than a set value. It is to install a cancellation means to cancel the

The present invention is constructed as described above, and when the low voltage detection circuit is obtained from the voltage detection circuit, the high temperature detection signal output from the temperature detection circuit is canceled by the company. Even when the voltage variable is lower than the set value and the remaining capacity of the battery is low, charging starts immediately, and after that, when the voltage variable becomes higher than the set value and approaches full charge, the charging current can be switched to the terminal current based on the temperature variable.

1 shows an embodiment of the present invention, in which 1 is an AC power source, 2 is a noise filter circuit, 3 is a rectifier circuit, 4 is a switching circuit, 5 is a transformer, 6 is a rectifier circuit, and 7 is A rechargeable battery (for example, a Ni-Cd battery) is used to rectify the AC power supply 1 as the rectifier circuit 3 and control the charging current in the switching circuit 4 to charge the battery 7. have. In addition, a direct current motor for driving a power tool is connected to the storage battery 7 via a switching SW ₁ as a load 15.

On the other hand, 8 is a voltage detecting circuit for determining whether the battery voltage of the battery 7 is lower than the set value, P is a sensor for detecting the temperature of the battery 7, and 10 is the sensor 7 output by the sensor 9 output. Is a temperature detection circuit that determines whether or not the battery temperature is higher than a set value, and 11 is reset as a low voltage detection signal output from the voltage detection circuit 8 and set as a high temperature detection signal output from the temperature detection circuit 9. As the RS flip-flop 11, a castle means for canceling the high temperature detection signal output from the temperature detection circuit 10 when the low voltage detection circuit signal is obtained from the voltage detection circuit 8 is formed. In the embodiment, the temperature variable is set as the stop temperature, but a temperature difference between the ambient temperature and the battery temperature, or a combination of the battery temperature and other constants and variables may be used.

12 is a current setting circuit which sets the output current to a predetermined value based on the voltage across the resistor R12 for detecting the output current and the state of the output and the switch SW ₁ of the flip-flop 11; 13 is an output voltage regulation circuit for regulating the output voltage of the rectifying circuit 6 to a predetermined value or less based on the state of the switch SW ₁ , and setting current in the PWM control circuit 14 for controlling the switching circuit 4. The output of the circuit 12 and the output voltage regulating circuit 13 are inputted to control the ON-duty of the switching by the switching circuit 4 so that a predetermined output current and output voltage can be obtained.

Here, the current setting circuit 12 charges the storage battery 7 without driving the load 15 and the current at the time of floating charging which charges while driving the load 15 by turning on the switch SW ₁ . The current at the time of charge and the current at the end of charge after completion of charging are set based on the state of the switch SW ₁ and the state of charge of the battery 7.

That is, in the floating charging in which the switch SW ₁ is turned on to charge the storage battery 7 while driving the load 15, the load 15 can be sufficiently driven, and in the light load, the storage battery 7 is charged. It is set to flow the current at the time of floating charging which can flow an electric current.

When the switch SW ₁ is turned off, the charging current is controlled in accordance with the output of the RS flip-flop 11 indicating the state of charge of the battery 7. At this time, when the battery voltage is low due to low residual capacity, the output of the voltage detection circuit 8 becomes ＂H＂ so that the RS flip-flop 11 is set regardless of the output of the temperature detection arc 10. It is set to flow.

On the other hand, when charging progresses and the battery voltage exceeds the low value and approaches full charge, the output of the voltage detection circuit 8 becomes ＂L＂ so that the reset input of the RS flip-flop 11 is released, and further charging progresses and the storage battery When (7) is charged over the 100% state of charge, the battery temperature rises and the output of the temperature detection circuit 10 becomes ＂H＂, and the RS flip-flop 11 is set so that the current at the end of charging It is set to flow.

As described above, in the present invention, since a cancel means composed of the RS flip-flop 11 is provided, the battery voltage is lower than the set value and the remaining capacity of the storage battery 7 is small even when the battery current is higher than the set value due to the large current discharge. In this case, the RS flip-flop 11 output becomes 충전 L ＂, and charging starts immediately. After that, when the battery voltage becomes higher than the set value and is nearing full charge, the output current is converted into the current at the end of charging based on the battery temperature. It is.

2 shows a specific circuit configuration, which will be specifically described below with reference to the configuration and operation of the current setting circuit 12. The same reference numerals are given to the above-described members, and 16 denotes a primary side power supply and 17 a secondary side power supply of the control circuit.

The switch SW ₁ which is switched in communication with the switch SW _{1 for} turning on and off the load 15 now, converts the output current into a current during charging and a current during floating charging. When driving 15), a large output current flows as compared with normal charging, and a load 15 such as an electric tool can be used even when the battery capacity of the storage battery 7 is not sufficient.

In this case, the output current is detected by the resistor R12, and the voltage at both ends thereof is input to the amplifier circuit composed of the operational amplifier OP ₁ , the preceding terms R ₁₉ , R ₂₀ , R ₂₁ , and the capacitor C ₆ . . In normal charging, since the switch SW ₂ is switched to the a side, the resistor R ₂₁ is connected in parallel to the resistor R20, and is multiplied by [1 + R ₁₉ / (R ₂₀ // R ₂₁ )] times. Since the switch SW ₂ is switched to the b side, the resistor R ₂₁ is separated and amplified by (1 + R ₁₉ / R ₂₀ ) times, and the set value of the output current is charged in inverse proportion to this amplification factor. The amplification circuit output is transmitted to the PWM control circuit 14 through the optical combiner PC ₁ and the duty of the switching circuit 4 is determined by the integrated circuit IC ₂ for PWM control. For example, when the output current increases, the voltage across the resistor R ₁₂ is turned on so that the input voltage to the amplification circuit increases, and the output increases so that the PWM control circuit 14 switches the switching circuit so that the on-duty becomes small. (4) is controlled, and as a result, the negative feedback control is performed so that the output current decreases to a predetermined value (current at the time of normal charging, current at the time of charging charging).

3A shows the normal charging operation for charging the storage battery 7 whose battery temperature is lower than the predetermined temperature and whose battery voltage is lower than the predetermined value. The voltage detecting circuit 8 outputs the HH temperature detecting circuit 10. FIG. The transistor Q7 is turned off because the output is? L, and the amplifying circuit output composed of the above-described operational amplifier OP ₁ is input to the PWM control circuit 14 to output the charge control circuit as the switching circuit 4. The current becomes the current during normal charging (rated charging current) set by the current setting circuit 12, and the normal storage battery 7 is charged.

Next, when the storage battery 7 is fully charged and the battery temperature rises above a predetermined value and the high temperature detection signal indicating that the storage battery 7 is fully charged is output from the temperature detection circuit 10, the RS flip-flop 11 ) Is set so that the RS flip-flop 11 output becomes ＂H＂, transistor Q ₇ is turned on, and current flows in optocoupler PC ₁ through resistor R ₂₂ , so that PWM control circuit ( 14 controls the switching circuit 4 to make the on-duty extremely small, and trickle-charges the battery 7 as the current for the final charging.

FIG. 3B shows the operation when discharging the battery 7 which has a high battery temperature and a low battery voltage due to a large current discharge. Although the output of the temperature detection circuit 10 is ＂H＂, the voltage detection circuit (8) Since the output is " H ", the RS flip-flop 11 output maintains the reset state " L " until the output of the voltage detection circuit 8 becomes " L " so that normal charging is performed.

Since the battery temperature decreases during this normal charging, the output of the temperature detection circuit 10 becomes ＂L＂, and when the charge progresses to near full charge, the output of the voltage detection circuit 8 becomes ＂L＂.

In this state, when the charging proceeds further and becomes a full charge, when the temperature of the battery increases and the output of the temperature detection circuit 10 becomes ＂H＂, the RS flip-flop 11 is set so that the output becomes 출력 H ＂and the output current ends. It is converted to the current at the time of charge.

By the way, in the case of floating charging, a large output current is output in order to supply sufficient load current to the load 15, but when the load 15 is driven at no load or light load and the load current decreases, all remaining currents are stored in the battery ( When 7) flows as a charging current and the remaining capacity of the storage battery 7 is large, a problem arises that the storage battery 7 is overcharged with a large current.

So, in the example embodiment a plurality of diodes (D ₈ ~D ₁₃₎ and which is to prevent the tube filled as described above by means of a switch (SW ₂₎ of the output voltage regulating circuit 13, the diode (D ₈ ~D _The regulation voltage level is set by the forward voltage VF of ₁₃ ) and the forward voltage VF 'of the light emitting diode of the optical coupler PC ₁ .

In this case, when the output voltage is higher than the regulated voltage level (6VF + VF ′) during the normal charging in which the switch SW ₂ is switched to the a side, the photocoupler PC ₁ is connected to the diode D ₈ through D ₁₃ . Current flows through the light emitting diode so that the PWM control circuit 14 controls the switching circuit 4 to reduce the on-duty.

In the floating charging in which the switching SW ₂ is switched to the b side, the diodes D ₈ and D ₉ are short-circuited and the output voltage is higher than the regulated voltage level (4VF + VF ′). A current flows through the light emitting diode of the optical coupler PC ₁ through D _{10 to} D ₁₃ to control the switching circuit 4 so as to reduce the on-duty of the PWM control circuit 14. Therefore, when the battery 7 has a sufficient battery capacity, when the charging current flows to increase the output voltage, the output voltage regulation circuit 13 operates to limit the output current, thereby eliminating overcharging of the battery 7.

In addition, the output voltage regulation for the output voltage regulation circuit 13 is mainly necessary for floating charging. If the normal voltage is operated at the same regulation level as for floating charging during normal charging, the charging current is increased when the battery voltage rises. Due to the limitation, the charging time may be long, and the temperature increase of the end of charging may not be completed. Therefore, if charging is normally performed, overvoltage breakdown of circuit components may be caused by setting a high regulated voltage level. (7) and the occurrence of overvoltage in the state in which the load 15 is separated), and at the time of floating charging, the regulated voltage level is appropriately lowered to prevent overcharge due to a large current when no load operation or light load operation is performed. Doing.

Next, in order to prevent the voltage detection circuit 8 from operating incorrectly when the battery voltage decreases due to the pore current, an integrating circuit composed of a resistor R ₃₅ and a capacitor C ₉ is provided to hold the battery voltage. In this case, it is possible to cope with this problem by increasing the CR time constant of the integrating circuit so that it does not respond to instantaneous voltage drop and prevents incorrect operation during startup. In other words, when the battery 7 is charged more than 100% in a situation where there is no such integrated circuit, and the charging is completed and the output current is the terminal charging current, driving the load 15 causes the starting current to be driven by the starting current. The battery voltage temporarily drops. Therefore, the voltage detection circuit 8 detects this low voltage, outputs a charge start signal, and starts charging.

Then, unnecessary charging is performed until the battery temperature rises to the set temperature, and as a result, overcharging is repeated every time the switch SW ₁ is turned on.

Advantageously, according to the present embodiment, since the circuit for holding the battery voltage is provided as described above, the circuit for charge control can be prevented from erroneous operation due to instantaneous battery voltage strengthening, and this charge control circuit can be operated with a large starting current. Even if it is applied to the power tool flowing through, it does not cause any inconvenience.

In yet an embodiment at the time of the floating charge, RS flip-flop 11, and to prohibit the charging control by the output malfunction prevention circuit for preventing the wrong operation is provided, a malfunction preventing circuit of a diode (D ₅₀₎ It is formed as an operational amplifier OP ₃ for comparing the voltage between both ends and the voltage between the diodes D ₈ and D ₉ connected in series and the diode D ₅₁ for countercurrent blocking. Thus, the operational amplifier (OP ₃₎ output by the "L" rodoe and, as a base forcibly transistor (Q ₇₎ "L" at the time of the floating charge is switched to a switch (SW ₂₎ b prohibit the charging control Doing.

In addition, during normal charging when the switch SW ₂ is switched to the a side, the operational amplifier OP3 output becomes ＂H＂, but transmission to another circuit is reduced by the diode D ₅₁ . In addition, since the battery voltage of the storage battery 7 is always input to the voltage detecting circuit 8, when the AC power supply 1 is connected and the first operation of the power supply of the control circuit starts, the voltage detecting integrated circuit ICX ₁ must be used. The reference voltage to be compared of the 2 pins of is started later than the voltage of the 3 pins, so that the comparator output (8 pins) in the IC ₁ is always L and no reset signal is input. .

Thus, in the embodiment, the input of the battery voltage to the voltage detection circuit 8 is configured such that the reference voltage starts later.

That is, the diodes D _{14 to} D ₁₆ are circuits for this purpose. When the AC power supply 1 is turned off, the charge of the capacitor C ₉ is discharged by the copper diodes D _{14 to} D ₁₆ , and the three-pin voltage becomes 4 VF. . When the AC power supply (1) is turned on again, the 3-pin voltage is charged with the time constants of the resistor (R ₃₅ ) and the condenser (C ₉ ) at ₄ VF, and the 3-pin voltage slowly rises, and the reference voltage starts first. Lose.

Thus, the problem that charging does not start by delaying input of the battery voltage to the voltage detection circuit 8 and starting a reference voltage at the time of power supply is prevented.

However, since the output current is generated by the output of the temperature detection circuit 10 which converts the output current into the current at the end of charging, if the temperature of the storage battery 7 is low, the current at the time of normal charging until the temperature rises (rated current) Is charged, and charging of the storage battery 7 is repeated when the AC power supply 1 is turned on and off.

Therefore, in order to prevent this, when the AC power supply 1 is turned on, the voltage detection circuit 8 operates to determine the application of the storage battery 7 by the battery voltage and to determine the output current by the signal.

In the embodiment, a capacitor C ₈ is provided, and when the AC power source 1 is supplied, the reference voltage of the capacitor C _V temperature detection circuit 10 starts later, and the output of the temperature detection circuit 10, in other words, The set input of the flip-flop 11 is set to HH, and the battery capacity is judged by the voltage detecting circuit 8 during this time, and the output current is determined.

Thus, when the charge control circuit of the present embodiment is used for a power tool or the like, the battery 7 is not overcharged by repeating the driving of a power tool that outputs a large current, or by repeatedly turning on or off an AC power supply, so that no deterioration of characteristics occurs. Furthermore, you can always charge up to 100%.

4 shows another example of a concrete circuit configuration, in which the output voltage regulating circuit 13 'is different from that of 2 degrees, and the output voltage regulating circuit 13' is connected to the differential amplifier circuit OP ₄ and the diode D ₈ `, `D _9, D ₁₀ and ~D if a _12), a diode (D <sub>8`,</sub> `D _9, D ₁₀ ~D ₁₂₎ and the volume (R ₄₄₎ determined, and the reference voltage and outputs a reference voltage by The output low voltage is regulated by amplifying the difference with the voltage as the differential amplifier circuit OP ₄ and flowing a current through the optocoupler PC ₁ .

This configuration can be controlled according to the temperature characteristic of an output voltage regulating circuit can arbitrarily set by the volume (R ₄₄₎ a regulation voltage level by (13`) and the battery (7).

The present invention is constructed as described above, and when the low voltage detection circuit is obtained from the voltage detection circuit, a canceling means for canceling the high temperature detection signal output from the temperature detection circuit is provided so that the temperature variable is higher than the set value. Even when the voltage variable is lower than the set value and the battery's remaining capacity is low, charging starts immediately, and then, when the voltage variable becomes higher than the set value and the full charge is near, the charging current is converted to the terminal current based on the temperature variable. There is.

Claims (4)

The charging circuit for supplying the charging current from the AC power source 1 to the storage battery 7 comprises a rectifier circuit 3, step-down means 5 and 6 and charging current changing means 4 and 14, and the charging current changing means. A temperature for detecting that the temperature variable is higher than the set value by comparing the set value of the charging current with the set value of the large current and the low level current terminal charging current by comparing the charging current with the set value by (4,14). In the charging circuit of the storage battery (7), when the high temperature detection signal is obtained from the detection circuit (10), the charging current changing means (4, 14) switches from the normal charging current to the terminal charging current. In the voltage detection circuit 8 for comparing whether the battery voltage is lower than the set value, the low voltage detection signal is inputted by the output detection signal and at the same time, the detection signal in the temperature detection circuit 8 and the low voltage detection circuit in the circuit voltage detection 8. The signal is being obtained When the charging control circuit of the battery, characterized in that by canceling the high-temperature detection circuit which is detected by the temperature detection circuit 10 grants control signal generated for a normal charging current to the charging current control means (4,14). 2. The storage battery according to claim 1, wherein a cancel means is formed as an RS flip-flop 11 that is reset as a low voltage detection signal and is set in a high temperature detection signal, and a charging current is controlled as an RS flip-flop 11 output. Charge control circuit. The charge control circuit for a storage battery according to claim 1, wherein the temperature variable is a battery temperature, and the temperature detection circuit (10) detects whether or not the battery temperature is higher than a set value. The charge control circuit for a storage battery according to claim 1, wherein the temperature variable is a temperature difference between the ambient temperature and the battery temperature, and the temperature detection circuit (10) detects whether the temperature difference is higher than the set value.

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