JP3435861B2 - Charging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in a charging device which stops charging by constant current control when the rising gradient of the battery temperature of a battery to be charged reaches a predetermined level, causes the battery to be recharged so as to be closer to full charge. Regarding the charging device.

[0002]

2. Description of the Related Art Conventionally, when charging a secondary battery, as a method for detecting full charge, a timer control for controlling the time from the start of charging in constant current charging by a timer and setting the full charge when a predetermined time is measured, The -ΔV control is known in which the battery voltage is fully charged when the battery voltage drops from the maximum level to a predetermined level. However, the timer control cannot always perform proper charging depending on the remaining capacity, and the -ΔV control charges the battery. It is necessary to take measures against the voltage decrease phenomenon that appears in the early stage.

Further, T control is known in which the battery is fully charged when the battery temperature T rises to a predetermined level. However, from the viewpoint that it is not affected by the environmental temperature, the rate of change in temperature rise (gradient).
Is obtained, and when this value reaches a predetermined level, full charge is performed Δ
T / Δt control is adopted.

[0004]

However, this Δ
Although the T / Δt control is less affected by other factors, it is not perfect in determining the time point of full charge, and thus it is not always easy to always charge to a desired full charge state.

The present invention has been made in view of the above,
An object of the present invention is to provide a charging device that charges a battery to be charged, which is a secondary battery charged by ΔT / Δt control, to a state as close to 100% as possible and quantitatively.

[0006]

SUMMARY OF THE INVENTION The present invention is a battery charger for stopping charging by constant current control when the rising gradient of the battery temperature of a battery to be charged reaches a predetermined level. Retrieval means for retrieving the battery voltage detected by the battery voltage detection means at the time point, recharging current generating means for supplying a charging current gradually increasing from a low level to a predetermined level after the charging is stopped, and recharging A recharge control means for stopping the recharge when the battery voltage coincides with the taken-in battery voltage is provided (Claim 1).

Further, the recharge current generating means controls the current so that the recharge current does not exceed the level of the constant current (claim 2).

[0008]

According to the first aspect of the present invention, the battery temperature T is detected by the temperature sensor during the constant current control of charging the battery to be charged, and the temperature rise gradient ΔT /
When Δt is obtained, and when this value reaches a predetermined level, it is considered that the battery is fully charged, the charging is stopped, and the battery voltage at this time is taken in. After the charging is stopped, the battery to be charged is recharged by supplying a charging current that gradually increases from a low level. By starting the recharging from a low level, the battery voltage starts to rise again, and when the rising battery voltage reaches the voltage value taken in above, 1
The charging is completed assuming that the battery has been charged to nearly 100%.

According to the second aspect of the present invention, the charging current at the time of recharging is gradually increased from a low level, but is maintained at the current value at the time of charging by the first constant current control, or is less than that. Maintained at some predetermined level.

[0010]

FIG. 1 is a block diagram showing the relationship between a charger equipped with a charging device according to the present invention and a battery to be charged by this charger. In the figure, 1 is a charger and 2 is a battery to be charged. If the battery 2 to be charged is, for example, a lithium battery, a ROM 2A as a memory is built therein, and parameters necessary for charging are stored in the ROM 2A in a predetermined format. The charger 1 and the battery 2 to be charged are connected by a required number of signal lines by mounting them.

In the charger 1, a microcomputer circuit 10 and a charging operation circuit section 10 'controlled and driven by the microcomputer circuit 10 are provided. The microcomputer circuit 10 performs charge control by constant current control or the like, and when the battery temperature increase gradient ΔT / Δt reaches a predetermined level, the microcomputer circuit 10 considers it as full charge and stops the charge, and is driven, and the charge is closer to 100%. The recharging unit 101 is provided for ensuring that

Further, the microcomputer circuit 10 has a battery voltage detecting / capturing unit 102 therein, which captures the battery voltage at the time of stopping charging in the first charging, and the recharging unit 101 captures the battery voltage during recharging. When it matches the voltage value, recharging is stopped.

FIG. 2 is a block diagram showing an example of a connection mode of a charger to which the charging device according to the present invention is applied. The charger 1 charges a lithium battery and other kinds of charged batteries. Reference numeral 3 is a load device that uses the battery to be charged 2 as a power source, and is, for example, a mobile phone. When the battery 2 to be charged is a lithium battery, the ROM 2A in the lithium battery also stores data necessary for the telephone to grasp the characteristics of the lithium battery. And
Power supply and transmission of the above data are performed via the line l1. The charger 1 can also be connected to the line l1 via a line l2.
The charging current of the charger 1 can be electrically connected to a line for power supply in the line l1, and a line for reading the above parameters can be electrically connected to a line for data transmission in the line l1.

FIGS. 3 and 4 are views for explaining this connection relationship. FIG. 3 is a schematic configuration diagram showing a connection state of each device, and FIG. 4 is a diagram showing an arrangement of connection terminals of each device. Is. The charger 1 has a plug 1A for connecting an AC power source, and at the top,
It is provided with a mounting portion 1B (see FIG. 4) that allows a lithium battery and other different secondary batteries to be mounted. Further, the charger 1 has a structure in which the telephone 3 can be mounted while the battery to be charged is loaded, and the troublesomeness of removing the battery 2 to be charged from the telephone 3 each time the battery is charged is reduced.

The lithium battery has, for example, a trapezoidal shape in a side view, and is formed in a state in which terminals indicated by are short-circuited via the inside on the upper and lower surfaces of its mounting tip portion. The terminal is for ground (GND), the terminal is for a temperature sensor, the terminal is for positive electrode + terminal, the terminal is for battery capacity (large / small) determination, and the terminal is for serial transmission of data and parameters from the ROM 2A. For read / write (R / W). Phone 3
The connection terminals are formed at appropriate positions on the lower surface in an array corresponding to the terminals 1 to, and when the lithium battery 2 is loaded, the connection terminals are brought into contact with each other. Further, similarly, the connection terminals are also arranged correspondingly inside the mounting portion 1B of the charger 1, so that when the lithium battery 2 is mounted, the respective connection terminals come into contact with each other. In the case of a different type of battery different from the lithium battery 2, terminals are not formed because the ROM 2A is not provided inside, but other terminals are formed similarly to the lithium battery. Also, regardless of the type of battery with a small battery capacity, the terminals are separated from each other, but with a battery with a large capacity, the terminals are short-circuited and the battery capacity can be checked by checking the potential of the terminals. Can be determined.

Here, the memory map of the ROM 2A in the lithium battery 2 will be described. In the ROM 2A, data indicating lithium performance and parameters for charging are written in advance in a predetermined format corresponding to the address. For example, it is data showing each type of lithium battery, and other parameters will be shown below by way of example.

Vc (cutoff voltage): an allowable voltage indicating an upper limit, 8,2 V or 8,4 V Vmin (lower limit voltage): minimum voltage Tmin (control lower limit temperature) at which rapid charging can be controlled: eg 5 ° C. In the embodiment, -30 ° C. or lower can be measured) Tmax (cutoff temperature): Control upper limit temperature, for example, 4
5 ° C. Il (quick charge low current): lower limit current value in high speed (rapid) charging mode (however, except when starting charging as described later) Ih (quick charge high current): high speed (rapid) charging mode Addition value td to current Il (full charge time): Time element considered to be full charge Is (full charge determination current): Current value to be considered full charge after approaching full charge and shifting from constant current control to constant voltage control Subsequently, a protection circuit for a lithium battery will be described with reference to FIG. As described above, the lithium battery has the GND terminal and the + terminal, and the cells Ce1 and Ce2 are connected in series between them. Usually, a lithium battery is constructed by connecting two to a plurality of cells in series.

Further, the lithium battery has a protection circuit 20 inside.
Is provided. The protection circuit performs various protection functions as will be described later, but in particular, when a sudden large current (for example, 50 mA or more) is rushed at the start of charging, the protection circuit works to prohibit the inflow of the charging current. It has become. Therefore, in order to perform the charging operation so that the protection circuit does not operate, it is necessary to prevent the inrush current from flowing immediately after the start of charging (hereinafter referred to as release).

The protection circuit 20 is provided with an IC 21 for control and field effect transistors FET1 to FET3 as switch circuits connected in series to the cells Ce1 and Ce2, and diodes are respectively connected in parallel to the FET1 to FET3. Has been done. The parallel circuit 22 including a diode and a resistor provided in the + terminal is for limiting the current during discharge.

The FET1 is turned off when the battery voltage drops to prevent further discharge, and the FET2
Is turned off due to the inrush of a large current, and the FET3 is turned off due to an overvoltage. The off control is based on the voltage across the cells Ce1 and Ce2 taken in.
It is performed by the switch signal output from 21.

FIGS. 6 to 8 show the circuits of the charging device according to the present invention separately. This charging device includes a rectifying / smoothing circuit unit 11, a conversion circuit unit 12, a drive circuit unit 13, a stop current control circuit unit 14, a charging control circuit unit 15, a battery state detection circuit unit 16, and a battery ROM (R / W) circuit. A microcomputer (hereinafter, referred to as a microcomputer circuit) 10 that is configured by a unit 17, a temperature sensor circuit unit 18, and a display circuit unit 19 and integrally controls each of the circuit units is provided.

The microcomputer circuit 10 is composed of a microcomputer μC1 having input / output terminals, a reference clock oscillator circuit OSC, and multistage (ladder) resistors R1 to R8, and is a program for performing charging processing and processing during access from the telephone 3. It is provided with a program ROM having a built-in memory, a RAM for temporarily storing processing data, and the like. Then, data is fetched from each input terminal, and a command signal is output from each output terminal in order to execute the processing based on the processing program by using a parameter for charging or a preliminary parameter. Further, in the program ROM, the ROM 2A in the battery to be charged 2 as described in FIG.
It is equipped with a program that creates a preliminary parameter when it is not possible to determine and read the parameter from the.

The ROM 11 stores preliminary parameters in the ROM 2A.
Is an internal memory that is stored in advance in the same format as.
For example, the address value of each parameter and the number of bits of parameter data match. Since the preliminary parameters in the ROM 11 are used even when the battery 2 to be charged is a lithium battery but the parameters cannot be read from the ROM 2A, both the lithium battery and other batteries are used. On the other hand, it is necessary that the parameters are effective and within a proper range. For example, the cutoff voltage Vc is 9,1 V, the lower limit voltage Vmin is 4,4 V, and the cutoff temperature Tmax and the control lower limit temperature Tmin are the same values, respectively, for the rapid charging low current Il. On the other hand, a slightly large value is relatively low for the fast charging high current Ih, but a little long for the full charge time td due to the holding of the current Ih, for example 3 hours to 4 hours. Is set. Also, the ROM 11
Since the battery state detection circuit 16 can determine whether the battery capacity is large or small, preliminary parameters corresponding to the large capacity and the small capacity are written.

It should be noted that the ROM 11 may be replaced with a program for creating a spare parameter so that the spare parameter can be created, or only the spare parameter of one capacity is stored and the result of the capacity determination is determined. According to the above, the other preliminary parameter may be created.

The resistance values of the multistage resistors R1 to R8 are sequentially 2
By arranging and arranging the doubled resistors, each stage is configured to correspond to a bit position. The output side of each resistor is connected to the terminal LC collectively. Therefore, by outputting high and low signals as bit information to the input side of each resistance of the microcomputer μC1, 256 levels of level voltage can be generated at the terminal LC in this embodiment. The output voltage of the terminal LC is used as a reference signal of the constant current control circuit 24 as described later. The number of resistance stages is determined in consideration of control accuracy in constant current or constant voltage control.

The rectifying / smoothing circuit section 11 rectifies and smoothes the commercial power source from the plug 1A. The input terminal has a fuse F, a Zener diode ZD11 for removing noise and surge, a resistor R11, a capacitor C11 and a choke. The rectifying bridge DB and the smoothing capacitor C12 are connected via the circuit composed of the coil Lc.

The conversion circuit section 12 includes a transformer T and rectifying diodes D21, D22, D23, and a secondary side constant voltage power supply generation circuit 121. The transformer T has a primary coil L1, a secondary coil L2 and a power supply coil L3 on the secondary side, and a drive coil L4.
The output side of the rectifying / smoothing circuit section 11 is connected to one end of the primary coil L1, and the other end side is connected to the drain of the FET 31 which is a switching transistor in the drive circuit section 13. Further, the diode D2 is provided at one end of the secondary coil L2.
1, D22 are connected in parallel in the same direction, and a smoothing capacitor C21 is connected to the output side thereof. With this configuration, the voltage induced across the secondary coil L2 is rectified and smoothed to generate a charging current, It is arranged to lead to the battery 2 to be charged. Further, one end of the power supply coil L3 is connected to the diode D2.
3 and the smoothing capacitor C22 are connected to the constant voltage power supply generation circuit 121 on the secondary side. At the terminal B of the constant voltage power supply generation circuit 121, for example, a constant voltage of 5V can be obtained.

By providing the power supply coil L3 in parallel with the secondary coil L2, when the voltage of the battery 2 to be charged is low, the induced voltage of the secondary coil L2 is pulled by the battery voltage to be lowered and a constant voltage power supply is generated. The constant voltage at the terminal B of the circuit 121 is prevented from being lowered, thereby ensuring the stable operation of the microcomputer circuit 10.

The drive circuit section 13 periodically turns on and off the FET 31 to switch the inflow current to the primary coil L1, and thereby the secondary coil L2 and other coils L3.
A voltage is induced in L4. The circuit in which the diode D31 is connected in series to the parallel circuit of the capacitor C31 and the resistor R31 is to improve the characteristics of the current flowing into the primary coil L1 and prevent the inflow of reverse current. Are connected in parallel. The source of the FET 31 is connected to the common line via the current detection resistor R32.

The activation resistor R33 is for applying a voltage to the gate of the FET 31 to activate the FET 31, and is connected between the positive electrode of the rectifying / smoothing circuit section 11 and the gate of the FET 31. A series circuit including a capacitor C32, a resistor R34, and a drive coil L4 is connected between the gate of the FET 31 and the common line to form a self-excited oscillation circuit. Then, the induced voltage of the drive coil L4 is FE
A resistor R35 is connected between the source of the FET 31 and the cathode of the Zener diode ZD31 while being applied to the gate of T31. This protects the gate of the FET 31 from being applied with a voltage higher than the Zener voltage Vz of the Zener diode ZD31.

Diode D32 and transistor Q31
Is a negative voltage generation circuit that charges the capacitor C33 to a negative voltage while the FET 31 is off, and is connected to both ends of the drive coil L4. Further, a discharging resistor R36 is connected in parallel to the capacitor C33.

The FET 31 is connected to both ends of the capacitor C32.
Control transistor Q32 that lowers the gate of the transistor to the off voltage, and the charge and F accumulated in the capacitor C32.
A control transistor Q33 for discharging the electric charge of the gate of ET31 is connected to each. That is, the collector of the control transistor Q32 has a capacitor C
At the connection point between the resistor 32 and the resistor R34, the control transistor Q3
3 has its collector connected to the connection point between the capacitor C32 and the gate of the FET 31.

The control transistors Q32 and Q33 are also provided.
Is connected to the anode of the Zener diode ZD32 via resistors R37 and R38, respectively, and the cathode thereof is connected to the source of the FET 31. The emitters of the control transistors Q32 and Q33 are connected to the negative voltage side of the capacitor C33.

Further, a photocoupler PC forming a part of the constant current control circuit section 14 is interposed in the drive circuit section 13. That is, the phototransistor Qpc forming the photocoupler PC is connected between the base of the transistor Q31 and the common line, and the light emitting diode D is connected to the secondary side.
pc is provided.

Here, the operation of the above circuit configuration will be described. When the input power source is connected, the capacitor C32 is charged through the starting resistor R33, which causes the FET
A voltage is applied to the gate of 31 and the FET 31 starts to turn on. Therefore, a current flows through the primary coil L1 to induce a feedback voltage in the drive coil L4, the induced voltage rises with a time constant determined by the drive coil L4, the resistor R34, and the capacitor C32, and the gate voltage of the FET 31 rises.
The current flowing from the source of the FET 31 increases. When the source current increases, the voltage across the resistor R32 rises and the Zener diode ZD32 turns on, so that the base current flows and both the control transistors Q32 and Q33 turn on, and the gate voltage of the FET 31 becomes the capacitor C3.
To a negative voltage of 3. At this time, by discharging the electric charge of the capacitor C33 by the control transistor Q32, the FET is combined with the control transistor Q33.
FET 31 is rapidly turned off as it removes the charge on the gate of 31.

After that, the FET3 is passed through the starting resistor R33.
The voltage is applied again to the gate of 1, and the FET 31 is turned on. That is, the FET 31 repeats switching,
By this switching, electric power is induced in the secondary coil L22 and rectified to obtain a constant current.

The constant current control circuit section 14 controls the output current on the secondary side. In addition to the photocoupler PC, the control voltage generation circuit 141 and a detection resistor for generating a voltage according to the output current at both ends thereof. A monitor circuit 142 for detecting R41 and the output current is provided.

As described above, the present invention makes it possible to charge different types of batteries. However, unlike nickel type batteries, lithium batteries are protected by a protection circuit 20 when a rapid charging current is supplied at the start of charging. Is activated and charging cannot be performed. The constant current control circuit unit 14 is for generating a gradually increasing charging current so as to release the protection circuit 20 at the start of charging, and thereafter generating a constant current.

The charging current generated on the secondary side is configured so as to flow through the + terminal, the battery 2 to be charged and the GND terminal and further through the detection resistor R41.

The control voltage generation circuit 141 includes a detection resistor R41.
The control voltage for feedback is generated based on the voltage generated across the resistor R41 by the current flowing through the resistor R41. That is, the control voltage generation circuit 141 has the operational amplifier OP1, the voltage dividing resistors R42 and R43 that divide the voltage between the detection voltage and the power supply voltage are provided at the inverting input terminal, and the power supply output of the constant voltage power supply circuit 121 is provided at the non-inverting input terminal. Voltage dividing resistors R44 and R45 for dividing the power supply voltage from the terminal B to obtain a reference voltage are connected. Voltage dividing resistors R43 and R45 are connected to both ends of the detection resistor R41. Then, a voltage of a level corresponding to the voltage across the detection resistor R41 based on the reference voltage is output from the operational amplifier OP1, and this voltage is applied to the anode of the light emitting diode Dpc forming the photocoupler PC. .

The constant current control by the constant current control circuit section 14 is performed by the following operation. When the output current on the secondary side decreases and no voltage is output from the control voltage generation circuit 141, no current flows in the light emitting diode Dpc and the phototransistor Qpc does not turn on. Therefore, the transistor Q31 does not turn on, and the capacitor C33 is less likely to be charged to a negative voltage. Therefore, the ON time of the FET 31 becomes long and the output current increases. On the other hand, when the output current increases and a voltage is output from the control voltage generation circuit 141, a current flows through the light emitting diode Dpc and the phototransistor Qpc is turned on. Therefore, the transistor Q3
1 is turned on, and the capacitor C33 is charged to a more negative voltage. Therefore, the ON time of the FET 31 is shortened and the output current is reduced. The constant current control is performed by the negative feedback functioning in this way.

A voltage of a predetermined level output from the LC terminal of the microcomputer circuit 10 is applied to the connection point of the voltage dividing resistors R44 and R45 so that the reference voltage can be variably controlled. When the reference voltage is changed, the negative feedback control is performed so that the input voltage to the non-inverting input terminal matches the reference voltage, so the output current on the secondary side can be adjusted to the required level according to the reference voltage. Become.

The monitor circuit 142 is the control voltage generation circuit 14.
This is for monitoring the suitability of the output current control according to the item 1. That is, the monitor circuit 142 has an operational amplifier OP2 as a differential amplifier, and its non-inverting input terminal is GND.
And the inverting input terminals are connected to both ends of the detection resistor R41. Then, a monitor voltage of a level corresponding to the voltage across the detection resistor R41 is output from the operational amplifier OP2, and this monitor voltage is guided to the IO terminal of the microcomputer μC1. The microcomputer μC1 compares the monitor voltage taken into the IO terminal with the desired monitor voltage indicated by the reference voltage output from the LC terminal. If they do not match, the voltages to the multistage resistors R1 to R8 are matched so that they match. The application is distributed and adjusted so that a monitor voltage that should be adjusted, that is, a predetermined secondary side output current can be obtained.

The charging control circuit section 15 is provided between the conversion circuit section 12 and the battery 2 to be charged, and supplies the output current on the secondary side to the battery 2 to be charged continuously or intermittently. In the charging control circuit unit 15, the emitter is the conversion circuit unit 12
On the output side of, the collector is connected to the + terminal, the base is connected to the cathode of the Zener diode ZD51, the collector is connected to the anode of the Zener diode ZD51 via the resistor R51, and the emitter is connected to GND. The base is C of the microcomputer circuit 10.
And a transistor Q52 connected to the H1 terminal.
Further, the CH1 terminal is pulled up by the constant voltage from the power supply output terminal B of the constant voltage power supply generation circuit 121 via the resistor R52, and the transistor Q52 is provided while the microcomputer μC1 outputs the high level signal to the CH1 terminal. Is turned on, whereby the transistor Q51 is turned on and the secondary side output signal is supplied to the battery 2 to be charged, while the transistor Q52 is turned off while the low level signal is output to the CH1 terminal. As a result, the transistor Q51 is turned off and the output signal on the secondary side is cut off. The intermittent charging of the battery 2 to be charged is performed by turning on and off the transistor Q51 in this manner. For the intermittent charging in this embodiment, for example, a cycle of 40 seconds is adopted and 2
A charging period of seconds (16 seconds) and a rest period of 38 seconds (24 seconds) are set. The average charging current in this case is 1/20 (2/5) of the current supplied during the charging period. Also,
The cycle, the charging period, and the rest period can be appropriately adjusted depending on the average current to be passed.

Further, the Zener diode ZD51 is connected to the base of the transistor Q51, and when the battery voltage is low, intermittent charging is performed to prevent the transistor Q51 from overheating, and the power supply coil L3.
Is maintained at a predetermined level so that a constant level power supply voltage can be obtained from the power supply output terminal B. For example, assuming that the output voltage of the secondary coil L2 is 5V and the battery voltage is 1V, the transistor Q51 outputs 4V.
As a result, a voltage drop of V occurs, which becomes a load and generates heat. Therefore, the Zener diode ZD51 is used to maintain the base voltage at the threshold level to prevent the transistor Q51 from generating heat.

The battery state detection circuit section 16 detects the capacity of the battery connected between the terminals. The battery state detection circuit section 16 is connected to the + terminal to detect the battery voltage, and is connected to the capacity determination terminal to indicate the battery type. It is composed of a determination circuit. That is, the + terminal has the detection terminal V1 at the connection point of the voltage dividing resistors R61 and R62 via the resistor R63 and the capacitor C61, and the capacitance determining terminal has the voltage dividing resistor R6.
The determination terminal S1 is connected to the connection point of R4 and R65 via a resistor R66 and a capacitor C62. Charged battery 2
Has a structure in which terminals having a small capacity are electrically separated from each other, while terminals having a large capacity are electrically connected. Therefore, when the same voltage is detected at the terminals, it is judged as a large capacity type battery, and when no voltage output is obtained at the terminal, it is judged as a small capacity type battery.

In a nickel-based battery, the battery voltage is 4 V or more in a normal state, and in a lithium battery, it is 1 V or more. Further, a nickel-based battery can be rapidly charged even at 4 V or less, but a lithium battery cannot be rapidly charged at 1 V or less due to abnormal heat generation. Therefore, the charging current is controlled as described later according to the detected battery voltage.

The in-battery ROM (R / W) circuit 17 is connected to the terminals and is for reading out the parameters of the ROM 2A in the lithium battery. ROM (R /
W) Circuit 17 is a resistor R71 provided between the terminal and the ROM terminal of the microcomputer μC1, a Zener diode ZD71 provided between the terminal and GND, a constant voltage power supply generation circuit 1
The resistor R provided between the power supply output terminal B of 2 and the ROM terminal
72 and a power output terminal B and a diode D71 interposed between the terminals. Prior to charging, the microcomputer circuit 10 transmits address data designating an address in the ROM 2A, receives a parameter read from the corresponding address in the ROM 2A, and stores the parameter in an internal RAM.

Further, when the microcomputer circuit 10 accesses the ROM 2A but does not receive any parameter data from the ROM 2A, or when no reply data is obtained after repeating the access a predetermined number of times, the parameters can be read. If it is determined that the backup parameter has not been stored, the backup parameter is read out to the internal RAM so as to start charging using the backup parameter stored in the ROM 11 which is the internal memory. Furthermore, when charging is started with the preliminary parameters,
Even during charging, the ROM 2A is repeatedly accessed at a predetermined cycle, and if the parameter can be read by removing the cause of the unreadableness during that time, this parameter is updated to the internal RAM instead of the preliminary parameter, and charging is performed. Is controlled to continue using the original parameters.

The temperature sensor circuit section 18 detects the temperature of the battery 2 to be charged and also detects the mounting of the battery. A thermistor TH, which is a temperature-sensitive element generally used as a sensor, is connected between the corresponding terminals of the battery to be charged 2.

The temperature sensor circuit portion 18 is connected to the GND terminal and the temperature sensor terminal, and a resistor R81 and capacitors C81 and C82 at both ends thereof are connected between the terminal and the detection terminal T1 of the microcomputer μC1. The terminal is connected to the power supply output terminal B of the constant voltage power supply generation circuit 12 via the resistor R82. Then, a current is made to flow from the power output terminal B to the thermistor TH via the resistor R82, and the divided voltage due to the resistance component of the thermistor TH at this time and the resistance component of the resistor R82 is applied to the detection terminal T1 as the detection voltage. It is output and guided to the microcomputer μC1.

The microcomputer circuit 10 measures the temperature information fetched from the detection terminal T1, that is, the temperature of the battery 2 to be charged, and if the temperature is within the range of 5 ° C. to 45 ° C., determines that the temperature is controllable. On the other hand, it is determined that the battery 2 to be charged is not mounted in a state where the current does not flow from the power output terminal B to the thermistor TH at −30 ° C. or lower.

The display circuit section 19 is for displaying the charge state in a distinguishable manner by color, and has two colors, for example, red and green L.
It has a light emitting element in which the ED is integrally incorporated. In the display circuit section 19, transistors Q91 and Q92 having collectors connected to the power output terminal B of the constant voltage power generation circuit section 12 via current limiting resistors R91 and R92, respectively, are provided in parallel, and both emitters are GND. , And the GR and RE terminals from the microcomputer μC1 are connected to the respective bases and resistors R93 and R94.
It is connected to the power supply output terminal B via and is pulled up. The green (green) LED 91 is a transistor Q
Connected between the collector of 91 and GND, red (RED)
The LED 92 is connected between the collector of the transistor Q92 and GND.

The green LED 91 is turned on when the GR terminal is high level and the transistor Q91 is turned on, and turned off when the GR terminal is low level and the transistor Q91 is turned off.
The red LED 92 is turned on when the RE terminal is at a high level and the transistor Q92 is turned on, and turned off when the RE terminal is at a low level and the transistor Q92 is turned off. Also, green,
When both the red LEDs 91 and 92 are turned on, they are turned on in yellow (YELLOW). At this time, flashing can be performed by repeating high and low. The microcomputer μC1 outputs high and low signals to the GR terminal and RE terminal, respectively, so that red light is lit during charging, green light is lit when charging is completed, and yellow light flashes in other than normal state. Control.

Next, a basic charging operation will be described with reference to the time chart of FIG. When charging starts, first
The microcomputer μC so that the charging current I gradually increases from 0
The reference voltage is output from the LC terminal 1 while increasing stepwise. This ensures that the protection circuit 20 is released when the battery 2 to be charged is a lithium battery.
Then, when it reaches a predetermined level, constant current control is performed.

The battery temperature T is detected by the thermistor TH,
The thermistor resistance decreases as the temperature rises, and the detection terminal T
The detection voltage at 1 decreases. The microcomputer μC1 converts the detected voltage to the temperature T (or remains the detected voltage), and increases the gradient ΔT / Δt from the temperature detected twice in succession.
To calculate. When the gradient ΔT / Δt reaches a predetermined level, it is determined that the battery is fully charged, the charging operation is terminated, and the battery voltage Vpeak at this time is fetched from the battery voltage input terminal V1 and stored. Further, the charging operation is restarted following the end of the charging operation. The charging current at the time of restart charging is controlled so as to gradually increase as at the time of starting the previous charging. When the rising of the current is controlled gently in this manner, the battery voltage, which has tended to decrease, starts to increase again. Then, the value Vpea in which the battery voltage is stored
If it matches k, the charging is completed. After this, the maintenance mode is entered.

In this way, once charging is completed,
The charging current is gradually increased again, and recharging is performed until the battery voltage rises and becomes equal to the voltage at the end of charging, so that the charging amount approaches the full charge as much as possible. By gradually increasing the current during recharging, the battery voltage continues to drop as it is or when a high-level current is suddenly supplied, and overcharging does not always match Vpeak. Is effectively prevented from becoming.

In the above embodiment, the end of the first charging is monitored by the temperature rising gradient, but the present invention is not limited to this.
When it is detected that the temperature gradient or the battery voltage rises just before full charge, the constant current control until then is switched to constant voltage control, and under this constant voltage control, as the charge current approaches full charge. Predetermined level (full charge discrimination current) Is
It may be determined that the charging is completed on the condition that the charge has decreased.

When the battery voltage is lower than the voltage close to the threshold level of the charge control circuit section 15 at the start of charging, intermittent charging or preliminary charging is performed to raise the battery voltage to the threshold level. After that, the heat transfer of the transistor Q1 of the charge control circuit section 15 is prevented and the power supply voltage level of the secondary side is secured by shifting to the quick charge.

Next, the details of the charging operation will be described with reference to the flowcharts of FIGS. Note that FIG.
0 and FIG. 11 show one flowchart divided. In the figure, among the lines that connect each step,
A two-dot chain line shows a lithium battery, a broken line shows a battery that cannot be distinguished from a lithium battery or a nickel-based battery, and a thin solid line shows a case common to both batteries.

This flowchart is started when the AC plug 1A is plugged into a commercial AC power source or a main switch (not shown) is turned on.

When the flow chart is started, first, ID
The mode is shifted to the LE mode, the charging current I is set to 0, all states are reset to OFF (step S2), and
The battery temperature T is measured. If the battery temperature T ≧ −30 ° C., it is determined that the battery 2 to be charged is mounted, and the process proceeds to step S4. In step S4, the battery voltage V
And the data of the battery temperature T are fetched. Also, myco μC
1 accesses the ROM 2A in the battery 2 to be charged, that is, an instruction to read the parameter is given, and it is determined whether or not the parameter can be read. Further, in this state, the LED 92 is turned on.

The battery temperature T is constantly checked thereafter, and if the battery temperature T is <-30 ° C. in any state (step), the process returns to step S2.

If the parameters can be read, it is determined that the battery 2 to be charged is a lithium battery, and the battery voltage V is the minimum level Vmi in the lithium battery.
Maximum level (cutoff voltage) above n (eg 1V)
When the battery temperature T is not higher than Vc and the battery temperature T is not lower than the minimum level Tmin and not higher than the maximum level Tmax, the mode is shifted to the rapid mode (step S6). On the other hand, if the parameters could not be read, it may be a battery other than a lithium battery,
Alternatively, even if the battery is a lithium battery, it is determined that the parameters cannot be read due to poor contact, and the battery voltage V is set to the preliminary parameter that satisfies both the condition of the lithium battery and the condition of the battery other than the lithium battery. Is above the minimum level Vmin (for example 4,4V) and below the maximum level Vmax, and the battery temperature T is above the minimum level Tmin and below the maximum level Tmax, the rapid mode (step S
Go to 6).

If the battery temperature T is lower than Tmin (5 ° C. in this embodiment), the trickle 1 is used regardless of the type of battery.
In the mode (step S8), the battery voltage V is the minimum level V
If it is less than min, the trickle 2 mode (step S1
In 0), if the battery temperature T exceeds Tmax (45 ° C. in this embodiment), the trickle 3 mode (step S12) is entered. Further, in the case of a lithium battery, the battery voltage V
Exceeds the cut-off voltage Vc, or if the battery cannot be identified as a lithium battery and the battery voltage V exceeds the cut-off voltage Vnc (> Vmax), the trickle 3 mode (step The process moves to S12).
This limit voltage Vnc corresponds to the cutoff voltage Vc of the lithium battery.

In the rapid mode, rapid charging is performed, and the rising of the charging current is stepped to release the protection circuit 20, and thereafter a large current is continuously supplied. The trickle 1 mode to trickle 3 mode are all for recovering from a state out of the normal state. The trickle 1 mode raises the battery voltage to a level at which quick charge is possible, or a temporary abnormality in the rapid mode. For example, when the battery voltage V drops below Vmin or Vth due to a contact failure, a short circuit, a sensor abnormality, or the like, and when the battery temperature T falls below Tmin, so-called recovery charging is performed until the abnormality is released. It is for. Trickle 2 mode is for raising the battery voltage to a level at which rapid charging is possible. The trickle 3 mode is to stop the charging current and wait for the battery temperature or the battery temperature to drop to a level at which rapid charging is possible.

The charging operation will be described below for different cases. (1) When the lithium battery is normally charged When the process shifts from step S4 to the rapid mode of step S6, the charging current I increases stepwise from 0 to Il + Ih (for example, about 1 A in total). This stepwise current increase is performed by sequentially increasing the reference voltage from the LC terminal of the microcomputer μC1. The current value is (I
When (l + Ih) is reached, power is continuously supplied while maintaining this level. The charging current is gradually increased by, for example, 640.
The monitor circuit 142 detects the charging current through the detection resistor after the reference voltage is switched from the LC terminal after continuous control at a time interval of ms, and when the charging current deviates from the charging current according to the instruction at the LC terminal. The reference voltage is finely adjusted so as to match them. It should be noted that by detecting the voltage generated at both ends of the detection resistor R41 in advance without connecting the battery to be charged 2 to the secondary side and compensating for this amount as an offset amount, that is, by setting it in the microcomputer μC1, the detection accuracy can be improved. As a result, the accuracy of current control can be further improved.

During the rapid charging, it is judged whether or not the battery voltage V exceeds the cutoff voltage Vc (step S6).
1) If not exceeded, charging is continued as it is, and if it is exceeded, constant current control is switched to constant voltage control (step S62). As a result, the current gradually decreases as the charging progresses and approaches full charge, and the current value is 20 m.
When it reaches A (= Is), it is determined that the battery is fully charged, and the maintenance mode (step S16) is entered. In the maintenance mode, the current is set to 0, the LED 91 is turned on, and the charging is completed.

(2) When the non-charged battery is normally charged when the parameter cannot be read In this case, the charge control is performed using the preliminary parameter. The start of charging is controlled by the microcomputer μC1 so that the charging current increases stepwise as in (1) above.
During charging, the battery voltage V is limited to the limit voltage Vsc (<
Vnc) or the cutoff voltage Vnc is reached, it is determined that the battery is fully charged, and the maintenance mode is entered. In the maintenance mode, a terminal current of a level that compensates for self-discharge is passed (step S16). Even after this, while the battery to be charged 2 is attached to the main charging device 1, the battery voltage V
Is checked, and if the battery voltage V drops by 1 V, for example, the process proceeds to step S4 to perform supplementary charging.

On the other hand, if the temperature rise ΔT / Δt reaches a predetermined value before the battery voltage V reaches each of the above conditions for ending the charging, the battery voltage at this point is taken in as Vpeak and the top-off for recharging is performed. Mode (Step S1
Go to 4). In the top-off mode (recharging), the charging current I is increased stepwise from 0 to (Il + Ih), as in the start of charging in the rapid mode. This stepwise current increase is performed by sequentially increasing the reference voltage from the LC terminal of the microcomputer μC1. In this way, by increasing the charging current from 0, the battery voltage will start to increase again. The current value is (Il + I
When h) is reached, the power is continuously supplied while maintaining this level. In this mode, the LED 91 is on. The current value in the top-off mode is (Il + Ih)
The following can be set to a predetermined level.

Further, the battery voltage V is detected during charging, and it is judged whether or not the stored voltage Vpeak is exceeded (step S141). If not, the current value is maintained at (Il + Ih). When the charging is continued (step S142) and V> Vpeak, the charging is completed and the maintenance mode (step S16) is entered.

In recharging in the top-off mode, when the total time from the start of charging in the rapid mode exceeds the full charge td, or the battery temperature T is Tmax.
When it exceeds, the battery is considered to be fully charged and charging is completed, and the mode shifts to maintenance mode.

(3) When shifting to trickle 3 mode from step S4 In the trickle 3 mode, charging is not started (I = 0), and LE is set.
Both D91 and LED92 are made to blink in synchronization (yellow flash). In this state, in the case of a lithium battery, it is determined whether the battery voltage V is (Vc-200 mV) or less and the battery temperature T is (Tmax-6 ° C.) or less, and recovery is performed, or the battery type is unknown. In the case of such a battery, it is determined whether the battery voltage V is (Vnc-200 mV) or less and the battery temperature T is (Tmax-6 ° C.) or less, and the recovery is made. If so, the mode is switched to the rapid mode. . In this case, if the normal state is not restored even after the lapse of a predetermined time, the process may return to step S2.

(4) Trickle 1 from steps S4 and S10
In case of shifting to the mode In the trickle 1 mode, first, it is determined whether or not the battery voltage V is equal to or lower than the threshold voltage Vth + 50 mV (step S81). This threshold voltage Vth is Veb (voltage between the emitter and base of the transistor Q1) + Vz (zener diode ZD) in the charge control circuit 15.
The Zener voltage of 51) is set to 3.5V in this embodiment.

If the battery voltage V is less than (Vth + 50 mV), in consideration of heat generation of the transistor Q1, intermittent charging is instructed (step S82), and if not, continuous (linear) charging is instructed (step S83). ). In both of the intermittent charging and the linear charging, the microcomputer μC1 controls the charging current to increase stepwise at the start of charging, thereby ensuring that the protection circuit 20 is released.

Next, it is judged whether or not the battery temperature T is lower than (Tmax + 1 ° C.) (step S84), and the battery temperature T
Is less than (Tmax + 1 ° C.), yellow flash is performed (step S85), and intermittent charging is started with a duty of 1, that is, for example, a charging time of 2 seconds and a rest period of 38 seconds and a cycle of 40 seconds (step). S86). If the battery voltage V is less than (Vth + 50 mV) and the battery temperature T is less than (Tmax + 1 ° C.), intermittent charging is continued. On the other hand, the battery temperature T rises (Tmin + 1
℃) or more, then the battery voltage V (Vmin + 5
0 mV) is determined (step S87),
If the battery voltage V is less than (Vmin + 50 mV), yellow flash is performed (steps S88, S85),
The intermittent charging with the duty 1 is continued. on the other hand,
When the battery voltage V exceeds (Vmin + 50mV), LE
D92 is turned on (step S89), and subsequently it is determined whether the battery voltage V is (Vth + 50 mV) or higher (step S90). Here, the battery voltage V is (V
If less than th + 50 mV), step S8
Since the battery voltage V was (Vmin + 50 mV) or more in No. 7, in order to increase the charging current, the duty is changed, that is, the intermittent charging is switched to, for example, the charging time is 16 seconds and the rest period is 24 seconds (step S91).

On the other hand, when linear charging is started in step S83, similar processing is executed. The intermittent charging is performed by the high and low signals from the CH1 terminal of the microcomputer μC1, and the charging and rest periods are appropriately changed according to the battery temperature, the battery voltage and the threshold level (steps SS86, S91 and S83).

Then, the battery voltage V is (Vth + 50 m
When V) or more, it is considered that the level has reached a level at which rapid charging is possible, and the mode shifts to the rapid mode.

(5) When shifting to trickle 2 mode from step S4 In the trickle 2 mode, the charging current is set to 50 mA, and the current value is monitored by the monitor circuit 142.
Maintained constant. At the start of the current supply, the current gradually increases from 0 to 50 mA, and the protection circuit 20
Has been secured. First, it is determined whether the battery voltage V is equal to or higher than the cutoff voltage Vc (step S10).
1). If the battery voltage V is equal to or higher than the cutoff voltage Vc, the mode shifts to the non-charge (non-charge) mode (step S18). If the battery voltage V is less than the cutoff voltage Vc,
Next, it is determined whether the current value is 50 mA or more (step S102). If the current value is less than 50 mA, the charging at 50 mA is repeated. If not, it is determined whether the battery temperature T exceeds Tmax (step S103). If the battery temperature T exceeds Tmax, the mode shifts to the trickle 3 mode, and if not, the mode shifts to trickle 2 mode.

On the other hand, when the mode is shifted from the step S101 to the non-charging mode, the charging is interrupted, and the battery voltage is Vmin to (Vc-200 m in the case of the lithium battery during this period.
V), Vmin to (Vm
ax-200 mV), the process proceeds to step S4.

In the flow chart of the charging operation described above, when the parameter cannot be read, the microcomputer μC1 outputs the access code to the ROM terminal at regular, periodic or specific steps during charging control. When the parameters can be read from the ROM 2A at this time, the read original parameters can be used in place of the preliminary parameters. Appropriate charging control can be achieved.

Next, the operation of accessing the ROM 2A will be described with reference to the flowchart shown in FIG. When the battery 2 to be charged is attached, the charging device 1 sends an access signal from the ROM terminal to the ROM 2A to read the parameters. At this time, first, as shown in FIG. 2, it is determined whether or not the connected telephone 3 is being accessed to read data from the ROM 2A, that is, whether or not communication is in progress (step S201). If the microcomputer μC1 is accessing,
To return. On the other hand, if the telephone 3 is not accessing, the microcomputer μC1 indicates that the own priority is given to the telephone.
As shown to the side, a priority signal (code) is output (step S202), and thereafter, access for reading is started (step S203). As the code indicating the priority signal, a pattern code different from the address code, the parameter code or the data code is adopted so that the priority signal can be discriminated from other signals. in this way,
Since both the charging device 1 and the telephone 3 transmit a code promised in advance to secure the priority right, it is possible to prevent each other from reading erroneous data and parameters, and to secure high reliability of communication. ing.

Further, instead of the priority signal, when there is any level signal of high or low on the transmission line at the time of access from the charging device 1, it is considered that the other device is being accessed. Alternatively, the access may be waited for a predetermined time.

In the present embodiment, the telephone is described as another device, but the present invention is not limited to this, and a beard capable of operating with a secondary battery and reading the characteristic data of the battery as needed. It is applicable to general battery-applied devices such as shaving machines and electric tools.

[0085]

As described above, according to the invention of claim 1, after the rising gradient of the battery temperature reaches a predetermined level, the battery is recharged by the charging current increasing from the low level. Since the completion time is set to coincide with the battery voltage at the time of the first charge stop, the full charge close to 100% can be achieved as quantitatively as possible.

According to the second aspect of the present invention, the upper limit of the charging current during recharging is limited to the initial charging current value, so that the battery to be charged can be overheated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a relationship between a charger including a charging device according to the present invention and a battery to be charged that is charged by the charger.

FIG. 2 is a configuration diagram showing an example of a connection mode of a charger to which the charging device according to the present invention is applied.

FIG. 3 is a schematic configuration diagram showing a connection state of each device.

FIG. 4 is a diagram showing an arrangement of connection terminals of each device.

FIG. 5 is a circuit diagram illustrating a protection circuit for a lithium battery.

FIG. 6 is a circuit diagram of a charging device according to the present invention.

FIG. 7 is a circuit diagram of a charging device according to the present invention.

FIG. 8 is a circuit diagram of a charging device according to the present invention.

FIG. 9 is a time chart illustrating a basic charging operation.

FIG. 10 is a flowchart illustrating a charging operation.

FIG. 11 is a flowchart illustrating a charging operation.

FIG. 12 is a flowchart illustrating an operation of accessing a ROM.

[Explanation of symbols]

1 charger 2 Charged battery 2A ROM 3 telephones 10 memory circuits 101 recharge unit 102 Battery voltage detection and capture section 11 Rectifying and smoothing circuit section 12 Conversion circuit section 13 Drive circuit section 14 Constant current control circuit 15 Charge control circuit 16 Battery status detection circuit 17 ROM (R / W) circuit section in the battery 18 Temperature sensor circuit section 19 Display circuit section 20 Protection circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02J ⁷ /34-7/36

Claims (2)

(57) [Claims] 1. A charging device for stopping charging by constant current control when a rising gradient of a battery temperature of a battery to be charged reaches a predetermined level, the battery voltage detecting means and the battery voltage detecting means at the time of stopping the charging. A capturing means for capturing the detected battery voltage, a recharging current generating means for supplying a charging current that gradually increases from a low level to a predetermined level after the charging is stopped, and a battery whose battery voltage is captured during recharging. And a recharging control means for stopping the recharging when the voltage matches the voltage. 2. The charging device according to claim 1, wherein the recharging current generating means controls the current so that the recharging current does not exceed the level of the constant current.