JP2008125297A - Charger-battery pack system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack system of small size and light weight, as well as a charger suitable for it. <P>SOLUTION: A charger 15 of a battery pack system 10 equipped with: a battery pack consisting of a plurality of unit cells comprises a charging part 16 that charges the battery pack in the battery pack system 10; voltage regulating parts 40a-40n which regulate a voltage of the unit cell; and a control unit 20 which is connected to the voltage regulating parts 40a-40n for controlling the voltage regulating parts 40a-40n. The control unit 20 commands the voltage regulating parts 40a-40n to set a preset constant value, otherwise to set a value obtained by dividing the output voltage of the charger 15 by the number of unit cells constituting the battery pack. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a charger used in a device incorporating a secondary battery, and relates to an apparatus for safely charging a secondary battery, particularly a lithium ion battery.
The charger may be built in the device, and relates to a device that can be used even when directly connected to the secondary battery when the secondary battery is removable from the device.

  In various portable devices, there has been a strong demand for reduction in size and weight, and secondary batteries with high energy density have been demanded. The secondary battery that responds to this is a lithium-ion battery, which realizes a high energy density that is more than three times that of lead-acid batteries, the mainstream of conventional secondary batteries. Used as a power source for portable devices, it has contributed to the reduction in size and weight of devices. In these electronic devices, this lithium ion battery is used as an assembled battery in which a plurality of single cells are connected in series, except for a mobile phone.

  As described above, this lithium ion battery contributes to reducing the size and weight of the device. However, in use, it is necessary to manage and protect the battery. In particular, it is desired to strictly manage overcharge and overdischarge. Yes. Overcharge means charging at a voltage value higher than the upper limit voltage value set for proper use. When placed in such an overcharged state at a certain voltage or higher, it is composed of organic matter. Decomposition of the electrolytic solution and expansion of the negative electrode occur. Such decomposition of the electrolytic solution leads to troubles such as damage to the battery case due to an increase in internal pressure and discharge of gas generated by decomposition of the electrolytic solution to the outside of the battery. On the other hand, when the negative electrode expands, the negative electrode constituent material that has passed through the separator between the positive electrode and the positive electrode may reach the positive electrode, causing a short circuit or the like, which is also a problem in the safe use of the battery.

  Therefore, in order to prevent such a battery trouble, various battery management measures are taken for the assembled battery of the lithium ion battery. For example, a battery protection IC as shown in FIG. 15 is used (see, for example, Non-Patent Document 1). This IC protects the battery by stopping the conduction of the circuit when an overdischarge, overcharge, or overcurrent of the assembled battery is detected. Such battery management / protection is also necessary even when used in a single battery state. However, in the case of a single cell, there is no need to install an overcharge protection device because it is connected one-on-one with the charger during charging. However, when used, an overdischarge prevention / overcurrent prevention function is required.

  This IC is connected to both ends of the assembled battery and the positive and negative terminals of each unit cell, monitors the voltage during charging and discharging, and operates the FET element when the voltage of any battery exceeds a predetermined threshold value. The battery is protected by stopping charging and discharging. Also, there is a protection function against overcurrent, and when a value equal to or greater than a predetermined current is detected, the current is adjusted by operating the semiconductor element (FET) as a resistor. FIG. 16 shows a normal state in the protection operation of the conventional lithium ion battery assembled battery control IC, FIG. 17 shows a state at the time of overcharge protection operation, FIG. 18 shows a state at the time of overcharge protection operation, and FIG. The state at the time is shown in FIG.

  Since this is small, it is effective when it is housed together with the assembled battery in the main body of a small electronic device such as a notebook computer. However, it does not have a function of adjusting the voltage of each unit cell in the assembled battery to a predetermined value. Therefore, at the time of charging, within the voltage range set by the IC, the battery voltage tends to vary, and the battery characteristics may be affected, for example, deterioration may proceed in a battery in which the voltage is kept high.

In view of this, there has also been proposed a method in which a battery management device is arranged in an assembled battery and the voltage of each single cell is adjusted as an overcharge prevention measure as described above (Patent Document 1). In this device, the reference voltage and the cell voltage are compared, and if a voltage rise occurs during charging, the battery voltage at the time of charging is bypassed by bypassing the excessive charging current that causes the voltage rise from the battery. The rise is suppressed.
Such a management device is effective in application to an assembled battery in a backup application where the assembled battery is not moved. This is because in a battery pack for backup use, a charger and a battery are used as a set, and they are not separated throughout the period of use. In such a situation, a management device equipped with a battery overcharge and overdischarge prevention function is installed as a set in the assembled battery. For example, when adding an assembled battery, a management device and a battery set are added. Just install it. In addition, relocation is possible with the assembled battery set. However, because of the structure integrated with the assembled battery, it is difficult to directly apply this method to portable electronic devices that are expected to be downsized. The same situation applies to an assembled battery for an electric vehicle that is expected to be lightweight. FIG. 20 is a diagram illustrating the operation of the assembled battery integrated with the management device in an electric vehicle (Non-Patent Document 2). In the present technology, since the assembled battery and the management device are integrated, the weight and size of the entire power supply unit are increased.
On the other hand, in portable devices and mobile devices, the battery is used only for discharging, and a charger is connected during charging after use. In these devices, the overcharge prevention function operates when connected to a charger and is charged, and is not necessary when the device is operating (that is, when the battery is discharged). Rather, the attachment increases the weight and capacity of the equipment. For this reason, it is desired to install it outside the equipment.
JP 2000-354335 A Seiko Instruments Inc. Masaichi Mori, “IC for Lithium Ion Secondary Battery Protection”, “Electronic Technology”, Nikkan Kogyo Shimbun, p. 31, September 1997 “Development of Lithium-ion Batteries for Electric Vehicles”, GS News Technical Report, Vol. 59, No. 2, p. 23, December 2000

  In the above-described prior art, a battery management device that performs management such as overcharge monitoring, overdischarge monitoring, overcurrent monitoring, and temperature rise monitoring is integrally installed in the assembled battery. The output is connected to the charging terminal of the battery pack and charging is performed. This is because the management function at the time of charging the battery and the management function at the time of discharging are integrated in the assembled battery. However, this increases the weight and size of the assembled battery, which has hindered the realization of a small and lightweight assembled battery required for portable devices and electric vehicles. For this reason, a management IC is applied to a small device, but this IC does not necessarily have a function necessary for securing the battery capacity.

  This invention is made | formed in view of such a situation, The objective is to provide a small and light assembled battery system and a charger suitable for this.

  In order to solve the above-described problems, the present invention provides a battery charger for an assembled battery system including an assembled battery composed of a plurality of single cells, and a charging unit that charges the assembled battery in the assembled battery system; A voltage adjustment unit that is connected in parallel to each of the cells in the assembled battery and adjusts the voltage of the cell, and a control unit that is connected to the voltage adjustment unit and controls the voltage adjustment unit. It is the charger characterized by this.

  Moreover, the present invention is characterized in that, in the charger described above, the voltage adjusting unit adjusts the voltage so that the connected unit cell voltage is equal to or lower than a voltage value instructed by the control unit.

  Further, according to the present invention, in the charger described above, the voltage value instructed by the control unit to the voltage adjustment unit is a predetermined constant value or an output voltage of the charger. It is a value divided by the number of batteries.

  Further, according to the present invention, in the charger described above, the control unit is provided in the assembled battery system when a temperature measurement value or a voltage measurement value of the assembled battery reaches a predetermined constant value. An opening signal of a charging / discharging circuit opening switch disposed in the charging / discharging wiring of the assembled battery is transmitted.

  Moreover, this invention is equipped with the connector connected with the said assembled battery system in the charger mentioned above.

Further, the present invention is an assembled battery system charged by the above-described charger, comprising a plurality of single cells connected to each of a plurality of voltage adjusting units in the charger, and the charging unit of the charger An assembled battery to be charged; a charge / discharge circuit open switch that is disposed in a charge / discharge wiring of the assembled battery and operates in response to a signal from the charger;
It is an assembled battery system characterized by including.

  Further, according to the present invention, in the assembled battery system described above, when it is observed that the battery voltage of the assembled battery has decreased to a preset value, or the temperature of the assembled battery increases to a preset value. The battery management control part which sends out the switch open signal which opens the said charge / discharge circuit open switch when it is observed is further characterized by the above-mentioned.

In order to solve the above-described problems, the present invention provides a charging unit and each unit cell in the assembled battery in an independent charger that is installed outside the assembled battery and connected to the assembled battery whenever necessary. A voltage adjusting unit for adjusting the voltage of And it is trying to connect with an assembled battery with a connector. Further, the assembled battery incorporates a function for preventing overdischarge during discharge as a minimum function.
As described above, in the present application, the voltage adjustment function and overcharge prevention function of the single cells in the assembled battery are attached to the charger side, and only the overdischarge prevention function is attached to the assembled battery.

As described above, according to the present invention, the external single charger has the charging unit and the voltage adjusting unit for adjusting the voltage of each unit cell in the assembled battery of the assembled battery system, and the assembled battery is charged at the time of charging. The system is connected with a connector, and the assembled battery system incorporates a function to prevent overdischarge during discharge.
Therefore, it is possible to reduce the size of an assembled battery unit such as a personal computer or an electric vehicle that incorporates the assembled battery system and operates with the built-in battery during normal use. At the time of charging the assembled battery, the charger according to the present embodiment can be charged without causing an increase in the voltage of each unit cell in the assembled battery.

Hereinafter, a charger according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a charger according to an embodiment of the present invention. The charger 15 includes a charging unit 16 that charges the assembled battery in the assembled battery system 10 and a control unit 17. The control unit 17 includes a control unit 20 and voltage adjustment units 40 a to 40 n (hereinafter collectively referred to as “voltage adjustment unit 40”) connected to the control unit 20. Furthermore, the control value of the battery temperature is input to the control unit 20 from the battery temperature measurement sensor connected to the assembled battery in the assembled battery system 10 and the measurement line 11, and the output includes an assembled battery circuit open signal. Further, the control unit 20 receives an output voltage from the charging voltage detection unit 18 in the charging unit 16. The output of each voltage adjusting unit 40 is connected to the positive and negative terminals of each secondary battery (unit cell) constituting the assembled battery in the assembled battery system 10 via the unit cell connector 12. The charging unit 16 is connected to a power source 50 such as a commercial power source, and the output of the charging unit 16 is connected to the assembled battery 2 via the connector 13.

  The control unit 17 has a “cell voltage adjustment” function and an “overcharge detection control” function. On the other hand, the “overdischarge detection control” function is realized by a device installed in the assembled battery system 10. For this purpose, an inter-cell wiring for monitoring the cell voltage of each unit cell 1 in the assembled battery 2 is attached between the assembled battery 2 and the control unit 17. Note that, from the viewpoint of ensuring the safety of the battery, the control unit 17 causes the assembled battery system 10 via the assembled battery circuit open signal transmission line 14 when the voltage of each cell exceeds a specified value and becomes overcharged. An open signal is sent to the assembled battery circuit open switch 4 (see FIG. 3). The control unit 17 has a “battery temperature detection” function. When the battery temperature measurement value of the assembled battery 2 in the assembled battery system 10 is input from the battery temperature measurement sensor and the measurement line 11, and the input battery temperature measurement value rises to a predetermined value, the assembled battery circuit is opened. An assembled battery circuit open signal is transmitted to the assembled battery circuit open switch 4 (see FIG. 3) in the assembled battery system 10 via the signal transmission line 14.

FIG. 2 is a circuit diagram showing a specific configuration of the control unit 17 according to the present embodiment. The control unit 17 includes a control unit 20 and a voltage adjustment unit 40. The control unit 20 corresponds to each of the unit cells 1a to 1n (hereinafter collectively referred to as “unit cell 1”), which are secondary batteries constituting the assembled battery 2 (see FIG. 3) in the assembled battery system 10. Voltage controllers 21a to 21n (hereinafter collectively referred to as “voltage controller 21”), voltage measurement unit 22 (voltage measurement unit), voltage calculation unit 23 (target voltage calculation unit), switch control unit 24, number of secondary batteries A storage unit 25 is included.
The voltage measurement unit 22 acquires the voltage supplied from the charging unit 16 to the assembled battery system 10 measured by the charging voltage detection unit 18, and outputs the voltage Va to the voltage calculation unit 23.

Based on the voltage Va output from the voltage measurement unit 22 and the number N of secondary batteries (unit cells 1) stored in the secondary battery number storage unit 25, the voltage calculation unit 23 charges each secondary battery. The target voltage Vp, which is the upper limit of is calculated. More specifically, the voltage calculation unit 23 divides the voltage Va measured by the voltage measurement unit 22 by the number N of secondary batteries stored in the secondary battery number storage unit 25, thereby obtaining a target voltage Vp (= Va / N) is calculated. The voltage calculation unit 23 outputs the calculated target voltage Vp to each of the voltage controllers 21a to 21n.
However, the voltage measurement unit 22 (voltage measurement unit), the voltage calculation unit 23 (target voltage calculation unit), and the secondary battery number storage unit 25 are not used, the set voltage is a constant, and this value is stored in the control unit 20. It is also possible to store in advance in the section.

The voltage controller 21 acquires the target voltage Vp from the voltage calculation unit 23 and outputs the target voltage Vp to the voltage adjustment unit 40, so that the battery voltage of the cell 1 (secondary battery) corresponding to itself becomes equal to or lower than the target voltage Vp. In addition, the current supplied from the charger 15 to the assembled battery 2 in the assembled battery system 10 is supplied to the unit cell 1. Further, the voltage controller 21 acquires the battery voltage of the single cell 1 and a bypass current value described later from the voltage adjustment unit 40 and outputs the acquired voltage to the switch control unit 24.
When the voltage of each cell (single cell 1) exceeds a specified value and the switch control unit 24 is overcharged, or the battery temperature measurement value input from the battery temperature measurement sensor and the measurement line 11 is a predetermined value. When the value is reached, an assembled battery circuit open signal is transmitted to the assembled battery circuit open switch 4 (see FIG. 3) in the assembled battery system 10 via the assembled battery circuit open signal transmission line 14.

Next, the voltage adjustment unit 40 in FIG. 2 will be described.
The voltage adjustment unit 40 includes a bypass current control element 41, a bypass current limiting element 42, a bypass current measuring element 43, a battery voltage error amplifier 44, and a battery voltage measuring error amplifier 45. Hereinafter, a certain voltage adjustment unit 40k (any one of the voltage adjustment units 40a to 40n) will be described as an example, but the other voltage adjustment units 40 have the same configuration. FIG. 2 shows a configuration when k = n−1.
The bypass current control element 41, the bypass current limiting element 42, and the bypass current measuring element 43 are connected in series and constitute a bypass circuit (bypass means). This bypass circuit is connected in parallel with the corresponding unit cell 1k.

The bypass current control element 41 is an element such as a transistor. When a control signal is received from the battery voltage error amplifier 44, the bypass current control element 41 flows a bypass current, which is a current that is not used for charging the unit cell 1k, to the bypass circuit. To control.
The bypass current limiting element 42 is an element such as a fuse, and when a current larger than an allowable bypass current value that is the maximum value of the bypassable current flows in the bypass circuit, the bypass current control element 41 and the bypass current measuring element The electric current which flows between 43 is interrupted | blocked.
The bypass current measuring element 43 measures the current value of the bypass current flowing through the bypass circuit, and outputs the measured value to the voltage controller 21k as the bypass current measured value.

The battery voltage error amplifier 44 compares the target voltage Vp (for example, 4.06 (V)) output from the voltage controller 21k with the battery voltage Vb of the single cell 1k output from the battery voltage measurement error amplifier 45. When the battery voltage Vb is higher than the target voltage Vp, a control signal that instructs the bypass current control element 41 to flow a bypass current is output to the bypass current control element 41.
The battery voltage measurement error amplifier 45 calculates the battery voltage of the single cell 1k from the difference between the positive and negative voltage values of the single cell 1k, and outputs the battery voltage Vb to the control unit 20 and the battery voltage error amplifier 44. To do.

  By inputting the target voltage Vp output from the voltage controller 21k and the measured value of the voltage of the single battery (secondary battery) 1k to the battery voltage error amplifier 44, the bypass current control element 41 of the bypass circuit is controlled. . If the bypass current control element 41 is completely turned on, a maximum allowable current flows as the bypass current. Also, if it is completely off, no bypass current flows. Furthermore, by using the bypass current control element 41 in the amplification region (unsaturated region), the same state as the variable resistor can be obtained, and the current value of the bypass current to be bypassed can be continuously adjusted.

  Thus, in this bypass circuit, since the bypass current control element 41 can be used in the same manner as the variable resistor, even when the battery voltage Vb approaches the set target voltage Vp and the charging current becomes a minute value, this is the case. Even a very small charging current can be bypassed. By such a control, the charging current is continuously bypassed by the bypass circuit according to the battery voltage value, so that each single battery (secondary battery) 1 is controlled so as not to exceed the specified target voltage Vp. it can.

In the present embodiment, since the voltage adjustment unit 40 is connected in parallel to each single battery 1 (secondary battery), the single battery having a high battery voltage according to the battery voltage of each single battery 1 in the assembled battery 2. 1, bypass of charging current proceeds, and charging of the unit cell 1 with a low battery voltage due to inflow of charging current proceeds. Therefore, in the assembled battery 2, the battery voltages of all the unit cells 1 become the target voltage Vp. It is controlled as follows.
As a result, the battery voltage of each unit cell 1 constituting the assembled battery 2 is adjusted so as to become the target voltage Vp. Therefore, the battery voltage of each unit cell 1 is charged so as to reduce variation, and the set voltage is set. The battery voltage is prevented from rising above the value.

  Next, the configuration of the assembled battery system 10 applied in the present application will be described. FIG. 3 describes the configuration of the assembled battery system 10, and the assembled battery system 10 is equipped with a function for preventing overdischarge during discharge. That is, the assembled battery system 10 includes an assembled battery 2, a battery management control unit 3, an assembled battery circuit open switch 4, and an assembled battery signal circuit that is an open signal transmission wiring for opening the assembled battery circuit open switch 4. A signal transmission line 5 is provided. When the discharge is started, the battery management control unit 3 monitors the voltage of each battery during the discharge. When a value equal to or lower than the specified voltage is observed in any unit cell 1, the battery pack 2 An open signal is sent to the assembled battery circuit open switch 4 arranged in series in the charge / discharge wiring. Further, the battery management control unit 3 has a “battery temperature detection” function, receives an input of a temperature measurement value of the assembled battery 2, and opens the assembled battery circuit when the battery temperature measurement value reaches a predetermined value. An assembled battery circuit open signal is sent to the switch 4.

  Hereinafter, the “overdischarge detection control function” of the assembled battery system 10 of the present application will be described. FIG. 4 is a diagram showing an “overdischarge detection control circuit” used in the battery management control unit 3 in the assembled battery system 10 according to the present embodiment. Specifically, when a voltage equal to or lower than a specified value is detected by monitoring the unit cell voltage, an open / close signal of the assembled battery circuit open switch 4 is transmitted. In the case of a lithium ion battery, the specified value is specified as 3 to 2.5 (V / cell).

  FIG. 4A is a diagram illustrating a configuration of an overdischarge detection circuit that detects a cell voltage and detects whether or not the voltage has decreased to an overdischarge voltage. When the unit cell voltage becomes equal to or lower than the overdischarge voltage, the control circuit receives a control signal from the overdischarge detection circuit and disconnects the discharge wiring open switch provided in the battery.

In the figure, C1 and C2 are unit cell voltage detectors, E1 is a reference voltage for overdischarge voltage, and D1 is a comparator for comparing the unit cell voltage and the reference voltage. The cell voltage detected by the cell voltage detectors C1 and C2 is connected to the + input terminal of the comparator D1, and the reference voltage E1 is connected to the-input terminal of the comparator D1. The driving power source of the comparator D1 is obtained from the unit cell to which the unit cell voltage detectors C1 and C2 are connected. When the cell voltage is higher than the reference voltage E1, the control signal output from the comparator D1 outputs a voltage present (signal H).
On the other hand, when the unit cell 1 is overdischarged and the unit cell voltage becomes lower than the reference voltage E1, the control signal which is the output of the comparator D1 becomes no voltage (signal L). The discharge wiring open switch operates and opens when it receives no control signal voltage (signal L), and does not operate when it receives the control signal voltage (signal H) and remains closed.
If overdischarge progresses and the unit cell voltage becomes equal to or lower than the operating voltage of the comparator D1, the comparator D1 stops operating, and the control signal output from the comparator D1 indicates that there is no voltage (signal L). Become. Therefore, in such a state, the discharge wiring open switch is opened to stop the discharge of the battery. As described above, only when the unit cell voltage is equal to or higher than the reference voltage, the control signal for the discharge wiring opening switch has voltage (signal H), and the wiring of the discharge circuit is secured. Here, a semiconductor switch such as a MOSFET is used for the discharge wiring open switch and the assembled battery circuit open switch 4.

  In the present embodiment, an assembled battery 2 in which a plurality of single cells 1 are connected in series is used. Therefore, an overdischarge detection for the assembled battery as shown in FIG. This is handled by the circuit configuration. That is, after the circuit shown in FIG. 4A as the unit cell voltage determination unit is connected to each unit cell 1, the control signals from each circuit are collected in the AND circuit F1. Then, the output of the AND circuit F1 is connected to the assembled battery circuit open switch 4. Since it has such a configuration, the AND circuit F1 outputs the signal H only when all of the output signals from the comparators D1 connected to each unit cell 1 have voltage (signal H), Otherwise, if L is included in the signal from the comparator connected to any single cell 1, the L signal is transmitted. As a result, when any one of the cells 1 connected in series reaches the overdischarge voltage, the signal sent to the assembled battery circuit open switch 4 becomes no voltage (signal L), and the assembled battery 2 Disconnected from the discharge line to.

  FIG. 5 shows an overcharge detection circuit that is used in the control unit 17 of the charger 15 and realizes an “overcharge prevention control function” for protecting the assembled battery 2 in the assembled battery system 10 from a rise in unit cell voltage. FIG. In the figure, when the cell voltage is input to the overcharge detection circuit and the overcharge detection circuit detects the overvoltage, a control signal is sent to the assembled battery circuit open switch 4 provided in the assembled battery 2 to open the switch. .

  FIG. 5A is a diagram illustrating a configuration of an overcharge detection circuit that detects a cell voltage and detects whether or not the voltage has increased to an overcharge voltage. In this circuit, the cell voltage detected by the cell voltage detectors C1 and C2 is connected to the negative input terminal of the comparator D1, and the overcharge reference voltage E2 is connected to the positive input terminal of the comparator D1. Thus, the output of the comparator D1 maintains the signal H until the unit cell voltage exceeds the overcharge reference voltage E2, and becomes the signal L when it exceeds the reference voltage E1. Therefore, when the control signal from the overcharge detection circuit becomes the signal L, the control signal is sent to the circuit open switch, and the switch is opened. The overcharge reference voltage is preset in the control unit.

  In the present embodiment, an assembled battery 2 in which a plurality of single cells 1 are connected in series is used. Therefore, overcharge detection for the assembled battery as shown in FIG. This is handled by the circuit configuration. That is, in the assembled battery 2 in which a plurality of unit cells 1 are connected in series, the circuit shown in FIG. 5A is connected to each unit cell 1 and then connected to each unit cell 1. The output of the comparator D1 is input to the AND circuit F1. As a result, all the outputs of the comparators D1 of the cells 1 have a voltage (signal H), that is, when all the cells 1 are below the overcharge reference voltage, the output of the AND circuit has a voltage (signal H). Become. When any one of the cells 1 is overcharged, the output of the AND circuit becomes no voltage (signal L). Therefore, when the output of the AND circuit is no voltage (signal L), a control signal is sent to the assembled battery circuit open switch 4 to open the switch and prevent overcharge.

FIG. 6 is a diagram illustrating a situation when the charger according to the present embodiment is applied to an electronic device. In this figure, the assembled battery system 10 is in a state of being built in the device, and is connected to the charger 15 via the single battery connector 12 and the connector 13.
When charging is started in this state, the charger 15 performs charging at a voltage obtained by multiplying the appropriate charging voltage of the unit cell 1 by the number of the unit cells 1 in the assembled battery 2. For example, when the appropriate charging voltage per unit cell 1 is 4.1 V / cell and the assembled battery 2 composed of ten unit cells 1 is charged, the output voltage setting value of the charger 15 is 4.1 × 10 = 41V.
While this charging is in progress, voltage monitoring and voltage adjustment (control) are performed on each single cell 1, and charging proceeds. At this time, the load on the apparatus main body side does not hinder the progress of charging during operation and during rest. In other words, power is supplied to the load while charging proceeds. Even if the state of the battery deteriorates during charging and the voltage rises, the assembled battery circuit is opened by the operation of the overcharge prevention function, so that safety can be maintained.

  Since the battery voltage rise occurs in the charging process after discharging, such overcharge prevention may be performed when the charger 15 is connected and charged. As described above, in the present embodiment, the control unit 17 that is a part for preventing overcharge is built in the external charger 15, so that installation in the device main body is unnecessary, and the weight of the device increases. Etc. can be prevented. Note that the state in which the charger 15 is removed is a situation in which the device is operated by the assembled battery system 10, and therefore, an overdischarge prevention function at the time of discharge may be operated instead of overcharge detection. Since this overdischarge prevention function is built in the assembled battery system 10, overdischarge during device operation can be prevented by the overdischarge prevention function in the assembled battery system 10.

  In addition, the assembled battery system 10 can be removed from the device and connected to the charger 15 alone for charging. FIG. 7 is a diagram illustrating a connection state between the charger 15 and the assembled battery system 10 according to the present embodiment. In this state, charging of the assembled battery 2 in the assembled battery system 10 proceeds in the same process as in FIG. However, in this case, since the device is not connected, charging of the assembled battery 2 proceeds independently.

  Moreover, FIG. 8 is a figure which shows the example at the time of connecting the charger by this Embodiment with an electronic device. A portable electronic device such as a notebook PC (personal computer) has a built-in battery system 10 for supplying power to a load in the electronic device, and a charger 15 via a single battery connector 12 and a connector 13. Connected. In this case, the assembled battery 2 in the assembled battery system 10 can be charged while using the electronic device.

Next, an example of operation | movement at the time of charging the assembled battery 2 in the assembled battery system 10 with the charger 15 of this Embodiment comprised in this way is demonstrated.
FIG. 9 is a control flow diagram specifically showing the charging process in the charger 15. At the start of charging, when the charger 15 and the assembled battery system 10 are connected (step S10), the charger 15 confirms the status of the assembled battery circuit open switch 4 in the assembled battery system 10 (step S11). . When the battery is opened due to overdischarge (step S11: Yes), the assembled battery circuit open switch 4 is closed (step S12), and charging is started (step S13). Then, unless the charging operation is stopped, the battery voltage and the battery temperature are measured, and the charging operation is continued unless the detection value at which the protection function operates is measured (step S14: YES, step S15; YES, step S16: NO). In addition, when charge stop operation is performed (step S16: YES), charge is stopped (step S17). Further, when an abnormal battery voltage due to a voltage drop is detected after the start of charging (step S14: NO), or when an abnormal battery temperature due to a temperature rise is detected (step S15: NO), the assembled battery circuit is opened. The switch 4 is opened (steps S18 and S19).

  As shown in FIG. 10, in the above-described process, charging by the charger 15 according to the present embodiment is performed by a constant current constant voltage charging method suitable for charging a lithium ion battery. At this time, assuming that the charging completion voltage per unit cell is 4.1 (V), the charging completion voltage of n assembled batteries 2 connected in series is initially set to n × 4.1 (V). Current charging is performed. Here, in the constant current charging, charging in the constant current mode is performed by the maximum value Imax of the charging current flowing through the assembled battery 2. Since charging is based on constant current and constant voltage control, when the total voltage of the assembled battery 2 reaches n × 4.1 (V), the constant voltage mode is set, and the output current of the charging unit 16 is reduced. As the total voltage of the assembled battery 2 gradually approaches n × 4.1 (V) in the course of this charging, a unit cell that reaches the charging completion voltage earlier appears due to the variation in battery characteristics. For example, at time t1 in FIG. 10, the voltage V1n of the unit cell 1n has reached the charge completion voltage, but the voltage V1a of the unit cell 1a and the voltage V1b of the unit cell 1b have not reached the charge completion voltage. After time t1, at time t2, the voltage V1a of the cell 1a reaches the charge completion voltage, but the voltage V1b of the cell 1b has not reached the charge completion voltage. Then, after time t2, at time t3, the voltage V1b of the cell 1b reaches the charge completion voltage. At time t1, the bypass operation of the voltage adjustment circuit of the unit cell 1n is performed, at time t2, the bypass operation of the voltage adjustment circuit of the unit cell 1a is performed, and at time t3, the bypass operation of the voltage adjustment circuit of the unit cell 1b is performed. Has started.

  FIG. 11 schematically shows the variation of each cell voltage at this time. The example of FIG. 11A shows a state in which the voltage of the unit cell 1n has reached 4.1 (V) at time t1. Other unit cells 1 have not yet reached the voltage of 4.1 (V). When charging further proceeds and any one battery reaches the charging completion voltage by charging, the voltage adjustment unit 40 of the battery is operated, and the internal bypass circuit bypasses the charging current. FIG. 11B schematically shows the voltage distribution of each unit cell 1 at time t2 at this time, and FIG. 11B schematically shows the voltage distribution of each unit cell 1 at time t3. 11 (c). As shown in FIG. 11 (b), at time t2, the voltages of the single cells 1a and 1n have reached 4.1 (V), but the other single cells 1 still have a voltage of 4.1 (V). Not reached. Further, as shown in FIG. 11 (c), at time t3, the voltages of the cells 1a, 1b, and 1n have reached 4.1 (V), but the other cells 1 still have the voltage of 4. 1 (V) has not been reached.

Corresponding to the voltage increase of each battery, a bypass current flows at each time as shown in FIGS. When each unit cell 1 reaches the charging completion voltage in this way, the voltage adjustment unit 40 of the unit cell 1 is operated each time so that the charging current is bypassed to suppress the increase in the unit cell voltage. The battery is unbalanced and charging proceeds. That is, as shown in FIG. 12 (a), at time t1, the voltage adjusting unit 40n of the cell 1n that first reached the charging current operates, and the charging current of the cell 1n is the maximum charging current flowing through the assembled battery 2. The value Imax is suppressed. Next, as shown in FIG. 12 (b), at time t2, the voltage adjusting unit 40a of the cell 1a that has reached the charging current next operates, and the charging currents of the cells 1a and 1n that have reached the charging current are The charging current It2 is smaller than the charging current maximum value Imax flowing in the assembled battery 2. Further, as shown in FIG. 12 (c), at time t3, the voltage adjusting unit 40b of the cell 1b that has reached the charging current next operates, and the charging currents of the cells 1a, 1b, and 1n that have reached the charging current. Is suppressed to a charging current It3 smaller than the charging current It2 at time t2.
By repeating such an operation, the battery that has reached the charging completion voltage 4.1 (V) is maintained at the charging completion voltage 4.1 (V), and reaches the other charging completion voltage 4.1 (V). For batteries that are not charged, the current required for charging can flow as it is, and the voltage of each battery reaches the charging completion voltage 4.1 (V) without affecting the progress of charging of the entire assembled battery 2. Can be made.

  FIG. 13 shows a control flow of the discharge process in the assembled battery system 10 according to the present embodiment. When the discharge of the assembled battery 2 is started, the battery voltage and the battery temperature are measured in the assembled battery system 10, and the measured value does not reach the value for opening the assembled battery circuit open switch 4 (step S20: YES, step S21: YES), the discharge proceeds until the discharge stop action is taken (step S22). When the voltage of any single cell drops to the overdischarge detection voltage (step S20: NO), or when an abnormal battery temperature is detected (step S21: NO), the assembled battery circuit open switch 4 is opened. Discharging is stopped (steps S23 and S24).

FIG. 14 shows a state when overdischarge is detected in the assembled battery system 10 according to the present embodiment. The voltage of each unit cell 1 in the assembled battery 2 is monitored, and in the example of the figure, the voltage of the unit cell 1g is reduced to the overdischarge detection voltage. Therefore, in this state in which the voltage of the single cell 1g has dropped to the overdischarge detection voltage (for example, 3.0 V), the assembled battery circuit open switch 4 is opened and the discharge is stopped.
At the same time, the voltage of the entire assembled battery 2 is also monitored. When the voltage is reduced to the voltage obtained by multiplying the overdischarge detection voltage by the number of the single cells 1 in the assembled battery 2, the assembled battery circuit open switch 4 is similarly opened. The discharge is stopped. For example, in the case of the assembled battery 2 composed of ten unit cells 1, when the voltage of the entire assembled battery 2 is reduced to 3 × 10 = 30V, the assembled battery circuit open switch 4 is opened. Further, since the battery management control unit 3 of the assembled battery system 10 receives an input of the temperature measurement value of the assembled battery 2, when the battery temperature measurement value reaches a predetermined value, the assembled battery circuit open switch 4 Sends the assembled battery circuit open signal.
When the assembled battery circuit open switch 4 is opened by the overdischarge detection function and the discharge is stopped, when the charging voltage is applied by the charging operation, the switch is reset and closed, and the charging operation is started.

As described above, according to this embodiment, the voltage adjusting unit 40 that adjusts the voltage of the charging unit 16 in the external single charger 15 and the voltage of each unit cell 1 in the assembled battery 2 of the assembled battery system 10 is provided. The battery pack 10 is connected to the battery pack system 10 via a connector during charging, and the battery pack system 10 incorporates a function for preventing overdischarge during discharge.
Therefore, it is possible to reduce the size of an assembled battery unit such as a personal computer or an electric vehicle that incorporates the assembled battery system 10 and operates with the built-in battery during normal use. At the time of charging the assembled battery 2, the charger 15 according to the present embodiment can be charged without causing a voltage increase of each unit cell 1 in the assembled battery 2.

As mentioned above, although embodiment of this invention has been explained in full detail with reference to drawings, the concrete composition is not restricted to this embodiment, and the design etc. of the range which does not deviate from the gist of this invention are included.
For example, measurement of the charging time after the start of charging and stop of charging after the set elapsed time ends or monitoring of the voltage of the assembled battery 2 in the assembled battery system 10 indicates that the mode has changed to the constant voltage charging mode. Recognizing and stopping automatic charging after the elapse of this time are included. Furthermore, the case where a plurality of assembled battery systems are arranged in the load device and these are connected to one charger via a connector is also included. In this case, since the assembled battery system is a connector connection, the quantity can be adjusted as appropriate in accordance with the increase or decrease of the battery capacity.

  The control unit 20 of the charger 15 may be realized by dedicated hardware, and the operation of the voltage controller 21, the voltage measurement unit 22, the voltage calculation unit 23, and the switch control unit 24 of the control unit 20 of the charger 15. The process can be performed by storing the process in a computer-readable recording medium in the form of a program, and reading and executing the program by the computer system. Here, the computer system includes a CPU, various memories, an OS, and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

The figure which shows the structure of the charger by one Embodiment of this invention. The functional block diagram of the control part in the charger by the embodiment. The figure which shows the structure of the assembled battery system by the embodiment. The figure which shows the overdischarge detection circuit integrated in the assembled battery system by the embodiment. The figure which shows the structural example of the overcharge prevention control circuit in the control part of the charger by the embodiment. The figure for demonstrating the apparatus to which the charger by the embodiment is applied. The figure for demonstrating the connection condition of the charger and assembled battery system by the embodiment. The figure for demonstrating the connection condition of the charger and assembled battery system by the embodiment in apparatuses, such as notebook PC. The figure which shows the charge control flow of the charger by the embodiment. The figure for demonstrating the charge condition in an assembled battery when the charger by the same embodiment is applied. The figure explaining the voltage adjustment condition in each cell in an assembled battery when the charger by the embodiment is applied. The figure explaining the bypass current which flows into a voltage adjustment circuit, when performing the voltage adjustment of each single cell in an assembled battery when the charger by the embodiment is applied. The figure which shows the discharge control flow of the assembled battery system by the embodiment. The figure explaining the state at the time of the overdischarge detection in the assembled battery by the said carrying. The figure which shows the connection state of the control IC for conventional lithium ion battery assembled batteries, and an assembled battery. The figure which shows the protection operation | movement in the conventional control IC for lithium ion battery assembled batteries. The figure which shows the protection operation | movement in the conventional control IC for lithium ion battery assembled batteries. The figure which shows the protection operation | movement in the conventional control IC for lithium ion battery assembled batteries. The figure which shows the protection operation | movement in the conventional control IC for lithium ion battery assembled batteries. The figure which shows the state of the battery management apparatus used for the assembled battery for conventional vehicles.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a-1n ... Single cell 2 ... Assembly battery 3 ... Battery management control part 4 ... Assembly battery circuit open switch 5, 14 ... Assembly battery signal circuit release signal sending line 10 ... Assembly battery system 11 ... Battery temperature measurement sensor and measurement Wire 12 ... Single cell connector 13 ... Connector 15 ... Charger 16 ... Charging unit 17 ... Control unit 18 ... Charge voltage detection unit 20 ... Control unit 21, 21a-21n ... Voltage controller 22 ... Voltage measurement unit 23 ... Voltage calculation unit 24 ... Switch control unit 25 ... Secondary battery number storage unit 40a to 40n ... Voltage adjustment unit 41 ... Bypass current control element 42 ... Bypass current limiting element 43 ... Bypass current measuring element 44 ... Battery voltage error amplifier 45 ... Error for measuring battery voltage amplifier

Claims (7)

A battery charger for an assembled battery system comprising an assembled battery composed of a plurality of single cells,
A charging unit for charging an assembled battery in the assembled battery system;
A voltage adjustment unit that is connected in parallel with each of the cells in the assembled battery and adjusts the voltage of the cell,
A controller that is connected to the voltage regulator and controls the voltage regulator;
A charger comprising:   The charger according to claim 1, wherein the voltage adjustment unit adjusts the voltage so that a connected cell voltage is equal to or less than a voltage value instructed by the control unit.   The voltage value instructed by the control unit to the voltage adjusting unit is a predetermined constant value or a value obtained by dividing the output voltage of the charger by the number of cells constituting the assembled battery. The charger according to claim 2.   When the temperature measurement value or voltage measurement value of the assembled battery reaches a predetermined constant value, the control unit is provided in the assembled battery system and is disposed in the charge / discharge wiring of the assembled battery. The charger according to any one of claims 1 to 3, wherein an open signal of a charge / discharge circuit open switch is transmitted.   The charger according to claim 1, further comprising a connector connected to the assembled battery system. An assembled battery system charged by the charger according to any one of claims 1 to 5,
A plurality of cells connected to each of a plurality of voltage adjusting units in the charger, and a battery pack charged by the charging unit of the charger;
A charging / discharging circuit opening switch that is arranged in the charging / discharging wiring of the assembled battery and operates in response to a signal from the charger;
An assembled battery system comprising:   When it is observed that the battery voltage of the assembled battery has dropped to a preset value, or when it has been observed that the temperature of the assembled battery has risen to a preset value, the charge / discharge circuit The assembled battery system according to claim 6, further comprising a battery management control unit that sends a switch open signal for opening the open switch.

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