JP2012227986A - Battery pack, electric power system, and electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack capable of achieving high safety and long-term reliability by reducing a charging voltage when a battery temperature is within a predetermined temperature range inside the battery pack.SOLUTION: The battery pack includes: one or a plurality of cells; a control section for controlling cell charging discharging; a temperature detection section for measuring a cell temperature and supplying measured temperature information to the control section; and a discharge control switch and a charging control switch disposed in a current path to the cell and respectively controlled by the control section. The control section reduces a charging voltage to the cell more than at normal charging when the detected temperature is within a temperature range requiring charging control.

Description

  The present disclosure relates to, for example, a battery pack of a secondary battery, an electric power system using the battery pack, and an electric vehicle.

  Battery packs including batteries such as lithium ion secondary batteries are widely used as electric tools, mobile electronic devices, electric vehicles, backup power supplies, and the like. A battery pack is defined as a configuration in which one or a plurality of secondary batteries and a protection circuit including a detection unit that detects battery voltage, current, and temperature are integrated by an exterior such as a laminate film or a synthetic resin case. The The battery pack may have an authentication circuit.

  The advantages of the lithium ion battery are small size, light weight, high voltage, high energy density and the like. On the other hand, since the full charge voltage is not determined by itself like the nickel-cadmium battery, the battery voltage increases by the amount of the applied voltage. If excessive charging is performed, the discharge capacity deteriorates, and extreme overcharging may cause a safety problem. On the other hand, the deterioration rapidly proceeds even in overdischarge. In order to compensate for these disadvantages, it is common to provide a protection circuit inside the lithium ion battery pack to control charging and discharging.

  Furthermore, in order to improve the safety and long-term reliability (longevity of the battery pack) of the battery pack, the demands related to the use temperature are increasing so that the temperature environment during charging does not become abnormal. The abnormal temperature environment refers to a temperature region outside the charging temperature range specified by the lithium ion battery pack. In some safety standards, it is currently recommended to control the charging temperature during charging as a guideline.

  Patent Document 1 describes securing the safety of charging due to a voltage drop using a diode. The technique described in Patent Document 1 is intended to ensure safety against overcharge when cell balance is lost in an assembled battery using a plurality of cells. The control method operates when the maximum cell voltage is equal to or higher than a specified voltage and the variation between cells connected in series increases. As a result, the charging current can be reduced by charging through the external diode, the voltage difference generated between the cells is suppressed, and the charging can be completed safely.

JP 2008-199717 A

  The present disclosure aims to satisfy the charging condition in the temperature range recommended by the battery pack, and can ensure safety and long-term reliability (long life). Regardless of the state of the cell voltage or the variation between cells, the control is performed only according to the state of the cell temperature. In the present disclosure, control is performed such that the charging voltage itself applied to the cell can be lowered by a parasitic diode of FET or an external diode. The present disclosure is different from that described in Patent Document 1.

  In addition, consumer products are designed with a combination of a charging circuit and a battery pack, the product cycle is relatively short, and it is relatively easy to match the combination of a charger (charging circuit) and a battery pack with the product. It is. However, in a product with a long product cycle or when the product is used without changing the charger because the products are in series, the correspondence between the combination of the charger and the battery pack and the product changes.

  Especially in the case of products for business use, there are often product cycles of 5 years or more, and there are products that produce 10 years or more. In such a case, changing the combination of the charger and the battery pack as in the case of a consumer increases the burden both in terms of cost and physically. However, if it is sufficient to replace only the consumable battery pack, the burden can be minimized.

  Therefore, an object of the present disclosure is to provide a battery pack, an electric power system, and an electric vehicle that can forcibly reduce a charging voltage in an abnormal temperature environment by adding a minimum number of parts to the battery pack. is there.

An apparatus of the present disclosure includes 11 or more batteries;
A control unit for controlling charging and discharging of the battery;
A temperature detector that measures the temperature of the battery and supplies the measured temperature information to the controller;
Disposed in the current path for the battery, each having a discharge control switch and a charge control switch controlled by the control unit,
The control unit turns off the discharge control switch and turns on the charge control switch when the temperature detected by the temperature detection unit is included in a temperature range that requires control of charging.
The battery pack uses a forward voltage drop of a diode connected in parallel to the discharge control switch to reduce the charging voltage for the battery as compared to normal charging.

The device of the present disclosure is a power system in which the above-described battery pack is charged by a power generation device that generates power from renewable energy.
An apparatus according to the present disclosure includes a conversion device that receives electric power from the battery pack and converts it into driving force of the vehicle, and a control device that performs information processing related to vehicle control based on information related to the battery pack. It is.
The apparatus of the present disclosure includes a power information transmission / reception unit that transmits and receives signals to and from other devices via a network.
It is an electric power system which performs charging / discharging control of the battery pack mentioned above based on the information which the transmission / reception part received.
The device of the present disclosure is a power system that receives power from the battery pack described above and supplies power to the battery pack from the power generation device or the power network.

  According to the embodiment, the safety and long-term reliability (long life) of the battery pack can be improved. According to the present disclosure, regardless of the specifications of the charger (charging circuit), purchasing a combination with a new charging circuit (charger) by controlling the temperature protection of charging inside the lithium ion battery pack The lithium ion battery pack can be used safely.

It is a block diagram of an example of a battery pack to which this indication can be applied. It is a block diagram of an example of a battery pack to which this indication can be applied. It is a block diagram of the 1st example of the battery pack and charger which have a temperature protection function. It is a block diagram of the 2nd example of the battery pack and charger which have a temperature protection function. It is a block diagram of the 3rd example of the battery pack and charger which have a temperature protection function. It is a block diagram of the battery pack which has a temperature protection function. It is a basic diagram used for description of one embodiment of a battery pack. It is a flowchart used for description of one embodiment. It is a connection diagram used for description of a configuration that causes a voltage drop. It is a basic diagram used for description of the charging operation of one Embodiment. It is a connection diagram used for description of a configuration that causes a voltage drop. It is a connection diagram used for description of a configuration that causes a voltage drop. It is a block diagram for demonstrating the application example of a battery pack. It is a block diagram for demonstrating the application example of a battery pack.

  Hereinafter, embodiments will be described. The embodiment described below is a preferable specific example, and various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

<Outline of battery pack to which the present disclosure can be applied>
FIG. 1 shows a circuit block configuration of a general lithium ion battery pack to which the present disclosure can be applied. The battery pack includes batteries (also referred to as unit batteries or cells) 1a and 1b such as lithium ion secondary batteries and a circuit unit 2a. The circuit unit 2a is mounted on a common printed wiring board. The batteries 1a and 1b are connected in series. However, the present disclosure can be applied not only to a series connection of two batteries but also to a configuration in which one or a plurality of batteries are connected in series and / or in parallel.

  The positive electrode terminal 3a and the negative electrode terminal 3b of the battery pack can be connected to the positive electrode terminal and the negative electrode terminal of the charger or electronic device (product), respectively. The electronic device is a mobile phone, a notebook PC (personal computer), or the like. Furthermore, as will be described later, there are cases in which it is connected to an electric vehicle or an in-home power system in addition to the portable device.

The circuit unit 2a includes a protection IC (Integrated Circuit) 4, a discharge control switch (hereinafter appropriately referred to as a discharge switch) 5, and a charge control switch (hereinafter appropriately referred to as a charge switch) 6. . As these switches, for example, FET (Field Effect Transistor) is used. The protection IC 4 receives the respective voltage values of the batteries 1a and 1b and controls on / off of the discharge switch 5 and the charge switch 6 so that the batteries 1a and 1b operate in a safe area. .

  At the time of charging, the positive electrode terminal 3a and the negative electrode terminal 3b of the battery pack are connected to the positive electrode terminal and the negative electrode terminal of the charger, respectively, and charging is performed. In the battery pack, when it is detected that the battery voltage has become the overcharge detection voltage, the protection IC 4 turns off the charging switch 6 so that the charging current does not flow through the current paths of the batteries 1a and 1b. . After the charging switch 6 is turned off, only discharging is possible.

  The discharge switch 5 is turned off when the battery voltage becomes the overdischarge detection voltage, and is controlled by the protection IC 4 so that the discharge current does not flow through the current paths of the batteries 1a and 1b. After the discharge switch is turned off, only charging is possible. After the discharge switch 5 is turned off, only charging is possible. Here, with a single lithium ion secondary battery, the overcharge detection voltage is determined to be 4.20 V ± 0.05 V, for example, and the overdischarge detection voltage is determined to be 2.4 V ± 0.1 V, for example.

As shown in FIG. 2, a battery pack having a communication function with an electronic device main body or a charger is known by a circuit unit 2b in which an MCU (Micro Controller Unit) 7 is added to the circuit unit 2a shown in FIG. . The MCU 7 is an embedded microprocessor in which a computer system is integrated into one integrated circuit. Unlike a general microprocessor, the MCU 7 has many peripheral functions such as memories such as ROM (Read Only Memory) and RAM (Random Access Memory) and I / O, etc. mounted on the MCU itself.

  The battery pack is provided with a communication terminal 3c connected to the MCU 7, so that the electronic device main body can receive necessary battery pack state information by communication. The usable time of the electronic device main body can be displayed to the end user using the received information. Further, even with a single battery pack, the remaining amount level display and alarm warning display are performed by using an LED (Light Emitting Diode) or the like, thereby improving the usability of the user.

  Furthermore, a current detection resistor 8 is provided to detect a charging current or a discharging current. The detected current value is supplied to the MCU 7. When a large current flows during charging, the protection switch 4 is turned off by the protection IC 4 and the charging current flowing through the current paths of the batteries 1a and 1b is controlled to be cut off. Further, when a large current flows during discharging, the discharge switch 5 is turned off by the protection IC 4 and the discharge current flowing through the current paths of the batteries 1a and 1b is controlled. The discharge switch 5 and the charge switch 6 can be controlled by both the protection IC 4 and the MCU 7.

  Instead of the MCU 7, a microcomputer constituted by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. may be used. Further, a nonvolatile memory such as an EEPROM (Erasable Programmable Read Only Memory) or an EEPROM (Electrically Erasable and Programmable Read Only Memory) may be provided in the battery pack.

<Control when battery pack temperature is abnormal>
The control when the existing battery temperature is abnormal will be described.
As shown in FIG. 1, a configuration example in the case of a battery pack without an MCU is shown in FIG. Unlike the configuration of FIG. 1, the circuit unit 2 c illustrated in FIG. 3 includes one battery 1, and the discharge switch 5 and the charge switch 6 are inserted in the negative line of the battery 1. Further, the battery pack and the charger are connected via the positive terminal 3a, the negative terminal 3b, and the thermistor terminal 3d.

The charger includes a charging control circuit 11 that controls charging power supplied to the positive terminal 3a and the negative terminal 3b of the battery pack. The charging control circuit 11 includes a charging power source and a control unit that controls charging. The charging power source is configured, for example, as a DC-DC converter that rectifies a commercial power source and generates a predetermined DC voltage. Furthermore, a power control switch 12 and a pull-up resistor 13 for turning on / off the supply of charging power are provided. A temperature detection element such as a NTC (Negative Temperature Coefficient thermistor 9) is connected between the thermistor terminal 3d of the battery pack and the negative electrode side. The temperature detection voltage divided by the pull-up resistor 13 and the thermistor 9 is the charge control circuit 11. The temperature detection voltage is a value that changes according to the temperature of the battery pack.

  By the combination of the thermistor 9 and the charging control circuit 11 on the electronic device main body side, a temperature protection operation is performed along with charging, and control is performed on the electronic device main body side. That is, the charge control circuit 11 that performs control related to the charging voltage, the charging current, the charging completion, etc. monitors the temperature of the battery pack being charged, and performs charging while confirming that there is no temperature abnormality. When the charge control circuit 11 monitors the resistance value (temperature detection voltage) of the thermistor 9 and detects a temperature abnormality, the charge control switch 12 is turned off to stop charging.

  As shown in FIG. 4, the thermistor 9 may be provided in the charger 11 without providing the thermistor 9 in the circuit portion 2 d of the battery pack. On the electronic device main body side, the thermistor 14 is provided in the vicinity of the battery pack. The configuration of FIG. 4 is advantageous in that the number of terminals required for connection between the battery pack and the charger is reduced from three to two. However, the detection accuracy of the battery temperature is lower than when a thermistor is mounted in the battery pack. For this reason, temperature correction may be required.

  In the configuration in which the battery pack is mounted with the MCU 7 (see FIG. 2), as shown in FIG. 5, the temperature information (state information) detected by the thermistor 9 is transmitted to the charging control circuit 11 of the charger through the communication terminal 3c. Reportedly.

  When the alarm display unit 15 is connected to the charging control circuit 11 of the charger, the charging control circuit 11 communicates with the MCU 7 and displays an alarm display when a temperature abnormality is detected in the battery pack during charging. The warning display informing the end user is performed by the unit 15. The response after the warning is displayed depends on the user.

  When the charging control switch 12 is connected to the charging control circuit 11 of the charger, the charging control circuit 11 communicates with the MCU 7 and detects a temperature abnormality in the battery pack during charging. 12 to stop charging. Since it is possible to determine what kind of control is performed on the charger side from the state information of the battery pack, finer settings are possible. Since the control is performed on the charger side, the charging can be completed without causing a battery abnormality.

  When temperature abnormality is detected in the battery pack during charging, the MCU 7 forcibly turns off the charging switch 6 of the battery pack and stops charging. Since charging is forcibly stopped on the battery pack side, battery abnormality occurs on the charger side. However, double protection can be performed by using together with the control by the charging control switch 12 of the charger. Specifically, by setting the battery pack side charge stop temperature that is equal to or higher than the charge stop temperature set value on the charger side, the charging can be completed without any discomfort to the end user during normal operation. Charging can be forcibly stopped when the side is abnormal.

  As described above, in the existing technology, it is necessary to control the voltage and current according to the temperature environment by the charge control circuit 11, and the battery pack alone has only a configuration that relies on the response of the end user by displaying an alarm. could not. Therefore, it is necessary to take a correspondence relationship between the charger and the battery pack, and when the battery pack is replaced, the charger needs to be replaced together.

  An example in which the charge control circuit 21 and the charge control switch 22 are mounted in the battery pack is shown in FIG. The MCU 7 transmits temperature information to the charge control circuit 21 through internal communication. The charge control circuit 21 performs temperature control such as on / off of the charge control switch 22 based on the temperature information. This configuration is the most reliable control method. However, there are the following disadvantages.

-The circuit scale inside the battery pack increases, which increases costs.
-Separate lines are required for charging and discharging. Or as shown in FIG. 6, the changeover switch 22 is required. The changeover switch 22 is controlled by the charge control circuit 21 so that it is turned off during charging and turned on during discharging.
-The power consumption of the circuit part 2f inside a battery pack becomes large.
The power supply circuit included in the charge control circuit 21 increases internal loss during charging and internal heat generation associated therewith. Furthermore, variation in cell deterioration occurs due to uneven heat distribution due to internal heat generation.
Since the power supply circuit included in the charge control circuit 21 is configured as a DC-DC converter, the battery pack has an oscillation circuit. As a result, the EMC (Electro-Magnetic) of the battery pack alone
Compatibility) management occurs, and development costs increase.

<Battery pack according to the present disclosure>
The present disclosure solves the problems of the above configuration. In the present disclosure, the temperature protection operation is performed in the battery pack alone. There are the following three methods for temperature protection during charging.

1. Stop charging.
2. Reduce the charging voltage.
3. Reduce the charging current.
The present disclosure is a protection method for reducing the second charging voltage, and easily limits the voltage applied to the battery during charging inside the battery pack.

  As shown in FIG. 7, in one embodiment, the battery pack includes a battery unit in which four lithium ion secondary batteries 1a, 1b, 1c, and 1d are connected in series, and a circuit unit 2g. . The circuit unit 2g is mounted on a common printed wiring board. The batteries 1a to 1d are connected in series. However, the present disclosure can be applied not only to a series connection of two batteries but also to a configuration in which one or a plurality of batteries are connected in series and / or in parallel.

  The positive electrode terminal 3a and the negative electrode terminal 3b of the battery pack can be connected to the positive electrode terminal and the negative electrode terminal of the charger or electronic device (product), respectively. The electronic device is a mobile phone, a notebook PC (personal computer), or the like. Furthermore, as will be described later, there are cases in which it is connected to an electric vehicle or an in-home power system in addition to the portable device.

  The circuit unit 2g includes a discharge FET Q1 constituting the discharge switch 5, a charge FET Q2 constituting the charge switch 6, an MCU 7, a current detection resistor 8, and a thermistor 9. A charging current or discharging current is detected by the current detection resistor 8, and the detected value is supplied to the MCU 7. The thermistor 9 is an NTC thermistor, for example, and has a negative temperature coefficient with respect to a temperature change. The resistance value (temperature information) of the thermistor 9 is supplied to the MCU 7.

  The discharge FET Q1 and the charge FET Q2 are controlled by the MCU 7. The MCU 7 receives the voltage values of the batteries 1 a to 1 d, the current value detected by the current detection resistor 8, and the temperature information detected by the thermistor 9. The MCU 7 monitors these voltage values, current values, and temperature information, and controls on / off of the discharge FET Q1 and the charge FET Q2, so that the batteries 1a to 1d operate in a safe region.

  At the time of charging, the positive electrode terminal 3a and the negative electrode terminal 3b of the battery pack are connected to the positive electrode terminal and the negative electrode terminal of the charger, respectively, and charging is performed. When it is detected in the battery pack that the battery voltage has become the overcharge detection voltage, the charging FET Q2 is turned off by the MCU 7 and control is performed so that the charging current does not flow through the current paths of the batteries 1a to 1d. Even when the charging current is excessive, the charging FET Q2 is turned off. After the charge FET Q2 is turned off, only discharge is possible through the discharge FET Q1 and the parasitic diode D2.

  The discharge FET Q1 is turned off when the battery voltage becomes the overdischarge detection voltage, and is controlled by the MCU 7 so that the discharge current does not flow in the current paths of the batteries 1a to 1d. After the discharge switch is turned off, only charging is possible. Even when the discharge current is excessive, the discharge FET Q1 is turned off. After the discharge FET Q1 is turned off, only charging is possible through the charge FET Q2 and the parasitic diode D1. Here, with a single lithium ion secondary battery, the overcharge detection voltage is determined to be 4.20 V ± 0.05 V, for example, and the overdischarge detection voltage is determined to be 2.4 V ± 0.1 V, for example.

  The MCU 7 is an embedded microprocessor in which a computer system is integrated into one integrated circuit. Unlike a general microprocessor, the MCU 7 has many peripheral functions such as memories such as ROM (Read Only Memory) and RAM (Random Access Memory) and I / O, etc. mounted on the MCU itself.

  The battery pack is provided with a communication terminal 3c connected to the MCU 7, so that the charger or the electronic device body can receive necessary battery pack status information by communication. The electronic device can display the usable time of the electronic device main body to the end user using the received information. Further, even with a single battery pack, the remaining amount level display and alarm warning display are performed by using an LED (Light Emitting Diode) or the like, thereby improving the usability of the user.

  Instead of the MCU 7, a microcomputer constituted by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. may be used. Further, a nonvolatile memory such as an EEPROM (Erasable Programmable Read Only Memory) or an EEPROM (Electrically Erasable and Programmable Read Only Memory) may be provided in the battery pack.

  The protection operation of one embodiment will be described with reference to the flowchart of FIG. The control of this flowchart is performed by the MCU 7.

  Starting from step A (start), control is transferred to step B (set). Step B is to connect the battery pack to the charger. Step B indicates a transition to a charging operation. In Step C after Step B, measurement of battery temperature, current (charge / discharge) and voltage is started, and the MCU 7 receives the measured values. Then, the MCU 7 determines the current state.

  Here, in order to control the charging temperature protection, a state of whether or not a charging current is flowing and a state of which temperature range the battery temperature is in are used. The temperature region is set as follows as an example. Tcell is the temperature of the batteries 1 a to 1 d detected by the thermistor 9.

Normal temperature range: 10 ° C ≦ Tcell ≦ 45 ° C
Temperature range requiring charge control: 0 ° C. ≦ Tcell <10 ° C. or
45 ℃ <Tcell ≦ 60 ℃
Temperature range where charging is prohibited: Tcell <0 ° C or Tcell> 60 ° C

As a result of the determination in step C, the following processing is performed.
When charging current is not flowing (ie when no load or discharging)
No need to activate temperature protection during charging. Therefore, the process proceeds from step C to step E. Step E is “normally charged, discharged, or left,” and in this state, the discharge FET Q1 and the charge FET Q2 are turned on.

  When the state of the FET is determined, the process proceeds to step G (various calculation processes). In step G, the remaining capacity calculation process of the battery pack and the recording process of the measurement result history in step C are performed. A series of processing from Step C to Step E to Step G is repeated every set time (for example, 1 second to several seconds) as long as there is no change in the state of the battery pack. During this time, the states of the FET Q1 and the FET Q2 are the latest. State is maintained. The change in the state of the battery pack in this case means that the direction in which the current flows changes in the charging direction.

During charging (when charging current> 0 [A], it is necessary to activate the charging temperature protection. Processing corresponding to the temperature region to which the battery temperature Tcell measured in step C belongs is performed.
・ Normal temperature range: 10 ℃ ≦ Tcell ≦ 45 ℃
In step E, the discharge FET Q1 and the charge FET Q2 are turned on to perform normal charging. The flow of the control sequence is the same as the case where the above-described charging current is not flowing. However, when the cell temperature deviates from the communication temperature range in the measurement of Step C that is repeatedly performed every set time, the state of the FET in Step E shifts to a state that matches the condition of the measurement result in Step C.

・ Temperature range where charging is prohibited: Tcell <0 ° C or Tcell> 60 ° C
If it is determined in step C that Tcell is included in the region where charging is prohibited, charging FET Q2 is turned off and discharging FET Q1 is turned on in step D, and charging is prohibited. In the measurement at every selection time in Step C, the state of the FET is kept as long as the temperature state of the battery does not change.

・ Temperature range that requires charge control: 0 ℃ ≦ Tcell <10 ℃
45 ℃ <Tcell ≦ 60 ℃
If it is determined in step C that Tcell is included in the temperature range that requires charge control, in the charge temperature protection state in step F, the charge FET Q2 is turned on and the discharge FET Q1 is turned off. In the measurement at every selection time in Step C, the state of the FET is kept as long as the temperature state of the battery does not change. Since the discharge FET Q1 is turned off, a charging current flows through the charging FET Q2 and the parasitic diode D1.

  As shown in FIG. 9, the state in which the discharge FET Q1 is off is equivalent to the state in which the discharge switch 5 is off and the parasitic diode D1 is connected in parallel with the discharge switch 5. Therefore, a voltage drop due to the forward voltage VF of the parasitic diode D1 occurs, and the charging voltage applied to the batteries 1a to 1d is reduced by the forward voltage VF. Unlike the resistor, this voltage drop does not change greatly even if the charging current (forward current) decreases. In a specific characteristic example, at 25 ° C., VF is 0.6 V when the forward current is 60 mA.

  In the example of VF = 0.6 [V], the voltage drop is 0.6V / 4 = 0.15V per battery stage. If the charging voltage during normal charging is 4.20 V per battery, the charging voltage can be reduced to 4.05 V.

  FIG. 10 shows the charging characteristics when charging is performed through the diode D1. It can be seen that the voltage difference (= VF) between the charging voltage and the assembled battery total voltage does not change greatly between the initial charging stage and the final charging stage and is stable.

  In the charging temperature protection state of Step F, if the battery temperature changes and enters the normal temperature range, for example, during charging, the normal charging state of Step E is entered, and the discharge FET Q1 is turned on. For this reason, a voltage drop due to the parasitic diode D1 does not occur, and the battery is charged with the voltage (4.20 V).

  Conversely, when the temperature of the battery changes from the normal charge state in step E to a temperature range that requires charge control, the process proceeds to the charge temperature protection state in step F. In this case, the charging current is determined by the voltage obtained by adding VF to the potential difference between the charging voltage (4.20 V) and the battery voltage. Even if it is just before the completion of charging, even if (charging voltage <battery voltage + VF) and the voltage could not be lowered to the intended voltage, the charging current is a small current value sufficiently narrowed down by the constant voltage control of the charging circuit. Become. Therefore, the control is the same as the control for reducing the third charging current in the temperature protection method during charging.

  Further, when the battery pack is disconnected from the charger during the temperature protection operation, the charging current becomes zero. In this case, immediately after the measurement in step C, the process shifts to step E (normal state, discharged state, left state) (discharge FET Q1 and charge FET Q2 are turned on), and is in a dischargeable state. The end user can use the battery pack without a sense of incongruity.

<Modification>
As mentioned above, although embodiment of this application was described concretely, it is not limited to each above-mentioned embodiment, Various deformation | transformation based on the technical idea of this indication is possible. For example, the configuration for generating the voltage drop may be a configuration other than those described above.
In the example described above, the parasitic diode D1 of the discharge FET Q1 is used to lower the charging voltage. This is because the necessary voltage drop can be covered by one parasitic diode of the FET Q1. This is the case when the number of batteries in series is about 2-5. It is necessary that the charging current value does not exceed the allowable loss value of the FET Q1.

  In the case of multiple changes exceeding 5 series or in the case of a large current specification, it is necessary to generate a voltage drop by a diode other than the parasitic diode. As a method for dealing with the above-described problem, as shown in FIG. 11, external diodes D12 and D13 and FET Q3 are connected in parallel with charging FET Q2. Diodes D12 and D13 and the drain and source of FET Q3 as changeover switch SW are connected in series. The current allowable condition of the FET Q3 is set so that it can flow to the charging current.

  During normal charging, the FET Q3 is turned off, the discharging FET Q1 and the charging FET Q2 are turned on, and a charging current flows to the battery through the FET Q1 and FET Q2. During the temperature protection operation, the FET Q3 is turned on, and both the FET Q1 and the FET Q2 are turned off. A charging current flows through FET Q3, external diodes D12 and D13, and parasitic diode D1. Therefore, the voltage drop is (VF1 + VF2 + VF3) as shown in FIG.

  Diode selection criteria (number, type, etc.) vary depending on the voltage value to be dropped. The value of the voltage drop is adjusted by one diode, a series connection of a plurality of diodes, and a diode having a different forward voltage drop VF such as a Schottky barrier diode or a rectifier diode. In particular, depending on the charging current value, the control method of the discharge FET Q1 further changes in addition to component selection.

  As described above, when the voltage drop is insufficient in VF1 of one parasitic diode D1, a required number of external diodes are connected in parallel with the charge FET Q2, as shown in FIG. If two voltage drops are necessary, it is possible to cope with this by adding one external diode connected in series to the parasitic diode D1 of the discharge FET Q1. If three voltage drops are required, it can be handled by increasing the number of diodes arranged in parallel with the charge FET Q2. For example, in a battery pack in which 10 batteries are connected in series, in order to have a charging temperature protection function, when a voltage drop of 0.15 V / cell or more is required, a voltage drop by a diode of 1.5 V or more is required.

  In FIG. 11, the discharge FET Q1 and the charge FET Q2 are controlled to be turned off, and the switching FET Q3 is controlled to be turned on. In this case, (VF1 + VF2 + VF3) is, for example, 1.8V. In 10 series, it becomes 0.18 V / cell. When charging at 4.20 V during normal charging, the charging voltage can be suppressed to 4.02 V / cell when the charging temperature protection operation is activated.

  When the charging current value is greater than or equal to the allowable loss of one FET, it corresponds as shown in FIG. A discharge FET Q4 is connected in parallel with the discharge FET Q1. The discharge FET Q4 also has a parasitic diode D4. When the charge temperature protection operation is activated, the discharge FETQ1 and FETQ4 are turned off. A current flows through the parasitic diodes D1 and D4 connected in parallel.

  However, when a current is passed through the parasitic diodes D1 and D4, a large amount of current may be biased toward a smaller VF due to variations in the forward voltage drop VF. There is no problem even if a parasitic diode is used if the charging current value does not exceed the allowable loss of one FET. However, when the charging current value exceeds the allowable loss of one FET, there is a possibility that the abnormal heat generation leads to destruction. Therefore, in the case of a parallel connection, it may be necessary to judge to stop using the parasitic diode of the FET.

  Therefore, in this case, only the charge FET Q2 (charge switch 6) is turned off, and the discharge FETs Q1 and Q4 are turned on. As a result, since the voltage drop of the parasitic diodes of the discharge FETQ1 and FETQ4 is not included, (VF2 + VF3) is a voltage drop.

The battery pack according to the present disclosure described above has the following advantages.
-Charging temperature protection can be limited with only a battery pack, ensuring safety and long-term reliability during charging.
-Charge temperature protection can be provided even for battery packs connected to an unspecified number of chargers.
-When charge / discharge protection is controlled by the MCU, it can be handled by changing only the software without changing the existing circuit.
・ Cost reduction is possible by using the parasitic diode of the discharge control FET.
-In the situation where parasitic diodes cannot be used, such as in the case of FETs that use large current charging or parallel connection, it is possible to cope with the minimum circuit change by combining with normal diodes.

<Application example>
The present disclosure is a power system in which the above-described battery pack is charged by a power generation device that generates power from renewable energy.
The present disclosure is a power system in which the above-described battery pack is charged by a power generation device that generates power from renewable energy.
The present disclosure is an electric vehicle including a conversion device that receives electric power from the battery pack and converts the power into a driving force of the vehicle, and a control device that performs information processing related to vehicle control based on information related to the battery pack. .
The present disclosure includes a power information transmission / reception unit that transmits and receives signals to and from other devices via a network.
It is an electric power system which performs charge / discharge control of the battery pack mentioned above based on the information which the electric power information transmission / reception part received.
The present disclosure is an electric power system that receives electric power from the above-described battery pack and supplies electric power to the battery pack from a power generation device or an electric power network.

"Storage system in a house as an application example"
An example in which the present disclosure is applied to a residential power storage system will be described with reference to FIG. For example, in the power storage system 100 for the house 101, electric power is stored from the centralized power system 102 such as the thermal power generation 102a, the nuclear power generation 102b, and the hydroelectric power generation 102c through the power network 109, the information network 112, the smart meter 107, the power hub 108, and the like. Supplied to the device 103. At the same time, power is supplied to the power storage device 103 from an independent power source such as the home power generation device 104. The electric power supplied to the power storage device 103 is stored. Electric power used in the house 101 is fed using the power storage device 103. The same power storage system can be used not only for the house 101 but also for buildings.

  The house 101 is provided with a power generation device 104, a power consumption device 105, a power storage device 103, a control device 110 that controls each device, a smart meter 107, and a sensor 111 that acquires various types of information. Each device is connected by a power network 109 and an information network 112. As the power generation device 104, a solar cell, a fuel cell, or the like is used, and the generated power is supplied to the power consumption device 105 and / or the power storage device 103. The power consuming device 105 is a refrigerator 105a, an air conditioner 105b, a television receiver 105c, a bath 105d, and the like. Furthermore, the electric power consumption device 105 includes an electric vehicle 106. The electric vehicle 106 is an electric vehicle 106a, a hybrid car 106b, and an electric motorcycle 106c.

  The battery pack of the present disclosure described above is applied to the power storage device 103. The power storage device 103 is composed of a secondary battery or a capacitor. For example, a lithium ion battery is used. The lithium ion battery may be a stationary type or used in the electric vehicle 106. The smart meter 107 has a function of measuring the usage amount of commercial power and transmitting the measured usage amount to an electric power company. The power network 109 may be any one or a combination of DC power supply, AC power supply, and non-contact power supply.

  The various sensors 111 are, for example, human sensors, illuminance sensors, object detection sensors, power consumption sensors, vibration sensors, contact sensors, temperature sensors, infrared sensors, and the like. Information acquired by the various sensors 111 is transmitted to the control device 110. Based on the information from the sensor 111, the weather condition, the human condition, etc. can be grasped, and the power consumption device 105 can be automatically controlled to minimize the energy consumption. Furthermore, the control device 110 can transmit information regarding the house 101 to an external power company or the like via the Internet.

The power hub 108 performs processing such as branching of power lines and DC / AC conversion. Communication methods of the information network 112 connected to the control device 110 include a method using a communication interface such as UART (Universal Asynchronous Receiver-Transceiver), wireless communication such as Bluetooth, ZigBee, and Wi-Fi. There is a method of using a sensor network according to the standard. The Bluetooth method is applied to multimedia communication and can perform one-to-many connection communication. ZigBee uses the physical layer of IEEE (Institute of Electrical and Electronics Engineers) 802.15.4. IEEE 802.15.4 is the name of a short-range wireless network standard called PAN (Personal Area Network) or W (Wireless) PAN.

The control device 110 is connected to an external server 113. The server 113 may be managed by any one of the house 101, the power company, and the service provider. The information transmitted and received by the server 113 is, for example, information related to power consumption information, life pattern information, power charges, weather information, natural disaster information, and power transactions. These pieces of information may be transmitted / received from a power consuming device (for example, a television receiver) in the home, or may be transmitted / received from a device outside the home (for example, a mobile phone). Such information may be displayed on a device having a display function, such as a television receiver, a mobile phone, or a PDA (Personal Digital Assistants).

  A control device 110 that controls each unit includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like, and is stored in the power storage device 103 in this example. The control device 110 is connected to the power storage device 103, the home power generation device 104, the power consumption device 105, various sensors 111, the server 113 and the information network 112, for example, a function of adjusting the amount of commercial power used and the amount of power generation have. In addition, you may provide the function etc. which carry out an electric power transaction in an electric power market.

  As described above, the electric power can be stored not only in the centralized power system 102 such as the thermal power 102a, the nuclear power 102b, and the hydraulic power 102c but also in the power generation device 104 (solar power generation, wind power generation) in the power storage device 103. it can. Therefore, even if the generated power of the home power generation device 104 fluctuates, it is possible to perform control such that the amount of power to be sent to the outside is constant or discharge is performed as necessary. For example, the electric power obtained by solar power generation is stored in the power storage device 103, and midnight power with a low charge is stored in the power storage device 103 at night, and the power stored by the power storage device 103 is discharged during a high daytime charge. You can also use it.

  In this example, the control device 110 is stored in the power storage device 103. However, the control device 110 may be stored in the smart meter 107, or may be configured independently. Furthermore, the power storage system 100 may be used for a plurality of homes in an apartment house, or may be used for a plurality of detached houses.

"Vehicle power storage system as an application example"
An example in which the present disclosure is applied to a power storage system for a vehicle will be described with reference to FIG. FIG. 14 schematically illustrates an example of a configuration of a hybrid vehicle that employs a series hybrid system to which the present disclosure is applied. The series hybrid system is a vehicle that runs on a power driving force conversion device using electric power generated by a generator driven by an engine or electric power once stored in a battery.

  The hybrid vehicle 200 includes an engine 201, a generator 202, a power driving force conversion device 203, driving wheels 204a, driving wheels 204b, wheels 205a, wheels 205b, a battery 208, a vehicle control device 209, various sensors 210, and a charging port 211. Is installed. The battery pack of the present disclosure described above is applied to the battery 208.

  The hybrid vehicle 200 runs using the power driving force conversion device 203 as a power source. An example of the power driving force conversion device 203 is a motor. The electric power / driving force converter 203 is operated by the electric power of the battery 208, and the rotational force of the electric power / driving force converter 203 is transmitted to the driving wheels 204a and 204b. In addition, by using a direct current-alternating current (DC-AC) or reverse conversion (AC-DC conversion) where necessary, the power driving force conversion device 203 can be applied to either an alternating current motor or a direct current motor. The various sensors 210 control the engine speed via the vehicle control device 209 and control the opening (throttle opening) of a throttle valve (not shown). The various sensors 210 include a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

  The rotational force of the engine 201 is transmitted to the generator 202, and the electric power generated by the generator 202 by the rotational force can be stored in the battery 208.

  When the hybrid vehicle decelerates by a braking mechanism (not shown), the resistance force at the time of deceleration is applied as a rotational force to the power driving force conversion device 203, and the regenerative power generated by the power driving force conversion device 203 by this rotational force is applied to the battery 208. Accumulated.

  The battery 208 is connected to a power source outside the hybrid vehicle, so that it can receive power from the external power source using the charging port 211 as an input port and store the received power.

  Although not shown, an information processing device that performs information processing related to vehicle control based on information related to the secondary battery may be provided. As such an information processing apparatus, for example, there is an information processing apparatus that displays a remaining battery level based on information on the remaining battery level.

  In the above description, a series hybrid vehicle that runs on a motor using electric power generated by a generator that is driven by an engine or electric power that is temporarily stored in a battery has been described as an example. However, the present disclosure is also effective for a parallel hybrid vehicle that uses both the engine and motor outputs as the drive source, and switches between the three modes of running with the engine alone, running with the motor alone, and engine and motor running as appropriate. Applicable. Furthermore, the present disclosure can be effectively applied to a so-called electric vehicle that travels only by a drive motor without using an engine.

DESCRIPTION OF SYMBOLS 1, 1a-1d ... Battery 2a-2g ... Circuit part 5 ... Discharge switch 6 ... Charge switch 7 ... MCU
8 ... Current detection resistor 9 ... Thermistor Q1 ... Discharge control FET
Q2 ... Charge control FET
D1, D2 ... Parasitic diode

Claims (10)

One or more batteries;
A control unit for controlling charging and discharging of the battery;
A temperature detection unit that measures the temperature of the battery and supplies the measured temperature information to the control unit;
Disposed in the current path for the battery, comprising a discharge control switch and a charge control switch respectively controlled by the control unit,
The controller, when the temperature detected by the temperature detector is included in a temperature region that requires charge control, turns off the discharge control switch, turns on the charge control switch,
A battery pack that reduces a charging voltage for the battery as compared with that during normal charging using a forward voltage drop of a diode connected in parallel to the discharge control switch. The discharge control switch is constituted by a first FET, the charge control switch is constituted by a second FET,
2. The first FET is turned off, the second FET is turned on, and a forward voltage drop of a parasitic diode of the first FET is used to reduce a charging voltage for the battery. Battery pack. The discharge control switch is constituted by a first FET, the charge control switch is constituted by a second FET,
Connecting a series circuit of a third FET and a diode in parallel with the second FET;
In order to reduce the charging voltage for the battery, the second FET is turned off and the third FET is turned on.
The battery pack according to claim 1, wherein a forward voltage drop of a diode connected in parallel to the second FET is used. The discharge control switch is constituted by a first FET, the charge control switch is constituted by a second FET,
Connecting a series circuit of a third FET and a diode in parallel with the second FET;
In order to reduce the charging voltage for the battery, the second FET is turned off and the third FET is turned on.
2. The battery pack according to claim 1, wherein a voltage of a sum of a forward voltage drop of a parasitic diode of the first FET and a forward voltage drop of a diode connected in parallel to the second FET is used.   2. The battery pack according to claim 1, wherein the temperature range that needs to be controlled for charging is set between a temperature range for which charging is prohibited and a temperature range for normal charging.   The battery pack according to claim 1, wherein the control unit controls a protection operation by software processing.   The electric power system with which the battery pack in any one of Claims 1-6 is charged by the electric power generating apparatus which produces electric power from renewable energy.   A conversion device that receives supply of electric power from the battery pack according to any one of claims 1 to 6 and converts it into driving force of a vehicle, and a control device that performs information processing related to vehicle control based on information related to the battery pack An electric vehicle. A power information transmission / reception unit that transmits / receives signals to / from other devices via a network,
The electric power system which performs charging / discharging control of the battery pack in any one of Claims 1-6 based on the information which the said electric power information transmission / reception part received.   The electric power system which receives supply of electric power from the battery pack in any one of Claims 1-6, and supplies electric power to the said battery pack from an electric power generating apparatus or an electric power network.

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