Battery system
The battery system maintains safe voltage ranges by adjusting SOC and current flow using switches and resistors/FETs/diodes, addressing voltage deviations at low temperatures to prevent battery deterioration.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA BATTERY CO LTD
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-07
Smart Images
Figure 2026112862000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a battery system including a secondary battery.
Background Art
[0002] Conventionally, various battery systems including secondary batteries have been proposed. When a secondary battery is charged in a low-temperature state, the maximum voltage during charging may be higher than the upper limit voltage of the secondary battery. Further, when the secondary battery discharges in a low-temperature state, the minimum voltage during discharge may be lower than the lower limit voltage of the secondary battery. In particular, the degree of voltage drop during discharge tends to be larger than the degree of voltage increase during charging. This is due to the voltage drop caused by the internal resistance of the secondary battery.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] As described above, when the voltage of the secondary battery exceeds the upper limit voltage, the secondary battery may deteriorate. Similarly, when the voltage of the secondary battery becomes lower than the lower limit voltage, the secondary battery may deteriorate. Therefore, when the temperature of the secondary battery decreases, it is preferable to keep the voltage of the secondary battery during charge and discharge within the range of a predetermined upper limit voltage and a lower limit voltage.
[0005] Regarding this point, Patent Document 1 discloses a power supply device for a forklift in which a load uses energy stored in a capacitor connected in parallel between the load and a maintenance plug. However, in this power supply device, when the temperature of the secondary battery decreases, the voltage of the secondary battery during charge and discharge cannot be kept within the range of a predetermined upper limit voltage and a lower limit voltage.
[0006] This disclosure aims to solve such problems and to provide a battery system that can keep the voltage of a secondary battery during charging and discharging within a predetermined upper and lower voltage range when the temperature of the secondary battery decreases. [Means for solving the problem]
[0007] A battery system comprising a secondary battery and a control device for controlling the charging and discharging of the secondary battery, The battery system is connected to a generator that supplies power to the secondary battery. The secondary battery consists of a first switch and a second switch connected in series, which are connected in parallel. The second switch has at least one resistor connected in series, The control device is A battery information acquisition unit that acquires the measured temperature of a secondary battery, It includes a temperature determination unit that determines whether the measured temperature is below a predetermined temperature threshold, If the control device determines that the measured temperature is below a predetermined temperature threshold, it turns off the first switch and supplies current from the generator to the secondary battery via the second switch and resistor to charge it. The resistance value of a resistor is the value that keeps the maximum voltage during charging of the secondary battery below the upper limit voltage of the secondary battery.
[0008] Furthermore, if the control device determines that the measured temperature is below a predetermined temperature threshold, it turns on the first switch to charge the secondary battery and executes a first SOC adjustment process to increase the State of Charge (SOC) of the secondary battery to the first SOC. The first SOC is the value that makes the minimum discharge voltage of a secondary battery at temperatures below the temperature threshold equal to or greater than the lower limit voltage of the secondary battery.
[0009] Furthermore, if the control device determines that the measured temperature exceeds a predetermined temperature threshold, it turns on the first switch to discharge the secondary battery and performs a second SOC adjustment process to reduce the state of charge (SOC) of the secondary battery to a second SOC that is smaller than the first SOC. The second SOC is the value that ensures the minimum discharge voltage of a secondary battery at temperatures exceeding the temperature threshold is equal to or greater than the lower limit voltage.
[0010] Furthermore, the control device includes a current determination unit that determines whether the value of the current input from the generator to the battery system is equal to or greater than a predetermined current threshold. If the control device determines that the value of the current input to the battery system is less than a predetermined current threshold, it may turn on the first switch to supply current from the generator to the secondary battery via the first switch and charge it.
[0011] A battery system comprising a secondary battery and a control device for controlling the charging and discharging of the secondary battery, The battery system is connected to a generator that supplies power to the secondary battery. The secondary battery consists of a first FET (Field Effect Transistor) connected in parallel and a second FET connected in series. The control device is A battery information acquisition unit that acquires the measured temperature of a secondary battery, It includes a temperature determination unit that determines whether the measured temperature is below a predetermined temperature threshold, If the control device determines that the measured temperature is below a predetermined temperature threshold, it turns off the first FET and supplies current from the generator to the secondary battery to charge it. When the second FET is ON, its resistance is greater than the resistance of the first FET when the first FET is ON, and this value keeps the maximum voltage during charging of the secondary battery below the upper limit voltage of the secondary battery.
[0012] Furthermore, if the control device determines that the measured temperature is below a predetermined temperature threshold, it turns on the first FET to charge the secondary battery and performs a first SOC adjustment process to increase the SOC of the secondary battery to the first SOC. The first SOC is the value that makes the minimum discharge voltage of a secondary battery at temperatures below the temperature threshold equal to or greater than the lower limit voltage of the secondary battery.
[0013] Furthermore, when it is determined that the measured temperature exceeds a predetermined temperature threshold, the control device turns on the first FET to discharge the secondary battery, and executes a second SOC adjustment process for reducing the SOC of the secondary battery to a second SOC smaller than the first SOC. The second SOC is a value that makes the minimum voltage during discharge of the secondary battery at a temperature exceeding the temperature threshold equal to or higher than the lower limit voltage.
[0014] Furthermore, the control device includes a current determination unit that determines whether or not the value of the current input from the generator to the battery system is equal to or greater than a predetermined current threshold. When it is determined that the value of the current input to the battery system is less than the predetermined current threshold, the control device can turn on the first FET and supply the current from the generator to the secondary battery through the first FET for charging.
[0015] A battery system including the secondary battery according to the present disclosure and a control device that controls charging and discharging of the secondary battery. The battery system is connected to a generator that supplies power to the secondary battery. The secondary battery has switches and resistors connected in parallel and then connected in series. The control device includes a battery information acquisition unit that acquires the measured temperature of the secondary battery, and a temperature determination unit that determines whether the measured temperature is equal to or lower than a predetermined temperature threshold. When it is determined that the measured temperature is equal to or lower than the predetermined temperature threshold, the control device turns off the switch and supplies the current from the generator to the secondary battery through the resistor for charging. The resistance value of the resistor is a value that makes the maximum voltage during charging of the secondary battery equal to or lower than the upper limit voltage of the secondary battery.
[0016] Also, when it is determined that the measured temperature is equal to or lower than the predetermined temperature threshold, the control device turns on the switch to charge the secondary battery and executes a first SOC adjustment process for increasing the SOC of the secondary battery to the first SOC. The first SOC is a value that makes the minimum voltage during discharge of the secondary battery at a temperature equal to or lower than the temperature threshold equal to or higher than the lower limit voltage of the secondary battery.
[0017] Further, when it is determined that the measured temperature exceeds a predetermined temperature threshold, the control device turns on the switch to discharge the secondary battery, and executes a second SOC adjustment process for reducing the SOC of the secondary battery to a second SOC smaller than the first SOC. The second SOC is a value that makes the minimum voltage during discharge of the secondary battery at a temperature exceeding the temperature threshold not less than the lower limit voltage.
[0018] Further, the control device includes a current determination unit that determines whether or not the value of the current input from the generator to the battery system is equal to or greater than a predetermined current threshold. When it is determined that the value of the current input to the battery system is less than the predetermined current threshold, the control device can turn on the switch and supply the current from the generator to the secondary battery through the switch for charging.
[0019] A battery system including the secondary battery according to the present disclosure and a control device that controls charging and discharging of the secondary battery The battery system is connected to a generator that supplies power to the secondary battery. The secondary battery has a first switch and a second switch connected in parallel and connected in series. The second switch has at least one diode that allows the charging current to pass through connected in series. The control device A battery information acquisition unit that acquires the measured temperature of the secondary battery, And a temperature determination unit that determines whether the measured temperature is less than or equal to a predetermined temperature threshold. When it is determined that the measured temperature is less than or equal to the predetermined temperature threshold, the control device turns off the first switch and supplies the current from the generator to the secondary battery through the second switch and the diode for charging. The resistance value of the diode is a value that makes the maximum voltage during charging of the secondary battery not more than the upper limit voltage of the secondary battery.
Advantages of the Invention
[0020] This disclosure provides a battery system that can maintain the voltage of a secondary battery during charging and discharging within a predetermined upper and lower voltage range when the temperature of the secondary battery decreases. [Brief explanation of the drawing]
[0021] [Figure 1] This diagram shows the relationship between the battery system related to this disclosure, the generator, and the power supply device. [Figure 2] This figure shows the time-series change in output power of the battery system, generator, and power supply device related to this disclosure. [Figure 3] This figure shows an example of the hardware configuration of a battery system according to one embodiment. [Figure 4] This figure shows an example of the configuration of the control device relating to this disclosure. [Figure 5] This figure shows an example of the processing performed by the control device related to this disclosure. [Figure 6] This figure shows an example of the first SOC adjustment process related to this disclosure. [Figure 7] This figure shows an example of the second SOC adjustment process related to this disclosure. [Figure 8] This figure shows the time-series change in the voltage of the secondary battery related to this disclosure. [Figure 9] This figure shows an example of the hardware configuration of a battery system according to another embodiment. [Figure 10] This figure shows an example of the hardware configuration of a battery system according to another embodiment. [Modes for carrying out the invention]
[0022] Figure 1 shows the relationship between the battery system 1, the generator 2, and the power supply device 3 according to this disclosure. The battery system 1, the generator 2, and the power supply device 3 are connected by a power line 4.
[0023] The battery system 1 is a system that supplies power to an external device or receives power from an external device. In this embodiment, the battery system 1 supplies power to the power supply target device 3. A specific example of the battery system 1 is a secondary battery pack, etc. Details of the battery system 1 will be described later.
[0024] Generator 2 is a device that generates electricity. Generator 2 supplies power to battery system 1 and power supply target device 3.
[0025] The power supply target device 3 is a device that receives power from the battery system 1 and / or the generator 2. Specific examples of the power supply target device 3 include inverter circuits that convert direct current to alternating current. However, the power supply target device 3 is not limited to inverter circuits; it also includes other devices that supply power from the battery system 1 and / or the generator 2 to devices other than the battery system 1 and / or the generator 2.
[0026] Figure 2 shows the time-series changes in the output power of the battery system 1, generator 2, and power supply device 3. As shown in Figure 2, when generator 2 is started, the output power of generator 2 is small, so power supply device 3 consumes the power of battery system 1. As the output power of generator 2 gradually increases, power supply device 3 begins to consume the power supplied by generator 2, and the power consumption of battery system 1 begins to decrease. When generator 2 is able to supply the power required by power supply device 3 on its own, power consumption of battery system 1 by power supply device 3 stops. After this, when power consumption by power supply device 3 ends, the power supplied by generator 2 gradually decreases. During this time, the secondary battery in battery system 1 is charged by the power supplied by generator 2. When the output power of generator 2 becomes 0, charging of the secondary battery ends.
[0027] Figure 3 shows an example of the hardware configuration of the battery system 1. It comprises secondary batteries 11A and 11B, a control device 10, a first switch SW1, a second switch SW2, a resistor R1, a positive terminal, and a negative terminal. The battery system 1 can be equipped with any number of secondary batteries.
[0028] The secondary batteries 11A and 11B are connected in parallel to a first switch SW1 and a second switch SW2, which are then connected in series. The second switch SW2 is connected in series to at least one resistor R1. The resistance value of resistor R1 is such that the maximum voltage of the secondary batteries 11A and 11B during charging is less than or equal to the upper limit voltage of the secondary batteries 11A and 11B. The upper limit voltage is the maximum voltage recommended when using the secondary batteries 11A and 11B.
[0029] When the first switch SW1 is ON and the second switch SW2 is ON, current flows through the electrical path including the first switch SW1, which has low resistance. Similarly, when the first switch SW1 is ON and the second switch SW2 is OFF, current flows through the electrical path including the first switch SW1, which has low resistance. On the other hand, when the first switch SW1 is OFF and the second switch SW2 is ON, current flows through the electrical path including the second switch SW2 and resistor R1. In this case, the current is consumed by resistor R1.
[0030] The control device 10 is a device that controls the charging and discharging of the battery system 1. Figure 4 is a diagram showing an example of the configuration of the control device 10. Specific examples of the control device 10 include an ECU (Electronic Control Unit). The control device 10 comprises at least one arithmetic unit 100, a storage device 120, and a communication interface (I / F) 130. Specific examples of the arithmetic unit 100 include a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The arithmetic unit 100 realizes the functional means shown in Figure 4 by executing instructions contained in a program stored in the storage device 120. Note that integrated circuits such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application Specific Integrated Circuits) may perform the processing executed by the control device 10. Integrated circuits such as processors, MPUs, FPGAs, and ASICs are equivalent to computers.
[0031] The storage device 120 stores various information such as programs executed by the arithmetic unit 100 and data processed by the arithmetic unit 100.
[0032] The communication interface 130 is an interface for data communication between the control device 10 and other devices.
[0033] The arithmetic unit 100 includes a switch control unit 101, a battery information acquisition unit 102, a temperature determination unit 103, a SOC calculation unit 104, an SOC determination unit 105, a power value acquisition unit 106, a power determination unit 107, and a current determination unit 108. These functional means can be implemented by a program.
[0034] The switch control unit 101 controls the on and off states of the first switch SW1 and the second switch SW2.
[0035] The battery information acquisition unit 102 acquires measurement information of the secondary batteries 11A and 11B. Specifically, the battery information acquisition unit 102 acquires the measured temperature Tb of the secondary batteries 11A and 11B from a temperature sensor (not shown) located near the secondary batteries 11A and 11B. The battery information acquisition unit 102 also acquires the measured voltage Vb of the secondary batteries 11A and 11B from a voltage sensor (not shown) electrically connected to each of the secondary batteries 11A and 11B.
[0036] The battery information acquisition unit 102 acquires the measured current Ib from a current sensor (not shown). This current sensor detects the current input from the generator 2 to the secondary batteries 11A and 11B (charging current) and the current output from the secondary batteries 11A and 11B to the power supply target device 3 (discharge current). The measured current Ib corresponds to either the charging current or the discharge current.
[0037] The temperature determination unit 103 determines whether the measured temperature Tb is below the temperature threshold Tb_th. Generally, the charge and discharge capacity of a secondary battery decreases as the temperature decreases. The temperature threshold Tb_th is set to be below the temperature at which the charge and discharge capacity of secondary batteries 11A and 11B decreases.
[0038] The SOC calculation unit 104 calculates the State of Charge (SOC) of secondary batteries 11A and 11B using the measured current Ib, measured voltage Vb, and measured temperature Tb of secondary batteries 11A and 11B. Specifically, the SOC calculation unit 104 calculates the charge / discharge amount (Ah) of secondary batteries 11A and 11B by integrating the measured current Ib. Next, the SOC calculation unit 104 calculates the SOC of secondary batteries 11A and 11B based on the fully charged capacity of secondary batteries 11A and 11B and the calculated charge / discharge amount. Then, the SOC calculation unit 104 identifies the internal resistance of secondary batteries 11A and 11B corresponding to the measured temperature Tb, based on the known correspondence between the measured temperature of secondary batteries 11A and 11B and the internal resistance of secondary batteries 11A and 11B. Next, the SOC calculation unit 104 calculates the open-circuit voltage (OCV) of secondary batteries 11A and 11B by subtracting the product of the measured current Ib and the internal resistance from the measured voltage Vb of secondary batteries 11A and 11B. Then, based on the known relationship between SOC and open-circuit voltage, the SOC calculation unit 104 derives the SOC corresponding to the calculated open-circuit voltage. Finally, the SOC calculation unit 104 can calculate the SOC of secondary batteries 11A and 11B by correcting the SOC obtained by integrating the measured current Ib using the SOC based on the open-circuit voltage.
[0039] The SOC calculation unit 104 can calculate the SOC of each of the secondary batteries 11A and 11B. Furthermore, the SOC calculation unit 104 can calculate the overall SOC of the secondary batteries 11A and 11B, such as the average SOC value.
[0040] The SOC determination unit 105 determines the State of Charge (SOC) of the secondary batteries 11A and 11B calculated by the SOC calculation unit 104. Specifically, the SOC determination unit 105 can compare the calculated SOC values of each secondary battery 11A and 11B with the first SOC. In addition, the SOC determination unit 105 can compare the calculated overall SOC value of the secondary batteries 11A and 11B with the first SOC.
[0041] The first SOC is the value that ensures the minimum discharge voltage of secondary batteries 11A and 11B at temperatures below the temperature threshold Tb_th is equal to or greater than the lower limit voltage of secondary batteries 11A and 11B. The lower limit voltage is the minimum voltage recommended when using secondary batteries 11A and 11B.
[0042] Furthermore, the SOC determination unit 105 compares the calculated SOC with the second SOC. The second SOC is a smaller value than the first SOC. The second SOC is a value that makes the minimum discharge voltage of the secondary batteries 11A and 11B at temperatures exceeding the temperature threshold Tb_th equal to or greater than the lower limit voltage of the secondary batteries 11A and 11B.
[0043] The power value acquisition unit 106 acquires a power value Pmes from the power supply target device 3, which indicates the output power of the power supply target device 3.
[0044] The power determination unit 107 determines whether the power value Pmes is greater than or equal to the power threshold P_out. The power threshold P_out is a value greater than 0 and less than the maximum output power of the power supply target device 3.
[0045] The current determination unit 108 determines whether the measured current Ib, which corresponds to the current input from the generator 2 to the battery system 1, is equal to or greater than the current threshold Ith. The current threshold Ith may be the current value corresponding to the upper limit voltage of the secondary batteries 11A and 11B.
[0046] Figure 5 is a flowchart showing an example of a process performed by the control device 10. In step S1, the switch control unit 101 turns on the first switch SW1 and the second switch SW2.
[0047] In step S2, the battery information acquisition unit 102 acquires the measured temperature Tb of the secondary batteries 11A and 11B. In step S3, the temperature determination unit 103 determines whether the measured temperature Tb is less than or equal to the temperature threshold Tb_th. If it is determined that the measured temperature Tb is less than or equal to the temperature threshold Tb_th (YES), in step S4, the control device 10 performs a first SOC adjustment process to increase the SOC of the secondary batteries 11A and 11B to the first SOC. On the other hand, if it is determined that the measured temperature Tb exceeds the temperature threshold Tb_th (NO), in step S5, the control device 10 performs a second SOC adjustment process to decrease the SOC of the secondary batteries 11A and 11B to the second SOC.
[0048] In step S6, the power value acquisition unit 106 acquires the power value Pmes of the power supply target device 3. In step S7, the power determination unit 107 determines whether the power value Pmes is equal to or greater than the power threshold P_out. If it is determined that the power value Pmes is less than the power threshold P_out (NO), the process returns to step S1. On the other hand, if the power value Pmes is equal to or greater than the power threshold P_out (YES), the process branches to step S8.
[0049] In step S8, the battery information acquisition unit 102 acquires the measured current Ib input to the battery system 1. In step S9, the current determination unit 108 determines whether the measured current Ib is greater than or equal to the current threshold Ith. If it is determined that the measured current Ib is less than the current threshold Ith (NO), the process returns to step S1. At this time, since the first switch SW1 is on, the current supplied from the generator 2 to the battery system 1 is supplied to the secondary batteries 11A and 11B via the first switch SW1, in other words, without going through the resistor R1. Therefore, the charging efficiency can be increased.
[0050] If it is determined that the measured current Ib is greater than or equal to the current threshold Ith (YES), in other words, if there is a possibility that a current corresponding to a voltage exceeding the upper limit voltage will be input to the secondary batteries 11A and 11B, the switch control unit 101 turns off the first switch SW1 in step S10, and the process returns to step S2. At this time, since the second switch SW2 is on, the current exceeding the current threshold Ith corresponding to the upper limit voltage is consumed by the resistor R1 and then flows to the secondary batteries 11A and 11B. Therefore, the voltage applied to the secondary batteries 11A and 11B can be kept below the upper limit voltage.
[0051] Figure 6 shows an example of the first SOC adjustment process. In step S20, the battery information acquisition unit 102 acquires the measured current Ib, measured voltage Vb, and measured temperature Tb of the secondary batteries 11A and 11B. In step S21, the SOC calculation unit 104 calculates the SOC of the secondary batteries 11A and 11B using the measured current Ib, measured voltage Vb, and measured temperature Tb. In step S22, the SOC determination unit 105 determines whether the SOC calculated in step S21 is the same value as the first SOC. If it is determined that the calculated SOC is the same value as the first SOC (YES), the first SOC adjustment process is completed.
[0052] On the other hand, if it is determined that the calculated SOC is not the same as the first SOC (NO), in step S23 the switch control unit 101 turns on the first switch SW1 and the second switch SW2. As a result, the charging current is input to the secondary batteries 11A and 11B via the first switch SW1. The discharge current is output via the first switch SW1.
[0053] In step S24, the battery information acquisition unit 102 acquires the measured current Ib, measured voltage Vb, and measured temperature Tb of the secondary batteries 11A and 11B. In step S25, the SOC calculation unit 104 calculates the SOC of the secondary batteries 11A and 11B using the measured current Ib, measured voltage Vb, and measured temperature Tb. In step S26, the SOC determination unit 105 determines whether the SOC calculated in step S25 is the same value as the first SOC. If it is determined that the calculated SOC is the same value as the first SOC (NO), the process returns to step S24. On the other hand, if it is determined that the calculated SOC is the same value as the first SOC (YES), the first SOC adjustment process is completed.
[0054] Figure 7 shows an example of the second SOC adjustment process. In step S30, the battery information acquisition unit 102 acquires the measured current Ib, measured voltage Vb, and measured temperature Tb of the secondary batteries 11A and 11B. In step S31, the SOC calculation unit 104 calculates the SOC of the secondary batteries 11A and 11B using the measured current Ib, measured voltage Vb, and measured temperature Tb. In step S32, the SOC determination unit 105 determines whether the SOC calculated in step S31 is the same value as the second SOC. If it is determined that the calculated SOC is the same value as the second SOC (YES), the second SOC adjustment process is completed.
[0055] On the other hand, if it is determined that the calculated SOC is different from the second SOC (NO), in step S33, the switch control unit 101 turns on the first switch SW1 and the second switch SW2. As a result, the charging current is input to the secondary batteries 11A and 11B via the first switch SW1. The discharge current is output via the first switch SW1.
[0056] In step S34, the battery information acquisition unit 102 acquires the measured current Ib, measured voltage Vb, and measured temperature Tb of the secondary batteries 11A and 11B. In step S35, the SOC calculation unit 104 calculates the SOC of the secondary batteries 11A and 11B using the measured current Ib, measured voltage Vb, and measured temperature Tb. In step S36, the SOC determination unit 105 determines whether the SOC calculated in step S35 is the same value as the second SOC. If it is determined that the calculated SOC is a different value from the second SOC (NO), the process returns to step S34. On the other hand, if it is determined that the calculated SOC is the same value as the second SOC (YES), the second SOC adjustment process is completed.
[0057] As described above, the battery information acquisition unit 102 of the control device 10 of the battery system 1 acquires the measured temperature of the secondary batteries 11A and 11B. The temperature determination unit 103 determines whether the measured temperature is below a predetermined temperature threshold Tb_th. If it is determined that the measured temperature is below the predetermined temperature threshold Tb_th, the control device 10 turns off the first switch SW1 and supplies power from the generator 2 to the secondary batteries 11A and 11B via the second switch SW2 and resistor R1 to charge them. The resistance value of resistor R1 is a value that keeps the maximum voltage of the secondary batteries 11A and 11B during charging below the upper limit voltage of the secondary batteries 11A and 11B.
[0058] By adopting this configuration, when the measured temperature of secondary batteries 11A and 11B is below a predetermined temperature threshold Tb_th, the maximum voltage of secondary batteries 11A and 11B during charging is kept below the upper limit voltage because the charging current is consumed by resistor R1, as shown in Figure 8. As a result, even when the temperature of secondary batteries 11A and 11B decreases, the voltage of secondary batteries 11A and 11B during charging and discharging can be kept within the predetermined upper and lower voltage limits.
[0059] Furthermore, if the control device 10 determines that the measured temperature is below a predetermined temperature threshold Tb_th, it turns on the first switch SW1 to charge the secondary batteries 11A and 11B and performs a first SOC adjustment process to increase the SOC of the secondary batteries 11A and 11B to a first SOC. The first SOC is a value that makes the minimum discharge voltage of the secondary batteries 11A and 11B at temperatures below the temperature threshold Tb_th equal to or greater than the lower limit voltage of the secondary batteries 11A and 11B.
[0060] Generally, the lower the temperature, the greater the voltage drop in the secondary battery, and therefore the minimum voltage of the secondary battery tends to fall below the lower limit voltage. In the above-described embodiment, by adopting the above configuration, when the measured temperature of secondary batteries 11A and 11B is below the temperature threshold Tb_th, the SOC of secondary batteries 11A and 11B increases to the first SOC, and as shown in Figure 8, it is possible to prevent the minimum voltage of secondary batteries 11A and 11B during discharge from falling below the lower limit voltage of secondary batteries 11A and 11B.
[0061] Furthermore, if the control device 10 determines that the measured temperature exceeds a predetermined temperature threshold Tb_th, it turns on the first switch SW1 to discharge the secondary batteries 11A and 11B and performs a second SOC adjustment process to reduce the SOC of the secondary batteries 11A and 11B to a second SOC. The second SOC is a value that makes the minimum voltage during discharge of the secondary batteries 11A and 11B at temperatures exceeding the temperature threshold Tb_th equal to or greater than the lower limit voltage.
[0062] By adopting this configuration, if the measured temperature of secondary batteries 11A and 11B exceeds the temperature threshold Tb_th, the SOC of secondary batteries 11A and 11B decreases to the second SOC. As shown in Figure 8, this prevents the maximum voltage of secondary batteries 11A and 11B during charging from exceeding the upper limit voltage of secondary batteries 11A and 11B.
[0063] Furthermore, the current determination unit 108 determines whether the value of the current input from the generator 2 to the battery system 1 is equal to or greater than a predetermined current threshold Ith. If it is determined that the value of the current input to the battery system 1 is less than the predetermined current threshold Ith, the control device 10 turns on the first switch SW1 and supplies current from the generator 2 to the secondary batteries 11A and 11B via the first switch SW1 to charge them.
[0064] By adopting this configuration, the current supplied from the generator 2 to the battery system 1 is supplied to the secondary batteries 11A and 11B without passing through the resistor R1, thereby improving charging efficiency.
[0065] Figure 9 shows an example of the hardware configuration of a battery system 5 according to another embodiment. In this embodiment, as shown in Figure 9, a first FET 20 may be used instead of the first switch SW1 of the battery system 1 described above, and a second FET 30 may be used instead of the second switch SW2 and resistor R1. In this case, the switch control unit 101 functions as an FET control unit that controls the on / off state of the FETs. The resistance value of the second FET 30 when the second FET 30 is on can be determined in the same way as the resistor R1. Specifically, the resistance value of the second FET 30 when the second FET 30 is on is a value that keeps the maximum voltage during charging of the secondary batteries 11A and 11B below the upper limit voltage of the secondary batteries 11A and 11B. Also, the resistance value of the second FET 30 when the second FET 30 is on is a value greater than the resistance value of the first FET 20 when the first FET 20 is on.
[0066] Figure 10 shows an example of the hardware configuration of a battery system 6 according to yet another embodiment. In this embodiment, as shown in Figure 10, multiple diodes 31 to 33 may be used instead of the resistor R1 provided in the battery system 1. Diodes 31 to 33 are connected in series with the switch SW2. Diodes 31, 32 and diode 33 are connected in parallel.
[0067] Diodes 31 and 32 are charging diodes that allow charging current to pass through to the secondary batteries 11A and 11B. The total resistance of the charging diodes 31 and 32 is a value that keeps the maximum voltage during charging of the secondary batteries 11A and 11B below the upper limit voltage of the secondary batteries 11A and 11B. Preferably, the number and resistance values of the charging diodes 31 and 32 are determined such that the total resistance of the charging diodes 31 and 32 keeps the maximum voltage during charging of the secondary batteries 11A and 11B below the upper limit voltage.
[0068] When the secondary batteries 11A and 11B are being charged, the switch control unit 101 turns switch SW1 off and switch SW2 on, so that the charging current is consumed by flowing through the charging diodes 31 and 32. This makes it possible to lower the maximum voltage of the secondary batteries 11A and 11B during charging.
[0069] Diode 33 is a discharge diode that allows the discharge current from secondary batteries 11A and 11B to pass through. When switch SW1 is off, diode 33 functions as an emergency discharge path when secondary batteries 11A and 11B suddenly enter a discharge state.
[0070] Furthermore, in other embodiments, the second switch SW2 of the battery system 1 may be omitted. In this case, the switch control unit 101 controls only the first switch SW1.
[0071] In the above example, the program describing the above-described process can be stored and provided to the computer using various types of non-transitory computer-readable medium. Non-transitory computer-readable mediums include various types of tangible storage mediums. Examples of non-transitory computer-readable mediums include magnetic storage media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical storage media (e.g., magneto-optical disks), CD-ROMs, CD-Rs, CD-R / Ws, and semiconductor memory (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, RAMs). Alternatively, the program may be provided to the computer using various types of transient computer-readable mediums. Examples of transient computer-readable mediums include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable mediums can supply the program to the computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels.
[0072] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from the spirit of this disclosure. [Explanation of Symbols]
[0073] 1: Battery System 2: Generator 3: Devices to which power is supplied 4: Power lines 5: Battery System 6: Battery System 10: Control device 100: Arithmetic device 101: Switch Control Unit 102:Battery information acquisition section 103:Temperature judgment section 104:SOC calculation section 105:SOC judgment section 106: Power Value Acquisition Unit 107: Power judgment section 108: Current judgment section 120: Storage device 130: Communication Interface 11A: Secondary battery 11B: Secondary battery 20: First FET 30: Second FET SW1: First switch SW2: The Second Switch 31, 32: Diode 33: Diode
Claims
1. A battery system comprising a secondary battery and a control device for controlling the charging and discharging of the secondary battery, The battery system is connected to a generator that supplies power to the secondary battery, The aforementioned secondary battery has a first switch and a second switch connected in series, which are connected in parallel. The second switch has at least one resistor connected in series, The control device is A battery information acquisition unit that acquires the measured temperature of the secondary battery, The system includes a temperature determination unit that determines whether the measured temperature is below a predetermined temperature threshold, When the control device determines that the measured temperature is below a predetermined temperature threshold, it turns off the first switch and supplies current from the generator to the secondary battery via the second switch and the resistor to charge it. The resistance value of the aforementioned resistor is a value that keeps the maximum voltage during charging of the secondary battery below the upper limit voltage of the secondary battery. Battery system.
2. When the control device determines that the measured temperature is below a predetermined temperature threshold, it turns on the first switch to charge the secondary battery and performs a first SOC adjustment process to increase the State of Charge (SOC) of the secondary battery to a first SOC. The battery system according to claim 1, wherein the first SOC is a value that causes the minimum voltage during discharge of the secondary battery at a temperature below the temperature threshold to be equal to or greater than the lower limit voltage of the secondary battery.
3. If the control device determines that the measured temperature exceeds a predetermined temperature threshold, it turns on the first switch to discharge the secondary battery and performs a second SOC adjustment process to reduce the SOC of the secondary battery to a second SOC that is smaller than the first SOC. The battery system according to claim 2, wherein the second SOC is a value that causes the minimum voltage during discharge of the secondary battery at a temperature exceeding the temperature threshold to be equal to or greater than the lower limit voltage.
4. The control device includes a current determination unit that determines whether the value of the current input from the generator to the battery system is equal to or greater than a predetermined current threshold. The battery system according to any one of claims 1 to 3, wherein if the value of the current input to the battery system is determined to be less than a predetermined current threshold, the control device turns on the first switch to supply current from the generator to the secondary battery via the first switch to charge it.
5. A battery system comprising a secondary battery and a control device for controlling the charging and discharging of the secondary battery, The battery system is connected to a generator that supplies power to the secondary battery, The aforementioned secondary battery has a first FET (Field Effect Transistor) and a second FET connected in series, which are connected in parallel. The control device is A battery information acquisition unit that acquires the measured temperature of the secondary battery, The system includes a temperature determination unit that determines whether the measured temperature is below a predetermined temperature threshold, When the control device determines that the measured temperature is below a predetermined temperature threshold, it turns off the first FET and supplies current from the generator to the secondary battery to charge it. The resistance value of the second FET when the second FET is ON is greater than the resistance value of the first FET when the first FET is ON, and is a value that keeps the maximum voltage during charging of the secondary battery below the upper limit voltage of the secondary battery. Battery system.
6. When the control device determines that the measured temperature is below a predetermined temperature threshold, it turns on the first FET to charge the secondary battery and performs a first SOC adjustment process to increase the SOC of the secondary battery to a first SOC. The battery system according to claim 5, wherein the first SOC is a value that causes the minimum voltage during discharge of the secondary battery at a temperature below the temperature threshold to be equal to or greater than the lower limit voltage of the secondary battery.
7. If the control device determines that the measured temperature exceeds a predetermined temperature threshold, it turns on the first FET to discharge the secondary battery and performs a second SOC adjustment process to reduce the SOC of the secondary battery to a second SOC that is smaller than the first SOC. The battery system according to claim 6, wherein the second SOC is a value that causes the minimum voltage during discharge of the secondary battery at a temperature exceeding the temperature threshold to be equal to or greater than the lower limit voltage.
8. The control device includes a current determination unit that determines whether the value of the current input from the generator to the battery system is equal to or greater than a predetermined current threshold. The battery system according to any one of claims 5 to 7, wherein if the value of the current input to the battery system is determined to be less than a predetermined current threshold, the control device turns on the first FET and supplies current from the generator to the secondary battery via the first FET to charge it.
9. A battery system comprising a secondary battery and a control device for controlling the charging and discharging of the secondary battery, The battery system is connected to a generator that supplies power to the secondary battery, The aforementioned secondary battery has a switch and a resistor connected in series, which are connected in parallel. The control device is A battery information acquisition unit that acquires the measured temperature of the secondary battery, The system includes a temperature determination unit that determines whether the measured temperature is below a predetermined temperature threshold, When the control device determines that the measured temperature is below a predetermined temperature threshold, it turns off the switch and supplies current from the generator to the secondary battery via the resistor to charge it. The resistance value of the aforementioned resistor is a value that keeps the maximum voltage during charging of the secondary battery below the upper limit voltage of the secondary battery. Battery system.
10. When the control device determines that the measured temperature is below a predetermined temperature threshold, it turns on the switch to charge the secondary battery and performs a first SOC adjustment process to increase the SOC of the secondary battery to a first SOC. The battery system according to claim 9, wherein the first SOC is a value that causes the minimum voltage during discharge of the secondary battery at a temperature below the temperature threshold to be equal to or greater than the lower limit voltage of the secondary battery.
11. When the control device determines that the measured temperature exceeds a predetermined temperature threshold, it turns on the switch to discharge the secondary battery and performs a second SOC adjustment process to reduce the SOC of the secondary battery to a second SOC that is smaller than the first SOC. The battery system according to claim 10, wherein the second SOC is a value that causes the minimum voltage during discharge of the secondary battery at a temperature exceeding the temperature threshold to be equal to or greater than the lower limit voltage.
12. The control device includes a current determination unit that determines whether the value of the current input from the generator to the battery system is equal to or greater than a predetermined current threshold. The battery system according to any one of claims 9 to 11, wherein if the value of the current input to the battery system is determined to be less than a predetermined current threshold, the control device turns on the switch to supply current from the generator to the secondary battery via the switch to charge it.
13. A battery system comprising a secondary battery and a control device for controlling the charging and discharging of the secondary battery, The battery system is connected to a generator that supplies power to the secondary battery, The aforementioned secondary battery has a first switch and a second switch connected in series, which are connected in parallel. The second switch has at least one diode connected in series to allow the charging current to pass through, The control device is A battery information acquisition unit that acquires the measured temperature of the secondary battery, The system includes a temperature determination unit that determines whether the measured temperature is below a predetermined temperature threshold, When the control device determines that the measured temperature is below a predetermined temperature threshold, it turns off the first switch and supplies current from the generator to the secondary battery via the second switch and the diode to charge it. The resistance value of the diode is such that the maximum voltage during charging of the secondary battery is less than or equal to the upper limit voltage of the secondary battery. Battery system.