JP5453877B2 - Power storage device temperature rising system - Google Patents

Description

  The present invention relates to a temperature raising system for raising the temperature of a power storage device including a plurality of power storage elements.

  When the secondary battery is in a low temperature state (for example, below freezing point), the input / output characteristics (characteristics related to charging / discharging) of the secondary battery may be deteriorated. Therefore, in order to suppress the secondary battery from being excessively cooled, there is a battery that heats the secondary battery by applying heat from the outside or generates heat inside the secondary battery.

  For example, Patent Document 1 describes a battery in which a positive electrode terminal and a negative electrode terminal of a single battery are connected by a short circuit having a resistance element. In this configuration, when the positive electrode terminal and the negative electrode terminal are short-circuited, heat can be generated inside the unit cell by the internal resistance of the unit cell. In addition, when the positive electrode terminal and the negative electrode terminal are short-circuited, a current flows through the resistance element and the resistance element generates heat. Therefore, the unit cell can be heated from the outside using this heat.

JP 2004-63397 A (paragraph 0031, FIG. 1) JP 2006-151091 A

  When a battery pack including a plurality of secondary batteries is mounted on a vehicle, if the single battery described in Patent Document 1 is used as each secondary battery, the structure of the battery pack becomes complicated or the battery pack becomes larger. I will. That is, since a short circuit must be provided for all the secondary batteries, the structure of the battery pack including a plurality of secondary batteries becomes complicated.

  Further, when all the secondary batteries constituting the battery pack are short-circuited, the total amount of heat generated by the resistance elements is excessively increased, which may adversely affect electronic devices arranged around the battery pack. In addition, if the amount of heat generated by the resistance element increases too much, heat energy that is not used to raise the temperature of the secondary battery may also be generated.

  Accordingly, an object of the present invention is to provide a temperature raising system capable of raising the temperature of a power storage device including a plurality of power storage elements with a simple configuration.

  The present invention is a temperature raising system that raises the temperature of a power storage device mounted on a vehicle. The power storage device constitutes the power storage device, and a plurality of power storage elements electrically connected in series, and a positive electrode terminal (total And a short circuit that is connected to the positive terminal) and the negative terminal (total negative terminal) to short-circuit the power storage device. Here, the short circuit includes a switching element that switches between allowing and prohibiting a short circuit of the power storage device and a resistance element that is energized when the power storage device is short circuited. Then, the resistance element transmits heat generated by energization at the time of the short circuit to at least one of engine oil and transmission oil used in the vehicle and heats at least one of the oils.

  The output of the power storage device can be used to start the internal combustion engine of the vehicle. Here, by causing the power storage device to generate heat by a short circuit, the input / output characteristics of the power storage device can be improved, and the internal combustion engine can be efficiently started at a low temperature. On the other hand, a resistance element can be arranged in a case that accommodates one of the oils and brought into contact with the one oil. Thereby, the heat generated in the resistance element can be efficiently transferred to one of the oils.

Further, Atsushi Nobori system of the present invention includes a temperature sensor for detecting the temperature of the power storage device, based on the temperature detected by the temperature sensor, and a controller for controlling the switching operation of the switch element. Here, when the detected temperature is lower than a predetermined temperature, Ru short-circuit the power storage device via a switch element. Thereby, it can suppress that the temperature of an electrical storage apparatus is cooled too much . Large difference component of detection temperature and the predetermined temperature I see, it increases the short-circuit time. Thereby, the power storage device can be raised to a desired temperature.

  Further, the current power storage amount in the power storage device is calculated, and when the calculated power storage amount is larger than the predetermined power storage amount, the power storage device is short-circuited via the switch element, and the calculated power storage amount is When the amount is less than the amount of electricity stored, a short circuit of the electricity storage device can be prohibited. Thus, for example, when starting the internal combustion engine using the output of the power storage device, the power storage device can hold the amount of power storage required to start the internal combustion engine.

  According to the present invention, by short-circuiting the power storage device by the short circuit, the plurality of power storage elements constituting the power storage device can generate heat due to the internal resistance, and each power storage element can be warmed. Further, since the short circuit is only provided for the power storage device, a simple configuration can be obtained. Furthermore, by using at least one of engine oil and transmission oil using the heat generated by the resistance element of the short circuit, the electric energy released from the power storage device at the time of the short circuit can be efficiently used.

In Example 1 of this invention, it is a figure which shows the structure of a part of vehicle provided with the battery pack. It is the schematic which shows the structure by which the resistive element was arrange | positioned in the oil pan. It is an external view which shows the structure of a resistive element. In Example 1, it is a flowchart which shows the temperature rising process of a battery pack.

  Examples of the present invention will be described below.

  A temperature raising system that is Embodiment 1 of the present invention will be described with reference to FIG. Here, FIG. 1 is a block diagram illustrating a partial configuration of a vehicle including a battery pack.

  The battery pack (power storage device) 10 of this embodiment is mounted on a vehicle. Such vehicles include hybrid vehicles and electric vehicles. A hybrid vehicle is a vehicle provided with an internal combustion engine and a fuel cell in addition to the battery pack 10 as a power source for running the vehicle. An electric vehicle is a vehicle that uses only the battery pack 10 as a power source of the vehicle.

  The battery pack 10 includes a battery module 11 configured by electrically connecting a plurality of single cells (electric storage elements) 12 in series. As the unit cell 12, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor (capacitor) can be used instead of the secondary battery. In addition, as a shape of the cell 12, there exist a cylindrical shape and a square, for example, and it can select suitably. Moreover, the number of the single cells 12 constituting the battery module 11 can be appropriately set based on the output of each single cell 12 and the output given to the battery pack 10.

  The total positive terminal and the total negative terminal of the battery module 11 are connected to the inverter 40 via system relays 61 and 62. The system relays 61 and 62 are switched between an on state and an off state by receiving a control signal from the controller 20 described later. If the system relays 61 and 62 are in an on state, charging / discharging of the battery module 11 is allowed, and if the system relays 61 and 62 are in an off state, charging / discharging of the battery module 11 is prohibited.

  The inverter 40 converts the DC power from the battery module 11 into AC power and outputs the AC power to the motor (three-phase AC motor) 50. The motor 50 is connected to the wheels, and the vehicle can travel by transmitting the driving force of the motor 50 to the wheels. On the other hand, when the vehicle is braked, the motor 50 functions as a generator by receiving kinetic energy from the wheels. Here, the braking of the vehicle includes a state where the accelerator pedal is not operated and a state where the brake pedal is operated. The AC power generated by the motor 50 is converted into DC power by the inverter 40 and then supplied to the battery module 11. Thereby, the battery module 11 is charged, and the kinetic energy generated when the vehicle is braked can be stored in the battery module 11 as regenerative power.

  Note that a DC / DC converter may be arranged between the battery module 11 and the inverter 40. In this case, the output voltage of the battery module 11 is boosted by the DC / DC converter and then supplied to the inverter 40, or the output voltage of the inverter 40 is stepped down by the DC / DC converter and then supplied to the battery module 11. You can do it. By using the DC / DC converter in this way, the number of single cells 12 constituting the battery module 11 can be reduced, and the battery pack 10 can be downsized.

  The battery pack 10 is provided with a temperature sensor 13 for detecting the temperature of the battery module 11 (unit cell 12) and a voltage sensor 14 for detecting the voltage of the unit cell 12. Information acquired by the temperature sensor 13 and the voltage sensor 14 is output to the controller 20.

  Here, the number of temperature sensors 13 can be set as appropriate. When a plurality of temperature sensors 13 are used, the temperature sensors 13 can be arranged at a plurality of positions in the battery pack 10. Thereby, the temperature in the several position of the battery pack 10 is detectable.

  The number of voltage sensors 14 can also be set as appropriate. Specifically, the voltage sensors 14 can be provided as many as the number of unit cells 12 constituting the battery module 11, and in this case, the voltage of each unit cell 12 can be detected. Moreover, the number of voltage sensors 14 smaller than the number of single cells 12 constituting the battery module 11 can be provided. In this case, the block voltage in the battery module 11 can be detected. The block voltage indicates a voltage value in each block when the plurality of single cells 12 constituting the battery module 11 are divided into a plurality of blocks.

  A short circuit 80 for short-circuiting the total positive terminal and the total negative terminal of the battery module 11 is connected to the battery module 11. The short circuit 80 includes a resistance element 30, and the resistance element 30 has a function of adjusting a current flowing between these terminals when the total positive terminal and the total negative terminal of the battery module 11 are short-circuited. doing. The resistance element 30 is electrically connected to the battery module 11 in parallel. A short-circuit relay (switch element) 70 is disposed between the total positive terminal of the battery module 11 and one end of the resistance element 30.

  The short-circuit relay 70 is switched between an on state and an off state in response to a control signal from the controller 20. When the short-circuit relay 70 is in the ON state, the current of the battery module 11 flows through the resistance element 30, and the battery module 11 is short-circuited via the resistance element 30. On the other hand, when the short-circuit relay 70 is in the OFF state, the short circuit of the battery module 11 is prohibited, and the current of the battery module 11 does not flow to the resistance element 30.

  As shown in FIG. 2, the resistance element 30 is disposed inside an oil pan (case) 90 that houses the engine oil 91 and is in contact with the engine oil 91. As shown in FIG. 3, a plurality of fins 31 projecting outward from the outer wall surface are provided on the outer wall surface of the resistance element 30. By providing the plurality of fins 31, the contact area with the engine oil 91 can be increased. In addition, the shape of the fin 31 can be set as appropriate, and it is sufficient that the contact area with the engine oil 91 can be increased.

  Moreover, the resistance element 30 should just be arrange | positioned in the accommodation space of the engine oil 91 formed inside the oil pan 90, and a specific position can be set suitably. Here, the resistance element 30 is preferably immersed in the engine oil 91 so that the entire surface of the resistance element 30 is in contact with the engine oil 91.

  The engine oil 91 accommodated in the oil pan 90 is sucked up by the oil pump through the strainer, moves through the oil gallery, and is guided to each part of the engine (internal combustion engine). Then, the engine oil 91 that reaches each part of the engine falls or moves along the parts of the engine and returns to the oil pan 90.

  In the present embodiment, when the short circuit relay 70 is turned on when the system relays 61 and 62 are in the off state, the total plus terminal and the total minus terminal of the battery module 11 are short-circuited via the resistance element 30. For this reason, each unit cell 12 can be made to generate heat by the internal resistance of each unit cell 12, and the temperature of the unit cell 12 can be raised.

  Here, if the unit cell 12 is excessively cooled, the input / output characteristics of the unit cell 12 may be deteriorated. In such a case, it is possible to prevent the input / output characteristics of the unit cells 12 from deteriorating by short-circuiting the battery module 11 to cause each unit cell 12 to generate heat. And when starting the engine of a vehicle using the output of the battery module 11 like a present Example, even when a vehicle (battery pack 10) is put into a low temperature state like a cold region, an engine is made efficient. It can be started well. Further, the kinetic energy generated during braking of the vehicle can be efficiently recovered, and the fuel efficiency of the vehicle can be improved.

  Further, when the battery module 11 is short-circuited, the current of the battery module 11 flows to the resistance element 30 and the resistance element 30 can generate heat. Since the resistance element 30 is in contact with the engine oil 91, the heat generated by the resistance element 30 is transmitted to the engine oil 91 and can warm the engine oil 91. That is, the electric energy discharged from the battery module 11 is used to warm the engine oil 91. Here, if the engine oil 91 is warmed, the viscosity of the engine oil 91 can be reduced, and the friction loss by the engine oil 91 can be reduced. Moreover, the load of the oil pump for sucking the engine oil 91 can be reduced, or the entire engine can be warmed to reduce the fuel spray amount.

  Here, when the engine oil 91 is in a low temperature state (for example, below freezing point), the friction loss due to the engine oil 91 also increases. In such a case, by causing the resistance element 30 to generate heat and warming the engine oil 91, friction loss due to the engine oil 91 can be efficiently reduced, and the engine can be efficiently started at a low temperature. Thereby, the fuel consumption of the vehicle can be improved.

  On the other hand, if the resistance element 30 is arranged at a position adjacent to the strainer (in other words, in the vicinity of the strainer), the engine oil 91 warmed by the resistance element 30 can be quickly guided to each part of the engine. In order to efficiently suck the engine oil 91 from the strainer, it is preferable to dispose the resistance element 30 apart from the strainer suction port. For example, the strainer can be disposed so that the suction port of the strainer faces the bottom surface of the oil pan 90, and the resistance element 30 and the strainer can be disposed side by side along the bottom surface of the oil pan 90.

  In this embodiment, the resistance element 30 is brought into contact with the engine oil 91. However, the present invention is not limited to this, and the resistance element 30 can be brought into contact with the transmission oil. Specifically, the resistance element 30 can be disposed in an oil pan provided in the transmission case and for accommodating transmission oil, and the resistance element 30 can be brought into contact with the transmission oil.

  In this configuration, heat generated in the resistance element 30 when the battery module 11 is short-circuited can be transmitted to the transmission oil, and the viscosity of the transmission oil can be reduced. Further, friction loss due to transmission oil can be reduced, and the operation of the transmission can be performed efficiently. Here, when the transmission oil is in a low temperature state (for example, below freezing point), friction loss due to the transmission oil also increases. In such a case, by causing the resistance element 30 to generate heat and warming the transmission oil, friction loss due to the transmission oil can be efficiently reduced.

  In the oil pan for transmission oil, the position where the resistance element 30 is disposed can be set as appropriate. However, similarly to the engine oil 91 described above, the position adjacent to the suction port for transmission oil (in other words, the suction port The resistive element 30 can be disposed in the vicinity. Thereby, the transmission oil warmed by the resistance element 30 can be quickly guided to each part of the transmission.

  On the other hand, two resistance elements 30 can be connected to the battery module 11 so that one resistance element 30 is in contact with the engine oil 91 and the other resistance element 30 is in contact with the transmission oil. Here, the two resistance elements 30 may be connected in series to the battery module 11 or may be connected in parallel. In this configuration, by short-circuiting the battery module 11, the two resistance elements 30 can generate heat, and both the engine oil 91 and the transmission oil can be warmed.

  Next, the temperature increasing process of the battery pack 10 will be described using the flowchart shown in FIG. The process shown in FIG. 4 is performed when starting the engine of the vehicle.

  In step S <b> 11, the controller 20 detects the temperature of the battery module 11 based on the output of the temperature sensor 13. In step S12, it is determined whether or not the temperature (battery temperature) detected in step S11 is lower than a threshold value.

  Here, the threshold value is the temperature of the battery module 11 when a minimum output for starting the engine is obtained, and differs depending on the characteristics of the unit cell 12 and can be obtained in advance. If the temperature of the battery module 11 is too low, the power of the battery module 11 may not reach the power (starting power) for starting the engine. In such a case, it is necessary to warm the battery module 11. is there. That is, by heating the battery module 11, the input / output characteristics of the single cell 12 can be improved, and the power of the battery module 11 can be made equal to or higher than the starting power.

  In step S12, if the detected temperature is lower than the threshold value, the process proceeds to step S13, and if not, the process proceeds to step S23. In step S <b> 13, the controller 20 calculates a short-circuit required time (A [second]). The short circuit required time is a short circuit time (duration) of the battery module 11 necessary to raise the temperature of the battery module 11 to the above-described threshold. In the present embodiment, as described above, the battery module 11 is short-circuited to cause the battery module 11 to generate heat, and the temperature rise in the battery module 11 varies depending on the short-circuit time.

  Here, the relationship between the temperature change (ΔT) of the battery module 11 and the short circuit time can be obtained in advance, and a map showing this relationship can be stored in the memory. If comprised in this way, a short circuit required time can be calculated | required based on the map in memory, and the difference ((DELTA) T) of the present temperature and threshold value of the battery module 11. FIG. In addition, the short circuit required time can also be calculated | required using the computing equation which shows the relationship between the temperature change of the battery module 11 and a short circuit time instead of a map. The short circuit required time calculated in step S13 can be stored in a nonvolatile memory such as an EEPROM.

  For example, when the battery module 11 is configured by using 60 unit cells 12 having a rated voltage of 3.6 [V] and a heat capacity of 200 [J / K], the battery module 11 (60 unit cells 12). In order to raise the temperature by 10 [° C.] in 10 [seconds], heat generation of 12 [kW] (= 200 [J / K] × 10 [K] ÷ 10 [seconds]) is required. Here, in order to protect the cell 12, when the lower limit voltage of the cell 12 is 1.8 [V] and the battery module 11 is short-circuited, 111 [A] (= 12 [kW] ÷ 1. 8 [V] × 60 cells) needs to flow for 10 seconds. This time (10 seconds) is the short-circuit required time.

  On the other hand, in order to maintain the lower limit voltage of the unit cell 12 at 1.8 [V], the short-circuit current must not exceed 111 [A]. Therefore, the electrical resistance value of the resistance element 30 is 0.972. [Ω]. Here, when the battery module 11 is short-circuited for 10 seconds as described above, the resistance element 30 generates heat at 12 [kW] (= 0.972 [Ω] × 111 [A] ^ 2 = 120 [kJ]). become. This amount of heat is used to heat the engine oil 91.

  In step S <b> 14, the controller 20 detects the voltage (or block voltage) of the unit cell 12 based on the output of the voltage sensor 14. In step S15, the SOC (State Of Charge) of the unit cell 12 is calculated using the detection voltage obtained in step S14. The SOC is the current charge amount (remaining capacity, charged amount) in the unit cell 12. In this embodiment, the SOC of the unit cell 12 is calculated based on the detection result of the voltage sensor 14, but a current sensor for detecting the current value of the battery module 11 is provided, and the current sensor is detected. Based on the result, the SOC of the unit cell 12 can also be calculated.

  In step S16, the controller 20 determines whether or not the SOC calculated in step S15 is greater than a preset threshold value (SOC). This threshold value (SOC) is the amount of charge of the unit cell 12 required to start the engine using the output of the battery module 11, and can be set in advance.

  If the calculated SOC is larger than the threshold value (SOC) in step S16, the process proceeds to step S17. Otherwise, the process proceeds to step S23. Here, when the calculated SOC is smaller than the threshold value (SOC), the engine is started in step S23 without performing the processing after step S17 described later (short-circuit processing of the battery module 11). . This is because if the battery module 11 is short-circuited, the SOC of the unit cell 12 is lowered and the engine cannot be started using the output of the battery module 11. .

  In step S <b> 17, the controller 20 calculates a short-circuitable time (B [seconds]). The short-circuitable time is the longest time that the battery module 11 can be short-circuited, and can be determined based on the SOC calculated in step S15. Here, when the single battery 12 is short-circuited (discharged), the SOC of the single battery 12 is lowered accordingly. If the SOC of the unit cell 12 is too low, the engine may not be started due to the output of the battery module 11. Therefore, in step S17, the longest time during which the unit cell 12 can be discharged is obtained in the unit cell 12 while ensuring the starting power of the engine.

  Specifically, the relationship between the SOC calculated in step S15 and the above-described threshold (SOC) difference and the short-circuitable time can be obtained, and a map indicating this relationship can be stored in the memory. Thereby, the shortable time can be specified based on the difference between the map and the SOC. In addition, the short circuit possible time can also be calculated | required using the arithmetic formula which shows the relationship between the difference of SOC, and short circuitable time instead of a map. The short-circuitable time calculated in step S17 can be stored in a nonvolatile memory such as an EEPROM.

  In step S18, the controller 20 determines whether or not the short-circuit possible time (B) calculated in step S17 is longer than the short-circuit required time (A) calculated in step S13. If the short-circuit possible time (B) is longer than the short-circuit required time (A), the process proceeds to step S19. Otherwise, the process proceeds to step S20.

  In step S <b> 19, the controller 20 short-circuits the battery module 11 via the resistance element 30 by switching the short-circuit relay 70 from the off state to the on state. Here, the time for which the short-circuit relay 70 is kept in the ON state is the short-circuit required time (A), and the controller 20 switches the short-circuit relay 70 from the ON state to the OFF state at the timing when this time has elapsed (step S21). .

  In Step S <b> 20, the controller 20 short-circuits the battery module 11 through the resistance element 30 by switching the short-circuit relay 70 from the off state to the on state. Here, the time for which the short-circuit relay 70 is kept in the on state is the short-circuit possible time (B), and the controller 20 switches the short-circuit relay 70 from the on state to the off state at the timing when this time has elapsed (step S21). .

  Then, after waiting for the voltage recovery time (C) in step S22, the controller 20 starts the vehicle (engine) using the output of the battery module 11 in step S23. Here, in the process of each step S19, 20, when the battery module 11 is short-circuited, the voltage value of the unit cell 12 is reduced. However, the voltage value of the unit cell 12 is waited only during the voltage recovery time. Can be recovered. Since the voltage recovery time (C) varies depending on the characteristics of the unit cell 12, it can be obtained in advance.

  According to the temperature increasing process described above, each cell 12 and the engine oil 91 are removed by short-circuiting the battery module 11 while securing the amount of charge (SOC) necessary for starting the engine in each cell 12. Can be warmed.

  In the present embodiment, the resistance element 30 is brought into contact with the engine oil 91, and the engine oil 91 is warmed by the heat generated in the resistance element 30, but this is not restrictive. That is, it is sufficient that the engine oil 91 can be warmed using the heat generated in the resistance element 30, and the resistance element 30 may not be in contact with the engine oil 91. In other words, it is sufficient that the resistance element 30 can warm the engine oil 91 directly or indirectly. In order to indirectly warm the engine oil 91, for example, the resistance element 30 is attached to the outer wall surface of the oil pan 90, and the heat generated in the resistance element 30 is transmitted to the engine oil 91 through the oil pan 90. be able to.

10: Battery pack (power storage device)
11: Battery module 12: Single battery (storage element)
13: Temperature sensor 14: Voltage sensor 20: Controller 30: Resistance element 40: Inverter 50: Motor 61, 62: System relay 70: Short-circuit relay (switch element)
80: Short circuit 90: Oil pan (case)
91: Engine oil

Claims (4)

A temperature raising system for raising the temperature of a power storage device mounted on a vehicle,
A plurality of power storage elements constituting the power storage device and electrically connected in series;
A short circuit connected to a positive electrode terminal and a negative electrode terminal of the power storage device for short-circuiting the power storage device, a switching element that switches between allowing and prohibiting a short circuit of the power storage device; and when the power storage device is short-circuited A short circuit having a resistance element to be energized ;
A temperature sensor for detecting the temperature of the power storage device;
A controller for controlling the switching operation of the switch element based on the temperature detected by the temperature sensor ,
The resistive element, the heat generated by the energization time of the short circuit, is transmitted to at least one of the oil out of the engine oil and transmission oil used in the vehicle, wherein at least one of the oil warming City,
When the detected temperature is lower than a predetermined temperature, the controller short-circuits the power storage device via the switch element, and the power storage is performed according to a difference between the detected temperature and the predetermined temperature being increased. A temperature raising system characterized by extending the short-circuit time of the device .   The temperature raising system according to claim 1, wherein the resistance element is disposed in a case that accommodates the one oil and is in contact with the one oil.   The temperature raising system according to claim 1, wherein the power storage device outputs electric power for starting an internal combustion engine of the vehicle. The controller calculates a current power storage amount in the power storage device, and when the calculated power storage amount is larger than a predetermined power storage amount, the power storage device is short-circuited via the switch element, and is calculated If the storage amount is less than the predetermined charged amount, Atsushi Nobori system according to claim 1, any one of 3, characterized in that prohibits shorting of the electric storage device.

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