JP2009140771A - Battery device, and on-board load control system including the battery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery device in which an output from a secondary battery at a low temperature time can be improved even when downsizing and weight-reduction are required, and to provide an on-board load control system. <P>SOLUTION: A battery control part 23 makes the secondary battery 20 discharge in order to supply power to the on-board load 3 when the secondary battery 20 is at the low temperature. In the secondary battery 20, the temperature of its own is elevated by an exothermic heat caused by the electric discharge, and the output is improved. Since a heating or a cooling means, such as a heater for adjusting the temperature of the secondary battery 20, is not necessary at this time, downsizing and weight-reduction can be achieved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a battery device including a rechargeable secondary battery. In particular, when a reduction in size and weight is required, the present invention relates to a battery device capable of improving the output from a secondary battery even at a low temperature and an in-vehicle load control system including the battery device.

  It is required to repeatedly use a large-capacity, high-voltage rechargeable secondary battery over a long period of time. The secondary battery has characteristics depending on temperature. The output decreases at a low temperature, and the output is maintained at a high temperature, but the possibility that the lifetime is shortened increases.

Patent Document 1 discloses a technique for controlling the temperature of a battery with high accuracy by using a calorific value calculated from the internal impedance of the battery and an entropy absorption / heat generation term in order to maintain the output from the secondary battery. Yes.
JP 2002-151166 A

  With the technique disclosed in Patent Document 1, it is possible to maintain the temperature of the battery within a certain range with high accuracy. However, when the battery device is required to be further reduced in size and weight, in the configuration using the heater, the weight of the heater itself and the power supply means to the heater may be a problem.

  The present invention has been made in view of such circumstances, and is configured to adjust its own temperature by its own calorific value at low temperatures, so that heating and cooling of a heater or the like can be achieved even when miniaturization and weight reduction are particularly required. It is an object of the present invention to provide a battery device capable of improving the output from a secondary battery at a low temperature without providing a means, and an in-vehicle load control system including the battery device.

  Another object of the present invention is to further increase the output from the secondary battery at low temperatures without providing a heating and cooling means by further measuring the operating state of the secondary battery and using it for control. An object of the present invention is to provide a battery device that can be improved and an in-vehicle load control system including the battery device.

  A battery device according to a first aspect of the present invention is a battery device comprising a secondary battery that is a power supply source for a plurality of loads and that can be charged, and a control unit that controls charging and discharging of the secondary battery. And measuring means for measuring the temperature of the plurality of loads when the temperature measured by the measuring means is equal to or lower than a predetermined value to discharge power to a specific load among the plurality of loads. It is characterized by being.

  In the battery device according to a second aspect of the present invention, the measuring means further includes means for measuring a voltage and / or current in the secondary battery, and the control means includes the temperature measured by the measuring means, the voltage and / or Charging / discharging is controlled based on the current value.

  An on-vehicle load control system according to a third aspect of the invention is a first or second aspect of the invention that serves as a plurality of loads mounted on a vehicle, an on-vehicle load control device that controls power feeding to the loads, and a power supply source to the load. When the temperature measured by the measurement means provided in the battery device is equal to or lower than a predetermined value, the control means of the battery device is directed to an in-vehicle load control device that controls power supply to a specific load. A control signal for feeding power is output.

  In the present invention, the temperature of the secondary battery serving as a power supply source to the plurality of loads is measured by the measuring unit, and when the measured temperature is equal to or lower than the predetermined value, the specific load among the plurality of loads is transferred. The secondary battery is discharged to supply power, and is supplied to a specific load. In a secondary battery, the temperature rises due to its own heat generation. It should be noted that it is desirable to select a load that does not cause a problem even if power supply is started and operates as a specific load that is fed by discharge.

  In the present invention, the charge of the secondary battery is determined comprehensively based on the operating state of the secondary battery by either or both of the measured current and voltage of the secondary battery and the temperature of the secondary battery. Discharge is controlled.

  In the case of the present invention, the temperature can be raised by its own heat generation without providing a heating / cooling means such as a heater. Therefore, when it is particularly required to reduce the size and weight when mounted on a vehicle, The output from the secondary battery can be improved.

  In the case of the present invention, charge / discharge is controlled in consideration of not only the temperature measured by the secondary battery but also the operating state such as voltage value and current value, so that the output from the secondary battery can be maintained more optimally. Can do.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

  In the present embodiment, the battery device according to the present invention is used as an auxiliary power supply system of an in-vehicle power supply system, and the output from the secondary battery is optimized according to the driving state of the in-vehicle load using the auxiliary power supply system as a power supply source. An example of realizing an in-vehicle power supply system capable of extending the life of a secondary battery will be described.

  FIG. 1 is a configuration diagram showing the configuration of the in-vehicle power supply system according to the present embodiment. The in-vehicle power supply system includes a main power supply system 1 and an auxiliary power supply system 2. The main power supply system 1 includes a secondary battery 10 using a lead battery and an alternator 11 that generates power by obtaining power from an engine and stores the power in the secondary battery 10 of the main power supply system 1. The auxiliary power supply system 2 includes a secondary battery 20 using a lithium ion battery, a DCDC converter 21 that receives power from the main power supply system 1 and charges the secondary battery 20, and a voltage, current, and temperature in the secondary battery 20. A battery state sensor 22 for measuring the charge, a battery control unit 23 for controlling charging / discharging of the secondary battery 20, and a relay 24 for switching on / off of power supply to the in-vehicle load 3 using the auxiliary power supply system 2 as a power supply source It consists of.

  The in-vehicle power supply system is connected to each of a plurality of in-vehicle loads 3 mounted on the vehicle to supply electric power. The in-vehicle power supply system and each in-vehicle load 3 are connected by a harness composed of a plurality of power supply lines, signal lines, and shields. In FIG. 1, a solid line connecting each component indicates a power supply line, and a broken line indicates a signal line.

  Some of the in-vehicle loads 3 among the plurality of in-vehicle loads 3 are connected to the auxiliary power source system 2 by a power line via a relay 24 and a harness, and operate by receiving power supplied from the auxiliary power source system 2. . A vehicle-mounted load 3 that is supplied with power from the auxiliary power supply system 2 is connected to a vehicle-mounted load ECU (Electronic Control Unit) 4 via a signal line, and the operation is controlled on / off.

  The in-vehicle load ECU 4 controls the operation of the in-vehicle load 3 based on a switch (not shown) or a signal from another in-vehicle load ECU 4. And the control signal which instruct | indicates ON / OFF of operation | movement of the vehicle-mounted load 3 is also received from the battery control part 23, and operation | movement of the vehicle-mounted load 3 is controlled according to a control signal. In addition, you may have a function which outputs the signal which shows the operation state of the vehicle-mounted load 3 to the battery control part 23 of the auxiliary power supply system 2. FIG.

  The DCDC converter 21 of the auxiliary power supply system 2 is connected to the main power supply system 1 and the secondary battery 20 of the auxiliary power supply system 2 by a power line. The DCDC converter 21 is connected to the battery control unit 23 through a signal line, receives power from the main power supply system 1 according to a control signal from the battery control unit 23, converts the voltage, and recharges the secondary battery of the auxiliary power supply system 2. Operates to charge 20.

  The output voltage of the secondary battery 20 of the auxiliary power supply system 2 is higher than 12 volts of the output voltage of the secondary battery 10 using the lead battery of the main power supply system 1, for example, 42 volts. As a result, the on-vehicle load 3 that requires a large amount of power supply in a short time can be operated. Since high output is realized and the amount of current can be reduced, it becomes possible to reduce the diameter of the power line included in the harness connected to each in-vehicle load 3 that is supplied with power from the auxiliary power system 2. The weight of the harness and the weight of the entire vehicle can be reduced.

  As an example of an in-vehicle load 3 that requires a large amount of power supply and receives power supply from the auxiliary power supply system 2, a seat heater that warms in a short time, a steering heater, and improved heating performance immediately after starting an engine that is used particularly in cold regions PTC (Positive Temperature Coefficient) heater, windshield defogger, deisa, diesel engine glow plug, electrically controlled electric stabilizer, electric suspension, and the like.

  The battery state sensor 22 includes a temperature sensor such as a thermistor and outputs a measurement value corresponding to the temperature. The battery state sensor 22 is connected to the battery control unit 23 through a signal line, and outputs a temperature measurement value to the battery control unit 23.

  The battery control unit 23 is connected to the DCDC converter 21 through a signal line, and outputs a control signal for controlling charging by supplying power from the main power supply system 1 to the DCDC converter 21. The control signal may be composed of a signal representing on / off, or may be composed of a signal for controlling on / off of charging by an output voltage. The battery control unit 23 is connected to an ignition switch (not shown) via a signal line, and can distinguish the vehicle state, that is, the accessory power-on state and the engine start state. In addition, it is possible to obtain a measurement value of the wheel speed output from the wheel speed sensor, and to distinguish the traveling state as the state of the vehicle. The battery control unit 23 is connected to the relay 24 via a signal line, and controls on / off of power supply to the in-vehicle load 3.

  The battery control unit 23 is also connected to the in-vehicle load ECU 4 through a signal line, and can output a control signal to the in-vehicle load ECU 4 to start the operation of the in-vehicle load. The in-vehicle load ECU 4 that is connected to the battery control unit 23 and receives a control signal from the battery control unit 23 is the in-vehicle load ECU 4 that controls the operation of a specific load described later. In addition, since the electric power supply to the battery control part 23 is received from the secondary battery 20, the battery control part 23 is also connected to the secondary battery 20 by the power wire. Further, the battery control unit 23 is connected to the battery state sensor 22 through a signal line, and can acquire the measured values of the voltage value, current value, and temperature in the secondary battery 20 output from the battery state sensor 22. is there.

  The battery control unit 23 acquires the temperature of the secondary battery 20 from the measured temperature value acquired from the battery state sensor 22. Note that the temperature of the secondary battery 20 may be calculated by using the voltage value and the current value acquired from the battery state sensor 22.

  The battery control unit 23 controls charging / discharging of the secondary battery 20 depending on whether the acquired or calculated temperature of the secondary battery 20 is equal to or lower than a predetermined value (for example, zero degrees Celsius), and supplies power to the in-vehicle load 3. Switch on / off. Then, the battery control unit 23 outputs a control signal to the in-vehicle load ECU 4 that controls the power supply to the specific in-vehicle load 3 in order to operate the specific in-vehicle load 3 that is fed by the discharge when discharging. The secondary battery 20 rises in temperature due to its own Joule heat due to discharge, and the output is improved. The battery control unit 23 controls charging / discharging so that the temperature of the secondary battery 20 maintains a predetermined temperature range (for example, from 16 ° C. to 20 ° C.). The in-vehicle load 3 starts to operate by a user's operation or control by another in-vehicle load ECU 4, and the temperature of the secondary battery 20 rises due to discharge for power supply to the in-vehicle load 3 to keep a predetermined temperature range. When it is possible, since it is not necessary to supply power to the specific vehicle-mounted load 3 to operate, a control signal for stopping power supply is output to the vehicle-mounted load ECU 4.

  The specific vehicle load 3 is preferably one that does not cause a problem even if power supply is started and operated without a user operation, or one that should be operated using this. In the in-vehicle power supply system according to the present embodiment, it is estimated that the low temperature period is immediately after the engine is started or during the accessory power-on state period. Therefore, as a specific example of the specific on-vehicle load 3, heaters such as a defogger, a deisa, a seat heater, and a steering heater are preferable. When the temperature inside and outside the vehicle is 0 ° C. or lower, the secondary battery 20 is discharged to improve the output of the secondary battery 20 to the in-vehicle load 3 that requires power supplied from the auxiliary power supply system 2, and self discharge The temperature of the vehicle can be raised by the heat generated by the vehicle, and the cooled seat and steering in the room are automatically warmed in a short time, so that the vehicle interior becomes comfortable and windshield fogging and icing are removed in a short time. It should be noted that the defogger and deisa are suitable as the specific in-vehicle load 3 because there is no hindrance to the operation even if the defogger and deisa operate when the windshield is cloudy or freezing.

  The process in which the battery control unit 23 controls the start / stop of charging / discharging and the power supply to the specific in-vehicle load 3 according to the temperature of the secondary battery 20 will be described with reference to a flowchart.

  FIG. 2 is a flowchart showing an example of a processing procedure of charge / discharge control by the battery control unit 23 of the auxiliary power supply system 2 constituting the in-vehicle power supply system in the present embodiment. The battery control unit 23 starts the following control when the accessory power is turned on by the ignition switch or when the engine is started.

  The battery control unit 23 determines whether the temperature of the secondary battery 20 is equal to or lower than a predetermined value (step S11). The predetermined value is a numerical value less than the lower limit of a suitable temperature range (for example, from 16 ° C. to 20 ° C.) in which the output is improved. However, when a lithium ion battery is used for the secondary battery 20, the output is zero ° C. or lower. It is preferable to set the predetermined value to zero ° C. because it decreases significantly.

  When the battery control unit 23 determines that the temperature of the secondary battery 20 is equal to or lower than the predetermined value (S11: YES), the battery control unit 23 starts discharging the secondary battery 20 (step S12) and closes the relay (step S13). Then, a control signal for starting power feeding is output to the vehicle load ECU 4 of the specific vehicle load 3 (step S14). If the battery control unit 23 determines that the temperature of the secondary battery 20 is higher than the predetermined value (S11: NO), the process proceeds to the next.

  Next, the battery control unit 23 determines whether or not the temperature of the secondary battery 20 is within a predetermined temperature range (T1 ° C. to T2 ° C., for example, T1 = 16, T2 = 20) (step S15). If the battery control unit 23 determines that the temperature of the secondary battery 20 is not within the predetermined temperature range (S15: NO), the process returns to step S11.

  When the battery control unit 23 determines that the temperature of the secondary battery 20 is within the predetermined temperature range (S15: YES), the output from the secondary battery 20 is expected to be maintained well, so that A control signal for stopping power feeding is output to the in-vehicle load ECU 4 of the in-vehicle load 3 (step S16). Then, the battery control unit 23 opens the relay (step S17), stops the discharge of the secondary battery 20 when there is no need to supply power to the other in-vehicle load 3 (step S18), and the process proceeds to step S11. return. Thereby, when the temperature becomes equal to or lower than the predetermined value again, discharging is performed to improve the output from the secondary battery 20. Of course, when the temperature of the secondary battery 20 is already within a predetermined range at the time when the accessory power supply is turned on or the engine is started, the processing from step S12 to step S14 is not performed, and a specific vehicle-mounted Since power supply to the load 3 is not performed, the processing from step S16 to step S18 is unnecessary.

  The battery control unit 23 ends the process when the engine is turned off by the ignition switch or when the accessory power source is turned off. Note that the battery control unit 23 ends the process after executing the processes from step S16 to step S18 when supplying power to the specific in-vehicle load 3.

  By performing the control as described above, the battery control unit 23 increases the temperature by causing the secondary battery 20 to generate heat by discharging even at a low temperature without providing a heater for adjusting the temperature of the secondary battery 20. And the output can be improved. Therefore, when weight reduction and size reduction of a vehicle-mounted power supply system etc. are calculated | required, the weight of a battery apparatus can be restrained and it can contribute to the weight reduction of the whole vehicle.

  Moreover, it is desirable to select the in-vehicle load 3 that does not cause a problem even if the power is automatically supplied at a low temperature, as the specific in-vehicle load 3 to be supplied by discharge. A secondary effect can be expected when the on-vehicle load 3 to be automatically fed at a low temperature is selected.

  The battery state sensor 22 may include a voltage sensor and a current sensor, and may be configured to measure and output a voltage value in the secondary battery 20 of the auxiliary power supply system 2 and to measure and output the current value. In this case, the battery control unit 23 may calculate the temperature of the secondary battery 20 using one or both of the voltage value and the current value in the secondary battery 20. Further, the battery control unit 23 acquires the output state from the secondary battery 20 using one or both of the voltage value and the current value in the secondary battery 20 output from the battery state sensor 22, and the secondary battery 20 It may be determined whether the output from the battery 20 satisfies a predetermined threshold value.

  FIG. 3 is a flowchart showing another example of the processing procedure of charge / discharge control by the battery control unit 23 of the auxiliary power supply system 2 constituting the in-vehicle power supply system in the present embodiment. Note that, among the processing procedures shown in the flowchart of FIG. 3, the same processing steps as those shown in the flowchart of FIG. 2 are denoted by the same step numbers, and detailed description thereof is omitted.

  When the battery control unit 23 determines in step S15 that the temperature of the secondary battery 20 is within the predetermined temperature range (S15: YES), the voltage value and / or current value acquired by the battery state sensor 22 are either or either. Based on one, it is determined whether the output satisfies a threshold value or more (step S21). If the battery control unit 23 determines that the output satisfies the threshold (S21: YES), the battery control unit 23 advances the process to step S16. When the battery control unit 23 determines that the output does not satisfy the threshold value (S21: NO), the process returns to Step S12, and when the discharge is not started, the discharge is started (S12), and Steps S13 and S14 are performed. When the process is executed and the discharge is started, the discharge is continued.

  Thereby, it becomes possible to maintain an output more optimally according to the operation state in the secondary battery 20.

  In the present embodiment, an example in which the battery device according to the present invention is used as an auxiliary power system of an in-vehicle power system is shown. However, the present invention is not limited to an in-vehicle power supply system, but is applied to various electric devices using secondary batteries such as lithium ion batteries, particularly power sources for electric devices that require high output while being reduced in size and weight. Of course, it is possible.

It is a block diagram which shows the structure of the vehicle-mounted power supply system in this Embodiment. It is a flowchart which shows an example of the process sequence of charging / discharging control by the battery control part of the auxiliary power supply system which comprises the vehicle-mounted power supply system in this Embodiment. It is a flowchart which shows another example of the process sequence of the charging / discharging control by the battery control part of the auxiliary power supply system which comprises the vehicle-mounted power supply system in this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main power supply system 10 Secondary battery 2 Auxiliary power supply system 20 Secondary battery 22 Battery state sensor (measuring means)
23 Battery control unit (control means)
3 Vehicle load 4 Vehicle load ECU (vehicle load control device)

Claims (3)

In a battery device comprising a secondary battery that is a power supply source of a plurality of loads and can be charged, and a control unit that controls charging and discharging of the secondary battery,
A measuring means for measuring the temperature of the secondary battery;
The battery device according to claim 1, wherein the control unit is configured to discharge the power to supply a specific load among the plurality of loads when the temperature measured by the measurement unit is equal to or lower than a predetermined value. The measuring means further comprises means for measuring voltage and / or current in the secondary battery,
The battery device according to claim 1, wherein the control unit controls charging / discharging based on a temperature measured by the measuring unit and a value of a voltage and / or current. A plurality of loads mounted on a vehicle, an in-vehicle load control device that controls power feeding to the load, and the battery device according to claim 1 or 2 serving as a power supply source to the load,
When the temperature measured by the measuring unit included in the battery device is equal to or lower than a predetermined value, the control unit of the battery device outputs a control signal for feeding power to the in-vehicle load control device that controls feeding to a specific load. In-vehicle load control system characterized by

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