JP2013254646A - Battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery system capable of efficiently using power to retain and warming a secondary battery by suppressing a number of charging and discharging times of the secondary battery by switching a warming method.SOLUTION: A battery system comprises: battery monitoring circuits 22a and 22b, the battery monitoring circuit 22a monitoring a state of a secondary battery 21a and the battery monitoring circuit 22b monitoring a state of a secondary battery 21b; temperature measuring units 23a and 23b, the temperature measuring unit 23a measuring a temperature of the secondary battery 21a and a temperature measuring unit 23b monitoring a temperature of the secondary battery 21b; keep-warm dummy resistors 25a and 25b, the keep-warm dummy resistor 25a arranged near the secondary battery 21a and warming the battery from the outside and the keep-warm dummy resistor 25b arranged near the secondary battery 21b and warming the battery from the outside; a step-up/down circuit 11 which is provided between the secondary batteries and steps up or down an input voltage and supplies the voltage to the secondary batteries; one or a plurality of switches 24a and 24b connected to the keep-warm dummy resistors, step-up/down circuit, and secondary batteries; and a warming control circuit 10a which operates the step-up/down circuit to switch a warming method by power delivery between the secondary batteries and operates the switches to switch a warning method by the warm-keep dummy resistors on the basis of temperature information from the temperature measuring units and battery state information from the battery monitoring circuits.

Description

  Embodiments described herein relate generally to a battery system having a plurality of lithium ion batteries and a warm-in dummy resistor.

  In general, the internal resistance of a lithium ion battery increases in a low temperature environment, and the charge / discharge characteristics are significantly deteriorated. For this reason, a battery can be used with the characteristic close | similar to normal temperature also in a low temperature environment by heating a battery from the inside or outside and raising battery temperature. When the battery is heated from the outside, a heater is generally used.

  In addition, in a battery system using a plurality of lithium ion batteries, proposals have been made to transfer power between a plurality of batteries (Patent Documents 1 and 2). Such a battery system is operated for a long time by supplying the power stored in the sub battery to the main battery, and the temperature of the battery is increased by power transfer. For example, a hybrid car power supply device described in Patent Document 1 warms a driving secondary battery using a nickel-metal hydride battery having poor temperature characteristics by an electrical secondary battery using a lead storage battery having good temperature characteristics. The battery is alternately charged and discharged.

JP 2003-92805 A JP 2003-259508 A

  However, the assembled battery has various forms such as a cell structure and a battery module structure in which a plurality of cells are combined, and is not necessarily structured to be easily heated from the outside. For this reason, the heating efficiency is poor, and the distribution of the temperature rise inside the battery module becomes non-uniform. For this reason, dispersion | variation generate | occur | produces in the temperature and voltage of a battery cell, and a cell and a battery module may deteriorate. Further, depending on the battery capacity and the battery structure, the power supply capacity for the heater increases.

  On the other hand, when the secondary battery is heated internally by power transfer, the temperature rises from the inside of the cell due to self-heating, so it is not insulated by the battery module structure, compared to the external heating method. The heating efficiency is very good.

  However, there is a limit to the number of times that the secondary battery can be charged / discharged due to the charge / discharge cycle characteristics, and if power is frequently exchanged between the secondary batteries, the life of the original secondary battery is shortened. In addition, when each secondary battery is fully charged, power transfer between the secondary batteries cannot be started unless the secondary battery has a free capacity.

  The problem to be solved by the present invention is to efficiently utilize the electric power held by the secondary battery during the heating of the secondary battery when using the battery system, and to switch the system to the secondary for heating. An object of the present invention is to provide a battery system that can reduce the number of times the battery is charged and discharged.

  According to the battery system according to the embodiment, a plurality of secondary batteries, a plurality of battery monitoring circuits provided corresponding to the plurality of secondary batteries and monitoring a battery state of the secondary battery, A plurality of temperature measuring units that are provided corresponding to the secondary battery and measure the temperature of the secondary battery, and one or more temperature measuring units that are disposed in the vicinity of the secondary battery and heat the secondary battery from the outside A temperature-retaining dummy resistor, a step-up / step-down circuit provided between the plurality of secondary batteries to increase or decrease an input voltage and supply the voltage to the plurality of secondary batteries, and the one or more heat-retaining dummy resistors One or more switches provided corresponding to the thermal insulation dummy resistor, the step-up / step-down circuit, and the secondary battery, temperature information from the plurality of temperature measurement units, and the plurality of battery monitors The step-up / step-down circuit based on the battery status information from the circuit A heating control circuit for controlling the heating of the secondary battery by switching between a heating method by operating and transferring power between the secondary batteries and a heating method by operating the switch and the warming dummy resistor; It is characterized by providing.

It is a block diagram which shows the structure of the battery system which concerns on 1st Embodiment. It is a flowchart which shows operation | movement of the battery system which concerns on 1st Embodiment.

  Hereinafter, a battery system according to an embodiment of the present invention will be described in detail with reference to the drawings.

First embodiment

  The battery system according to the first embodiment transfers power between a plurality of lithium ion secondary batteries to improve the charge / discharge characteristics of a secondary battery that deteriorates in a low-temperature environment. It has a heating method that heats the secondary battery using heat generation, and a heating method that heats the secondary battery using heat generation by a dummy resistance for heat retention arranged near the secondary battery, The two heating methods are switched based on voltage information and temperature information of the secondary battery.

  FIG. 1 is a block diagram showing the configuration of the battery system according to the first embodiment. The battery system includes a power generator 2, a charger 3, an operation input unit 5, a secondary battery module 20a, temperature measurement units 23a and 23b, switches 24a and 24b, heat insulation dummy resistors 25a and 25b, and loads 30a and 30b. Yes.

  The power generator 2 is connected to the input end side of the charger 3, and supplies power for charging to the charger 3. The secondary battery module 20 a and the switch 24 a are connected to one end on the output side of the charger 3, and the secondary battery module 20 b and the switch 24 b are connected to the other end on the output side of the charger 3. The charger 3 includes charging circuits 1a and 1b for charging the secondary battery module 20a and the secondary battery module 20b, a charging control circuit 10 for controlling these charging circuits, and a step-up / down circuit 11. .

  The secondary battery modules 20a and 20b include secondary batteries 21a and 21b and battery monitoring circuits 22a and 22b, and the step-up / down circuit 11 and switches 24a and 24b are connected to the secondary batteries 21a and 21b. The secondary batteries 21a and 21b are normally charged by the power from the charging circuits 1a and 1b, and are charged and stored by the power from the step-up / down circuit 11 except during normal times (for example, when power is not supplied from the charging circuit). The supplied electric power is supplied to the loads 30a and 30b.

  The battery monitoring circuits 22a and 22b monitor the battery state such as the battery voltage and battery temperature of the secondary batteries 21a and 21b, estimate the battery remaining capacity (SOC), and charge the battery state information. Output to the control circuit 10. The temperature measurement units 23 a and 23 b measure the temperature of the secondary battery modules 20 a and 20 b and output the measured temperature information to the charge control circuit 10.

  The switches 24a and 24b are turned on / off by a heat retention control signal from the warming / temperature raising control circuit 10a, and operate to discharge the charges of the secondary batteries 21a and 21b to the heat insulation dummy resistors 25a and 25b when turned on. .

  The charging control circuit 10 controls the charging circuits 1a and 1b for charging the secondary batteries 21a and 21b, and includes a heating control circuit 10a. The heating control circuit 10a operates the step-up / step-down circuit 11 based on the temperature information from the temperature measuring units 23a and 23b and the battery state information from the battery monitoring circuits 22a and 22b, and power between the secondary batteries 21a and 21b. Heating control of the secondary batteries 21a and 21b is performed by switching between the heating method by transfer and the switches 24a and 24b to switch the heating method by the heat-insulating dummy resistors 25a and 25b.

The step-up / step-down circuit 11 is disposed between the secondary battery modules 20a and 20b in order to transfer power between the secondary battery modules 20a and 20b, and is input with a heating control signal from the heating control circuit 10a. Is stepped up or down to supply power to the secondary batteries 21a and 21b.
The thermal insulation dummy resistors 25a and 25b are disposed in the vicinity of the secondary battery modules 20a and 20b, and heat the secondary battery modules 20a and 20b from the outside by heat generated by the resistors. Switches 24a and 24b are connected to one end of the warming dummy resistors 25a and 25b, and the secondary batteries 21a and 21b and the step-up / step-down circuit 11 are connected to the other ends of the switches 24a and 24b.

  Next, the operation of the battery system according to the first embodiment configured as described above will be described. FIG. 2 is a flowchart showing the operation of the battery system according to the first embodiment. The operation of the battery system according to the first embodiment will be described with reference to FIG. Here, the heating control of the secondary batteries 21a and 21b will be described.

  In this example, warming dummy is performed when warming is performed by power transfer between the secondary batteries 21a and 21b at low temperature startup, and then the temperature of the secondary battery module 20a or 20b on one side decreases during operation. Description will be made assuming that the heating control is performed by the resistors 25a and 25b, and thereafter the temperature of the secondary batteries 21a and 21b is uniformly maintained.

  First, it is checked whether or not there is an abnormality in the battery system when starting the battery system (step S11). If there is no abnormality in the battery system, the battery monitoring circuits 22a and 22b are connected to the secondary batteries 21a and 21b. The voltage information is monitored, and the battery remaining capacity SOC is monitored (step S12). Further, the temperature measuring units 23 a and 23 b measure the temperatures of the secondary batteries 21 a and 21 b and output them to the charge control circuit 10.

  Next, the charge control circuit 10 determines whether or not a charge / discharge request is input from the operation input unit 5 (step S13). When a charge / discharge request is input from the operation input unit 5, the charge control circuit 10 determines whether or not the temperature of the secondary batteries 21a and 21b measured by the temperature measurement units 23a and 23b is low (step S14). ).

  When the temperature of the secondary batteries 21a and 21b is low, that is, when the temperature is in a temperature range where the charge / discharge characteristics are lowered, the process shifts to a heating control sequence based on power transfer between the secondary batteries. In the heating control sequence based on power transfer between the secondary batteries, the SOC of the target secondary batteries 21a and 21b is monitored before execution (step S15).

  If both of the secondary batteries 21a and 21b are fully charged (YES in step S16), either one of the warming dummy resistors, for example, the switch 24a of the warming dummy resistor 25a is closed, and the secondary battery is closed. After discharging 21a (step S17), the process proceeds to step S20.

  On the other hand, when both the secondary batteries 21a and 21b are not fully charged, the charging control circuit 10 determines whether or not both the secondary batteries 21a and 21b are nearly completely discharged (step S18). When both the secondary batteries 21a and 21b are close to complete discharge, the charge control circuit 10 charges one secondary battery, for example, the secondary battery 21a (step S19), and proceeds to the process of step S20.

    In the process of step S20, charge / discharge control between the secondary batteries 21a and 21b is started by the step-up / down circuit 11. Then, for example, cycle control is performed such that one secondary battery 21a is discharged for 30 seconds, paused for 5 seconds, charged with the secondary battery 21a for 30 seconds, and paused for 5 seconds. In the process of this step, when viewed from the other secondary battery 21b, the secondary battery 21b is charged for 30 seconds, paused for 5 seconds, the secondary battery 21a is discharged for 30 seconds, and paused for 5 seconds. When the measured temperature reaches a predetermined temperature, the above-described cycle control is stopped (steps S21 to S22). Or, even when charging / discharging with sufficient charging / discharging current, even if the measured time has passed the time set by the timer, the measured temperature does not reach the predetermined temperature, It may be determined that the battery system is abnormal.

  When the measured temperature reaches the target temperature due to power transfer between the secondary batteries 21a and 21b, the heating control is stopped, and then the charge / discharge operation is performed according to the charge / discharge request from the operation input unit 5.

  In this case, when the usage frequency of one of the secondary batteries in operation is low, the temperature of the secondary batteries 21a and 21b may decrease during the operation process. For this reason, the charge control circuit 10 determines whether the temperature of the secondary batteries 21a and 21b has dropped during operation (step S23).

  When the temperature of the secondary batteries 21a and 21b decreases, the switches 24a and 24b are turned on from the charge control circuit 10 by the signals from the temperature measuring units 23a and 23b, and the warming dummy resistors 25a and 25b are connected to the charger 3. And the secondary batteries 21a and 21b are heated by the heat generated by the warming dummy resistors 25a and 25b (step S24). Further, the temperature measuring units 23a and 23b measure the temperatures of the secondary batteries 21a and 21b (step S25).

  As described above, the switches 24a and 24b are controlled to be opened and closed by the heat-retaining operation set temperature, and the temperature decrease of the secondary batteries 21a and 21b that are not frequently used can be prevented.

  As described above, according to the battery system according to the first embodiment, the secondary battery 21a uses the self-heat generated by the internal resistance of the secondary batteries 21a and 21b by transferring power between the secondary batteries 21a and 21b. , 21b, and a heating system that heats the secondary batteries 21a, 21b using heat generated by the thermal insulation dummy resistors 25a, 25b disposed in the vicinity of the battery. By switching the two heating methods based on the voltage information and temperature information of the batteries 21a and 21b, the heating control of the secondary batteries 21a and 21b can be performed according to the situation.

  Therefore, the heat-insulating dummy resistors 25a and 25b, which are heaters, can be reduced in size and weight, and the number of times of charging and discharging by transferring power between the secondary batteries 21a and 21b as compared to a system of heating method alone by transferring power. It is possible to provide a battery system that can suppress the above.

  Moreover, even if each secondary battery 21a, 21b is in a fully charged state, by using the heat-insulating dummy resistors 25a, 25b without wasting power on the load side, the secondary batteries 21a, 21b are energy efficient. Warming can be performed.

  In general, the charge / discharge cycle characteristics of a lithium ion secondary battery are not so good. For example, by using a lithium ion secondary battery with good charge / discharge cycle characteristics employing lithium titanate as a negative electrode material, the battery system of Example 1 is used. Can be used effectively.

In lithium ion secondary batteries with poor charge / discharge cycle characteristics, frequent power transfer between secondary batteries shortens battery life, but only one operation at low temperature startup. By adding this limitation, the battery system of Example 1 can be applied.
In the battery system of Example 1, a battery system having two secondary battery modules 20a and 20b has been illustrated, but the present invention can also be applied to a battery system having three or more secondary battery modules. Further, since the heat insulation dummy resistors are not necessarily required for each battery module, some of the heat insulation dummy resistors can be reduced.

  Moreover, in the battery system of Example 1, the heating control by the internal resistance is performed by the power transfer between the secondary batteries at the time of starting at low temperature, and after the temperature reaches the target temperature, the temperature is maintained when the temperature decreases. Control was performed to heat the secondary battery with a dummy resistor. For example, from the beginning, heating control by internal resistance by power transfer between the secondary batteries and control to heat the secondary battery with a warming dummy resistor And may be used in combination.

  Alternatively, when the temperature decreases after the temperature reaches the target temperature, the heating control by the internal resistance by the power transfer between the secondary batteries may be performed again. Alternatively, when it is only necessary to raise the temperature a little, there is a case where heating is started by a dummy resistance for heat retention, and various control sequences can be used depending on the situation.

  As mentioned above, although several embodiment was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1a, 1b Charging circuit 2 Generator 3 Charger 5 Operation input part 10 Charging control circuit 10a Heating control circuit 11 Buck-boost circuit 20a, 20b Secondary battery module 21a, 21b Secondary battery 22a, 22b Battery monitoring circuit 23a, 23b Temperature measurement unit 24a, 24b Switch 25a, 25b Thermal insulation dummy resistor 30a, 30b Load

Claims (3)

A plurality of secondary batteries;
A plurality of battery monitoring circuits provided corresponding to the plurality of secondary batteries and monitoring a battery state of the secondary battery;
A plurality of temperature measuring units provided corresponding to the plurality of secondary batteries and measuring the temperature of the secondary battery;
One or more heat-retaining dummy resistors which are arranged in the vicinity of the secondary battery and heat the secondary battery from the outside;
A step-up / step-down circuit that is provided between the plurality of secondary batteries and boosts or steps down an input voltage and supplies the voltage to the plurality of secondary batteries;
One or more switches provided corresponding to the one or more heat insulation dummy resistors and connected to the heat insulation dummy resistor, the step-up / step-down circuit, and the secondary battery;
Based on the temperature information from the plurality of temperature measuring units and the battery state information from the plurality of battery monitoring circuits, the heating and boosting circuit by operating the step-up / step-down circuit and transferring power between the secondary batteries and the switch A heating control circuit for controlling the heating of the secondary battery by operating and switching the heating method by the dummy resistance for heat retention;
A battery system comprising:   When all of the plurality of secondary batteries are fully charged, the heating control circuit selects one secondary battery among the plurality of secondary batteries and is connected to the selected secondary battery. The switch is closed and the selected secondary battery is discharged by the heat-retaining dummy resistor. When the remaining battery level reaches a certain level, the switch is opened and the secondary battery is discharged. The battery according to claim 1, wherein the battery is charged from a secondary battery other than the discharged secondary battery by controlling the step-up / step-down circuit and controlling the step-up / down circuit. system.   The battery system according to claim 1, wherein each of the plurality of secondary batteries is a lithium ion secondary battery.

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