JP2014075297A - Power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage system capable of warming a power storage device while charging the power storage device.
A power storage system includes a power storage device (10) that performs charging / discharging, a device (27) that applies heat to the power storage device, and an external power supply while supplying power from the external power supply (52) to the power storage device. And a controller (30) for driving the device using a part of the electric power of the device. The controller can drive the device when the current value flowing through the power storage device is smaller than the current value flowing through the charging path for supplying power from the external power source to the power storage device.
[Selection] Figure 1

Description

  The present invention relates to a power storage system capable of warming a power storage device while charging the power storage device.

  When the temperature of the secondary battery is lowered, the internal resistance of the secondary battery is increased, and it becomes difficult for current to flow through the secondary battery. Therefore, in the technique described in Patent Document 1, when charging the secondary battery, the secondary battery is first heated using a heater, and after the secondary battery is heated, the secondary battery is charged. Like to start.

JP 2011-238428 A JP-A-11-341698 JP 11-055869 A

  In the technique described in Patent Document 1, charging of the secondary battery cannot be started unless the secondary battery is sufficiently heated. Moreover, in the technique described in Patent Document 1, since the process of heating the secondary battery and the process of charging the secondary battery are individually performed at different timings, the charging time of the secondary battery is shortened. Above, there is room for improvement.

  The power storage system according to the present invention includes a power storage device that performs charging / discharging, a device that heats the power storage device, and a device that uses part of the power from the external power supply while supplying power from the external power supply to the power storage device. And a controller for driving. According to the present invention, the power storage device can be charged by supplying a part of the power from the external power source to the power storage device. In addition, the power storage device can be warmed by driving the device using the remaining power from the external power source.

  When the temperature of the power storage device decreases, the internal resistance of the power storage device increases and the value of the current flowing through the power storage device decreases. In such a state, even if a predetermined value of charging current is caused to flow to the power storage device, only a current having a value smaller than the predetermined value may flow to the power storage device. Thus, by supplying a part of the power from the external power source to the device, the power storage device can be warmed using the device while charging the power storage device.

  Here, since the power supplied to the device is power that is not used for charging the power storage device, even if a part of the power from the external power supply is supplied to the device, the charging efficiency of the power storage device is not reduced. Absent. On the other hand, by supplying a charging current to the power storage device or warming the power storage device using a device, the temperature of the power storage device can be easily increased, and the internal resistance of the power storage device can be easily decreased. Thereby, it becomes easy to let an electric current flow into an electrical storage apparatus, and it can suppress that time until it completes charge of an electrical storage apparatus is prolonged.

  Here, the device can be driven when the value of the current flowing through the power storage device is smaller than the value of the current flowing through the charging path for supplying power from the external power source to the power storage device. When the current value flowing through the power storage device is smaller than the current value flowing through the charging path, a current that cannot flow through the power storage device can be supplied to the device.

  As the current supplied to the device, a current corresponding to the difference between the current value flowing through the power storage device and the current value flowing through the charging path can be used. Thereby, all of the electric power supplied from the external power source can be divided into charging of the power storage device and driving of the device, and the electric power from the external power source can be used efficiently.

  As the current value flowing through the power storage device decreases, the current value supplied to the device can be increased. The current that cannot flow through the power storage device increases as the current becomes less likely to flow through the power storage device. For this reason, as the value of current flowing through the power storage device decreases, the current value supplied to the device increases, so that the device can be driven more easily, and the power storage device can be efficiently heated using the device.

  A DC / DC converter can be connected to a charging path for supplying power from an external power source to the power storage device. Here, the DC / DC converter can convert power from an external power source into input power to the device. Thereby, electric power suitable for driving the device can be supplied to the device. On the other hand, the DC / DC converter can also have a function of converting the discharge power of the power storage device into input power to another power storage device different from the power storage device. By giving two functions to one DC / DC converter, an increase in the number of parts can be suppressed.

  Two charging paths can be provided as the charging path. In the first charging path, a predetermined current can be supplied to the power storage device. In the second charging path, a current having a value larger than the value of the current flowing in the first charging path can be supplied to the power storage device. By providing the first and second charging paths, these charging paths can be selected.

  Here, the device can be operated by supplying power from the second charging path to the device. Since the current value flowing through the second charging path is larger than the current value flowing through the first charging path, the current that can be supplied to the device can be increased in a state where current does not easily flow through the power storage device. Accordingly, the device can be easily driven, and the power storage device can be easily warmed using the device.

  Further, when the current value flowing through the second charging path is larger than the current value flowing through the first charging path, the charging time using the second charging path is charged using the first charging path. It tends to be shorter than time. Here, the charging time is a time until charging of the power storage device is completed. As described above, by driving the device to easily warm the power storage device, it is possible to easily pass a current through the power storage device, and it is easy to shorten the charging time using the second charging path. Thereby, it becomes easy to ensure the charging time required for the second charging path.

  The power storage device can be mounted on a vehicle. Here, by converting the electrical energy output from the power storage device into kinetic energy, the vehicle can be driven using this kinetic energy. As the power storage device mounted on the vehicle, an assembled battery including a plurality of secondary batteries can be used.

It is a figure which shows the structure of the battery system in Example 1. FIG. It is the schematic which shows the structure which adjusts the temperature of a main battery. It is a flowchart explaining an external charge process. It is a flowchart explaining a temperature rising process. It is a figure which shows the relationship between the electric current which flows into a main battery, the electric current used with a temperature control device, and battery temperature. It is a figure which shows the relationship between charging current and charging time. It is a figure which shows the relationship between charging time, charging current, and battery temperature. 6 is a diagram showing a configuration of a battery system in a modification of Example 1. FIG.

  Examples of the present invention will be described below.

  A battery system (corresponding to a power storage system) that is Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a battery system. The battery system of the present embodiment can be mounted on a vehicle, for example. As will be described later, the present invention can be applied to any system that supplies power from an external power source to a battery.

  Vehicles include hybrid cars and electric cars. The hybrid vehicle includes other power sources such as an engine or a fuel cell in addition to a main battery described later as a power source for running the vehicle. The electric vehicle includes only a main battery described later as a power source for running the vehicle. Here, as will be described later, the main battery can be charged by supplying the power from the external power source to the main battery. Such charging is called external charging.

  A main battery (corresponding to a power storage device) 10 has a plurality of single cells 11 connected in series. As the cell 11, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. In addition, an electric double layer capacitor can be used instead of the secondary battery. Here, the number of the single cells 11 constituting the main battery 10 can be appropriately set in consideration of the output required for the main battery 10. Moreover, the main battery 10 may include a plurality of single cells 11 connected in parallel.

  The monitoring unit 20 detects the voltage between the terminals of the main battery 10 or detects the voltage between the terminals of each unit cell 11 and outputs the detection result to the controller 30. The voltage detected by the monitoring unit 20 is used when controlling charging / discharging of the main battery 10. For example, in order to suppress overcharge and overdischarge of the main battery 10, charging / discharging of the main battery 10 is controlled so that the voltage detected by the monitoring unit 20 changes between the upper limit voltage and the lower limit voltage. Can do. Here, the upper limit voltage is set to suppress overcharge of the main battery 10 or the single battery 11, and the lower limit voltage is set to suppress overdischarge of the main battery 10 or the single battery 11.

  The temperature sensor 21 detects the temperature of the main battery 10 (unit cell 11) and outputs the detection result to the controller 30. Here, the number of the temperature sensors 21 can be set as appropriate. When a plurality of temperature sensors 21 are used, the temperature sensors 21 can be arranged at different positions with respect to the main battery 10. The temperature detected by the temperature sensor 21 can be used when controlling charging / discharging of the main battery 10.

  The current sensor 22 detects the current value flowing through the main battery 10 and outputs the detection result to the controller 30. In the present embodiment, when the main battery 10 is discharged, a positive value can be used as the current value detected by the current sensor 22. Further, when the main battery 10 is being charged, a negative value can be used as the current value detected by the current sensor 22.

  In the present embodiment, the current sensor 22 is provided on the positive line PL connected to the positive terminal of the main battery 10, but the present invention is not limited to this. The current sensor 22 only needs to be able to detect the value of the current flowing through the main battery 10. Specifically, the current sensor 22 can be provided in at least one of the positive electrode line PL and the negative electrode line NL. Here, the negative electrode line NL is a line connected to the negative electrode terminal of the main battery 10.

  A system main relay SMR-B is provided in the positive electrode line PL. System main relay SMR-B is switched between on and off by receiving a control signal from controller 30. A system main relay SMR-G is provided in the negative electrode line NL. System main relay SMR-G is switched between on and off by receiving a control signal from controller 30.

  A system main relay SMR-P and a current limiting resistor R are connected in parallel to the system main relay SMR-G. System main relay SMR-P and current limiting resistor R are connected in series. System main relay SMR-P is switched between on and off by receiving a control signal from controller 30. The current limiting resistor R is used to suppress the inrush current from flowing when the main battery 10 is connected to a load (specifically, a booster circuit 23 described later).

  The main battery 10 is connected to the booster circuit 23 via the positive electrode line PL and the negative electrode line NL. The booster circuit 23 boosts the output voltage of the main battery 10 and outputs the boosted power to the inverter 24. Further, the booster circuit 23 can step down the voltage output from the inverter 24 and output the reduced power to the main battery 10. The controller 30 can control the operation of the booster circuit 23.

  The inverter 24 converts the DC power output from the booster circuit 23 into AC power, and outputs the AC power to the motor generator (MG) 25. The inverter 24 converts AC power generated by the motor / generator 25 into DC power and outputs the DC power to the booster circuit 23. The controller 30 can control the operation of the inverter 24. For example, a three-phase AC motor can be used as the motor / generator 25.

  The motor / generator 25 receives AC power from the inverter 24 and generates kinetic energy for running the vehicle. When the vehicle is driven using the output power of the main battery 10, the kinetic energy generated by the motor / generator 25 is transmitted to the wheels.

  When the vehicle is decelerated or stopped, the motor / generator 25 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The inverter 24 converts the AC power generated by the motor / generator 25 into DC power and outputs the DC power to the booster circuit 23. Booster circuit 23 steps down the output voltage from inverter 24 and outputs the reduced power to main battery 10. Thereby, regenerative electric power can be stored in the main battery 10.

  When connecting the main battery 10 to the booster circuit 23, the controller 30 first switches the system main relays SMR-B and SMR-P from off to on. Thereby, a current can be passed through the current limiting resistor R, and an inrush current can be suppressed from flowing. Next, the controller 30 switches the system main relay SMR-P from on to off after switching the system main relay SMR-G from off to on. Thereby, the connection between the main battery 10 and the booster circuit 23 is completed, and the battery system shown in FIG.

  When disconnecting the connection between the main battery 10 and the booster circuit 23, the controller 30 switches the system main relays SMR-B and SMR-G from on to off. Thereby, the battery system shown in FIG. 1 is in a stopped state (Ready-Off). Here, information related to on / off of the ignition switch of the vehicle is input to the controller 30. The controller 30 activates the battery system shown in FIG. 1 when the ignition switch is on, and stops the battery system shown in FIG. 1 when the ignition switch is off.

  The controller 30 has a built-in memory 31, and the memory 31 stores various information for the controller 30 to perform predetermined processing (particularly processing described in the present embodiment). In this embodiment, the memory 31 is built in the controller 30, but the memory 31 can be provided outside the controller 30.

  A DC / DC converter 26 is connected to lines PL and NL connecting the main battery 10 and the booster circuit 23 via DC relays DCR-B and DCR-G. The DC relays DCR-B and DCR-G are switched between on and off in response to a control signal from the controller 30. The DC / DC converter 26 converts the output voltage of the main battery 10 and supplies the converted power to the temperature adjustment device 27 or to the auxiliary battery 40. That is, the DC / DC converter 26 steps down the output voltage of the main battery 10. Here, when the DC / DC converter 26 supplies power to the auxiliary battery 40, the DC relays DCR-B and DCR-G are switched from OFF to ON.

  As will be described later, the temperature adjustment device 27 is used to adjust the temperature of the main battery 10 (unit cell 11). The temperature adjustment device 27 is connected to the DC / DC converter 26 via the relay TDR, and the power from the DC / DC converter 26 is supplied to the temperature adjustment device 27 when the relay TDR is on. Thereby, the temperature control device 27 can be driven. Here, the relay TDR receives a control signal from the controller 30 and switches between on and off.

  The auxiliary battery 40 can be charged and discharged, and is used to supply electric power to an auxiliary machine mounted on the vehicle. The auxiliary battery 40 is connected to the DC / DC converter 26, and power from the main battery 10 is supplied to the auxiliary battery 40 via the DC / DC converter 26. Thereby, the auxiliary battery 40 can be charged. In addition, as an auxiliary machine, a power window motor, a door lock unit, a switch unit, an automatic door opening / closing unit etc. are mentioned, for example.

  A charger 41 is connected to the lines PL and NL connecting the main battery 10 and the booster circuit 23 via charging lines CPL and CNL. The charging lines CPL and CNL are provided with charging relays CHR-B1 and CHR-G1, and the charging relays CHR-B1 and CHR-G1 receive a control signal from the controller 30 and are turned on and off. Switch.

  The charger 41 is mounted on a vehicle and connected to an inlet (so-called connector) 42. The inlet 42 is connected to a plug (so-called connector) 51 connected to the external power source 52. The plug 51 and the external power source 52 are provided outside the vehicle. When the plug 51 is connected to the inlet 42, the power from the external power source 52 can be guided to the charger 41.

  As the external power source 52, for example, a commercial power source can be used. The charger 41 can convert AC power supplied from the external power supply 52 into DC power, and supply the DC power to the main battery 10. Here, a constant charging current is supplied from the charger 41 to the main battery 10.

  As described above, when the plug 51 connected to the inlet 42 is directly connected to the external power supply 52, the main battery 10 can be charged using the inlet 42 and the charger 41. Here, charging the main battery 10 using the charger 41 and the inlet 42 is referred to as AC (Alternate Current) charging.

  In this embodiment, the charger 41 is connected to a positive line PL that connects the system main relay SMR-B and the booster circuit 23 and a negative line NL that connects the system main relay SMR-G and the booster circuit 23. . Therefore, when the system main relays SMR-B and SMR-G are on and the charging relays CHR-B1 and CHR-G1 are on, power is supplied from the charger 41 to the main battery 10. .

  Charger 41 is connected to a positive electrode line PL that connects the positive terminal of main battery 10 and system main relay SMR-B, and a negative electrode line NL that connects the negative terminal of main battery 10 and system main relay SMR-G. You can also In this case, even if the system main relays SMR-B and SMR-G are not turned on, power is supplied from the charger 41 to the main battery 10 only by turning on the charging relays CHR-B1 and CHR-G1. be able to.

  On the other hand, an inlet (so-called connector) 43 is connected to the lines PL and NL connecting the main battery 10 and the booster circuit 23 via charging lines CPL and CNL. Charging lines CPL and CNL are provided with charging relays CHR-B2 and CHR-G2. The charging relays CHR-B2 and CHR-G2 receive a control signal from the controller 30 and are turned on and off. Switch.

  A plug (so-called connector) 53 installed outside the vehicle is connected to the inlet 43. The plug 53 is connected to an external charger 54, and the external charger 54 is connected to an external power source 52. The external charger 54 converts AC power supplied from the external power source 52 into DC power. When the plug 53 is connected to the inlet 43, DC power from the external charger 54 can be supplied to the main battery 10. Here, a constant charging current is supplied from the external charger 54 to the inlet 43.

  Thus, when the external charger 54 is installed outside the vehicle, the main battery 10 can be charged by connecting the plug 53 to the inlet 43. Here, charging the main battery 10 using the inlet 43 is referred to as DC (Direct Current) charging. The current value when performing DC charging can be made larger than the current value when performing AC charging.

  In this case, the charging time for DC charging can be made shorter than the charging time for AC charging. The charging time here is a time until the SOC (State of Charge) of the main battery 10 is raised to the designated SOC by charging the main battery 10. The SOC is the ratio of the current charge capacity to the full charge capacity. The designated SOC is the SOC of the main battery 10 when external charging (AC charging or DC charging) is completed, and is set as appropriate.

  In this embodiment, the inlet 43 is connected to a positive line PL that connects the system main relay SMR-B and the booster circuit 23, and a negative line NL that connects the system main relay SMR-G and the booster circuit 23. Therefore, power is supplied from the inlet 43 to the main battery 10 when the system main relays SMR-B, SMR-G are on and the charging relays CHR-B2, CHR-G2 are on.

  Inlet 43 is connected to a positive line PL that connects the positive terminal of main battery 10 and system main relay SMR-B, and a negative line NL that connects the negative terminal of main battery 10 and system main relay SMR-G. You can also. In this case, power is supplied from the inlet 43 to the main battery 10 only by turning on the charging relays CHR-B2 and CHR-G2 without turning on the system main relays SMR-B and SMR-G. Can do.

  In AC charging or DC charging, wired or wireless can be used in the path for supplying power from the external power source 52 to the main battery 10. As the wire, a power cable can be used. As wireless, a so-called non-contact charging method using electromagnetic induction or resonance phenomenon can be used. As the non-contact charging method, a known technique can be appropriately used.

  A DC / DC converter 26 is connected to the charging lines CPL and CNL via charging relays CHR-B3 and CHR-G3. Charging relays CHR-B3, CHR-G3 are switched between on and off in response to a control signal from controller 30. When charging relays CHR-B3 and CHR-G3 are on and charging relays CHR-B2 and CHR-G2 are on, power from inlet 43 is supplied to main battery 10 and a DC / DC converter. 26 is also supplied. Here, when the DC / DC converter 26 supplies the electric power from the inlet 43 to the temperature adjustment device 27, the charging relays CHR-B3 and CHR-G3 are switched from OFF to ON.

  Next, a structure for adjusting the temperature of the main battery 10 will be described with reference to FIG.

  The circulation duct 61 is provided with a temperature adjustment device 27 and a blower 62. The drive of the blower 62 is controlled by the controller 30. When the blower 62 is driven, an air flow is generated in the circulation duct 61 in the direction indicated by the arrow. The temperature adjustment device 27 is provided downstream in the air movement direction with respect to the blower 62, and converts the air guided from the blower 62 into air used for temperature adjustment of the main battery 10.

  When the temperature of the main battery 10 rises due to charging / discharging of the main battery 10 or the environmental temperature around the main battery 10, the main battery 10 needs to be cooled. When the main battery 10 is cooled, the temperature adjustment device 27 cools the air from the blower 62 and supplies the cooled air to the main battery 10. Thereby, the temperature of the main battery 10 can be suppressed by exchanging heat between the cooling air and the main battery 10.

  When the main battery 10 is cooled, for example, a Peltier element or a compressor heat pump can be used as the temperature adjustment device 27. The Peltier element is an element that generates heat or absorbs heat depending on the direction of current flow and the current value. By absorbing heat using the Peltier element, the air supplied to the main battery 10 can be cooled. In the compressor heat pump, the temperature of the heat medium is reduced to lower the temperature, so that heat is taken from the air from the blower 62 and the air supplied to the main battery 10 can be cooled.

  When the temperature of the main battery 10 decreases due to the environmental temperature around the main battery 10, it is necessary to warm the main battery 10. By heating the main battery 10, it becomes easy to secure input / output of the main battery 10. When the main battery 10 is warmed, the temperature adjustment device 27 warms the air from the blower 62 and supplies the warmed air to the main battery 10. Thereby, the temperature of the main battery 10 can be suppressed by heat exchange between the air for heating and the main battery 10.

  When the main battery 10 is warmed, for example, a heater, a Peltier element, or a compressor heat pump that generates heat when energized can be used as the temperature adjustment device 27. If a current is supplied to the heater, the heater can generate heat, and the air supplied to the main battery 10 can be warmed using the heat generated by the heater. If a current in a predetermined direction is supplied to the Peltier element, the Peltier element can be heated, and the air supplied to the main battery 10 can be warmed using the heat generated by the Peltier element. In the compressor heat pump, the air supplied to the main battery 10 can be warmed by pressurizing the heat exchange medium to increase the temperature of the heat exchange medium.

  Based on the output of the temperature sensor 21, the controller 30 can determine whether or not the main battery 10 is warmed or determine whether or not the main battery 10 is cooled. By maintaining the temperature of the main battery 10 within a desired temperature range, the input / output characteristics of the main battery 10 can be prevented from deteriorating.

  In this embodiment, the air from the temperature control device 27 is guided not only to the main battery 10 but also to the system main relays SMR-B, SMR-P, and SMR-G. At least the main battery 10 may be led. Moreover, the structure which guides the air for temperature control with respect to each single battery 11 which comprises the main battery 10 can be set suitably.

  When a so-called square battery is used as the single battery 11, the main battery 10 can be configured by arranging a plurality of single batteries 11 in a predetermined direction. In this case, a space can be formed between two unit cells 11 arranged adjacent to each other in a predetermined direction, and temperature adjusting air can be guided to this space. When a so-called cylindrical battery is used as the unit cell 11, temperature adjusting air may be flowed along the outer peripheral surface of the unit cell 11.

  The air exchanged heat with the main battery 10 moves through the circulation duct 61 and is guided to the blower 62. The air that has passed through the blower 62 is converted into air suitable for temperature adjustment of the main battery 10 by the temperature adjustment device 27, and then supplied again to the main battery 10. In the present embodiment, the temperature of the main battery 10 is adjusted using air, but the present invention is not limited to this. Specifically, a gas other than air or a liquid can be used.

  In this embodiment, air is circulated using the circulation duct 61, but the present invention is not limited to this. Specifically, by driving the blower 62, air from outside can be taken in and supplied to the main battery 10. The air exchanged with the main battery 10 can be discharged to the outside. The term “outside” as used herein means, for example, the interior of the vehicle or the outside of the vehicle.

  When the main battery 10 is heated, the temperature of the main battery 10 (unit cell 11) is lowered. As the temperature of the main battery 10 (unit cell 11) decreases, the internal resistance of the main battery 10 (unit cell 11) is likely to increase, and current does not easily flow to the main battery 10 (unit cell 11). Here, when the main battery 10 is charged by AC charging or DC charging, the current value flowing through the main battery 10 is smaller than the current value supplied from the external power supply 52.

  When the current value (charging current) flowing through the main battery 10 decreases, the time for charging the main battery 10 also increases. If a charging current flows through the main battery 10 (unit cell 11), the main battery 10 (unit cell 11) can be warmed by heat generation (self-heating) associated with the internal resistance of the unit cell 11. If the main battery 10 (single cell 11) is warmed, the internal resistance of the main battery 10 (single cell 11) can be reduced, and a charging current can easily flow through the main battery 10 (single cell 11). However, only the self-heating of the unit cell 11 cannot sufficiently warm the unit cell 11, and the time for charging the main battery 10 cannot be efficiently shortened.

  Therefore, in the present embodiment, when AC charging or DC charging is performed, a current that is supplied from the inlets 42 and 43 to the main battery 10 is not limited to the main battery 10, but the temperature adjustment device via the DC / DC converter 26. 27 is also supplied. As described above, even if a predetermined value of current is caused to flow from the inlets 42 and 43 to the main battery 10, only a current having a value smaller than the predetermined value may flow to the main battery 10 due to the internal resistance of the main battery 10. .

  In consideration of this point, in this embodiment, a current that cannot be supplied to the main battery 10 is supplied to the temperature adjustment device 27. That is, in this embodiment, when the temperature of the main battery 10 is lowered when external charging is started, the main battery 10 is warmed by driving the temperature adjustment device 27 while charging the main battery 10. I am doing so.

  Hereinafter, processing when external charging (here, DC charging) is performed will be described with reference to the flowchart shown in FIG. The process shown in FIG. 3 is executed by the controller 30 and can be started when the plug 53 is connected to the inlet 43, for example. When performing DC charging, the controller 30 switches the system main relays SMR-B and SMR-G and the charging relays CHR-B2 and CHR-G2 from off to on.

  In step S <b> 101, the controller 30 detects the temperature Tb of the main battery 10 based on the output of the temperature sensor 21. In step S102, the controller 30 determines whether or not the battery temperature Tb detected in the process of step S101 is lower than a threshold value (temperature) Tth.

  The threshold value Tth is a temperature for determining whether or not the main battery 10 is to be warmed, and can be appropriately set in consideration of input / output characteristics with respect to the temperature of the main battery 10. Information regarding the threshold value Tth can be stored in the memory 31. Here, when the temperatures are detected at a plurality of different locations in the main battery 10 and the detected temperatures are different from each other, the lowest detected temperature can be used as the battery temperature Tb.

  When the battery temperature Tb is lower than the threshold value Tth, the controller 30 determines that the main battery 10 needs to be heated, and proceeds to the process of step S103. On the other hand, when the battery temperature Tb is higher than the threshold value Tth, the controller 30 determines that it is not necessary to warm the main battery 10, and proceeds to the process of step S108.

  In step S103, the controller 30 detects the current value (charging current) Ib flowing through the main battery 10 based on the output of the current sensor 22. In step S104, the controller 30 determines whether or not the current value Ib detected in the process of step S103 is smaller than a threshold value (current value) Ith. The threshold value Ith is a current value that can be passed through the main battery 10 without prolonging the charging time, and can be set as appropriate.

  Specifically, the current value supplied from the inlet 43 to the main battery 10 or a current value slightly smaller than this current value can be used as the threshold value Ith. The slightly smaller current value is a current value that hardly affects the extension of the charging time in the magnitude relationship between the current value flowing through the main battery 10 and the current value supplied from the inlet 43 to the main battery 10. In the present embodiment, as the threshold value Ith, a current value is used to flow through the main battery 10 when the battery temperature Tb is the threshold value Tth. Information regarding the threshold value Ith can be stored in the memory 31.

  When the current value Ib is larger than the threshold value Ith, the controller 30 determines that it is possible to flow a sufficient charging current to the main battery 10 and it is not necessary to warm the main battery 10, and the process proceeds to step S108. If a sufficient charging current can be supplied to the main battery 10, the external charging of the main battery 10 can be efficiently performed without prolonging the external charging time more than necessary.

  On the other hand, when the current value Ib is smaller than the threshold value Ith, the controller 30 cannot flow a sufficient charging current to the main battery 10 due to the increase in the internal resistance of the main battery 10 and needs to warm the main battery 10. And the process proceeds to step S105. If a sufficient charging current cannot be supplied to the main battery 10, the external charging time will be prolonged. Therefore, it is necessary to warm the main battery 10 and reduce the internal resistance of the main battery 10. If the internal resistance of the main battery 10 is reduced, a charging current can easily flow through the main battery 10, and external charging of the main battery 10 can be performed efficiently.

  In step S105, the controller 30 determines whether or not the charging relays CHR-B3 and CHR-G3 are on. When the charging relays CHR-B3 and CHR-G3 are off, the controller 30 proceeds to the process of step S106. On the other hand, when the charging relays CHR-B3 and CHR-G3 are on, the controller 30 proceeds to the process of step S107.

  In step S106, the controller 30 switches the charging relays CHR-B3 and CHR-G3 from off to on. Thereby, the charging current when performing DC charging flows not only to the main battery 10 but also to the DC / DC converter 26. In step S <b> 107, the controller 30 performs a process (temperature increase process) for heating the main battery 10 by driving the temperature adjustment device 27. Details of the temperature raising process will be described later. After performing the temperature raising process, the controller 30 returns to the process of step S101.

  When the process proceeds from step S102 to step S108, the controller 30 stops the temperature raising process. When the temperature raising process is not performed, the controller 30 does not perform the temperature raising process. In step S109, the controller 30 calculates the current SOC of the main battery 10, and determines whether or not the SOC of the main battery 10 is higher than the designated SOC. The designated SOC is the SOC of the main battery 10 when external charging (DC charging) is completed as described above.

  The SOC of the main battery 10 can be estimated by integrating the current value flowing through the main battery 10. That is, when performing DC charging, the current SOC of the main battery 10 is calculated based on the SOC of the main battery 10 at the start of DC charging and the value obtained by integrating the current value flowing through the main battery 10 during DC charging. Can be estimated.

  Further, the SOC of the main battery 10 can be calculated (estimated) based on the voltage value of the main battery 10 detected by the monitoring unit 20. Since SOC and OCV (Open Circuit Voltage) have a predetermined correspondence, if the OCV of the main battery 10 is measured, the SOC of the main battery 10 can be estimated based on the correspondence between the SOC and the OCV.

  When the SOC of the main battery 10 is lower than the designated SOC, the controller 30 determines that charging (DC charging) of the main battery 10 has not been completed, and returns to the process of step S101. On the other hand, when the SOC of the main battery 10 is higher than the designated SOC, the controller 30 determines that charging of the main battery 10 (DC charging) has been completed, and proceeds to the process of step S110.

  In step S110, the controller 30 switches the charging relays CHR-B3 and CHR-G3 from on to off. As a result, the charging current does not flow to the temperature adjustment device 27 via the DC / DC converter 26. Further, when completing the DC charging, the controller 30 switches the charging relays CHR-B2, CHR-G2 from on to off.

  In this embodiment, the temperature raising process is performed while performing DC charging, but the present invention is not limited to this. Specifically, the temperature raising process can be performed while performing AC charging. Even in this case, a process similar to the process shown in FIG. 3 may be performed.

  Here, since the current value at the time of DC charging tends to be larger than the current value at the time of AC charging, the current value that cannot flow to the main battery 10 when the temperature of the main battery 10 is reduced is AC It tends to be larger when performing DC charging than when performing charging. For this reason, if the temperature raising process is performed while performing DC charging, the current supplied to the temperature adjustment device 27 via the DC / DC converter 26 can be increased. If more current is supplied to the temperature adjustment device 27, the main battery 10 can be efficiently heated using the temperature adjustment device 27.

  In addition, since the current value during DC charging tends to be larger than the current value during AC charging, the charging time due to DC charging tends to be shorter than the charging time due to AC charging. For this reason, it is preferable to suppress extending the charging time by DC charging. Therefore, it is preferable to perform the temperature raising process while performing DC charging as in this embodiment.

  Next, details of the temperature raising process in step S107 of FIG. 3 will be described using the flowchart shown in FIG. The process shown in FIG. 4 is executed by the controller 30.

  In step S <b> 201, the controller 30 calculates a current value that can be passed through the temperature adjustment device 27. Specifically, the controller 30 calculates a current value that can be passed through the temperature adjustment device 27 based on the following equation (1).

  I_dev = Ic−Ib (1)

  In the above formula (1), I_dev is a current value that can flow through the temperature adjustment device 27, and Ib is a current value (charging current) that flows through the main battery 10. The controller 30 can acquire the current value Ib based on the output of the current sensor 22.

  In the above formula (1), Ic is a current value (charging current) supplied from the external charger 54 to the inlet 43. Since a constant current is supplied from the external charger 54 to the inlet 43, the current value Ic is a fixed value. For example, the controller 30 can acquire the current value Ic by performing communication with the external charger 54.

  Here, the behavior of the current values Ib and I_dev and the battery temperature Tb is shown in FIG. In FIG. 5, the left vertical axis indicates the current value, and the right vertical axis indicates the battery temperature. Further, the horizontal axis indicates the charging time, and the charging time becomes longer as it goes to the right side of FIG.

  When the battery temperature Tb is decreasing, the current value Ib is smaller than the current value Ic due to the internal resistance of the main battery 10 (unit cell 11). Here, the difference between the current value Ic and the current value Ib is the current value I_dev. If the temperature raising process is performed while external charging is performed, the battery temperature Tb rises with the lapse of time due to self-heating of the main battery 10 (unit cell 11) accompanying charging and heating using the temperature adjustment device 27. It becomes easy.

  If the battery temperature Tb rises, the internal resistance of the main battery 10 (unit cell 11) decreases, so that a charging current easily flows through the main battery 10 (unit cell 11). That is, the current value Ib increases. On the other hand, since the current value I_dev is the difference between the current values Ic and Ib, the current value I_dev decreases as the current value Ib increases. As shown in FIG. 5, when the current value Ib reaches the current value Ic, the current value I_dev becomes 0 [A].

  In this embodiment, the current of the current value I_dev calculated from the above formula (1) is supplied to the temperature adjustment device 27, but the present invention is not limited to this. Specifically, a current having a current value smaller than the current value I_dev calculated from the above equation (1) can be supplied to the temperature adjustment device 27.

  In step S <b> 202 shown in FIG. 4, the controller 30 outputs a drive signal to the DC / DC converter 26 in order to start driving of the DC / DC converter 26. Further, the controller 30 switches the relay TDR from off to on.

  In step S <b> 203, the controller 30 supplies power from the DC / DC converter 26 to the temperature adjustment device 27 by controlling the driving of the DC / DC converter 26. Here, the controller 30 controls the driving of the DC / DC converter 26 based on the current value I_dev calculated in the process of step S201.

  As described with reference to FIG. 5, the current value I_dev decreases as the current value Ib increases. That is, as the current value Ib flowing through the main battery 10 increases, the current value I_dev input to the DC / DC converter 26 decreases. Here, if the output of the DC / DC converter 26 can be changed, the output of the DC / DC converter 26 can be changed according to the fluctuation of the current value I_dev. That is, power corresponding to the current value I_dev can be supplied to the temperature adjustment device 27.

  According to the present embodiment, the temperature adjustment device 27 can be driven by supplying a part of the charging current to the temperature adjustment device 27 via the DC / DC converter 26. Thereby, the main battery 10 can be warmed using the temperature control device 27. Here, the charging current supplied to the DC / DC converter 26 is a current that cannot flow through the main battery 10 and cannot be used for charging the main battery 10. That is, even if the charging current of the main battery 10 is decreased by the amount of charging current supplied to the DC / DC converter 26, the charging efficiency of the main battery 10 is not affected.

  For this reason, if the temperature control device 27 is driven using a current that cannot be passed through the main battery 10, the temperature control device 27 is used to warm the main battery 10 without reducing the charging efficiency of the main battery 10. Can do. If the main battery 10 is warmed and the internal resistance of the main battery 10 is lowered, a larger amount of current can flow through the main battery 10 and the main battery 10 can be charged efficiently. That is, it can be suppressed that the time until external charging is completed is prolonged.

  FIG. 6 is a diagram for explaining the time until charging is completed when the main battery 10 in a low temperature state is charged. In FIG. 6, the horizontal axis indicates the charging time, and the vertical axis indicates the charging current. In FIG. 6, a line L <b> 1 indicates the behavior of the current value flowing through the main battery 10 when the temperature adjustment device 27 is not driven. A line L2 indicates the behavior of the current value flowing through the main battery 10 when the temperature adjustment device 27 is driven.

  When the temperature control device 27 is not driven, the current value flowing through the main battery 10 does not reach the current value Ic supplied from the external charger 54 to the inlet 43, and external charging is completed at time t3. . On the other hand, when the temperature adjustment device 27 is driven, the main battery 10 is easily warmed, and the current value flowing through the main battery 10 increases as the internal resistance of the main battery 10 decreases.

  Thereby, when the temperature control device 27 is driven, the current value flowing through the main battery 10 reaches the current value Ic at time t1. If the current easily flows to the main battery 10, the SOC of the main battery 10 is likely to increase, and external charging can be completed at time t2. The time t2 is shorter than the time t3, and the charging time can be shortened by the difference between the times t2 and t3.

  FIG. 7 shows the relationship between the temperature of the main battery 10 when starting external charging (battery temperature), the charging time, and the current value that can be passed through the main battery 10. In FIG. 7, the horizontal axis represents the battery temperature, the left vertical axis represents the charging time, and the right vertical axis represents the charging current.

  In FIG. 7, the dotted line indicates the relationship between the battery temperature and the charging time when the temperature adjustment device 27 is not used. The solid line indicates the relationship between the battery temperature and the charging time when the temperature adjustment device 27 is used. The alternate long and short dash line indicates the relationship between the current value (charge current) that can flow through the main battery 10 and the battery temperature.

  As shown in FIG. 7, the internal resistance of the main battery 10 increases as the battery temperature decreases, and the current value that can flow through the main battery 10 decreases. In such a state, if the temperature adjustment device 27 is driven, the charging time can be shortened compared to the case where the temperature adjustment device 27 is not driven.

  In particular, as the battery temperature at the start of external charging decreases, the difference in charging time between the case where the temperature adjustment device 27 is driven and the case where the temperature adjustment device 27 is not driven is likely to widen. That is, if the temperature raising process is performed while external charging is performed as in the present embodiment, the charging time is easily shortened as the battery temperature when starting external charging decreases.

  On the other hand, the current value (charging current) that can be passed through the main battery 10 increases as the battery temperature when starting external charging increases. When the battery temperature is higher than the temperature T1, the charging time does not change regardless of whether the temperature adjustment device 27 is driven or not.

  As shown in FIG. 7, the threshold value (temperature) Tth described in the process of step S102 of FIG. 3 can be set to a temperature lower than the temperature T1. Further, the threshold value (current value) Ith described in the process of step S104 in FIG. 3 can be a current value smaller than the current value Ic.

  When the battery temperature Tb is higher than the threshold value Tth, or when the current value Ib flowing through the main battery 10 is larger than the threshold value Ith, the charging time of the main battery 10 hardly changes regardless of the battery temperature Tb or the current value Ib. Become. In this case, it is not necessary to drive the temperature adjustment device 27 to heat the main battery 10. Therefore, as described in the process shown in FIG. 3, when the battery temperature Tb is higher than the threshold value Tth or when the current value Ib is higher than the threshold value Ith, the temperature raising process is not performed.

  On the other hand, when the battery temperature Tb is lower than the threshold value Tth, or when the current value Ib flowing through the main battery 10 is lower than the threshold value Ith, the charging time varies depending on whether or not the temperature adjustment device 27 is driven. Is likely to occur. Here, the threshold value Tth and the threshold value Ith can be appropriately set in consideration of the fact that a difference is likely to occur in the charging time.

  In the present embodiment, as described in the processing of step S102 and step S104 in FIG. 3, when the battery temperature Tb is lower than the threshold value Tth or the current value Ib is lower than the threshold value Ith, the temperature adjustment device 27 is used. The temperature raising process used is performed. Thereby, as shown in FIG. 7, it becomes easy to shorten the charging time when externally charging the main battery 10 in a low temperature state.

  Here, since the DC / DC converter 26 is connected to the current path (charge lines CPL, CNL) between the inlet 43 and the main battery 10, the temperature before being input to the main battery 10 is used to change the temperature. The adjustment device 27 can be driven. Thereby, the temperature adjustment device 27 can be driven without discharging the main battery 10.

  In the battery system of the present embodiment, the power of the main battery 10 can be supplied to the DC / DC converter 26 by turning on the DC relays DCR-B and DCR-G. For this reason, the temperature adjustment device 27 can also be driven using the output power of the main battery 10. However, in this case, since the main battery 10 must be discharged, the discharged main battery 10 must be further charged. Along with this, there is a possibility that the time until the main battery 10 is finally charged will be prolonged.

  In this embodiment, power is directly supplied from the inlet 43 to the DC / DC converter 26 to drive the temperature adjustment device 27, so that it is not necessary to drive the temperature adjustment device 27 due to the discharge of the main battery 10. . Thereby, the charging of the main battery 10 and the driving of the temperature adjustment device 27 can be performed efficiently, and the charging time can be prevented from being prolonged.

  In this embodiment, the DC / DC converter 26 converts the output voltage of the main battery 10 into the input voltage of the auxiliary battery 40 and converts the power from the inlet 43 into the input power of the temperature adjustment device 27. It has a function. Thus, by giving two functions to one component, an increase in the number of components can be suppressed. However, it is also possible to prepare two DC / DC converters and give each DC / DC converter each function.

  Specifically, the configuration shown in FIG. 8 can be used instead of the configuration shown in FIG. In the configuration shown in FIG. 8, members having the same functions as those described in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 8, the plugs 51 and 53, the external power source 52, and the external charger 54 shown in FIG. 1 are omitted.

  In the configuration shown in FIG. 8, the DC / DC converter 26 is connected to the main battery 10 via DC relays DCR-B and DCR-G. The DC / DC converter 26 converts the output voltage of the main battery 10 and supplies the converted power to the auxiliary battery 40.

  On the other hand, the DC / DC converter 28 is connected to charging lines CPL and CNL via charging relays CHR-B3 and CHR-G3. The DC / DC converter 28 can supply a part of the power supplied from the inlet 43 to the main battery 10 to the temperature adjustment device 27. Even with the configuration shown in FIG. 8, the same effect as the configuration shown in FIG. 1 can be obtained.

  In the present embodiment (configuration shown in FIG. 1), the DC / DC converter 26 is connected to the path for supplying power from the inlet 43 to the main battery 10, but the present invention is not limited to this. Specifically, the DC / DC converter 26 can be connected to a path for supplying power from the charger 41 to the main battery 10. In this case, when performing AC charging, the temperature adjustment device 27 can be driven by using a part of the charging power.

  Here, with respect to a route (a part of the charging lines CPL and CNL) in which a route for supplying power from the inlet 43 to the main battery 10 and a route for supplying power from the charger 41 to the main battery 10 overlap each other, DC / DC converter 26 can be connected. In this case, regardless of whether AC charging or DC charging is performed, the temperature adjustment device 27 can be driven using a part of the charging current.

  In this embodiment, a part of the charging current is supplied to the temperature adjustment device 27 using the DC / DC converter 26, but the present invention is not limited to this. Specifically, the DC / DC converter 26 can be omitted. In this case, a part of the charging current is directly input to the temperature adjustment device 27. Even if it is such a structure, the effect similar to a present Example can be acquired.

10: main battery (power storage device), 11: single cell, 20: monitoring unit,
21: Temperature sensor, 22: Current sensor, 23: Booster circuit, 24: Inverter,
25: Motor generator 26: DC / DC converter 27: Temperature control device
30: Controller, 31: Memory, 40: Auxiliary battery, 41: Charger,
42, 43: Inlet, 51, 53: Plug, 54: External charger, 52: External power supply,
61: Circulation duct, 62: Blower, PL: Positive electrode line, NL: Negative electrode line,
CPL, CNL: charging line,
SMR-B, SMR-G, SMR-P: System main relay,
CHR-B1, CHR-B2, CHR-B3: charging relay,
CHR-G1, CHR-G2, CHR-G3: charging relay DCR-B, DCR-G: DC relay, TDR: relay, R: current limiting resistor

Claims (8)

A power storage device for charging and discharging; and
A device for applying heat to the power storage device;
A controller that drives the device using a portion of the power from the external power supply while supplying power from the external power supply to the power storage device;
A power storage system comprising:   2. The controller drives the device when a current value flowing through the power storage device is smaller than a current value flowing through a charging path for supplying power from the external power source to the power storage device. The power storage system described in 1.   The power storage system according to claim 2, wherein the controller supplies a current corresponding to a difference between a current value flowing through the power storage device and a current value flowing through the charging path to the device.   The power storage system according to claim 2 or 3, wherein the controller increases a current value supplied to the device as a current value flowing through the power storage device decreases.   A DC / DC converter that is connected to a charging path that supplies power from the external power source to the power storage device and that converts power from the external power source into input power to the device. Item 5. The power storage system according to any one of Items 1 to 4.   The power storage system according to claim 5, wherein the DC / DC converter converts discharge power of the power storage device into input power to another power storage device different from the power storage device. The charging path for supplying power from the external power source to the power storage device is:
A first charging path for supplying a predetermined current to the power storage device;
A second charging path that supplies a current having a value larger than a current value flowing through the first charging path to the power storage device,
The power storage system according to any one of claims 1 to 6, wherein the device operates by receiving power from the second charging path. The power storage system according to any one of claims 1 to 7, wherein the power storage device outputs electrical energy converted into kinetic energy for running the vehicle.

Images