JP2012252907A - Electric vehicle charging system and charging control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the rate of rise in temperature by temperature rise control during external charging of a plurality of parallel connected power storage devices which are externally incorporated in an electric vehicle.SOLUTION: When temperature rise control is needed during external charging of a power storage unit 10, an ECU 60 controls external charging so that a set of a first charge period and a second charge period will be provided. In the first charge period, the ECU 60 turns a charge relay CHR on and also turns only one of battery relays RLB1 and RLB2 on, causing only one of battery units BU1 and BU2 to be charged with power from a charger 80. In the second period after the first period, the ECU 60 turns the charge relay CHR off and also turns both of the battery relays RLB1 and RLB2 on. In the second charge period, a charge/discharge current is generated between the battery units BU1 and BU2.

Description

  The present invention relates to a charging system and a charging control method for an electric vehicle, and more particularly, to charging control for an electric vehicle equipped with a plurality of power storage devices connected in parallel.

  An electric vehicle, a hybrid vehicle, or a fuel cell vehicle is known as an electric vehicle configured to be able to drive a drive motor using electric power from an in-vehicle power storage device represented by a secondary battery. In an electric vehicle, a configuration has been proposed in which an in-vehicle power storage device is charged by a power source outside the vehicle (hereinafter also simply referred to as “external charging”). Hereinafter, charging of the power storage device by external charging is also simply referred to as “external charging”.

  In an externally chargeable electric vehicle, a configuration in which a plurality of power storage devices are arranged in parallel is known in order to extend a period during which the vehicle can be driven by electric energy. For example, JP 2008-109755 A (Patent Document 1) describes a configuration in which two power storage units are connected in parallel.

  Further, it is known that the characteristics of the power storage device have temperature dependency. Typically, since the internal resistance of a secondary battery (hereinafter also simply referred to as “battery”) has temperature dependence, the increase in internal resistance at low temperatures makes it difficult to output high power. It has been. For this reason, a technique for efficiently heating the battery is used.

  For example, Japanese Patent Laying-Open No. 2003-272712 (Patent Document 2) describes a configuration that can efficiently raise the battery temperature without adding parts. Specifically, it is described that the temperature of the battery is increased by repeatedly charging and discharging the battery within a predetermined SOC range when the battery temperature decreases.

  Further, in Patent Document 1, in order to increase the temperature of power storage configured by a battery or the like, two power storage devices are externally charged in parallel so as not to reach a fully charged state, and then one power storage device is connected to the other power storage. It is described that control is performed so as to supply power to the apparatus. Thereby, the temperature of the power storage device can be increased by charging and discharging between the batteries.

JP 2008-109755 A JP 2003-272712 A

  In the configurations described in Patent Documents 1 and 2, the temperature increase control of the power storage device represented by the battery can be executed without providing additional parts. In particular, Patent Document 2 describes temperature increase control when externally charging a plurality of power storage devices connected in parallel.

  Here, the temperature rise amount in the temperature rise control of the power storage device depends on the magnitude of power consumption indicated by the product of the square of the charge / discharge current of the power storage device and the internal resistance. Therefore, in order to realize efficient temperature rise control with a large temperature rise amount, it is necessary to increase the charge / discharge current of the power storage device. In this regard, there is room for improvement in the temperature rise control described in Patent Document 2.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a power storage device for external charging in an electric vehicle equipped with a plurality of power storage devices connected in parallel. This is to increase the amount of temperature rise by the temperature rise control.

  In one aspect of the present invention, an electric vehicle charging system includes a plurality of power storage devices connected in parallel to the first and second power lines, a plurality of switches, a charger, a charging switch, A plurality of switches, a charging switch, and a control device for controlling charging of the plurality of power storage devices by the charger. The plurality of switches are respectively connected in series with the plurality of power storage devices between the first and second power lines. The charger is configured to supply charging power of the plurality of power storage devices to the first and second power lines. The charging switch is connected between the charger and the first and second power lines. When it is necessary to raise the temperature of the plurality of power storage devices, the control device connects a part of the power storage devices of the plurality of power storage devices to the first and second power lines, and the remaining of the plurality of power storage devices. In a state in which the plurality of switches are controlled so as to disconnect the power storage device from the first and second power lines, the charging switch is turned on to supply power from the charger to the first and second power lines. After the charging period and the first charging period, the charging switch is turned off, and the plurality of switches are controlled so as to connect a part of the power storage devices and at least a part of the remaining power storage devices. The plurality of power storage devices are charged so as to provide the second charging period.

  Preferably, the control device controls the charger, the charging switch, and the plurality of switches so that the first and second charging periods are set a plurality of times.

  Preferably, the control device controls the charger, the charging switch, and the plurality of switches so as to provide a third charging period for charging the plurality of power storage devices in parallel after the end of the second charging period. .

  More preferably, the control device selects a part of the power storage devices to be charged in the first charging period based on the temperature of each of the plurality of power storage devices when starting the first charging period.

  Alternatively, more preferably, the control device is configured to charge one of the plurality of power storage devices having the lowest temperature when starting the first charging period, to be charged in the first charging period. Select power storage device.

  More preferably, when the control device executes the first charging period from the second time onward, the control device replaces the power storage device that is different from the power storage device charged in the previous first charging period with the current first time. Selected for some power storage devices to be charged in the charging period.

  In another aspect of the present invention, there is provided a charging control method for an electric vehicle, wherein the electric vehicle includes a plurality of power storage devices connected in parallel to the first and second power lines through a plurality of switches, respectively. And a charger for supplying charging power for the plurality of power storage devices to the first and second power lines via the charging switch. In the control method, when it is necessary to raise the temperature of the plurality of power storage devices, a part of the plurality of power storage devices is selected as a charging target, and the first power storage device and the second power storage device are selected. In a state where the plurality of switches are controlled so that the remaining power storage devices of the plurality of power storage devices are disconnected from the first and second power lines, the charging switch is turned on to A step of providing a first charging period for supplying power to the first and second power lines; and after the first charging period, the charging switch is turned off, and among some of the power storage devices and the remaining power storage devices Providing a second charging period for controlling the plurality of switches so as to connect at least a part of the second switch.

  Preferably, the control method further includes a step of controlling the charger, the charging switch, and the plurality of switches so that the first and second charging period sets are provided a plurality of times.

  Preferably, the control method controls the charger, the charging switch, and the plurality of switches so as to provide a third charging period for charging the plurality of power storage devices in parallel after the end of the second charging period. The method further includes the step of:

  More preferably, in the selecting step, a part of the power storage devices to be charged in the first charging period is selected based on the temperature of each of the plurality of power storage devices when starting the first charging period.

  More preferably, in the selecting step, one of the plurality of power storage devices that has the lowest temperature when starting the first charging period is charged in the first charging period. The power storage device is selected.

  Alternatively, more preferably, in the step of selecting, when the first charging period is executed for the second time or later, a power storage device different from the power storage device charged in the previous first charging period is selected. A part of the power storage devices to be charged in one charging period is selected.

  According to the present invention, in an electrically powered vehicle externally mounted with a plurality of power storage devices connected in parallel, the amount of temperature increase due to temperature increase control of the power storage device during external charging can be increased.

It is a block diagram which shows schematic structure relevant to the charging system of the electric vehicle by embodiment of this invention. It is a 1st figure explaining the temperature dependence of the internal resistance of an electrical storage apparatus. It is a 2nd figure explaining the temperature dependence of the internal resistance of an electrical storage apparatus. It is a flowchart which shows the control processing procedure at the time of the external charge in the charging system of the electric vehicle by embodiment of this invention. It is a conceptual diagram for demonstrating transition of SOC of each battery unit in temperature rising control. It is an equivalent circuit diagram at the time of charge / discharge operation between batteries. It is a notional waveform figure which shows transition of the electric current and voltage at the time of charge / discharge operation between batteries. It is a block diagram explaining the structure of the electrical storage part by the modification of embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

  FIG. 1 is a block diagram showing a schematic configuration related to a charging system for an electric vehicle according to an embodiment of the present invention.

  Referring to FIG. 1, electrically powered vehicle 100 includes a power storage unit 10, a PCU (Power Control Unit) 20, a motor generator 30, a power transmission gear 40, drive wheels 50, and a control device 60.

  The control device 60 includes a CPU (Central Processing Unit), a storage device, and an electronic control unit including an input / output buffer (not shown). Control device 60 (hereinafter also referred to as ECU 60) controls each device mounted on electric vehicle 100. Note that these controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  Power storage unit 10 includes a plurality of power storage devices BU1 and BU2 connected in parallel to each other between power lines PL1 and NL1, and battery relays RLB1 and RLB2.

  Each of power storage devices BU1 and BU2 is typically configured by a secondary battery such as a lithium ion battery or a nickel metal hydride battery. Note that the power storage device may be configured by an electric double layer capacitor or a combination of a secondary battery and a capacitor.

  In this embodiment, a secondary battery is exemplified as the power storage device. Therefore, hereinafter, power storage devices BU1 and BU2 are also referred to as battery units BU1 and BU2. For example, in the configuration example of FIG. 1, the battery units BU1 and BU2 are configured by separate assembled batteries. Battery units BU1 and BU2 correspond to “a plurality of power storage devices”.

  Battery sensors BS1 and BS2 are arranged in battery units BU1 and BU2, respectively. Battery sensor BS1 detects a state quantity of battery unit BU1, for example, battery current Ib1, battery voltage Vb1, and battery temperature Tb1. The detected state quantity of the battery unit BU1 is sent to the ECU 60.

  Similarly, battery sensor BS2 detects a state quantity of battery unit BU2, for example, battery current Ib2, battery voltage Vb2, and battery temperature Tb2. The detected state quantity of the battery unit BU2 is sent to the ECU 60.

  Battery relay RLB1 is connected in series with battery unit BU1 between power lines PL1 and NL1. Similarly, battery relay RLB2 is connected in series with battery unit BU2 between power lines PL1 and NL1. Opening (off) and closing (on) of battery relays RLB1, RLB2 are controlled by ECU 60. The battery relays RLB1, RLB2 correspond to “a plurality of switches”.

  Furthermore, a current sensor CS is further arranged so that a current flowing between the battery units BU1 and BU2 can be detected when the battery units BU1 and BU2 are connected. The detection value (Ibb) by the current sensor CS is sent to the ECU 60.

  System main relay SMR is connected between power lines PL1 and PL2 and between power lines NL1 and NL2. The ECU 60 controls opening (off) and closing (on) of the system main relay SMR.

  System main relay SMR is turned on when the vehicle travels. Further, when battery relays RLB1 and / or RLB2 are turned on, battery units BU1 and / or BU2 are connected to power lines PL1 and NL1. When the vehicle travels, both battery units BU1 and BU2 may be connected in parallel, or one of them may be used in turn.

  PCU 20 converts the DC power of power lines PL <b> 2 and NL <b> 2 into power for driving and controlling motor generator 30. For example, the motor generator 30 is composed of a permanent magnet type three-phase synchronous motor. PCU 20 is configured to include a three-phase inverter (not shown).

  The output torque of the motor generator 30 is transmitted to the drive wheels via a power transmission gear 40 constituted by a speed reducer and a power split mechanism. The electric vehicle 100 can travel with this torque. The motor generator 30 can generate power by the rotational force of the drive wheels 50 during regenerative braking of the electric vehicle 100. Then, the generated power is converted by PCU 20 into charging power for power storage unit 10 (battery unit BU1 and / or BU2).

  Therefore, electrically powered vehicle 100 can travel with charging / discharging of battery units BU1 and / or BU2 connected to power lines PL1 and NL1 by turning on system main relay SMR and battery relays RLB1 and / or RLB2. it can.

  In a hybrid vehicle in which an engine (not shown) is mounted in addition to motor generator 30, the necessary vehicle driving force of electric vehicle 100 is generated by operating this engine and motor generator 30 in a coordinated manner. . At this time, it is also possible to charge power storage unit 10 (battery unit BU1 and / or BU2) using the power generated by the rotation of the engine.

  That is, the electric vehicle 100 indicates a vehicle on which an electric motor for generating vehicle driving force is mounted, and includes a hybrid vehicle that generates vehicle driving force by an engine and an electric motor, an electric vehicle that does not have an engine, a fuel cell vehicle, and the like. .

  Electric vehicle 100 further includes a charger 80, a charging inlet 90, power lines PL3, PL4, NL4, and charging as a configuration (external charging system) for externally charging power storage unit 10 with electric power from external power supply 200. And a relay CHR. Generally, the external power source 200 is composed of a commercial AC power source.

  A charging connector 205 of a charging cable for electrically connecting the external power source 200 and the electric vehicle 100 is connected to the charging inlet 90. Then, electric power from external power source 200 is transmitted to electric vehicle 100 through a charging cable.

  Power line PL3 electrically connects between charging inlet 90 and charger 80. An LC filter (not shown) for removing harmonic components of the AC voltage may be inserted and connected to power line PL3.

  Charger 80 converts the AC voltage from external power supply 200 transmitted to power line PL3 into a DC voltage for charging power storage unit 10 (battery unit BU1 and / or BU2). The converted DC voltage is output to power lines PL4 and NL4. At this time, the DC voltage of power lines PL4 and NL4 is controlled to a voltage level suitable for charging power storage unit 10 (battery unit BU1 and / or BU2). The charger 80 can have an arbitrary circuit configuration as long as the above-described AC / DC conversion is possible.

  Charging relay CHR is electrically connected between power lines PL4 and PL1 and power lines NL4 and NL1. As described above, power line PL1 is electrically connected to battery units BU1 and BU2 via battery relays RLB1 and RLB2.

  Therefore, when external power supply 200 is connected to electrically powered vehicle 100 through the charging cable, charger 80 is operated and charging relay CHR is turned on, so that the charging power of the battery unit (power storage device) is supplied to power line PL1. , NL1. Further, the battery unit to be externally charged can be selected by turning on / off the battery relays RLB1, RLB2. Specifically, the battery units BU1 and BU2 can be externally charged in parallel by turning on both of the battery relays RLB1 and RLB2. Further, by turning on one of the battery relays RLB1, RLB2, only one of the battery units BU1 or BU2 can be selectively externally charged.

  On the other hand, at the time of external charging, system main relay SMR is turned off. Thus, power lines PL2 and NL2 are electrically disconnected from charger 80 and power storage unit 10 by system main relay SMR in the off state. Accordingly, since no voltage is applied to the traveling system equipment including the PCU 20, it is possible to prevent the durability life of the components of the traveling system equipment from being reduced by external charging.

  Conversely, the charging relay CHR is turned off when the vehicle is traveling. Thereby, since a voltage is not applied to the charger 80, it can prevent that the lifetime of the component of the charger 80 falls.

  Each of charging relay CHR, system main relay SMR, and battery relays RLB1 and RLB2 is typically closed (turned on) when excitation current is supplied by an excitation circuit (not shown), while when excitation current is not supplied. It is composed of an electromagnetic relay that is opened (turned off). However, any circuit element can be used as the charging relay, the system main relay, or the battery relay as long as it is a switch that can control conduction (ON) / interruption (OFF) of the energization path.

  Instead of the configuration shown in FIG. 1, the external power source 200 and the electric vehicle 100 may be electromagnetically coupled in a non-contact manner to supply power. For example, a primary coil is provided on the external power supply side, a secondary coil is provided on the vehicle side, and electric power is supplied from the external power supply 200 to the electric vehicle 100 using the mutual inductance between the primary coil and the secondary coil. May be. Even when such external charging is performed, the configuration after the power line PL3 for converting the power supplied from the external power source 200 can be shared.

  Here, the temperature characteristics of the power storage device (battery) will be described with reference to FIGS. 2 and 3 show temperature dependency data of the internal resistance of the power storage device (battery).

  FIG. 2 shows changes in internal resistance with respect to the SOC (State of Charge) of the battery for each battery temperature. FIG. 3 shows changes in internal resistance with respect to battery temperature for each SOC.

  2 and 3, it is understood that the internal resistance of the battery changes depending on the SOC and the battery temperature. In general, the internal resistance increases at low temperatures and at low SOC. When the internal resistance rises, the voltage drop and power consumption inside the battery increase, which may make it difficult to secure the output voltage and output power.

  Although the SOC is increased during external charging, the battery temperature may not be sufficiently increased even at the end of external charging during severe cold. In this case, when the vehicle travels after the end of external charging, the output power from the power storage unit 10 is limited, which may cause an effect such as a reduction in acceleration performance. Therefore, when the battery temperature is low, or when the outside air temperature is low and the battery temperature may drop during external charging, the battery temperature rise control is executed to increase the amount of heat generated by the battery during external charging. It is preferable to do.

  Therefore, in the electric vehicle according to the present embodiment, the temperature increase control during external charging as described below is executed.

  FIG. 4 is a flowchart showing a control processing procedure during external charging in the electric vehicle charging system shown in FIG. 1.

  A series of control processes according to the flowchart shown in FIG. 4 are executed by the ECU 60 during external charging. That is, each step of the flowchart shown in FIG. 4 is realized by software processing and / or hardware processing by the ECU 60.

  For example, when the charging cable is attached, power from the external power supply 200 is supplied to the charger 80, and when the start of external charging is instructed by a user operation or the like, the flowchart shown in FIG. 4 is followed. Control processing is started.

  Referring to FIG. 4, when external charging is started, ECU 60 first determines in step S100 whether temperature increase control is necessary.

  The determination in step S100 is determined based on whether or not the temperature increase control is required for at least one of the battery units BU1 and BU2, for example, whether or not the battery temperatures Tb1 and Tb2 are lower than a predetermined temperature. When the battery temperature is low and temperature increase control is necessary, step S100 is determined as YES.

  Alternatively, the outside air temperature may be further reflected in the determination in step S100. For example, when the outside air temperature is low and the battery temperature is expected to drop during external charging, it is preferable to make the determination in step S100 as YES.

  As will be described later, when the temperature raising control is executed, the amount of heat generated by the internal resistance of the battery unit is increased by charging and discharging the electric power once charged in the battery unit between the battery units. For this reason, the efficiency of external charging is reduced by the temperature rise control. Therefore, it is preferable that step S100 is determined as YES only in a scene where temperature increase control is necessary.

  When temperature increase control is not required (NO in S100), ECU 60 proceeds to step S200 and performs normal external charging. In normal external charging, for example, the battery units BU1 and BU2 are charged in parallel with the electric power from the charger 80. In this case, the charging relay CHR and the battery relays RPB1, RPB2 are turned on throughout the external charging period. And external charging can be terminated in response to the SOC of the battery unit BU1 or BU2 reaching the full charge level.

  Or you may perform normal external charge by charging each of battery unit BU1 and BU2 in order to a full charge level independently.

  When the SOC of battery unit BU1 and / or BU2 reaches the full charge level by normal external charging, step S200 is terminated, and ECU 60 proceeds to step S250 and terminates external charging. When the external charging is finished, the charger 80 is stopped and the charging relay CHR is turned off.

  On the other hand, when ECU 60 determines that charge control is necessary (when YES is determined in S100), ECU 60 performs temperature increase control in steps S110 to S190.

  When the temperature raising control is started, the ECU 60 first selects a charging battery from the battery units BU1 and BU2 in step S110. Here, the description will be given assuming that the battery unit BU1 is selected as the charging battery in step S110.

  FIG. 5 conceptually shows the SOC transition of each battery unit in the temperature rise control. As shown in FIG. 5A, the SOCs of the battery units BU1 and BU2 are assumed to be equal at the start of the temperature raising control.

  Referring to FIG. 4 again, in step S120, ECU 60 executes external charging for only the rechargeable battery selected in step S110. That is, in the configuration of FIG. 1, the battery relay RLB1 is turned on together with the charging relay CHR. On the other hand, the battery relay RLB2 is turned off. Thereby, the power supplied from the charger 80 is transmitted to the battery unit BU1. Thereby, battery unit BU1 is externally charged. On the other hand, the battery unit BU2 is not charged.

  The ECU 60 determines in step S130 whether or not the charge amount ΔS of external charging in step S120 has reached a predetermined amount S1. Until the charge amount ΔS reaches the predetermined amount S1 (when NO is determined in S130), external charging of only the charged battery in step S120 is continued. During the execution of step S130, the charge amount ΔS is sequentially calculated by integrating the battery current Ib1. The period during which the charging battery is charged in step S <b> 130 corresponds to the “first charging period”.

  When the charge amount ΔS reaches the predetermined amount S1 (when YES is determined in S130), the ECU 60 stops external charging of the charging battery in step S140. That is, the battery relay RLB1 is turned off by the ECU 60. Thereby, the “first charging period” ends.

  As shown in FIG. 5B, at the end of the first charging period, the SOC of the battery unit BU1 increases by S1 from the state of (a). On the other hand, the SOC of the battery unit BU2 remains in the state (a).

  Referring to FIG. 4 again, when the first charging period ends in step S140, ECU 60 advances the process to step S150 and executes the inter-battery charging / discharging operation. Specifically, ECU 60 turns on battery relays RLB1, RLB2 while turning off charging relay CHR. Thereby, battery unit BU1 which is a charging battery and battery unit BU2 which is a non-charging battery are connected to each other in a state where charger 80 is disconnected. That is, the period during which the inter-battery charge / discharge operation is executed in step S150 corresponds to the “second charge period”.

FIG. 6 shows an equivalent circuit diagram during the inter-battery charge / discharge operation.
Referring to FIG. 6, battery voltage Vb1 is represented by the sum of the open circuit voltage of battery unit BU1 and the voltage change (Ib1 · r1) generated in internal resistance r1 by battery current Ib1. On the other hand, the battery voltage Vb2 is indicated by the sum of the open circuit voltage of the battery unit BU2 and the voltage change (Ib2 · r2) generated in the internal resistance r2 by the battery current Ib2.

  At the start of the inter-battery charging / discharging operation, the SOC difference as shown in FIG. 5B is generated between the battery units BU1 and BU2, so that Vb1> Vb2. Therefore, charging / discharging current Ibb between battery units (hereinafter also referred to as inter-battery current) flows from battery unit BU1 to battery unit BU2. That is, the inter-battery current Ibb is generated so that the discharge current from the battery unit BU1 charges the battery unit BU2 (so that Ib1 <0, Ib2> 0 in FIG. 6). The inter-battery current Ibb is determined by the voltage difference ΔV between the battery units BU1 and BU2 and the internal resistances r1 and r2 (Ibb = ΔV / (r1 + r2)).

  FIG. 7 shows a conceptual waveform diagram of current and voltage during the charge / discharge operation between batteries.

  Referring to FIG. 7, the voltage difference ΔV between the batteries is maximum at the start of the charge / discharge operation. The voltage difference ΔV at this time is a voltage corresponding to the charge amount (S1) in the first charging period. Due to the inter-battery current Ibb corresponding to the voltage difference ΔV, the charge charged in the battery unit BU1 during the first charging period moves to the battery unit BU2. That is, charging / discharging between batteries is performed so that the charging battery (battery unit BU1) in the first charging period is discharged while the non-charging battery (battery unit BU2) in the first period is charged. Is done.

  The voltage difference ΔV and the inter-battery current Ibb are attenuated as the charging / discharging between the batteries progresses. When Vb1 = Vb2 (ΔV = 0), charging / discharging is completely completed, and the inter-battery current Ibb = 0. For example, when Ibb becomes lower than a predetermined determination current Ith near zero, it is determined that Vb1 and Vb2 are substantially equal, and the inter-battery charge / discharge operation can be terminated.

  Alternatively, when the inter-battery current Ibb decreases, the amount of heat generated by charging / discharging between the batteries also decreases. On the other hand, it takes some time for the inter-battery current Ibb to decay to zero. Therefore, in order to avoid prolonged external charging, the inter-battery charging / discharging operation may be terminated as the inter-battery current Ibb decreases to a level at which the temperature rise effect becomes low. At this time, the determination current Ith is the charging current in the first charging period or the charging current during parallel charging of each battery unit (for example, the charging current in the first charging period is divided by the number of battery units). (Current value) can be set.

  At the end of the inter-battery charging / discharging operation (second charging period), as shown in FIG. 5C, the SOCs of the battery units BU1 and BU2 are substantially equal.

  As described above, the maximum value of the inter-battery current Ibb is determined by ΔV at the start of the inter-battery charge / discharge operation, that is, the charge amount in the first charging period (that is, the predetermined amount S1). Therefore, the predetermined amount S1 in step S130 is determined so that the inter-battery current Ibb does not become excessive. For example, if the upper limit current value allowed for the component is Imax, it is necessary to determine the upper limit value ΔVmax of ΔV so that the following equation (1) is obtained.

ΔVmax <Imax · (r1 + r2) (1)
Then, in consideration of the characteristics of the battery unit, the charge amount S1 in the first charging period can be determined so as to correspond to the SOC difference that causes ΔVmax.

  As for the internal resistance value (r1 + r2) in equation (1), a map is created in advance reflecting the characteristics of FIGS. 2 and 3, and the map is referred to based on the battery temperature and the like in the first charging period. Can be determined by Alternatively, it is possible to calculate r1 and r2 based on the battery currents Ib1 and Ib2 and the battery voltages Vb1 and Vb2 when the vehicle travels immediately before or during external charging. That is, the predetermined amount S1 in step S130 is not set to a fixed value, but is preferably set variably according to the state of the battery units BU1 and BU2 at the start or during the first charging period. . Alternatively, in S130, whether or not to end the first charging period may be determined based on a comparison between the voltage difference ΔV between the battery voltages Vb1 and Vb2 and the ΔVmax.

  Referring to FIG. 4 again, ECU 60 compares inter-battery current Ibb and determination current Ith in step S160 during the inter-battery charge / discharge operation in step S150. Step S150 is repeatedly executed until Ibb <Ith (NO in S160).

  On the other hand, when Ibb <Ith (YES in S160), ECU 60 ends the inter-battery charge / discharge operation. Further, in step S170, ECU 60 compares the SOC shortage amount until battery unit BU1 and / or BU2 is fully charged with predetermined amount S1. This predetermined amount S1 is the same as S1 in step S130. Therefore, as described above, it is preferable to set the variable in accordance with the state of the battery units BU1 and BU2. Strictly speaking, it is preferable to compare the higher value of the SOCs of the battery units BU1 and BU2 with the predetermined amount S1.

  When the SOC shortage amount is smaller than predetermined amount S1 (when YES is determined in S170), ECU 60 ends the temperature increase control and advances the process to step S180.

  In step S180, the ECU 60 charges the battery units BU1 and BU2 in parallel. That is, by turning on each of charging relay CHR and battery relays RLB1 and RLB2, all battery units BU1 and BU2 are charged in parallel by the power from charger 80. The period in which the parallel charging in step S180 is performed corresponds to the “third charging period”.

  Then, when either battery unit BU1 or BU2 is fully charged (when YES is determined in S190), ECU 60 proceeds to step S250 and terminates external charging.

  On the other hand, when the SOC shortage amount at the end of the inter-battery charge / discharge operation (second charging period) is smaller than the predetermined amount S1 (NO determination in S170), the ECU 60 returns the process to step S110. , Steps S110 to S170 are executed again.

  At this time, at step S110, the battery unit having the lowest battery temperature among the plurality of battery units can be selected as the charging battery. Or you may comprise the process by step S110 so that the battery unit different from the charge battery in the last 1st charge period may be selected as a charge battery. Further, in order to reduce the number of times the battery relays RLB1 and RLB2 are turned on and off, when the temperature of the charging battery in the previous first charging period becomes higher than the temperature of the other battery units by a predetermined value or more, You may make it switch. That is, in step S110, a charging battery can be arbitrarily selected from the viewpoint of improving the temperature rise control efficiency.

  Thereby, as shown in FIG. 5D, the first charging period in which one of the battery units BU1 and BU2 is charged again in the same manner as in FIG. 5B is provided again. Thereafter, similarly to (c) of FIG. 5, the inter-battery charging / discharging operation is performed using the charging power in the second first charging period. Thus, the set of the 1st and 2nd charging period is provided again.

  The above-described temperature increase control in steps S110 to S170 is repeatedly executed until step S170 is determined to be YES.

  In step S170, as in step S130, determination based on the battery voltage can be executed. For example, for each battery unit BU1, BU2, the determination in step S170 can be executed by comparing the amount of voltage shortage with respect to the battery voltage in the fully charged state and the above ΔVmax.

  As described above, according to the charging system for an electric vehicle according to the present embodiment, the first charging period in which only a part of the battery units is charged, and the second charging period in which the inter-battery charging / discharging operation is performed. External charging is performed so as to provide the set. Thereby, since the charging current in the first charging period becomes larger than that in parallel charging, the amount of heat generated by the charging battery increases. And in a 2nd charge period, the temperature of both a charging battery and a non-charging battery can be raised by charging / discharging between batteries. At this time, since the non-charged battery is not charged in the first charging period, the inter-battery current Ibb can be increased, so that the heat generation amount can be increased. As a result, the temperature rise amount of the battery (power storage device) due to the temperature rise control is increased, so that the temperature rise control can be executed efficiently.

(Modification)
In FIG. 1, the configuration of the power storage unit 10 in which the two battery units BU1 and BU2 are connected in parallel has been described.

  However, application of external charging including temperature increase control according to the embodiment of the present invention is not limited to the example of FIG. For example, the same external charging can be applied to a configuration in which n (n: natural number of 3 or more) battery units BU1 to BUn are connected in parallel.

  FIG. 8 is a block diagram illustrating a configuration of a power storage unit according to a modification of the embodiment of the present invention.

  Referring to FIG. 8, in a charging system for an electric vehicle according to a modification of the embodiment of the present invention, power storage unit 10 # is mounted instead of power storage unit 10 shown in FIG. Power storage unit 10 # has n battery units BU1 to BUn connected in parallel between power lines PL1 and NL1.

  Battery sensors BS1 to BSn are provided in each of the battery units BU1 to BUn. Battery sensors BS1 to BSn detect state quantities (battery current, battery voltage, and battery temperature) of battery units BU1 to BUn, respectively. Furthermore, battery relays RLB1 to RLBn are connected in series with battery units BU1 to BUn between power lines PL1 and NL1, respectively.

  Furthermore, in order to detect the inter-battery current during the inter-battery charging / discharging operation with respect to the n battery units BU1 to BUn, it is necessary to arrange (n−1) current sensors CS1 to CSn−1. It is understood.

  Also in power storage unit 10 # in FIG. 8, by turning on only a part of battery relays RLB1 to RLBn, a “first charging period” in which only a part of battery units BU1 to BUn is selected as a charging battery. Can be provided. Furthermore, by turning on all of the battery relays RLB1 to RLBn, charging / discharging can be executed between the charging battery and the non-charging battery in the first charging period. That is, a “second charging period” can be provided.

  Therefore, the control processing according to the flowchart shown in FIG. 4 can also be applied to external charging of power storage unit 10 # shown in FIG. At this time, the selection of the charging battery in the first charging period in step S110 and the selection of the non-charging battery to be subjected to the inter-battery charging / discharging operation in step S150 are selected from n battery units. It is necessary to consider the points.

  As described above, increasing the charge / discharge current leads to an increase in the amount of temperature increase in the temperature increase control. Therefore, it is preferable to reduce the number of charging batteries in the first charging period. In the second charging period, it is also possible to charge not only a part of the non-charged battery but a part of the non-charging battery in the first charging period.

  In common with the configurations of FIGS. 1 and 8, only a part of the plurality of battery units is charged in the first charging period, and in the second charging period, the non-charging in the first charging period is not performed. At least a part of the charging battery is connected to the charging battery in the first charging period. By repeatedly providing such a set of the first and second charging periods until the SOCs of all the battery units are close to full charge, efficient temperature rise control with a large temperature rise is realized.

  Thus, it is possible to apply the external charging control processing procedure including the temperature increase control according to the present embodiment to a configuration in which a plurality of arbitrary battery units (power storage devices) are connected in parallel. is there.

  In the present embodiment, the configuration of the vehicle drive system is not limited to the illustration of FIG. That is, as described above, among electric vehicles equipped with a traveling electric motor such as an electric vehicle, a hybrid vehicle, and a fuel cell vehicle, a configuration in which a plurality of power storage devices connected in parallel is charged by a power source outside the vehicle. The present invention can be applied in common. Also, the number of electric motors for traveling is not particularly limited.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to external charging of an electric vehicle equipped with a plurality of power storage devices connected in parallel.

  DESCRIPTION OF SYMBOLS 10 Power storage part, 30 Motor generator, 40 Power transmission gear, 50 Driving wheel, 60 Control apparatus, 80 Charger, 90 Charging inlet, 100 Electric vehicle, 200 External power supply, 205 Charging connector, BS1, BS2-BSn Battery sensor, BU1 , BU2 to BUn battery unit (power storage device), CHR charging relay, CS, CS1 to CSn current sensor, Ib1, Ib2 battery current, Ibb current between batteries (battery charge / discharge operation), Ith determination current, NL1, NL4, PL1 ~ PL4 power line, RLB1, RLB2-RLBn battery relay, SMR system main relay, Tb1, Tb2 battery temperature, Vb1, Vb2 battery voltage, r1, r2 internal resistance.

Claims (12)

A plurality of power storage devices connected in parallel to the first and second power lines;
A plurality of switches connected in series with the plurality of power storage devices, respectively, between the first and second power lines;
A charger for supplying charging power of the plurality of power storage devices to the first and second power lines;
A charge switch connected between the charger and the first and second power lines;
A control device for controlling charging of the plurality of power storage devices by the plurality of switches, the charging switch, and the charger;
The controller is configured to connect a part of the plurality of power storage devices to the first and second power lines when the temperature needs to be increased when charging the plurality of power storage devices, and In a state where the plurality of switches are controlled so that the remaining power storage devices of the power storage devices are disconnected from the first and second power lines, the charging switch is turned on to supply the power from the charger. After the first charging period supplied to the first and second power lines, and after the first charging period, the charging switch is turned off, and among the part of the power storage devices and the remaining power storage devices A charging system for an electric vehicle that charges the plurality of power storage devices so as to provide a pair with a second charging period for controlling the plurality of switches so as to connect at least a part thereof.   2. The charging of the electric vehicle according to claim 1, wherein the control device controls the charger, the charging switch, and the plurality of switches so that the set of the first and second charging periods is provided a plurality of times. system.   The control device includes the charger, the charging switch, and the plurality of switches so as to provide a third charging period for charging the plurality of power storage devices in parallel after the end of the second charging period. The electric vehicle charging system according to claim 1, which is controlled.   The control device selects the part of the power storage devices to be charged in the first charging period based on the temperature of each of the plurality of power storage devices at the start of the first charging period. Item 3. A charging system for an electric vehicle according to Item 1 or 2.   The control device is configured to charge one of the plurality of power storage devices having the lowest temperature when starting the first charging period, the partial power storage charged in the first charging period. The electric vehicle charging system according to claim 4, which is selected as a device.   When the control device executes the first charging period from the second time onward, the control device uses a power storage device that is different from the power storage device charged in the previous first charging period as the current first charging time. The charging system for an electric vehicle according to claim 2, wherein the power storage device is selected for the part of the power storage devices to be charged in a period. A plurality of power storage devices connected in parallel to the first and second power lines via a plurality of switches, respectively, and the plurality of power storages to the first and second power lines via a charging switch A charging control method for an electric vehicle having a charger for supplying charging power of the device,
Selecting a part of the plurality of power storage devices to be charged when charging is required when charging the plurality of power storage devices; and
The plurality of switches are connected to connect the partial power storage devices to the first and second power lines and to disconnect the remaining power storage devices of the plurality of power storage devices from the first and second power lines. In a controlled state, providing a first charging period for turning on the charging switch and supplying power from the charger to the first and second power lines;
After the first charging period, the charging switches are turned off, and the plurality of switches are controlled to connect the part of the power storage devices and at least a part of the remaining power storage devices. And a step of providing a second charging period.   The charging control of the electric vehicle according to claim 7, further comprising a step of controlling the charger, the charging switch, and the plurality of switches so that the first and second charging periods are set a plurality of times. Method.   Controlling the charger, the charging switch and the plurality of switches so as to provide a third charging period for charging the plurality of power storage devices in parallel after the second charging period ends. The charge control method of the electric vehicle of Claim 7 provided.   The selecting step selects the part of the power storage devices to be charged in the first charging period, based on the temperature of each of the plurality of power storage devices at the start of the first charging period. The charging control method for an electric vehicle according to claim 7 or 8.   In the selecting step, one of the plurality of power storage devices that has the lowest temperature when starting the first charging period is charged in the first charging period. The charging control method for an electric vehicle according to claim 10, which is selected as a power storage device.   In the selecting step, when the first charging period is executed for the second time or later, a power storage device that is different from the power storage device charged in the previous first charging period is selected as the first charging period. The charging control method for an electric vehicle according to claim 8, wherein selection is made for the part of the power storage devices that are charged in a charging period.

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