JP2015186339A - Power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an opportunity of required equalization processing in accordance with a result of intention confirmation to a user while suppressing a sense of incompatibility upon charging time extension via the intention confirmation to the user when performing the equalization processing during external charging.SOLUTION: A power storage system performs confirmation processing that makes the user select whether to implement equalization processing for equalizing charging capacitances among power storage elements forming a power storage device via a display device of a vehicle in the case of external charging that is not reserved charging. While performing control so as to implement the equalization processing with the external charging in the case where the user selects the implementation of the equalization processing, the number of times where the user does not select the implementation of the equalization processing is stored. In the case where the stored number of times is equal to or less than a predetermined threshold, control is performed for enabling the user to select whether to implement the equalization processing via confirmation processing. In the case where the stored number of times exceeds the threshold, control is performed so as to implement the equalization processing with the external charging, without performing the confirmation processing to the user.

Description

  The present invention relates to a power storage system mounted on a vehicle.

  An assembled battery in which a plurality of battery cells are connected in series can include an equalization circuit for equalizing the voltage between the battery cells. When the charging capacity (voltage) varies between battery cells, the usage width of the charging capacity becomes small. For this reason, the variation in the charge capacity between battery cells can be eliminated by discharging the battery cells individually through the equalization circuit.

  On the other hand, the equalization process cannot be performed unless the battery cells are charged / discharged. As described in Patent Document 1, an equalization process opportunity can be ensured by performing equalization before external charging for supplying power from an external power source to the assembled battery.

Japanese Patent Laid-Open No. 10-271699

  However, since the equalization process requires time, if the equalization process is performed during external charging, the charging time becomes longer. For this reason, if the equalization process is performed without notifying the user, the user may only feel that the charging time is extended and the user may feel uncomfortable even though the equalization is performed as battery maintenance. .

  In addition, in view of the extension of the charging time, if the user selects whether or not to perform the equalization process, the charging time is equal to the user who does not want to extend the charging time (for example, wants to increase the time for using the vehicle). The opportunity to carry out the conversion process cannot be secured, and the variation in the charge capacity between the battery cells cannot be eliminated.

  Accordingly, an object of the present invention is to suppress an uncomfortable feeling of extension of the charging time through confirmation of intention to the user during external charging when performing equalization processing for equalizing the charging capacity between a plurality of power storage elements constituting the power storage device. However, an object of the present invention is to provide a power storage system that can secure a necessary equalization processing opportunity according to the result of the intention confirmation with the user.

  A power storage system mounted on a vehicle according to the present invention includes a plurality of power storage elements, is connected to a load for charging / discharging, and can store external power supplied from an external power source, and each power storage element And an equalization circuit for equalizing the charge capacities of the respective storage elements, and a controller for controlling an equalization process between the storage elements via the equalization circuit.

  The controller determines whether or not the equalization process is to be performed via the display device of the vehicle at the time of external charging that is not reserved charging that charges the power storage device with external power based on the reservation time set by the user. Perform the confirmation process to be selected, and if the user chooses to perform the equalization process, the user does not choose to perform the equalization process while controlling to perform the equalization process with external charging Accumulate the number of times. When the accumulated number is equal to or less than a predetermined threshold, the user is controlled to select whether or not the equalization process is performed through the confirmation process, and when the accumulated number exceeds the threshold, confirmation to the user is performed. Control is performed so that equalization processing is performed with external charging without performing processing.

  According to the present invention, when it is not reserved charging, the user is informed of the necessity of equalization processing accompanying external charging, and the user confirms whether or not the equalization processing is to be performed. It is possible to suppress the user's discomfort with respect to the charging time extension for the time required for the equalization process.

  Further, since the equalization process is performed regardless of the user's intention according to the number of times the user has not selected to perform the equalization process based on the result of the confirmation process to the user, charging between the storage elements It is possible to secure a necessary equalization processing opportunity without leaving a state in which the variation in capacity is not eliminated.

It is a figure which shows the structure of a battery system. It is a figure which shows the structure of an assembled battery and a voltage monitoring unit. It is a figure which shows the processing flow of the external charge control including an equalization process. It is a figure which shows the processing flow following FIG.

  Examples of the present invention will be described below.

  FIG. 1 is a diagram showing the configuration of the battery system of this example. The battery system shown in FIG. 1 can be mounted on a vehicle, for example. Examples of vehicles include PHV (Plug-in Hybrid Vehicle) and EV (Electric Vehicle).

  In the PHV, in addition to the assembled battery described later, another power source such as an engine or a fuel cell is provided as a power source for running the vehicle. Moreover, in PHV, an assembled battery can be charged using the electric power from an external power supply. Furthermore, in a PHV equipped with an engine, the assembled battery can be charged using this electric energy by converting the kinetic energy generated by the engine into electric energy.

  The EV includes only the assembled battery as a power source of the vehicle, and can receive the power supply from the external power source to charge the assembled battery. An external power source is a power source (for example, a commercial power source) installed separately from the vehicle outside the vehicle.

  The assembled battery (corresponding to a power storage device) 100 has a plurality of unit cells (corresponding to power storage elements) 10 connected in series. As the unit cell 10, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor can be used instead of the secondary battery. The number of unit cells 10 can be appropriately set based on the required output of the assembled battery 100 and the like.

  The voltage monitoring unit 200 detects the inter-terminal voltage of the assembled battery 100 or detects the inter-terminal voltage of each unit cell 10 and outputs the detection result to an ECU (Electric Control Unit) 300. Current sensor 201 detects a current flowing through battery pack 100 and outputs the detection result to ECU 300. The temperature sensor 202 detects the temperature of the assembled battery 100 and outputs the detection result to the ECU 300.

  The ECU (corresponding to a controller) 300 has a memory 301, and the memory 301 stores various information for the ECU 300 to perform predetermined processing (for example, processing described in the present embodiment). . In the present embodiment, the memory 301 is built in the ECU 300, but the memory 301 may be provided outside the ECU 300.

  System main relays SMR-B and SMR-G are provided on the positive line PL and the negative line NL, respectively. A system main relay SMR-P and a current limiting resistor 203 are connected in parallel to the system main relay SMR-G, and the system main relay SMR-P and the current limiting resistor 203 are connected in series.

  When connecting the assembled battery 100 to the inverter 204 (load), the ECU 300 first switches the system main relay SMR-B from off to on and switches the system main relay SMR-P from off to on. Thereby, a current flows through the current limiting resistor 203, and an inrush current can be suppressed from flowing.

  Next, ECU 300 switches system main relay SMR-P from on to off after switching system main relay SMR-G from off to on. Thereby, the connection between the assembled battery 100 and the inverter 204 is completed, and the battery system shown in FIG. Information regarding on / off (IG-ON / IG-OFF) of the ignition switch of the vehicle is input to ECU 300, and ECU 300 activates the battery system in response to the ignition switch switching from OFF to ON.

  On the other hand, when the ignition switch is switched from on to off, ECU 300 switches system main relays SMR-B and SMR-G from on to off. As a result, the connection between the assembled battery 100 and the inverter 204 is cut off, and the battery system enters a stopped state (Ready-Off).

  The inverter 204 converts the DC power output from the assembled battery 100 into AC power, and outputs the AC power to the motor / generator 205. As the motor generator 205, for example, a three-phase AC motor can be used. Motor generator 205 receives AC power output from inverter 204 and generates kinetic energy for running the vehicle. By transmitting the kinetic energy generated by the motor / generator 205 to the wheels, the vehicle can be driven.

  When the vehicle is decelerated or stopped, the motor generator 205 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The inverter 204 converts the AC power generated by the motor / generator 205 into DC power and outputs the DC power to the assembled battery 100. Thereby, the assembled battery 100 can store regenerative electric power.

  The assembled battery 100 may be connected to the booster circuit, and the booster circuit may be connected to the inverter 204. By using the booster circuit, the output voltage of the assembled battery 100 can be boosted. The booster circuit can step down the output voltage from the inverter 204 to the assembled battery 100.

  A charger 206 is connected to the positive electrode line PL and the negative electrode line NL. The charger 206 is connected to a positive electrode line PL that connects the positive electrode terminal of the assembled battery 100 and the system main relay SMR-B, and a negative electrode line NL that connects the negative electrode terminal of the assembled battery 100 and the system main relay SMR-G. Yes. The charger 206 is connected to the inlet 207.

  Charging relays Rch1 and Rch2 are provided on each line connecting charger 206 and lines PL and NL. Charging relays Rch1 and Rch2 are switched between on and off in response to a control signal from ECU 300.

  A charging plug 208 extending from the external power source 210 via the charging cable 209 is connected to the inlet 207. By connecting the charging plug 208 to the inlet 207, power from the external power source 210 can be supplied to the assembled battery 100 via the charger 206. Thereby, the assembled battery 100 can be charged using the external power supply 210. When the external power source 210 supplies AC power, the charger 206 converts AC power from the external power source into DC power and supplies the DC power to the assembled battery 100. ECU 300 can control the operation of charger 206. Note that the charger 206 can also convert the voltage of power supplied from the external power supply 210 and supply it to the assembled battery 100.

  Here, charging the assembled battery 100 by supplying power from the external power source 210 to the assembled battery 100 while the vehicle is stopped is referred to as external charging. In the battery system of the present embodiment, power from the external power source 210 is supplied to the assembled battery 100 when the charging relays Rch1 and Rch2 are on. When external charging is performed, a constant current can be supplied to the assembled battery 100, and the assembled battery 100 can be charged under a constant current. During external charging, system main relays SMR-B and SMR-G can be turned off.

  In this embodiment, external charging is performed by connecting the charging plug 208 to the inlet 207, but the present invention is not limited to this. Specifically, the electric power of the external power source 210 can be supplied to the assembled battery 100 by using a so-called contactless charging system. In a non-contact charging system, electric power can be supplied without using a cable by using electromagnetic induction or a resonance phenomenon. As the non-contact charging system, a known configuration can be adopted as appropriate.

  In the present embodiment, the charger 206 is mounted on the vehicle, but the present invention is not limited to this. That is, the charger 206 may be installed separately from the vehicle outside the vehicle. In this case, ECU 300 can control the operation of charger 206 by communication between ECU 300 and charger 206.

  ECU 300 calculates (estimates) the SOC of battery pack 100 based on the voltage value detected by voltage monitoring unit 200, the current value detected by current sensor 201, and the battery temperature detected by temperature sensor 202, Based on the calculated SOC and the estimated full charge capacity, charge / discharge control of the assembled battery 100 can be performed. ECU 300 can be configured to include each function as an SOC estimation unit, a full charge capacity calculation unit, and an external charge control unit.

  The SOC (State Of Charge) indicates the ratio of the current charge capacity (charge state) to the full charge capacity of the assembled battery 100, and the full charge capacity is the upper limit value of the SOC. As a method for estimating the SOC, a known method can be adopted as appropriate, and description of a specific method for estimating the SOC is omitted.

  The ECU 300 can also be provided for each inverter 204 and motor / generator 205. In addition, a separate ECU for performing the SOC estimation process, the full charge capacity estimation process, and the external charge process can be provided independently of the vehicle control. In other words, the central control device that controls the entire vehicle may control each unit, or may be configured such that an individual ECU is provided for each control of the respective units and the central control device is connected to each individual ECU.

  FIG. 2 is a diagram illustrating configurations of the assembled battery 100 and the voltage monitoring unit 200. As shown in FIG. 2, the voltage monitoring unit 200 is connected to each unit cell 10 via a plurality of voltage detection lines L1, L2.

  The two voltage detection lines L1 are connected to the positive terminal and the negative terminal of the assembled battery 100, respectively. The positive terminal of the assembled battery 100 corresponds to the positive terminal of the unit cell 10 located at one end in the circuit configuration of the assembled battery 100 shown in FIG. The negative electrode terminal of the assembled battery 100 corresponds to the negative electrode terminal of the unit cell 10 located at the other end in the circuit configuration of the assembled battery 100 shown in FIG. The voltage detection line L2 is connected to the negative terminal of one unit cell 10 and the positive terminal of the other unit cell 10 in the two unit cells 10 electrically connected in series.

  In the example of FIG. 2, the voltage (total voltage) between the positive terminal and the negative terminal of the assembled battery 100 can be detected by detecting the voltage between the two voltage detection lines L1 and L1. Moreover, the voltage of each cell 10 can be detected by detecting the voltage between the two voltage detection lines L1, L2 or L2, L2.

  Each voltage detection line L1, L2 is provided with an equalizing discharge circuit composed of a switch SW1 and a resistor R. Switch SW1 is switched between on and off by receiving a control signal from ECU 300. The switch SW1 is used to equalize voltage values in all the unit cells 10 constituting the assembled battery 100.

  In the assembled battery 100 in which the plurality of unit cells 10 are electrically connected in series, the voltage (in other words, the SOC) may vary between the plurality of unit cells 10 due to charging / discharging of the assembled battery 100. . Therefore, the ECU 300 monitors the voltage of each unit cell 10 and, for example, compares the unit cell having the highest voltage value with the unit cell having the lowest voltage value, and the voltage difference is larger than a predetermined value. By operating the equalization circuit and discharging one or a plurality of unit cells 10 on the higher voltage side, the voltage variation between the unit cells 10 is eliminated.

  Specifically, when the voltage value of the specific cell 10 is higher than the voltage value of the other cell 10, the switch SW <b> 1 electrically connected in parallel with the specific cell 10 is switched from OFF to ON. Thus, the specific unit cell 10 can be discharged. That is, when the switch SW1 is turned on, the discharge current of the specific unit cell 10 can flow through the resistor R, and the voltage value of the specific unit cell 10 can be lowered. Thereby, the voltage value of the specific cell 10 can be aligned with the voltage value of the other cell 10.

  In addition, although the equalization discharge circuit of a present Example is provided in the voltage monitoring unit 200, you may provide separately between the assembled battery 100 with respect to the voltage monitoring unit 200. FIG.

  3 and 4 are diagrams showing a processing flow of external charging control including equalization processing of the present embodiment. In this embodiment, the equalization process is performed with external charging. The equalization process and the external charging control are performed by the ECU 300.

  As shown in FIG. 3, first, the ECU 300 determines whether or not equalization processing is necessary. The determination process regarding the necessity of the equalization process can be performed in advance at an arbitrary timing such as when the external charging control shown in FIG. 3 is performed or when the battery system is activated.

  The ECU 300 detects the voltage of each unit cell 10 (S101), compares the unit cell having the highest voltage value with the unit cell having the lowest voltage value, and determines whether or not the voltage difference is greater than a predetermined value. Is discriminated (S102). When the voltage difference is larger than the predetermined value, the ECU 300 controls the equalization flag to ON and calculates the equalization required time ta (S103). Since the discharge amount of the equalization discharge circuit can be specified from the resistance value of the resistor R, the equalization required time ta can be calculated according to the voltage difference. When the voltage difference is smaller than the predetermined value, the ECU 300 controls the equalization flag to be OFF (S104).

  Next, when the charging plug 208 is inserted into the inlet 207 (YES in S105), the ECU 300 confirms the equalization flag ON / OFF, and if the equalization flag is ON (YES in S106), External charge control including equalization processing is performed. On the other hand, if the equalization flag is OFF (NO in S106), external charging control (normal charging process) that does not include the equalization process is performed.

  The ECU 300 calculates the time required for charging (charging time) with external charging (S107). The charging time can be calculated based on the current SOC (starting SOC) detected before starting charging and the completion target SOC. For example, when charging from the current SOC at a predetermined charging rate, the time until the SOC of the assembled battery 100 reaches the completion target SOC can be calculated as the charging time. The completion target SOC is set as the upper limit SOC of the battery pack 100, and can be set to a full charge capacity or a value lower than the full charge capacity.

  Next, ECU 300 determines whether or not the user desires reserved charging. Reserved charging is timer charging that starts charging at a charging start time (reserved time) set by the user or completes charging by a charging end time (reserved time) set by the user. In the reserved charging, for example, when a timer charging switch (not shown) provided in the vehicle is pressed, the ECU 300 controls the user so that the charging start time and the charging end time can be reserved and set. When the time comes, charging is started, or when the charging start time calculated from the set charging end time and the current time is reached, charging is started.

  When the timer charging switch is pressed by the user (YES in S108), ECU 300 performs the setting process for the reserved charging time as described above (S109). The ECU 300 displays the current time, the charging time calculated in step S107, and the equalization required time ta calculated in step S103 on the display panel (display device) of the vehicle, and the reserved time (charging completion time) to the user. Control to set.

  At this time, ECU 300 controls not to accept a setting shorter than “current time + charge time + equalization required time” at the reservation time set (input) by the user (S110). For example, it is assumed that the current time is “11 pm”, the charging time is 6 hours, and the equalization required time is 30 minutes. In this case, ECU 300 performs control so that a time shorter than “5:30 am” cannot be set as a time (charge completion time) that can be reserved by the user (NO in S110), and after “5:30 am” The user is notified through the display panel so as to set the time.

  When a reservation time longer than “current time + charge time + equalization required time” is set (YES in S110), ECU 300 starts an equalization process (S111). The equalization process is performed before external charging is started. As described above, the ECU 300 turns on the switch SW1, operates the equalization circuit, and discharges one or more unit cells 10 on the higher voltage side, thereby eliminating the voltage variation between the unit cells 10. Let The ECU 300 monitors the voltage value of each unit cell 10, and when the voltage of the higher unit cell becomes the voltage of the lower unit cell, the ECU 300 turns off the switch SW1 and ends the equalization process (S112). ).

  The ECU 300 resets the counter of the equalization rejection count (for example, initializes it to 0) (S113), and starts external charging for charging the battery pack 100 with the electric power of the external power source 210.

  After the equalization process, ECU 300 waits until the current time reaches the charging start time corresponding to the reservation time set in steps S109 and S110 (S114). The assembled battery 100 is charged with the external power supplied from the power source 210 through the charger 206 (S115).

  The ECU 300 monitors the voltage of the assembled battery 100. When the SOC of the assembled battery 100 reaches a preset completion target SOC (S116), the external charging is terminated (S117). Similarly, when the charging completion time is reached, the external charging is terminated.

  In this way, when external charging is performed in a state where it is determined that equalization processing is necessary, when external charging is controlled by reserved charging, control is performed so as to set a reserved time that takes into account the time required for equalization. To do. By configuring in this way, the user can confirm that the equalization process is necessary for battery maintenance and can confirm that the charging time is extended by the time of the equalization process. An opportunity for equalization processing can be ensured while suppressing a sense of incongruity.

  Next, when the timer charging switch has not been pressed by the user (NO in S108), the ECU 300 confirms the number of rejections of the equalization process. And it is discriminate | determined whether the frequency | count of rejection is below a predetermined threshold value (S118).

  When the number of rejections is equal to or less than the threshold value, the ECU 300 inquires of the user whether the equalization process may be performed together with the necessity of the equalization process, and performs a confirmation process for allowing the user to select whether or not the equalization process is performed ( S119). For example, display on the display panel of the vehicle “The charging completion time will be slightly longer due to main battery maintenance, but is it okay to carry out the maintenance?” And accepts the answer (performed / not performed) .

  In the case of performing maintenance (OK answer, YES in S120), ECU 300 performs equalization processing similar to steps S111 and S112 described above (S121, S122), and resets the counter of the number of rejections (S123). Then, external charging is started after the equalization process (S124), and when the SOC of the assembled battery 100 reaches the completion target SOC (YES in S126), the external charging is terminated (S127).

  On the other hand, if maintenance is not performed (NG answer, NO in S120), ECU 300 counts up the number of rejections that the user has not selected to perform equalization without performing equalization (S125). ). ECU 300 counts up the number of rejections and then starts external charging (S124). When the SOC of assembled battery 100 reaches the completion target SOC (YES in S126), ECU 300 ends external charging (S127).

  In this embodiment, if the number of rejections of the equalization process is equal to or less than the threshold value in step S118, the user is controlled to select whether or not the equalization process is performed through the confirmation process in step S119, and the equalization process is performed. When the number of rejections of the equalization process exceeds the threshold value while controlling the extension of the charging time due to the execution to be not forced by the user, the equalization process is not performed without performing the confirmation process for the user (NO in S118). (S121).

  In this way, when it is not reserved charging, the user is informed of the necessity of equalization processing accompanying external charging, and the user confirms whether or not the equalization processing is to be performed. It is possible to suppress the user's uncomfortable feeling with respect to the extension of the charging time for the time required for processing.

  Furthermore, since the equalization process is performed regardless of the user's intention according to the number of times the user has not selected to perform the equalization process (rejection count) based on the result of the confirmation process to the user, A necessary equalization process opportunity can be secured without leaving a state in which the variation in the charge capacity between the batteries 10 is not eliminated.

  In the above description, when it is reserved charging, external charging is performed on the assumption that equalization processing is performed without performing confirmation processing to the user and count (accumulation) processing of the number of rejections. Although it is secured the opportunity to perform the equalization process through the above-described confirmation process and rejection count (accumulation) process even during reserved charging, When the number of rejections is larger than the threshold value, it is possible to perform steps S109 and S110 to control reservation charging that ensures an equalization processing opportunity.

10: single cell, 100: battery pack, 200: voltage monitoring unit, 201: current sensor, 202: temperature sensor, 203: current limiting resistor, 204: inverter, 205: motor generator, 206: charger, 207: inlet 208: charging plug, 209: charging cable, 210: external power supply, 300: ECU, 301: memory, SMR-B, SMR-P, SMR-G: system main relay, PL: positive line, NL: negative line, SW1: Switch, R: Resistance

Claims (1)

A power storage system mounted on a vehicle,
A power storage device composed of a plurality of power storage elements, connected to a load for charging and discharging, and capable of charging external power supplied from an external power source,
An equalization circuit connected to each of the storage elements, and equalizing the charge capacity of each of the storage elements;
A controller for controlling an equalization process between the electric storage elements via the equalization circuit,
Whether or not the controller performs equalization processing via the display device of the vehicle at the time of external charging when the external power is not reserved charging for charging the power storage device based on the reserved time set by the user The user performs the confirmation process, and when the user selects to perform the equalization process, the user performs the equalization process while controlling the equalization process to be performed in accordance with the external charging. Accumulate the number of times you did not choose
When the accumulated number of times is less than or equal to a predetermined threshold value, control is performed so that the user can select whether or not equalization processing is performed through the confirmation process, and to the user when the accumulated number of times exceeds the threshold value The power storage system is controlled so as to perform the equalization process with the external charging without performing the confirmation process.