Charging system

Abstract

Provided is a charging system that easily ensures a discharge amount for a battery needed to measure the open circuit voltage of a battery.　According to the present invention, a charging system that charges a battery 11 installed on a vehicle 1 using power supplied from an external power supply has a charging / discharging control unit 32 that controls charging / discharging of the battery 11, a voltage acquisition unit 33 that acquires measurement results for the voltage of the battery 11 for prescribed timing from a voltage measurement unit 14 that measures the voltage of the battery 11, a charge / discharge amount determination unit 29 that determines a charge / discharge amount for the battery 11 needed to measure the open circuit voltage OCV of the battery 11, and a discharge distribution determination unit 31 that determines a discharge distribution that is the distribution between an internal discharge amount consumed by an internal apparatus 18 of the vehicle 1 and an external discharge amount consumed by an external apparatus 111 for the vehicle 1 needed to discharge the charge / discharge amount from the battery 11. The discharge distribution determination unit 31 allows the distribution to be such that the internal discharge amount and the external discharge amount are simultaneously greater than 0.

Description

Technical Field

[0001] The present invention relates to a charging system.

Background Art

[0002] When using V2X (Vehicle to X) to connect an EV (Electric Vehicle) to a house or a power system, the charge and discharge opportunities of the battery mounted on the EV increase. Therefore, it is important to grasp (diagnose) the state of the battery such as battery deterioration. When diagnosing the state of this battery, there is a method of measuring the open circuit voltage of the battery and estimating the charge rate.

[0003] For example, in paragraph 0007 of Patent Document 1, "As a result of repeating experiments to reduce the influence of hysteresis generated in the correspondence relationship between the open circuit voltage and the charge rate, the present inventors have found that the influence of hysteresis can be reduced by performing both discharge and charge of a lithium ion secondary battery. Based on this, before estimating the charge rate of the lithium ion secondary battery, discharge and charge are performed, and then the charge rate of the lithium ion secondary battery is estimated from the open circuit voltage obtained thereafter. Thereby, the charge rate can be estimated from the open circuit voltage with the influence of hysteresis reduced, and the estimation accuracy of the charge rate of the lithium ion secondary battery can be improved. The full charge capacity estimation unit estimates the full charge capacity using the charge rate with improved estimation accuracy. Therefore, the estimation accuracy of the full charge capacity can also be improved." is described.

[0004] Here, in FIG. 1 and paragraphs 0025 to 0027 of Patent Document 1, it is described that power is supplied to the load L in the building as a discharge destination.

[0005] Furthermore, paragraph 0038 of Patent Document 1 states, "Here, the charge / discharge control unit 35 causes the battery 12 to discharge in accordance with the power demand of the load L. Therefore, the discharge power of the battery 12 depends on the power demand, and the discharge power cannot be controlled. Accordingly, the charge / discharge control unit 35 grasps the discharge current amount of the battery 12 discharged in accordance with the power demand, and controls the bidirectional inverter 32 so that the discharge current amount and the charging current amount are the same, thereby discharging and charging the battery 12."

[0006] Furthermore, paragraph 0067 of Patent Document 1 states that "the embodiments and the following modifications can be implemented in combination with each other to the extent that they are not technically contradictory."

[0007] Furthermore, paragraphs 0067 to 0068 of Patent Document 1 describe a modified example in which power is supplied to an on-board load 80 as the discharge destination. Paragraph 0068 of Patent Document 1 states that "the load 80 is an on-board load driven by the power of the battery 12, and is, for example, a motor for driving the vehicle or a motor for driving an electric compressor used in air conditioning." [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2020-41977 [Overview of the project] [Problems that the invention aims to solve]

[0009] The modification described in Patent Document 1 appears to envision using, for example, a motor for driving a traction motor or a motor for driving an electric compressor used in air conditioning as the discharge destination, instead of supplying power to a load L inside the building as the discharge destination. However, in that case, there is a problem that a sufficient discharge amount may not be secured.

[0010] While Patent Document 1 states that "they can be combined and implemented in a manner that is not technically contradictory," it does not clearly specify how they should be combined.

[0011] Patent Document 1 states that "the battery 12 is made to discharge according to the power demand of the load L," so, for example, as an example of combinations, one configuration can be considered in which the discharge destination is selected and switched, such as discharging to the outside when the power demand of the external load L is high, and discharging to the internal onboard load 80 when it is low. However, even in that case, since it can only discharge to either the outside or the inside, there is a problem that a sufficient amount of discharge may not be secured.

[0012] The problem that this invention aims to solve is to provide a charging system that makes it easy to secure the amount of battery discharge necessary for measuring the open-circuit voltage of the battery. [Means for solving the problem]

[0013] To solve the above-mentioned problems, the present invention provides a charging system for charging a battery mounted on a vehicle using power supplied from an external power source, comprising: a charge / discharge control unit that controls the execution of charging and discharging the battery; a voltage acquisition unit that acquires the measurement result of the battery voltage at a predetermined timing from a voltage measurement unit that measures the voltage of the battery; a charge / discharge amount determination unit that determines the amount of charge / discharge of the battery necessary for measuring the open-circuit voltage of the battery; and a discharge distribution determination unit that determines the distribution of the internal discharge amount consumed by the vehicle's internal equipment and the external discharge amount consumed by the vehicle's external equipment, which is necessary for performing the charge / discharge amount discharge from the battery, wherein the discharge distribution determination unit allows the distribution of the internal discharge amount and the external discharge amount to be greater than 0 at the same time. [Effects of the Invention]

[0014] According to the present invention, a discharge distribution determination unit is provided, allowing a distribution in which both the internal discharge amount and the external discharge amount are greater than 0 at the same time, so that it is possible to provide a charging system that easily secures the discharge amount of the battery necessary for measuring the open-circuit voltage of the battery.

[0015] Other configurations and effects of the present invention will be described in the examples.

Brief Description of the Drawings

[0016] [Figure 1] A circuit diagram showing an equivalent circuit model of a lithium-ion secondary battery cell. [Figure 2] A waveform diagram explaining the voltage behavior of the battery cell after charging stops. [Figure 3] A functional block diagram of the overall configuration including the charging system of Example 1. [Figure 4] A waveform diagram explaining an example of using the vehicle for V2H. [Figure 5] A waveform diagram explaining the process of discharging the battery to eliminate polarization. [Figure 6] A diagram explaining the process in which the discharge distribution determination unit selects a discharge destination. [Figure 7] A flowchart explaining the operation of Example 2. [Figure 8] A waveform diagram of the time series of the power demand of a house for explaining the operation of Example 3. [Figure 9] A timing chart for explaining the operation of Example4. [Figure 10] A waveform diagram for explaining the operation of Example 5. [Figure 11] A flowchart explaining the operation of Example 6. [Figure 12] A waveform diagram explaining the process of measuring the apparent OCV for explaining the operation of Example 7.

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure and each embodiment, the same or similar components are denoted by the same reference numerals, and duplicate descriptions are omitted.

Embodiment

[0018] FIG. 1 is a circuit diagram showing an equivalent circuit model of a lithium-ion secondary battery cell.

[0019] The voltage source Vo is an electromotive force resulting from directly converting chemical energy into electrical energy by the insertion and extraction reaction of lithium ions into the positive and negative electrodes constituting the lithium-ion secondary battery used for the battery. The voltage of the voltage source Vo corresponds to the open-circuit voltage OCV (Open Circuit Voltage) of the battery. Hereinafter, the open-circuit voltage OCV may be simply abbreviated as OCV.

[0020] Hereinafter, the lithium-ion secondary battery is referred to as a battery cell, and unless otherwise specified, the battery cell is intended to be a lithium-ion secondary battery. A plurality of such battery cells are used and combined by series connection or parallel connection so that desired characteristics can be obtained, for example, as a power source for driving an electric vehicle, and the resulting product is called a battery module.

[0021] The resistance component R0 represents the resistance component when current flows through the electrolyte solution and electrodes constituting the battery cell. The electrode reaction accompanying the charge and discharge of the battery cell involves the charging of the electric double layer existing at the interface between the electrode active material and the electrolyte solution, the charge transfer reaction within the electrode active material and the electrode, and the diffusion reaction within the electrode active material. The capacitance component C1 corresponding to the charging of the electric double layer and the resistance components R1 based on various reactions are included in the equivalent circuit model.

[0022] In actual battery cell operation, the terminal voltage Vc can be measured by a voltage sensor or similar device. The OCV (Open Voltage Variable) has a known correspondence with the battery cell's charge level. By obtaining this information in advance and storing it as a table function in a control device such as an integrated controller, the battery cell's charge level can be determined from the OCV measurement results. When using a battery module as the power source for an electric vehicle, knowing the charge level makes it possible to estimate the driving range.

[0023] Furthermore, the relationship between OCV and charge level can be used to estimate degradation, taking advantage of how it changes as the battery cell deteriorates. In other words, measuring or estimating OCV by some method is an essential step when operating a battery cell.

[0024] Figure 2 is a waveform diagram illustrating the voltage behavior of a battery cell after charging has stopped. In Figure 2, the vertical axis represents the terminal voltage Vc, and the horizontal axis represents time t.

[0025] When a battery cell is charged with a constant current, the terminal voltage Vc shown in Figure 1 increases as charging progresses during the charging period Tc.

[0026] This is because, during the charging process, the lithium transition metal composite oxide, which is the positive electrode material constituting the battery cell, is oxidized, and lithium ions are extracted into the electrolyte solution within the battery cell, causing the positive electrode potential to shift in the noble direction. Conversely, lithium ions are incorporated between the crystal layers of the carbon material, which is the negative electrode material, causing the negative electrode potential to approach the lithium metal potential, i.e., shift in the negative direction. As a result, the potential difference between these two increases, causing the voltage source Vo (=OCV) to rise. In addition, the flow of current generates DC voltages across the resistance components R0 and R1.

[0027] During the charging period Tc, the terminal voltage Vc is a combination of the voltage source Vo, the DC voltage Vdc generated by the resistive components R0 and R1, and the polarization voltage Vp generated by the charge accumulation in the capacitive component C1 during the charging reaction. Therefore, during and immediately after charging, the voltage source Vo < terminal voltage Vc.

[0028] During the static period Ts, when charging stops, the DC voltage Vdc generated across the resistive components R0 and R1 by the charging current disappears, causing the terminal voltage Vc to immediately decrease. However, the charge accumulated in the capacitive component C1 generates a polarization voltage Vp, so the terminal voltage Vc gradually decreases until the charge in the capacitive component C1 is consumed, and eventually the terminal voltage Vc converges to the voltage source Vo (=OCV).

[0029] In the case of discharge, the opposite is true: immediately after discharge, the voltage source Vo > terminal voltage Vc. When the discharge stops, the voltage drop caused by the DC voltage Vdc is eliminated and the voltage rises immediately. Then, the voltage drop due to the polarization voltage Vp is eliminated and the terminal voltage Vc gradually rises toward the voltage source Vo (=OCV) and converges to the voltage source Vo.

[0030] Resolving this polarization voltage Vp requires several minutes to several hours, and this time is especially long for battery cells that contain silicon as the negative electrode active material in order to increase their capacity. From this, it is clear that OCV measurement cannot be performed immediately after stopping charging and discharging.

[0031] Therefore, by performing a short discharge on a battery cell immediately after charging, and a short charge on a battery cell immediately after discharging, the charge that generates the polarization voltage Vp is consumed, making OCV measurement possible at an early stage.

[0032] Figure 3 is a functional block diagram of the overall configuration including the charging system of Example 1.

[0033] Figure 3 illustrates an example where a motorized vehicle (Vehicle 1) is connected to a house (House 100) that is assumed to be a detached house. However, House 100 is not necessarily limited to a detached house where the owner of Vehicle 1 resides. For example, it could be an apartment building, or the facility corresponding to House 100 could be a business office or a parking lot. Multiple Vehicle 1s may also be connected.

[0034] The charging system of Embodiment 1 is a system for charging a battery 11 mounted on a vehicle 1 with power supplied from an external power source, and comprises an integrated controller 27, a battery 11, a voltage measuring unit 14, a bidirectional charger 20, internal equipment 18, and a power converter 17.

[0035] The battery 11 is mounted on the vehicle 1 and consists of a battery module that can achieve desired output characteristics by connecting multiple battery cells 12 in series or in parallel.

[0036] A monitoring unit 13 capable of detecting the state of the battery 11 is connected to the battery 11. The monitoring unit 13 includes a voltage measurement unit 14 capable of detecting the voltage of the battery 11, more specifically the battery cells 12 of the battery 11; a current measurement unit 15 capable of detecting the current flowing through the battery cells 12; and a temperature measurement unit 16 capable of detecting the temperature of the battery 11. The voltage measurement unit 14 is configured by attaching voltage lines between the battery cells 12 so that the voltage of each terminal of the battery cells 12 can be measured individually. In Figure 3, the current measurement unit 15 shows a sensor that detects current by measuring the voltage of a shunt resistor Rsht, for example, but it is not limited to this, and sensors such as Hall elements can be used. The temperature measurement unit 16 can use thermistors or thermocouples. In this way, the monitoring unit 13 detects the state of the battery 11 by converting it into voltage information. Therefore, it can be configured with semiconductor devices such as general-purpose analog front-end ICs or ASICs (Application Specific Integrated Circuits). By providing an A / D converter, the state of the battery 11 detected as voltage can be converted into digital values ​​that can be used in calculation processing such as programs.

[0037] The battery 11 is connected to the power converter 17 and the internal equipment 18 uses the electrical energy in the desired manner.

[0038] The power converter 17 converts the power discharged from the battery 11 and supplies it to the internal equipment 18.

[0039] The power converter 17 is, for example, a bidirectional inverter, which drives the traction motor used to propel the vehicle 1. The bidirectional inverter consists of a DC / DC converter section and an inverter section. The DC / DC converter section converts the DC voltage of the battery 11 to the voltage required to drive the traction motor, and the inverter section converts the DC power to AC power, thereby controlling the frequency according to the rotational speed of the traction motor to propel the traction motor and obtain rotational force (driving torque) to accelerate the vehicle. Alternatively, when the vehicle is decelerating, regenerative driving is performed to regenerate the vehicle's kinetic energy as electricity, and the electricity is sent back to the battery 11 via the DC / DC converter section to charge the battery cells 12.

[0040] The internal equipment 18 is, for example, the aforementioned traction motor, which accelerates the vehicle 1 by utilizing electricity as rotational force, and while the vehicle 1 is running, it works in conjunction with the bidirectional inverter to drive the traction motor as a generator, thereby regenerating the inertial force of the vehicle 1 as electricity.

[0041] To achieve this operation, the power converter 17 is equipped with a controller (not shown) that adjusts the output voltage of the DC / DC converter by controlling the duty cycle of the switching elements of the DC / DC converter, and adjusts the driving force of the traction motor by adjusting the switching frequency and current phase of the inverter. The internal components 18 are equipped with various sensors so that the power converter 17 can control the internal components 18 to the desired state.

[0042] The power converter 17 is also an inverter different from, for example, the bidirectional inverter used to drive the aforementioned traction motor, and the internal equipment 18 is also a motor for driving the compressor. Together, these drive the air conditioner for air conditioning the passenger compartment of vehicle 1.

[0043] In other words, the power converter 17 and internal equipment 18 are means of consuming the power of the battery 11, or to put it another way, they are one of the means of discharging the power of the battery 11, and the vehicle 1 is equipped with multiple power converters 17 and internal equipment 18.

[0044] The battery 11 is connected to the charging circuit 19.

[0045] The charging circuit 19 supports AC charging via the bidirectional charger 20 and DC charging via the stationary charger 101. AC charging and DC charging are used exclusively within the charging circuit 19 by relays and semiconductor switches (not shown). The bidirectional charger 20 is mounted on the vehicle 1 and converts power in both directions between power supplied from an external power source such as the house 100 and power discharged from the battery 11. The stationary charger 101 is installed outside the vehicle 1 and the house 100 and converts power in both directions between power supplied from a power source such as the house 100 and power discharged from the battery 11.

[0046] In AC charging, the bidirectional charger 20 is further connected to a charging cable 25 via an AC charging port 24, and the charging cable 25 is connected to an AC outlet 105 in the house 100. The AC outlet 105 in the house 100 is connected to a distribution board 106, and the distribution board 106 is further electrically connected to the power grid 109 via an ampere breaker 107 and a power meter 108.

[0047] In DC charging, the stationary charger 101 is connected via a DC charging port 26 through a different path than the bidirectional charger 20 in the charging circuit 19, and the stationary charger 101 is connected to the distribution board 106 in the house 100. From there, it is electrically connected to the power grid 109, similar to AC charging.

[0048] The bidirectional charger 20 comprises at least a DC / DC converter unit 21 capable of transforming DC voltage, an inverter unit 22 capable of rectifying AC power from the AC outlet 105 into DC and converting the DC power output from the DC / DC converter unit 21 into AC power, and a control unit 23 that controls these.

[0049] The stationary charger 101, like the bidirectional charger 20, is equipped with a DC / DC converter unit 102, an inverter unit 103, and a control unit 104.

[0050] When charging the battery 11, a so-called CC-CV (Constant Current, Constant Voltage) charging method is performed, which combines constant current charging and constant voltage charging corresponding to the battery cells 12 within the battery 11.

[0051] Specifically, when the battery 11 is at a low charge level, constant current charging is performed and the charging speed is adjusted so that the current flowing through the battery cells 12 within the battery 11 does not exceed a predetermined value. If excessive current flows through the battery cells 12, lithium ions will not be taken into the negative electrode active material layers within the battery cells 12, causing lithium metal to deposit on the negative electrode, resulting in an internal short circuit and potentially leading to thermal runaway, including ignition or explosion of the battery cells 12. To prevent this, it is necessary to control the charging speed, i.e., the current, so that excessive current does not flow.

[0052] As the battery 11 charges and the voltage of the battery cells rises, it switches to constant voltage charging. If the voltage of the battery cell 12 rises excessively, lithium ions are extracted from the positive electrode active material, the electrode structure becomes brittle, and the increased reactivity of the positive electrode causes the electrolyte to decompose, generating gas within the battery cell 12. This decomposition reaction also generates heat. Since the gas and electrolyte generated within the battery cell 12 are flammable, ignition of these can lead to destruction such as ignition of the battery cell 12 or rupture due to increased gas pressure. Similar to the current, the voltage also needs to be controlled to prevent it from becoming excessive.

[0053] Taking the bidirectional charger 20 as an example, the inverter unit 22 rectifies the AC power obtained through the AC charging port 24 into DC power, and controls the charging current and charging voltage flowing to the battery cells 12 and, consequently, the battery 11 by controlling the duty cycle of the switching elements in the DC / DC converter unit 21. Similarly, in the stationary charger 101, the inverter unit 103 rectifies the AC power obtained through the distribution board 106 into DC power, and controls the charging current and charging voltage flowing to the battery cells 12 and, consequently, the battery 11 by controlling the duty cycle of the switching elements in the DC / DC converter unit 102.

[0054] As described above, the battery 11 can be charged using the bidirectional charger 20 or the stationary charger 101.

[0055] When supplying power from the battery 11 to the house 100, the DC / DC converter unit 21 of the bidirectional charger 20 adjusts the voltage to match the AC power used in the house 100. The inverter unit 22 generates AC so that its frequency and phase are synchronized with the AC power used in the house 100. The control unit 23 adjusts the duty cycle of the switching signal commanded to the switching element of the DC / DC converter unit 21 for voltage adjustment, and also adjusts the switching command of the inverter unit 22 to synchronize with the frequency and phase of the AC power inside the house 100 by feeding it back in order to supply power to the house 100.

[0056] The same applies when supplying power from the battery 11 to the house 100 via the stationary charger 101; the DC / DC converter unit 102, inverter unit 103, and control unit 104 are operated in the same way as the DC / DC converter unit 21, inverter unit 22, and control unit 23 of the bidirectional charger 20.

[0057] By making the power from the battery 11 available for use in the house 100 via the bidirectional charger 20 or the stationary charger 101, it can be used, for example, to utilize the power from the battery 11 when there is no power supply from the power grid 109 during a disaster, or to reduce the amount of electricity purchased from the power grid 109 and lower the electricity bill for the house 100.

[0058] House 100 may also be equipped with a solar power generation system 110 or a fuel cell system (not shown) as an alternative power source to the power grid 109.

[0059] In addition to the aforementioned solar power generation system 110, external devices 111 are connected to the distribution board 106 of house 100. The external devices 111 are the household equipment and so-called electrical appliances of house 100, and include, for example, white goods such as air conditioners for air conditioning house 100, hot water supply systems, lighting, cooking appliances, refrigerators, and washing machines, as well as black goods such as televisions and audio equipment, and information appliances such as personal computers and telephones.

[0060] Supplying power from the battery 11 to the house 100 via the bidirectional charger 20 or the stationary charger 101 consumes power from the battery 11, or in other words, it is another way of discharging power from the battery 11.

[0061] House 100 is equipped with a Home Energy Management System (HEMS) 112, which can perform operations such as monitoring the operating status and power generation of the solar power generation system 110 and the hot water supply system as an external device 111, adjusting the timing of water heating for the hot water supply system as an external device 111 according to the electricity demand of House 100 obtained from the electricity meter 108, monitoring the operating status of the air conditioner as an external device 111, and selling surplus electricity from the solar power generation system 110 to the power grid 109. Furthermore, the HEMS 112 is configured to allow external inquiries to be made regarding the electricity demand of House 100 via a communication module 113, and the integrated controller 27 of Vehicle 1 is configured to obtain information such as the electricity demand of House 100 and the upper limit power of the ampere breaker 107 held by the HEMS 112 from the communication module 113 via the telematics unit 28 of Vehicle 1. The upper limit power of the ampere breaker 107 is also the amount of electricity that House 100, which is an external power source, can supply.

[0062] The integrated controller 27 includes, as functional blocks, a charge / discharge amount determination unit 29, a power information acquisition unit 30, a discharge distribution determination unit 31, a charge / discharge control unit 32, and a voltage acquisition unit 33. Details of the operation of each functional block of the integrated controller 27 will be described later.

[0063] The integrated controller 27 comprises an arithmetic unit consisting of a CPU and the like, and a storage unit consisting of memory such as RAM and ROM, and a recording medium, and realizes each functional block of the integrated controller 27 by executing programs stored in the storage unit.

[0064] As shown by the dashed lines in Figure 3, the integrated controller 27 can acquire the operating status of the power converter 17 and internal equipment 18, as well as the status of the battery 11, as needed. It is also configured to communicate with the bidirectional charger 20 that constitutes the charging circuit 19 and with the stationary charger 101 via the DC charging port 26. Furthermore, the integrated controller 27 can also communicate via the AC charging port 24 and the charging cable 25. For the communication shown by the dashed lines in Figure 3, communication methods such as CAN (Controller Area Network) and LIN (Local Interconnect Network), as well as Ethernet connections, can be used. It is acceptable to use different methods depending on the situation, such as using CAN or LIN within the vehicle 1 and Ethernet communication within the house 100. Communication using PLC (Power Line Communication) may also be used. Not only wired communication but also wireless communication is acceptable.

[0065] Figure 4 is a waveform diagram illustrating an example of using a vehicle for V2H (Vehicle-to-Home) applications.

[0066] The upper graph in Figure 4 shows the electricity demand of house 100 (solid line) and the power output of the solar power generation system 110 installed in house 100 (dashed line). The vertical axis shows consumption at the top and power generation at the bottom, and the horizontal axis shows time. The lower graph in Figure 4 shows the simulation results of the change in the charge rate of battery 11 of vehicle 1. The vertical axis shows the charge rate and the horizontal axis shows time.

[0067] Figure 4 shows an operation (using V2H) aimed at reducing the amount of electricity purchased from the power grid 109 by supplying power from battery 11 to house 100, thereby lowering the electricity bill for house 100. The solid line in the lower part of Figure 4 shows the result with V2H, and the dashed line shows the result without V2H. The time on the horizontal axis is set for a 5-day period from 0:00 on day 1 to 24:00 on day 5 (0:00 on day 6).

[0068] As shown in the upper part of Figure 4, House 100 is an all-electric house, and during the nighttime hours, a large electricity demand is generated as an external device 111 due to the operation of the hot water heating system. During the day, electricity generated by the solar power generation system 110 is consumed within House 100, and any surplus is used to charge the battery 11, sold to the power grid 109, or both, while adjusting the amount of charge to the battery 11 so that the electricity cost for House 100 is the lowest possible.

[0069] In the lower part of Figure 4, the shaded period represents the EV driving period, during which vehicle 1 is used to transport residents and the connection between vehicle 1 and house 100 is disconnected. Therefore, the change in charge rate during this period is due to the driving of vehicle 1. Compared to using the power of the onboard battery 11 only for driving (without V2H), when V2H is used (with V2H), the battery 11 is repeatedly charged and discharged, and it can be seen that the time that can be left still to eliminate the polarization voltage generated in the battery cells 12 within the battery 11 during OCV measurement is limited. If the OCV of the battery cells 12 can be obtained early, the time during which charging and discharging of the battery 11 is stopped for OCV measurement or estimation to detect the charge rate and determine degradation can be shortened, and the opportunity to obtain the electricity cost reduction effect described above can be increased.

[0070] When charging the battery 11, the house 100 is used as a power source, and the battery 11 is charged by power supplied from the power grid 109 or the solar power generation system 110. On the other hand, when discharging the battery 11, the power of the battery 11 can be discharged by using the external equipment 111 of the house 100, as well as by using the power converter 17 and internal equipment 18 of the vehicle 1.

[0071] As shown in Figure 4, the electricity demand of house 100 fluctuates continuously, so simply discharging battery 11 to satisfy the electricity demand of house 100 may not be sufficient to ensure a sufficient discharge amount to eliminate the polarization voltage generated in the battery cells 12 of battery 11.

[0072] Therefore, the integrated controller 27 of the charging system in Example 1 includes a charge / discharge amount determination unit 29, a power information acquisition unit 30, a discharge distribution determination unit 31, a charge / discharge control unit 32, and a voltage acquisition unit 33 to address these problems.

[0073] The charge / discharge control unit 32 controls the charging and discharging of the battery 11. Specifically, the charge / discharge control unit 32 controls the charging and discharging of the battery 11 by issuing predetermined operation commands to a controller (not shown) of the power converter 17, the control unit 23 of the bidirectional charger 20, and the control unit 104 of the stationary charger 101, thereby causing them to perform predetermined operations.

[0074] The voltage acquisition unit 33 acquires the measurement result of the battery voltage 11 at a predetermined timing from the voltage measurement unit 14, which measures the voltage of the battery 11.

[0075] The charge / discharge amount determination unit 29 determines the charge / discharge amount of the battery 11 necessary for measuring the open-circuit voltage OCV of the battery 11.

[0076] The discharge distribution determination unit 31 determines the discharge distribution, which is the distribution between the amount of internal discharge consumed by the internal equipment 18 of the vehicle 1 and the amount of external discharge consumed by the external equipment 111 of the vehicle 1, in order to perform the aforementioned charge and discharge amounts from the battery 11. Here, the discharge distribution determination unit 31 allows the distribution of both the internal discharge amount and the external discharge amount to be greater than 0 at the same time. In other words, instead of the external equipment 111 alone or the internal equipment 18 alone consuming the power discharged from the battery 11, the unit allows both the external equipment 111 and the internal equipment 18 to consume the power discharged from the battery 11 at the same time, making it easier to secure the amount of discharge from the battery 11 necessary for measuring the open-circuit voltage OCV of the battery 11.

[0077] More specifically, in this embodiment, the charge / discharge amount determination unit 29 determines the charge / discharge amount necessary to eliminate the polarization of the battery 11, and the voltage acquisition unit 33 acquires the measurement result of the battery 11's voltage at the timing after both charging and discharging of the aforementioned charge / discharge amount have been performed in the battery 11. At this time, the aforementioned charge / discharge amount includes information on the magnitude and timing of the current, and it is desirable for the charge / discharge amount determination unit 29 to determine the charge / discharge amount such that the magnitude of the current performed later is greater than or equal to the magnitude of the current performed earlier. This allows for early elimination of the polarization of the battery 11 and enables OCV measurement.

[0078] In this embodiment, the power information acquisition unit 30 acquires the power that can be consumed by the external device 111 and the power that can be consumed by the internal device 18. The discharge distribution determination unit 31 then determines the discharge distribution based on the aforementioned charge and discharge amounts and the information from the power information acquisition unit 30. This makes it possible to determine an appropriate discharge distribution considering the power that can be consumed by the external device and the power that can be consumed by the internal device 18.

[0079] The following describes the operation of the charge / discharge amount determination unit 29, power information acquisition unit 30, discharge distribution determination unit 31, charge / discharge control unit 32, and voltage acquisition unit 33 within the integrated controller 27, divided into cases where the battery 11 is discharged to eliminate polarization of the battery cells 12 within the battery 11, and cases where it is charged.

[0080] Figure 5 is a waveform diagram illustrating the process of discharging the battery to eliminate polarization. The upper part of Figure 5 is a time chart showing the voltage change of the battery cell 12, with the vertical axis representing the terminal voltage Vc [V] and the horizontal axis representing time t. The lower part of Figure 5 is a time chart showing the current change of the battery cell 12, with the vertical axis representing the current Ic [A], where a positive current value shown upwards on the paper indicates that the current flows in the direction of charging the battery cell 12, and the horizontal axis represents time t.

[0081] In Figure 5, we will explain an example where, at time T1, the integrated controller 27 plans to supply a reverse current during charging in order to perform OCV measurement. We will then explain an example where charging, discharging for OCV measurement, and voltage measurement are to be completed by time T6. Time T1 is set according to the purpose of OCV measurement, such as when a predetermined time has elapsed since the start of charging of the battery cell 12, when the charge rate of the battery cell 12 reaches a predetermined value, or before time T2 at which the charge rate reaches a predetermined value at time T2 when charging is stopped (described later).

[0082] At time T1, the charge / discharge amount determination unit 29 determines whether the operation to depolarize the battery cell 12 between time T3 and time T4 is charging or discharging, based on the amount of electricity charged up to time T1, the charge state and temperature of the battery cell 12, and the state of the charging or discharging operation currently being performed (direction of current Ic). It also calculates the charge / discharge amount, which is the amount of electricity to be charged or discharged to depolarize the battery cell 12.

[0083] The amount of electricity required to depolarize the battery cell 12 is set to be larger the greater the absolute value of the current or the amount of electricity used for charging or discharging performed up to a time before T1, and is set to be larger the lower the temperature of the battery cell 12 (or battery 11) or the more advanced the degradation of the battery cell 12.

[0084] Such amounts of electricity are preferably set based on experiments conducted on the battery cell 12 or simulation results using an equivalent circuit model as shown in Figure 1. The amount of electricity required to depolarize the battery cell 12 is preferably stored in the charge / discharge amount determination unit 29 by constructing a lookup table, response surface function, or neural network model so that the corresponding amount of electricity can be referenced depending on whether the previous charge / discharge was a charge or a discharge, the magnitude of the amount of electricity in the previous charge / discharge, the temperature of the battery cell 12, and the degradation state of the battery cell 12.

[0085] A lookup table that references multiple conditions would involve a huge amount of computation to access the table and a vast number of combinations of electrical quantities recorded at the grid points. Therefore, it is acceptable to use a configuration where factors that have a significant impact on the electrical quantity required to eliminate polarization are referenced from the lookup table, and other factors are multiplied by individual correction amounts as coefficients.

[0086] The amount of electricity required to depolarize the battery cell 12 is highly correlated with the amount of electricity used in the previous charge or discharge and the charge level of the battery cell 12. Therefore, the amount of electricity required to depolarize can be calculated by setting up a lookup table that shows the relationship between the amount of electricity used in the previous charge or discharge, i.e., the change in charge level, and the charge level, and multiplying this by a correction coefficient related to the temperature of the battery cell 12 and a correction coefficient related to the degradation state of the battery cell 12.

[0087] Furthermore, factors with a small influence may be omitted, and corrections may be made using factors different from those mentioned above. The charge / discharge amount determination unit 29 only needs to obtain the charge / discharge amount of the battery cell 12 necessary to eliminate the polarization of the battery cell 12.

[0088] If the amount of charge and discharge of the battery cell 12 required to eliminate the polarization of the battery cell 12 is to be set based on the simulation results using an equivalent circuit model, for example, the amount of electricity required to eliminate the polarization can be estimated by applying the voltage change from time T2 to time T3 to an equivalent circuit model like the one in Figure 1.

[0089] These processes determine the amount of charge needed to depolarize battery 11, which corresponds to the area from time T2 to time T1 in Figure 5, and the amount of electricity needed to depolarize the area shown in shaded area from time T3 to time T4 in Figure 5. The shaded area in the figure represents the amount of electricity needed to depolarize, which corresponds to the required discharge amount Pd from the amount of charge and discharge needed to depolarize battery 11.

[0090] When discharging from time T3 to time T4, it is preferable that the absolute value of the discharge current is the same as or greater than the current used for charging at time T1 (negatively large in the case of Figure 5). The larger the discharge current, the shorter the time required to eliminate polarization, thus reducing the time required for OCV measurement. However, extremely large currents, such as a current that discharges the nominal capacity of the battery cell 12 in one hour (the so-called 1C rate), should be avoided, as currents exceeding 3C should be avoided. This is because it creates a new polarization due to the concentration gradient of lithium ions in the electrolyte solution within the battery cell 12. Therefore, it is preferable to set the discharge current to be the same as or greater than the current value used for charging (but not exceeding 3C). Although it is possible to perform the measurement with a discharge current that has a smaller absolute value than the charging current, the effect of reducing the time required for OCV measurement will decrease. In order to perform OCV measurement, it is sufficient that the amount of electricity required to eliminate polarization calculated by the charge / discharge amount determination unit 29 can be discharged.

[0091] Furthermore, the charge / discharge amount determination unit 29 may, through the power information acquisition unit 30, detect a discharge destination that can accept the power when discharging the battery 11. The charge / discharge amount determination unit 29 may also determine the charge / discharge amount by taking into consideration the information from the power information acquisition unit 30.

[0092] The power information acquisition unit 30 acquires the power available for consumption by the external devices 111 of the house 100 by acquiring the power demand of the house 100 held by the HEMS 112 from the communication module 113 via the telematics unit 28. Note that when the battery 11 is charging, the power demand measured by the power meter 108 includes the power required to charge the battery 11, so by subtracting this, the power available for consumption by the external devices 111 of the house 100 can be estimated. Similarly, the power information acquisition unit 30 may also acquire the power available for supply by the house 100, which is an external power source, by acquiring the upper limit power of the ampere breaker 107 of the house 100 held by the HEMS 112. Furthermore, the power information acquisition unit 30 also acquires the power available for consumption by the internal devices 18 of the vehicle 1. The power available for consumption by the internal devices 18 may include losses in the power converter 17. The specific method of power consumption by the internal devices 18 will be described later.

[0093] Based on the detection results of discharge destinations that can consume the power of the battery 11, obtained through the power information acquisition unit 30, the discharge allocation determination unit 31 determines the discharge destinations that will consume the power of the battery 11 from time T3 to time T4. It is not a problem if multiple discharge destinations are selected.

[0094] The discharge distribution determination unit 31 basically determines the discharge distribution so that it prioritizes power consumption through the external equipment 111 of the house 100, and allocates any deficit to the internal equipment 18. As already explained, the magnitude of the current is also related to efficiently eliminating polarization, so it is desirable that the charge / discharge amount and discharge distribution include information on the magnitude and timing of the current. The method for determining the distribution will be described later.

[0095] The charge / discharge control unit 32 controls the execution of battery discharge from time T3 to time T4 based on the charge / discharge amount determined by the charge / discharge amount determination unit 29 and the discharge distribution determined by the discharge distribution determination unit 31. It is also desirable to use the information from the current detection result by the current measurement unit 15 of the monitoring unit 13. In this way, discharge is carried out until the amount of electricity necessary to eliminate the polarization set by the charge / discharge amount determination unit 29 is consumed.

[0096] The integrated controller 27 prohibits charging and discharging of the battery 11 between time T4 and time T6, and at time T5 during that period, the voltage acquisition unit 33 measures the OCV of the battery cell 12 through the voltage measurement unit 14 of the monitoring unit 13. For the time between time T4 and time T5, it is sufficient that enough time has elapsed for the polarization of the battery cell 12 to be considered resolved, and there is no problem as long as a predetermined value based on experimental or simulation results is set, similar to the amount of electricity required to resolve polarization.

[0097] After time T6, the restriction on charging and discharging battery 11 will be lifted.

[0098] In the above explanation, subsequent timings were determined based on time T1. However, if, for example, time T6 is already determined as the scheduled time for battery 11 to be fully charged, then time T6 can be determined first, and other times can be set in reverse. In this case, since the discharge period from time T3 to time T4 is not predictable, it is advisable to set the time in a way that does not depend on the power demand of the house 100, and assumes that the internal equipment 18 of vehicle 1 is the discharge destination.

[0099] Furthermore, even if the amount of electricity that can be discharged to eliminate polarization is not sufficiently discharged due to a significant decrease in the power available to the external device 111 while the method described in this embodiment is being implemented, the effect of shortening the OCV measurement time can still be obtained compared to the case where no discharge is performed, because charge is consumed to eliminate polarization compared to the case where no discharge is performed.

[0100] Furthermore, while the above explanation described an example where charging is performed first, this is not the only option; discharging can also be performed first. The basic concept is the same, so a detailed explanation will be omitted.

[0101] Next, we will explain a specific method by which the power information acquisition unit 30 acquires the power that can be consumed by the internal equipment 18 of the vehicle 1.

[0102] For example, if the internal device 18 is an air conditioner, the bidirectional inverter, which is the power converter 17, converts the power from the battery 11 and consumes power by driving the air conditioner. Therefore, the power information acquisition unit 30 acquires the sum of the power consumption of the air conditioner and the loss due to the bidirectional inverter, which is the power converter 17, as the power that can be consumed by the internal device 18.

[0103] If the internal component 18 is a traction motor, the charge / discharge control unit 32 controls the power converter 17 based on the discharge distribution to supply power to the traction motor that generates a driving torque that does not cause the traction motor to rotate. Specifically, a controller (not shown) of the power converter 17 receives a command from the charge / discharge control unit 32 and performs vector control of the bidirectional inverter with a driving torque that does not cause the traction motor to rotate as the upper limit. More specifically, a controller (not shown) of the power converter 17 detects the mechanical angle of the traction motor and drives the bidirectional inverter to apply alternating current to a phase in which the q-axis component that generates torque in the traction motor is zero and current flows only in the d-axis current component for generating magnetic flux. While it is preferable for the q-axis component to be 0, this may be difficult depending on the motor's mechanical angle. In practice, the power information acquisition unit 30 assumes that braking is reliably performed by the vehicle 1's parking brake or other braking device, and, under the condition (upper limit) that the drive motor does not rotate, it estimates and acquires the power consumed by energizing the drive motor, including the losses in the bidirectional inverter, as the power available for the drive motor. Therefore, in cases where the vehicle 1's braking force is insufficient or when it is stopped on a slope, the power information acquisition unit 30 obtains the result that there is no power available for the drive motor.

[0104] In addition, if the internal device 18 is an auxiliary battery (not shown) of the vehicle 1, the power information acquisition unit 30 can select a DC / DC converter for charging the auxiliary battery (not shown) as the power conversion device 17, select the auxiliary battery (not shown) as the internal device 18, and acquire the power consumed when the power of the battery 11 is consumed by driving the aforementioned DC / DC converter to charge the auxiliary battery, including the losses in the DC / DC converter, as the power that can be consumed by the internal device 18.

[0105] The internal device 18 is not limited to these, and is not particularly limited as long as it can consume the power of the battery 11.

[0106] Figure 6 illustrates the process by which the discharge distribution determination unit selects the discharge destination.

[0107] Step S01 is the charge / discharge amount determination step, where the charge / discharge amount determination unit 29 determines the charge / discharge amount required to eliminate the polarization of the battery 11. The details are explained in Figure 5, so the explanation will be omitted here. The shaded area represents the required discharge amount, which is 12.5As in Figure 6, so a discharge of 0.9kW for 5 seconds is required.

[0108] Step S02 is a power information acquisition step, in which the power information acquisition unit 30 acquires the power that can be consumed by the external device 111 and the power that can be consumed by the internal device 18. In this example, the vertical axis of the graph represents the power that can be consumed, and the horizontal axis shows the breakdown of the external device or the internal device. It is obtained that the power that can be consumed by the external device 111 is 0.5kW, and the power that can be consumed by the internal device 18 is a maximum of 2kW when the drive motor is energized and 1kW when the air conditioner is energized.

[0109] Step S03 is a discharge distribution determination step, in which the discharge distribution determination unit 31 determines the discharge distribution based on the charge / discharge amount determined in step S01 and the information obtained from the power information acquisition unit 30 in step S02. Here, the discharge distribution determination unit 31 selects a discharge destination by evaluating whether the power of the battery 11 can be effectively utilized and whether power control is easy.

[0110] For example, if discharging power to the house 100 causes external equipment 111 within the house 100 to consume power, it is expected that the electricity bill for the house 100 will be reduced. Therefore, while meeting the power demand of the house 100 of 0.5 kW, the remaining 0.4 kW is consumed by supplying power to the driving motor. By determining the distribution in this way, it is possible to secure the amount of discharge necessary to eliminate the polarization of the battery 11. Note that supplying power to the driving motor consumes energy as heat, so priority is given to distributing power to the external equipment 111 in order to make effective use of the battery 11's power.

[0111] Furthermore, by allowing discharge to the external device 111 and discharge to the internal device 18 to occur simultaneously, it becomes easier to secure the necessary discharge amount. [Examples]

[0112] Example 2 is a modification of Example 1, in which the discharge distribution determination unit 31 determines the discharge distribution by prioritizing the distribution destination that can promote the warming up of vehicle 1 when the remaining time until the scheduled departure time of vehicle 1 is less than or equal to a predetermined value and the outside air temperature is less than or equal to a predetermined value.

[0113] Figure 7 is a flowchart illustrating the operation of Example 2.

[0114] Steps S101 to S104 are the same as in Example 1.

[0115] In step S101, the integrated controller 27 determines whether to measure OCV. If OCV is not measured (NO), the process ends. If OCV is measured (YES), the process proceeds to step S102.

[0116] In step S102, the integrated controller 27 determines whether to perform charging and discharging to eliminate the polarization of the battery 11. If it is determined not to perform charging and discharging (NO), for example by measuring the OCV using another method, the process ends. If it is determined to perform charging and discharging (YES), the process proceeds to step S103.

[0117] Step S103 corresponds to step S01 in Figure 6, and step S104 corresponds to step S02 in Figure 6.

[0118] Steps S105 through S110 are steps that are performed instead of step S03 in Figure 6.

[0119] In step S105, the discharge distribution determination unit 31 of the integrated controller 27 obtains the scheduled departure time of vehicle 1 through the telematics unit 28 or the like. For example, it calculates the scheduled departure time based on information such as the time set in advance as the target time for charging completion or whether the air conditioning has been reserved before boarding.

[0120] In step S106, the discharge distribution determination unit 31 determines whether the remaining time until departure is less than or equal to a predetermined value. If it is less than or equal to the predetermined value (YES), the process proceeds to step S107. If it is greater than the predetermined value (NO), the process proceeds to step S110.

[0121] In step S107, the discharge distribution determination unit 31 obtains the ambient temperature through, for example, an ambient temperature sensor (not shown). The ambient temperature may be estimated by obtaining the coolant temperature through, for example, a coolant temperature sensor (not shown).

[0122] In step S108, the discharge distribution determination unit 31 determines whether the ambient temperature is below a predetermined value (for example, below freezing or 5 degrees or less) and whether it is a temperature at which it would be advisable to accelerate the warming of vehicle 1. If it is below the predetermined value (YES), the process proceeds to step S109. If it is above the predetermined value (NO), the process proceeds to step S110.

[0123] In step S109, since it is deemed beneficial to promote warm-up, the discharge distribution determination unit 31 determines the discharge distribution prioritizing destinations that can promote warm-up of the vehicle 1, such as the air conditioner of the vehicle 1's internal equipment 18, as the destination for discharging power from the battery 11. Since warming up the vehicle 1 requires the use of power from the battery 11, as in Embodiment 2, when warm-up is necessary, distributing power to the air conditioner of the vehicle 1 is a more effective use of the battery 11's power than distributing it to external equipment.

[0124] In step S110, since warming up the vehicle 1 is not required, the discharge distribution determination unit 31 determines the discharge distribution prioritizing the external equipment 111, similar to the first embodiment.

[0125] While this explanation uses ambient temperature as the basis for judgment, it is not limited to this; other temperatures, such as coolant temperature, may also be used. [Examples]

[0126] Embodiment 3 is a modification of Embodiment 1, in which the power information acquisition unit 30 acquires a time series of power that can be consumed by the external device 111, and the discharge distribution determination unit 31 prioritizes distribution to the internal device 18 if the minimum value of the time series of power that can be consumed by the external device 111 is less than or equal to a predetermined value.

[0127] Figure 8 is a time-series waveform diagram of the electricity demand of a house to illustrate the operation of Example 3. In Figure 8, the vertical axis shows the electricity demand of the external equipment 111 of the house 100, and the horizontal axis shows the time.

[0128] In this embodiment, the power information acquisition unit 30 periodically checks the power demand while the vehicle 1 is connected to the house 100 and stores it as a time series.

[0129] As shown in Figure 8, if the power demand of house 100 fluctuates significantly and repeatedly, such as when only one washing machine or air conditioner is running in house 100, selecting external equipment 111 as the discharge destination may result in not being able to obtain the expected power demand, making it impossible to secure the discharge amount, or it may take a long time to secure the discharge amount, which could delay OCV measurement.

[0130] Therefore, in this embodiment, the discharge distribution determination unit 31 prioritizes distribution to the internal device 18 if the minimum time-series value of the power that can be consumed by the external device 111 is less than or equal to the predetermined value shown by the dotted line in Figure 8. This avoids the problems described above. [Examples]

[0131] Embodiment 4 is a modification of Embodiment 1, in which the power information acquisition unit 30 acquires the operation plan of the external device 111, and the charge / discharge amount determination unit 29 detects a time period when the external device 111 has a large amount of power available to consume based on this operation plan, and sets this time period as the timing for the next open-circuit voltage measurement.

[0132] Figure 9 is a timing chart illustrating the operation of Example 4.

[0133] In this embodiment, the power information acquisition unit 30 acquires the operating plan of the external device 111 through the HEMS 112.

[0134] The upper part of Figure 9 shows the operation plan for the hot water supply system, and the middle part shows the operation plan for the floor heating system. The horizontal axis represents time, and the vertical axis indicates whether the system is operating or not. In this way, if the operation of the external equipment 111 can be determined in advance, power from the battery 11 can be supplied to the house 100 during times when the house's electricity demand is high, and the power from the battery 11 can be used efficiently without waste.

[0135] Therefore, as shown in the lower part of Figure 9, the charge / discharge amount determination unit 29 sets the OCV measurement timing to match the operating period of these external devices 111. For example, the charge / discharge amount determination unit 29 sets the time T5 of the OCV measurement timing in Figure 5 and the period (from time T3 to time T4) for performing discharge to eliminate polarization. [Examples]

[0136] Example 5 is a modification of Example 1, in which the power information acquisition unit 30 acquires the charging and discharging timing of other vehicles 1, and the discharge distribution determination unit 31 determines the discharge distribution so that it discharges at the timing when other vehicles 1 are charging.

[0137] Figure 10 is a waveform diagram illustrating the operation of Example 5.

[0138] In this embodiment, when multiple vehicles 1 are connected to a house 100, the OCV measurement timing is set so that the power demand of the house 100 is not exceeded, and the charging and discharging necessary to eliminate polarization are not performed simultaneously.

[0139] The power information acquisition unit 30 acquires the measurement results of the power meter 108 as the power demand of the house 100 via the HEMS 112, and also communicates with other vehicles 1 connected to the house 100 via the telematics unit 28 to adjust the timing of charging and discharging so that the discharge performed to depolarize the battery 11 does not exceed the power demand of the house 100.

[0140] Furthermore, this type of adjustment also includes adjusting the charging time of other vehicles 1 and the discharging time in the OVC measurement of the own vehicle so that when other vehicles 1 are charging, the own vehicle 1 discharges, thereby increasing the electricity demand of the house 100 as seen from vehicle 1.

[0141] The upper part of Figure 10 shows the electricity demand of House 100, the middle part shows the power forecast for charging and discharging of Vehicle 1 (the vehicle itself), and the lower part shows the power forecast for charging and discharging of another Vehicle 1. The vertical axis represents power, and the horizontal axis represents time. In addition, the vertical axis in the middle and lower parts shows charging upwards and discharging downwards.

[0142] If multiple vehicles 1 discharge their batteries 11 to eliminate polarization, there is a risk that the combined discharge rate may exceed the electricity demand of the house 100 when these discharges overlap.

[0143] To avoid this, the charging and discharging times of each vehicle are adjusted so that the discharge time for OCV measurement of the vehicle 1 (shown by the fine shading) and the discharge time for OCV measurement of the other vehicle 1 (shown by the coarse shading) do not overlap. This allows charging and discharging to eliminate polarization to be performed without exceeding the power demand of the house 100, and consequently without a shortage of the amount of discharge necessary to eliminate polarization. [Examples]

[0144] Example 6 is a modification of Example 1, and is an example in which the amount of discharge required to eliminate polarization can be secured even when the power information acquisition unit 30 has not obtained information on the power demand of the house 100. To this end, the discharge distribution determination unit 31 prioritizes distribution to external equipment 111 and distributes the deficit to internal equipment 18.

[0145] Figure 11 is a flowchart illustrating the operation of Example 6.

[0146] In this embodiment, we assume a case where the power demand of the house 100 cannot be obtained through the telematics unit 28. For example, this applies when the HEMS 112 is not installed in the house 100 and AC charging is performed through the AC charging port 24, charging cable 25, and AC outlet 105. It is also possible to implement this embodiment when the power information acquisition unit 30 is unable to obtain the power demand of the house 100.

[0147] Steps S201 to S203 are the same operations as S101 to S103 in Figure 7 of Examples 1 and 2, so their explanation will be omitted.

[0148] Steps S204 through S207 are steps that are performed instead of step S03 in Figure 6.

[0149] In step S204, the discharge distribution determination unit 31 determines the discharge distribution to satisfy the unknown power demand of the house 100 in order to satisfy the discharge amount determined in step S203, and the charge / discharge control unit 32 starts the discharge.

[0150] In step S205, the power information acquisition unit 30 or the discharge distribution determination unit 31 measures and acquires the power that the bidirectional charger 20 is discharging to the house 100 as the power Wr that can be discharged to the house 100.

[0151] In step S206, the discharge distribution determination unit 31 compares the target value Wd of the discharge amount necessary to eliminate polarization, determined by the charge / discharge amount determination unit 29, with the power Wr that can be discharged to the house 100, obtained in step S205. If Wd > Wr, i.e., the power demand of the house 100 is insufficient to eliminate polarization (YES), the process proceeds to step S207. If Wd > Wr is not true (NO), the process proceeds to step S209.

[0152] In step S207, the discharge distribution determination unit 31 distributes the insufficient amount to the internal equipment 18 of the vehicle 1, thereby shortening the time required for OCV measurement. Specifically, in step S207, the discharge distribution to the internal equipment 18 is determined by setting the discharge amount to the internal equipment 18 as Wm = Wd - Wr.

[0153] In step S208, the charge / discharge control unit 32 continues discharging to the house 100 with Wd, while distributing the Wm determined in step S207 to the internal equipment 18 for discharge.

[0154] In step S209, the charge / discharge control unit 32 continues discharging to the house 100 because the electricity demand of the house 100 is sufficient to eliminate the polarization of the battery cell 12.

[0155] In step 210, the voltage acquisition unit 33 performs OCV measurement when a predetermined amount of electricity has been discharged.

[0156] As a result, even if the power information acquisition unit 30 does not obtain the power demand of the house 100, the discharge distribution is determined so that the power from the battery 11 is discharged to the house 100 and the deficit is discharged to the internal equipment 18. This makes it possible to effectively utilize the power from the battery 11 while shortening the time required for OCV measurement.

[0157] Furthermore, although this embodiment describes a case where the power demand of the house 100 cannot be obtained from the telematics unit 28 by the power information acquisition unit 30, it is not limited to this case, and can also be applied when the power demand of the house 100 acquired by the power information acquisition unit 30 fluctuates between the discharge timing time T3 and time T4, and the power demand decreases. That is, in order to satisfy the target value Wd of the discharge amount necessary to eliminate polarization, the discharge distribution determination unit 31 may adjust the power consumed by the internal equipment 18 while feeding back the power that the bidirectional charger 20 (or stationary charger 101) sends to the house 100. [Examples]

[0158] Example 7 is a modification of Example 1, and is an example in which apparent OCV measurement is performed when the electricity demand of house 100 is large, using a different method than in Example 1.

[0159] In this embodiment, in the equivalent circuit model of the battery cell shown in Figure 1, if the resistance components R0 and R1 are the same value for charging and discharging, then by performing charging and discharging in such a way that the absolute value of the current is approximately the same, the same DC voltage is generated with respect to the resistance components R0 and R1. Therefore, it is assumed that the average value of the terminal voltage Vc+ during charging and the terminal voltage Vc- during discharging corresponds to the OCV. Here, "approximately the same" means the same within an acceptable range of error, and it is sufficient if it falls within an acceptable error considering the accuracy that can be controlled by the current and voltage sensors, charging means, and discharging means that are usable in actual operation.

[0160] Specifically, in this embodiment, the power information acquisition unit 30 acquires the power that can be supplied by the external power source and the power demand of the external device 111, the charge / discharge amount determination unit 29 determines the charge / discharge amount for low-rate charging and discharging if the power demand acquired by the power information acquisition unit 30 is greater than a predetermined amount, and the voltage acquisition unit 33 acquires the measurement results of the battery 11 voltage at each timing during low-rate charging / discharging and low-rate discharging, and estimates the open-circuit voltage OCV based on the average value of the two.

[0161] Here, the charge / discharge amount includes information on the magnitude and timing of the current, and it is desirable that the charge / discharge amount determination unit 29 determines the charge / discharge amount such that the difference between the absolute value of the magnitude of the charging current and the absolute value of the magnitude of the discharging current is within 5%.

[0162] Figure 12 is a waveform diagram illustrating the process of measuring the apparent OCV to explain the operation of Example 7.

[0163] The upper part of Figure 12 shows the electricity demand P of house 100, with the vertical axis representing electricity demand P [kVA] and the horizontal axis representing time t. The contracted power Pmax of house 100, shown by the dashed line in the figure, is 10 kVA, indicating that house 100's electricity demand P is large and there is no margin to reach the contracted power Pmax.

[0164] The middle section of Figure 12 shows the voltage change of the battery cells 12 in the battery 11 of vehicle 1, with the vertical axis representing the terminal voltage Vc [V] and the horizontal axis representing time. At time T1, the battery is discharging to the house 100, and a portion of the house 100's power demand P is being met by the power from the battery 11.

[0165] The lower part of Figure 12 shows the charge and discharge current of the battery cell 12. The vertical axis represents the current Ic [A], and a positive upward current indicates that the current is flowing in the direction of charging the battery cell 12. The horizontal axis represents time. In such cases, it is possible to postpone the measurement of the OCV of the battery cell 12, but in this embodiment, the apparent OCV is measured.

[0166] If, following the method of Example 1, an attempt is made to supply a charging current to the battery cell 12 such that its absolute value is equal to or greater than the discharge current of the battery cell 12 at time T1 in order to eliminate polarization, the stationary charger 101 or the bidirectional charger 20 will request power from the house 100. However, at time T1, the power demand P of the house 100 is high, and if charging is started, the ampere breaker 107 of the house 100 is likely to trip, causing the breaker of the house 100 to malfunction.

[0167] Therefore, in this embodiment, if the electricity demand P of the house 100 is greater than a predetermined value, low-rate charging and discharging are performed on the battery cell 12, and the voltage of the battery cell 12 is measured by the voltage measurement unit 14 during charging and discharging, and the apparent OCV is measured by taking the average.

[0168] Whether the electricity demand P of the house 100 is greater than a predetermined value can be determined, for example, by comparing the electricity demand P of the house 100 with a threshold value. The threshold value can be calculated, for example, by multiplying the upper limit power of the ampere breaker 107, which is the power that the external power source acquired by the power information acquisition unit 30 can supply, i.e., the contracted power Pmax, by a predetermined coefficient less than 1. However, the threshold value may be predetermined.

[0169] When measuring apparent OCV, it is desirable to ensure that the absolute values ​​of the charging current and discharging current are approximately the same, for example, with a difference of 5% or less. Similarly, the charging time from time T3 to time T5 and the discharging time from time T6 to time T8 should also be approximately the same, for example, with a difference of 5% or less. In this case, the charge amount Pc and the discharge amount Pd, which are the shaded areas in the lower part of Figure 12, will be approximately the same. Note that the absolute value of the current has a greater influence than time, so the charging time and discharging time do not necessarily have to be approximately the same.

[0170] Here, low-rate charging is preferably 0.2C or less, such as 0.2C or 0.01C, and is set within a range where charging the battery cell 12 does not cause a power outage in the house 100. To achieve this, it is desirable to determine the low-rate charging amount within a range where the house 100 does not experience a power outage, and then determine the low-rate discharge amount based on that. Also, since the sensor cannot measure if the rate is too low, it is desirable that the rate be 0.01C or higher.

[0171] Based on the equivalent circuit model of the battery cell 12 shown in Figure 1, if we assume that the DC components R0 and R1 have the same resistance values ​​during charging and discharging, the apparent OCV is the average of the charging terminal voltage Vc+ obtained at time T4 and the discharging terminal voltage Vc- obtained at time T7.

[0172] The apparent OCV obtained is not strictly the same as the true OCV. Therefore, after making appropriate corrections that reflect experimental and simulation results, it can be used as the OCV for determining the charge level and estimating degradation.

[0173] In this way, even if the electricity demand P of the house 100 increases and charging is performed to depolarize the battery cells 12, which may cause the contracted power Pmax of the house 100 to be exceeded, the apparent OCV can still be measured.

[0174] Although embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible within the scope of the technical idea of ​​the present invention. Furthermore, some or all of the configurations described in each embodiment may be combined and applied. [Explanation of symbols]

[0175] 1...Vehicle, 11...Battery, 12...Battery cell, 13...Monitoring unit, 14...Voltage measurement unit, 15...Current measurement unit, 16...Temperature measurement unit, 17...Power converter, 18...Internal equipment, 19...Charging circuit, 20...Bidirectional charger, 21...DC / DC converter unit, 22...Inverter unit, 23...Control unit, 24...AC charging port, 25...Charging cable, 26...DC charging port, 27...Integrated controller, 28...Telematics unit, 29...Charge / discharge amount determination unit, 30...Power information acquisition unit, 31...Discharge distribution determination unit, 32...Charge / discharge control unit, 33...Voltage acquisition unit, 100...House, 101...Stationary charger, 102...DC / DC converter unit, 103...Inverter unit, 104...Control 105...AC outlet, 106...distribution board, 107...ampere breaker, 108...power meter, 109...power system, 110...solar power generation system, 111...external equipment, 112...HEMS, 113...communication module, Vo...voltage source, Vc...terminal voltage, R0, R1...resistive component, C1...capacitive component, OCV...open circuit voltage, Vdc...DC voltage, Vp...polarization voltage, Tc...charging period, Ts...standing period, t...time, Rsht...shunt resistance, Ic...current, Pd...discharge amount, Wr...power that can be discharged to the house, Wd...target value of the discharge amount required to eliminate polarization, Wm...discharge amount to internal equipment, P...house power demand, Pmax...house contracted power, Pc...charge amount.

Claims

1. A charging system that charges a battery mounted on a vehicle using power supplied from an external power source, A charge / discharge control unit that controls the execution of charging and discharging of the battery, A voltage acquisition unit that acquires the measurement result of the battery voltage at a predetermined timing from a voltage measurement unit that measures the voltage of the battery, A charge / discharge amount determination unit that determines the charge / discharge amount of the battery necessary for measuring the open-circuit voltage of the battery, The system includes a discharge distribution determination unit that determines the distribution of the amount of internal discharge consumed by the vehicle's internal equipment and the amount of external discharge consumed by the vehicle's external equipment, which are necessary to perform the charge / discharge of the battery by the amount of charge / discharge. The charging system is characterized in that the discharge distribution determination unit allows the internal discharge amount and the external discharge amount to be distributed to be greater than zero at the same time.

2. In claim 1, The charge / discharge amount determination unit determines the charge / discharge amount necessary to eliminate the polarization of the battery, The charging system is characterized in that the voltage acquisition unit acquires the measurement result of the battery voltage at a timing after both charging and discharging of the charge / discharge amount has been performed in the battery.

3. In claim 2, The charge / discharge amount includes information on the magnitude and timing of the current, The charging system is characterized in that the charge / discharge amount determination unit determines the charge / discharge amount such that the magnitude of the current performed later in the charging or discharging process is greater than or equal to the magnitude of the current performed earlier in the charging or discharging process.

4. In claim 2, It has a power information acquisition unit that acquires the power that can be consumed by the external device and the power that can be consumed by the internal device. The charging system is characterized in that the discharge distribution determination unit determines the discharge distribution based on the charge / discharge amount and the information from the power information acquisition unit.

5. In claim 4, The charging system is characterized in that the discharge distribution determination unit prioritizes distribution to the external device and distributes the remaining amount to the internal device.

6. In claim 4, The charging system is characterized in that, when the remaining time until the scheduled departure time of the vehicle is below a predetermined value and the outside air temperature is below a predetermined value, the discharge distribution determination unit prioritizes the distribution destination that can promote the warming up of the vehicle when determining the discharge distribution.

7. In claim 4, The power information acquisition unit acquires a time series of power that can be consumed by the external device, The charging system is characterized in that the discharge distribution determination unit prioritizes distribution to the internal device when the minimum value in the time series of power that can be consumed by the external device is less than or equal to a predetermined value.

8. In claim 4, The power information acquisition unit acquires the operating plan of the external equipment, The charging system is characterized in that the charge / discharge amount determination unit detects a time period in which the external device has a large amount of power available for consumption based on the operation plan, and sets the time period as the timing for the next measurement of the open-circuit voltage.

9. In claim 4, The aforementioned power information acquisition unit acquires the charging and discharging timing of other vehicles, The charging system is characterized in that the discharge distribution determination unit determines the discharge distribution so that it performs discharge at the same time as the other vehicle is charging.

10. In claim 2, The charging system is characterized in that the discharge distribution determination unit prioritizes distribution to the external device and distributes the remaining amount to the internal device.

11. In claim 1, The system includes a power information acquisition unit that acquires the power that the external power supply can supply and the power demand of the external device, The charge / discharge amount determination unit determines the charge / discharge amount for performing charge / discharge at a low rate if the power demand acquired by the power information acquisition unit is greater than a predetermined amount. The charging system is characterized in that the voltage acquisition unit acquires the measurement results of the battery voltage at the timing of charging and discharging at the low rate and at the timing of discharging at the low rate, and estimates the open-circuit voltage based on the average value of the two.

12. In claim 11, The charge / discharge amount includes information on the magnitude and timing of the current, The charging system is characterized in that the charge / discharge amount determination unit determines the charge / discharge amount such that the difference between the absolute value of the magnitude of the charging current and the absolute value of the magnitude of the discharging current is within 5%.

13. In any of claims 1 to 12, The aforementioned battery, The voltage measurement unit, A bidirectional charger that converts power in both directions between the power supplied from the external power source and the power discharged from the battery, The aforementioned internal equipment, A charging system characterized by having a power conversion device that converts the power discharged from the battery into power and supplies it to the internal equipment.

14. In claim 13, The charging system is characterized in that the internal equipment includes a drive motor used for driving the vehicle, and the charge / discharge control unit controls the power converter based on the discharge distribution to supply power to the drive motor that generates a drive torque that does not cause the drive motor to rotate.

15. In claim 13, The charging system is characterized in that the internal components include an air conditioner.

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