Charge / discharge control device, and method of controlling charge / discharge control device

Abstract

To provide a charge / discharge control device for increasing an opportunity of being used as V2H (Vehicle to Home) while suppressing storage deterioration and cycle deterioration of an on-vehicle battery, and to provide a control method therefor.SOLUTION: A charge / discharge control device for controlling a charge / discharge device that enables externally charging of charging a battery of an electric vehicle, and externally discharging of discharging power of the battery performs: setting a reference value in a charge state of the battery within a predetermined time from a control start time to a target completion time based on the charging state of the battery, the target completion time, a target value in the charge state at the target completion time, and an output of the charge / discharge device; setting a target charge / discharge range defined by an upper limit value in a charge state within the predetermined time from the control start time to the target completion time; and when the charge state of the battery is in a region between the upper limit value in the charge state and the reference value, after control-starting, carrying out charging by an output smaller than a charging output in the other region.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] The present invention relates to a configuration of a charge and discharge control device for controlling charging and discharging of a battery and a control method thereof, and particularly relates to a technique effective when applied to a charge and discharge control device for an in-vehicle battery that can be used as an auxiliary power source.

Background Art

[0002] An electric vehicle uses an electric motor as a driving power source, is equipped with a battery that serves as a power source for the electric motor, and runs on the power stored in the battery. In addition to this, the electric vehicle is externally charged by power supplied from outside the vehicle or the battery is charged by a generator provided in the electric vehicle.

[0003] It is possible to perform external discharge that uses the power of the battery provided in the electric vehicle as an auxiliary power source by supplying the power to a house or a power grid, and there are high expectations for the utilization of electric vehicles.

[0004] Forms of using the battery of an electric vehicle as an auxiliary power source include V2H (Vehicle to Home) that connects an electric vehicle (EV: Electric vehicle) to a house, V2G (Vehicle to G) that connects to a power grid, V2L (Vehicle to Load) that connects to an electrical load, V2V (Vehicle to Vehicle) that connects vehicles to each other, and V2X (Vehicle to Everything) that connects to any device that performs power transfer, which is a general term for them. Since an electric vehicle is used not only as a means of transportation but also as a power source, deterioration of the battery becomes a problem.

[0005] It is known that battery deterioration includes storage deterioration associated with storage and cycle deterioration caused by charging and discharging. In the storage deterioration of the battery, the state of charge and temperature during storage are affected, and in cycle deterioration, in addition to the magnitude of the current (output) at the time of charging and discharging opportunities and the range of the state of charge at which charging and discharging are performed (referred to as DoD: Depth of Discharge, etc.), temperature is also known to be dominant, similar to storage deterioration.

[0006] The state of charge is referred to as SOC (State of charge) and is defined in the form of 0 to 1 or 0% to 100% as the ratio of the amount of electricity charged in the battery to the full charge capacity of the battery. The closer the SOC is to 1, and especially the higher the temperature, particularly at temperatures exceeding room temperature (25°C), the more the deterioration progresses.

[0007] Due to the deterioration of the battery, the discharge capacity that the battery can discharge decreases. When the discharge capacity decreases, the driving range of the electric vehicle decreases, or the capacity of the auxiliary power source decreases, and the convenience is impaired. Alternatively, due to the deterioration of the battery, the internal resistance of the battery increases, leading to a decrease in the output of the electric vehicle and an increase in the amount of heat generated. Due to the decrease in the driving range and the capacity of the auxiliary power source, it is necessary to charge frequently, and the increase in the amount of heat generated due to the increase in resistance causes the battery temperature to rise, falling into a vicious cycle where the deterioration further progresses.

[0008] An example of a charge and discharge control method for suppressing such deterioration is disclosed in Patent Document 1.

[0009] According to Patent Document 1, the charging and discharging of the driving battery are controlled by a charge and discharge control device. At this time, the scheduled start time of using the electric vehicle is set as the target charge end time, and based on this, the full charge start time is set. A plurality of storage charge amounts smaller than the full charge amount of the driving battery are set for each temperature of the driving battery as the charge amount of the driving battery to be maintained during the storage period before the electric vehicle is used before the full charge start time.

[0010] During the storage period, a charge and discharge control device is shown that selects a storage charge amount based on the temperature information and state of charge information of the driving battery, and instructs the charge and discharge equipment to charge or discharge the driving battery so that the charge amount of the driving battery is maintained at the selected storage charge amount.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] When an electric vehicle is used not only as a means of transportation but also as a power source, even when the electric vehicle is parked and connected to a house or the like through a charging and discharging device, while performing charging and discharging, it is necessary to suppress storage deterioration associated with storage and cycle deterioration through charging and discharging, and minimize a decrease in discharge capacity and an increase in resistance.

[0013] Patent Document 1 discloses a method of suppressing the progress of storage deterioration by selecting an SOC suitable for storage based on temperature, but it focuses only on storage deterioration. However, as described above, in addition to storage deterioration, cycle deterioration also exists, and since no consideration is given to such a deterioration form, there is a risk that the progress of cycle deterioration cannot be suitably suppressed when the battery is utilized as an auxiliary power source.

[0014] Also, until the timing when the full charge start time is reached, it is regarded as a storage period and is held at the charge amount of the battery for running to be held. Therefore, during the period regarded as the storage period, the battery of the electric vehicle cannot be used as an auxiliary power source.

[0015] That is, the method disclosed in Patent Document 1 has a problem that the progress of cycle deterioration that occurs when the battery of an electric vehicle is used as an auxiliary power source cannot be suitably suppressed, and the opportunity to use the battery of the electric vehicle as an auxiliary power source is limited.

[0016] Therefore, an object of the present invention is to provide a charge and discharge control device and a control method thereof that can increase the opportunity to be used as an auxiliary power source such as V2H (Vehicle to Home) while suppressing storage deterioration and cycle deterioration of an in-vehicle battery.

Means for Solving the Problems

[0017] In order to solve the above problems, the present invention is a charge-discharge control device that controls a charge-discharge device capable of external charging for charging a battery of an electric vehicle with an external power source and external discharging for discharging the power of the battery to an external device. Based on the state of charge of the battery, the target completion time, the target value of the state of charge at the target completion time, and the output of the charge-discharge device, a reference value of the state of charge of the battery at a predetermined time from the start of control to the target completion time is set, a target charge-discharge range defined by an upper limit value of the state of charge at a predetermined time from the start of control to the target completion time is set, and after the start of control, when the state of charge of the battery is in the region between the upper limit value of the state of charge and the reference value, when charging the battery, charging is performed with an output smaller than the charging output in other regions.

[0018] Further, the present invention is a control method for a charge-discharge control device that controls a charge-discharge device capable of external charging for charging a battery of an electric vehicle with an external power source and external discharging for discharging the power of the battery to an external device, the method including: (a) setting a reference value of the state of charge of the battery at a predetermined time from the start of control to the target completion time based on the state of charge of the battery, the target completion time, the target value of the state of charge at the target completion time, and the output of the charge-discharge device; (b) setting a target charge-discharge range defined by an upper limit value of the state of charge at a predetermined time from the start of control to the target completion time based on the state of charge of the battery, the target completion time, the target value of the state of charge at the target completion time, and the output of the charge-discharge device; and (c) after the start of control, when the state of charge of the battery is in the region between the upper limit value of the state of charge and the reference value, when charging the battery, charging is performed with an output smaller than the charging output in other regions.

Advantages of the Invention

[0019] According to the present invention, it is possible to realize a charge-discharge control device and a control method thereof that can increase the opportunity to be used as an auxiliary power source such as V2H (Vehicle to Home) while suppressing storage deterioration and cycle deterioration of an in-vehicle battery.

[0020] Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0021]

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[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same components or components having similar functions are denoted by the same reference numerals, and detailed descriptions of overlapping parts are omitted. EXAMPLES

[0023] With reference to FIGS. 1 to 10, a charge / discharge control device and its control method according to Embodiment 1 of the present invention will be described.

[0024] [Configuration of Electric Vehicle and House] FIG. 1 is a block diagram showing a schematic configuration of a power system including an electric vehicle 100 provided with an integrated controller 101 having a charge / discharge control device 1 according to Embodiment 1 of the present invention. An example in which a power system including the electric vehicle 100 is connected to a house 200 using an AC charging port 105 is shown.

[0025] FIG. 1 uses an example of connecting an electric vehicle 100, which is an electric vehicle or a plug-in hybrid vehicle, to a house 200. However, the house 200 is not necessarily limited to a detached house where the owner or user of the electric vehicle 100 lives. For example, it may be an apartment building, and the present invention is applicable even if the facility corresponding to the house 200 is an office or a parking lot. Also, a configuration in which a plurality of electric vehicles 100 are connected may be adopted.

[0026] As shown in FIG. 1, the charge / discharge control device 1 of the present embodiment is a system that charges and discharges a drive battery 102 mounted on the electric vehicle 100 with electric power supplied through the house 200. The electric vehicle 100 includes, in addition to the drive battery 102, an integrated controller 101 including the charge / discharge control device 1, an in-vehicle charger 103, and a battery control unit (hereinafter, appropriately referred to as BCU. BCU: Battery control unit) 104 that detects the state of the drive battery 102.

[0027] For the drive battery 102, for example, a lithium-ion secondary battery, a nickel-metal hydride secondary battery, etc. are used, and the present invention can particularly preferably suppress the deterioration of the lithium-ion secondary battery. The drive battery 102 is composed of a battery module capable of realizing desired output characteristics by connecting a plurality of secondary battery cells (not shown) in series or in parallel.

[0028] In addition, the electric vehicle 100 is equipped with a low-voltage battery (not shown) as a power source for instruments and lights (not shown). In addition to the above secondary batteries, a lead-acid battery or the like can also be preferably used for the low-voltage battery.

[0029] The BCU 104 includes a voltage measurement unit capable of detecting the voltage of battery cells, a current measurement unit capable of detecting the current flowing through the battery cells, and a temperature measurement unit capable of detecting the temperature of the drive battery 102 in order to detect the state of the drive battery 102. The voltage measurement unit is configured in such a way that voltage lines are attached between the battery cells so that the terminal voltages of a plurality of battery cells can be individually measured. The current measurement unit can use sensors such as Hall elements in addition to a method of detecting current by measuring the voltage of a shunt resistor, for example. A thermistor, a thermocouple, or the like can be used for the temperature measurement unit.

[0030] In this way, the BCU 104 converts the state of the drive battery 102 into voltage information and detects it. Therefore, it can be composed of semiconductor devices such as general-purpose analog front-end ICs and ASICs (Application Specific Integrated Circuits). Also, by providing an A / D converter, the state quantity of the drive battery 102 detected as a voltage can be converted into a digital value that can be used in arithmetic processing such as a program.

[0031] The state of the drive battery 102 detected by the BCU 104 is transmitted to the integrated controller 101 through the communication bus 107. The integrated controller 101 includes a CPU that performs arithmetic processing, a RAM that holds calculation results and the program being executed, and a storage unit such as a memory and a recording medium such as a ROM that stores programs, control setting values, and the like, and realizes each functional block of the integrated controller 101 by executing the programs stored in the storage unit.

[0032] The integrated controller 101 is configured to be able to acquire the operating states of the power converter 111 and the driving motor 112 and the state of the drive battery 102 as necessary, and to communicate with components described later through the communication bus 107 and with components outside the electric vehicle 100 through the communication bus 107 and the communication unit 109. Inside the electric vehicle 100, communication methods such as CAN (Controller Area Network) and LIN (Local Interconnect Network) are used. For communication between the electric vehicle 100 and the house 200, in addition to making appropriate use of methods such as Ethernet connection, communication by PLC (Power Line Communication) may also be used. Also, not only wired communication but also wireless communication may be performed.

[0033] Although not shown in the figure, the in-vehicle charger 103 is equipped with a power converter and converts the AC power obtained through the AC charging port 105 into DC power necessary for charging the drive battery 102. In addition, it has a function of changing the DC voltage and current in order to adjust the charging power of the drive battery 102. Furthermore, it has a function of converting the DC power of the drive battery 102 into AC power that can be used in the house 200.

[0034] That is, the in-vehicle charger 103 is configured to be able to perform two-way power transfer so that the drive battery 102 can be charged with power supplied from the house 200 and the power of the drive battery 102 can be discharged (fed) to the house 200. Power input and output are performed through the charging cable 106 via the AC charging port 105 and through the outlet 201 of the house 200.

[0035] In the house 200, it is further connected from the outlet 201 to the power adjustment means 203. From the power adjustment means 203, it is further connected to the power grid 204 through an ampere breaker and a watt-hour meter (not shown). Connected to the power adjustment means 203 are, in addition to the solar power generation system 205, the power generated by the solar power generation system 205, the power purchased from the power grid 204, and further, a battery system 206 and a communication means 207 that can charge and discharge the power obtained from the drive battery 102.

[0036] Also, in the house 200, the self - contained load 208 is connected from the power adjustment means 203 via the distribution board 202. The self - contained load 208 includes the house equipment of the house 200 and so - called electrical appliances. For example, in addition to white goods such as the air conditioner, hot water supply system, lighting, cooking appliances, refrigerator, and washing machine in the house 200, black goods such as TVs and audio equipment, and information appliances such as personal computers and telephones are connected.

[0037] The power adjustment means 203 may be a system called HEMS (Home Energy Management System). It can adjust the power generation amount of the solar power generation system 205, adjust the operating state of the hot water supply system, adjust the boiling timing of the hot water supply system according to the power demand of the house 200 obtained from the power meter, adjust the operating state of the air conditioner, and sell the surplus power of the solar power generation system 205 to the power grid 204.

[0038] The power adjustment means 203 may be configured such that the power demand of the house 200 can be queried from the outside via the communication means 207. The integrated controller 101 of the electric vehicle 100 may be configured to be able to acquire information such as the power demand of the house 200 held by the power adjustment means 203 through the communication unit 109 of the electric vehicle 100.

[0039] Also, the power adjustment means 203 can issue a command to prohibit discharging from the drive battery 102 or the battery system 206 so as not to discharge more power than that obtained from the solar power generation system 205 according to the power generation amount of the solar power generation system 205 to the power grid 204.

[0040] Self - contained loads 208 such as air conditioners and hot water supply systems operate by consuming the power of the drive battery 102 in addition to the power purchased from the power grid 204, the power generated by the solar power generation system 205, or the power stored in the battery system 206. The house 200 may be equipped with a solar power generation system 205 or a fuel cell system (not shown) as a power source alternative to the power grid 204.

[0041] The in-vehicle charger 103 includes a power conversion unit 113 having a DC / DC converter unit capable of transforming DC voltage, a rectification unit that rectifies AC power into DC power when charging the drive battery 102 with AC power from the distribution board 202, and an inverter unit capable of converting the DC power output from the DC / DC converter unit into AC power when feeding power from the drive battery 102 to the house 200. Further, the in-vehicle charger 103 includes a power sensing unit 114 capable of detecting the current, voltage, and frequency of the power line connected to the in-vehicle charger 103, and a power conversion control unit 115 that controls the power conversion unit 113 based on the information obtained through the power sensing unit 114, in order to control these components.

[0042] When charging the drive battery 102, so-called CC-CV (Constant Current, Constant Voltage) charging, which combines constant current charging and constant voltage charging corresponding to the battery cells in the drive battery 102, is performed.

[0043] Specifically, when the charge state of the drive battery 102 is low, constant current charging is performed and the charging speed is adjusted so that the current flowing through the battery cells in the drive battery 102 does not exceed a predetermined value. If an excessive current flows through the battery cells, lithium ions may not be incorporated into the negative electrode active material layer in the battery cells, but instead lithium metal may precipitate on the negative electrode, causing an internal short circuit, which may lead to thermal runaway accompanied by ignition or rupture of the battery cells. To prevent this, it is necessary to control the charging speed, that is, the current, so that no excessive current flows.

[0044] When the charging of the drive battery 102 progresses and the voltage of the battery cell rises, the charging shifts to constant voltage charging. If the voltage of the battery cell rises excessively, lithium ions are excessively extracted from the positive electrode active material, which not only embrittles the electrode structure but also increases the reactivity of the positive electrode, causing the decomposition reaction of the electrolyte to proceed and generating gas inside the battery cell. Also, the decomposition reaction of the electrolyte proceeds and generates heat as well. Since the gas and electrolyte generated inside the battery cell are flammable, there is a risk of ignition of these, leading to destruction such as ignition of the battery cell or rupture due to an increase in gas pressure. Similar to the current, it is necessary to control the voltage so that it does not become excessive.

[0045] Taking the in-vehicle charger 103 as an example, the power conversion unit 113 rectifies the AC power obtained through the AC charging port 105 into DC, and controls the charging current and charging voltage flowing into the battery cell, and thus the drive battery 102, by controlling the duty ratio of the switching element of the DC / DC converter unit inside the power conversion unit 113. As described above, the in-vehicle charger 103 can charge the drive battery 102.

[0046] When supplying the power of the drive battery 102 to the house 200, the DC / DC converter unit of the power conversion unit 113 of the in-vehicle charger 103 adjusts the voltage according to the AC power used in the house 200 detected by the power sensing unit 114. The inverter unit of the power conversion unit 113 generates AC so that the frequency and phase of the AC power used in the house 200 are synchronized.

[0047] The power conversion control unit 115 adjusts the duty ratio of the switching signal that commands the switch element of the DC / DC converter unit for voltage adjustment, and while adjusting the switching command of the inverter unit so as to feedback and synchronize with the frequency and phase of the AC power in the house 200 in order to send power into the house 200, it slightly adjusts the voltage and phase to transfer AC power to the house 200.

[0048] By enabling the power of the drive battery 102 to be used in the house 200 through the in-vehicle charger 103, for example, the power of the drive battery 102 can be utilized in the house 200 when there is no power supply from the power grid 204 during a disaster, or it can meet applications such as reducing the electricity purchase amount from the power grid 204 to cut the electricity bill of the house 200.

[0049] The drive battery 102 is connected to the power converter 111. The power converter 111 is a bidirectional inverter, which drives the driving motor 112 used for the running of the electric vehicle 100. The bidirectional inverter is composed of a DC / DC converter section and an inverter section. The DC / DC converter section converts the DC voltage of the drive battery 102 into the voltage required for driving the driving motor 112, and the inverter section converts the DC power into AC power, thereby performing frequency control according to the rotational speed of the driving motor 112 to drive the driving motor 112. Thereby, a rotational force (driving torque) for accelerating the electric vehicle 100 is obtained.

[0050] Alternatively, when decelerating the electric vehicle 100, the driving motor 112 is driven regeneratively, the kinetic energy of the electric vehicle 100 is regenerated as electric power, and the regenerated electric power is sent to the drive battery 102 through the DC / DC converter section, and the drive battery 102 is charged with this electric power.

[0051] Acceleration or deceleration of the electric vehicle 100 is realized by the vehicle control unit 110 in the integrated controller 101 generating a drive command for the power converter 111. By detecting the driver's acceleration / deceleration request through the operation of the accelerator pedal or brake pedal of the electric vehicle 100 (not shown), a drive command for the power converter 111 is generated within the vehicle control unit 110.

[0052] As the amount of depression of the accelerator pedal increases, it is assumed that the driver is requesting acceleration, and an increase in the voltage or frequency generated by the power converter 111 is commanded to increase the torque of the drive motor 112. Conversely, when the amount of depression of the accelerator pedal decreases or the brake pedal is operated, a decrease in the voltage or frequency generated by the power converter 111 is commanded, and the regenerative drive of the drive motor 112 is commanded. In this way, the operations of driving and stopping the electric vehicle 100 are realized. Even if control other than that described here is realized by the power converter 111 or the drive motor 112, there is no problem.

[0053] The electric vehicle 100 includes an HMI (Human Machine Interface) 108 and a communication unit 109. The HMI 108 is composed of an input means 116 for receiving various settings from the user of the electric vehicle 100 and a display means 117 for providing information for the user to confirm and grasp various settings.

[0054] The communication unit 109 provides wireless communication means for connecting to a mobile phone network or a wireless local area connection for the electric vehicle 100 to perform communication, and further includes a gateway controller, and performs communication by a wired connection via a charging cable 106 or the like. The communication unit 109 is configured to be connectable to the power adjustment means 203 via the communication means 207.

[0055] FIG. 2 is a block diagram showing a modification of FIG. 1. An example in which a power supply system including the electric vehicle 100 is connected to a house 200 using a DC charging port 118 is shown.

[0056] So far, the method of using the in-vehicle charger 103 and the AC charging port 105 as the charging and discharging method of the drive battery 102 has been described. However, the present invention is also applicable to a connection using an installation-type charger 209 and a DC charging port 118 as shown in FIG. 2. The power conversion unit 113, the power sensing unit 114, and the power conversion control unit 115 included in the in-vehicle charger 103 are distributed to the installation-type charger 209 and the power adjustment means 203.

[0057] In the stationary charger 209, a function equivalent to the DC / DC converter section provided in the power conversion section 113 of the in-vehicle charger 103 is realized, and the current and voltage for charging the drive battery 102 are adjusted. In the power adjustment means 203, functions equivalent to the inverter section and the power sensing section 114 provided in the power conversion section 113 of the in-vehicle charger 103 are realized. In order to feed power into the house 200, the frequency and phase of the AC power in the house 200 are fed back and the switching command of the inverter section is adjusted to synchronize with it. When charging the drive battery 102, the AC power in the house 200 is converted into DC power used by the stationary charger 209. Since the photovoltaic power generation system 205 and the battery system 206 are facilities that supply DC power, there is no need for power conversion and the DC power can be directly used by the stationary charger 209. At this time, if the system voltage of the photovoltaic power generation system 205 or the battery system 206 is different from the voltage for operating the drive battery 102, a mechanism for eliminating the voltage difference, such as a DC / DC converter section (not shown), may be added to the stationary charger 209 or the power adjustment means 203.

[0058] AC charging through the AC charging port 105 and DC charging through the DC charging port 118 are exclusively used in the in-vehicle charger 103 by relays or semiconductor switches (not shown). The in-vehicle charger 103 is mounted on the electric vehicle 100 and performs bi-directional power conversion between the power supplied from an external power source such as the house 200 and the power discharged from the drive battery 102. The stationary charger 209 is installed outside the electric vehicle 100 and the house 200 and performs bi-directional power conversion between the power supplied from a power source such as the house 200 and the power discharged from the drive battery 102.

[0059] The user of the electric vehicle 100 can selectively use AC charging through the AC charging port 105 and DC charging through the DC charging port 118 depending on the available power source. When the residence 200 is equipped with the power conditioning means 203 and the stationary charger / discharger 209, the stationary charger / discharger 209 that can directly utilize DC power enables high-power, i.e., fast, charging compared to AC charging. On the other hand, for AC charging, it is only necessary to be able to use the outlet 201, and the drive battery 102 of the electric vehicle 100 can be charged even if the residence 200 does not have the power conditioning means 203 or the stationary charger / discharger 209.

[0060] The electric vehicle 100 further includes, as an external sensor 119, a temperature detection means 120 and a position detection means 121. The temperature detection means 120 measures the outside air temperature around the electric vehicle 100. The position detection means 121 is, for example, a GPS (Global Positioning System) and detects the position of the electric vehicle 100.

[0061] [Charge / Discharge Control Method] As described above, the method disclosed in Patent Document 1 has a problem that the progress of cycle degradation that occurs when using the battery of the electric vehicle as an auxiliary power source cannot be suitably suppressed, and the opportunity to use the battery of the electric vehicle as an auxiliary power source is limited. From here, a charge / discharge control method that can increase the opportunity to use the battery of the electric vehicle as an auxiliary power source while suppressing cycle degradation in addition to storage degradation, which is an object of the present invention, will be described.

[0062] Battery degradation within the cells of the drive battery 102 is typified by storage degradation associated with storage and cycle degradation due to charge and discharge. The storage degradation of the battery is mainly attributed to the growth of the passive layer (hereinafter, SEI: Solid Electrolyte Interphase) formed particularly on the negative electrode of the battery cell. A stable and uniform SEI is required to protect the current collector of the negative electrode from corrosion. However, non-uniform SEI growth causes corrosion of the current collector of the battery cell negative electrode, lithium precipitation on the surface of the battery cell negative electrode, growth of needle-like crystals (dendrites) of the precipitated lithium, generation of cracks on the negative electrode surface, and a decrease in ionic conductivity due to excessive formation of SEI, etc.

[0063] In cycle degradation, in the positive and negative electrodes of the battery cell, loss of the positive electrode active material due to insertion and extraction of lithium ions, corrosion of the current collector of the positive electrode, irreversible changes in the crystal structure of the transition metal oxide, etc. occur. Lithium ions that should originally be used for the charge and discharge reaction are consumed by the above-mentioned side reactions, resulting in capacity degradation of the battery and a decrease in the discharge capacity. The resistance of the battery cell increases due to corrosion of the current collector of the battery cell positive electrode or the battery cell negative electrode and a decrease in ionic conductivity.

[0064] SEI growth is a chemical reaction. As the state of charge during storage increases, a voltage increase (overvoltage) that promotes the reaction occurs, and in addition, the progress of degradation is accelerated by an increase in the reaction rate due to an increase in temperature. In cycle degradation, an increase in the amount of lithium ions inserted and extracted due to an increase in the magnitude of the current (output) during charge and discharge opportunities and the range of the state of charge at which charge and discharge are performed affects the increase in side reactions. In addition, temperature is also dominant as in storage degradation. Therefore, degradation is suppressed by adjusting the state of charge and the charge and discharge rate.

[0065] Figure 3 is a block diagram showing a configuration example of the charge and discharge control device 1 of FIGS. 1 and 2. The charge and discharge control device 1 includes an acquisition unit 2, an estimation unit 3, a range setting unit 4, a command value generation unit 5, and a control unit 6.

[0066] The acquisition unit 2 acquires the state-of-charge information regarding the state of charge of the drive battery 102, the temperature information regarding the temperature, and the characteristic information regarding various characteristics of the drive battery 102 from the BCU 104 through the communication bus 107. Further, the acquisition unit 2 acquires, through the communication unit 109, the outlook of the outside air temperature at the location where the electric vehicle 100 performs charging and discharging as weather information.

[0067] It is also possible to acquire, as the target charge completion time information, the target charge completion time of the electric vehicle 100 set through the HMI 108 and the communication unit 109, and as the target charge state information, the target battery state of charge at the time of charge completion.

[0068] The estimation unit 3 includes a departure scheduled time estimation unit, a target charge state estimation unit, and a battery state prediction unit (not shown in the figures).

[0069] The departure scheduled time estimation unit estimates the time when it is expected that the electric vehicle 100 will finish the electrical connection with the house 200, that is, the scheduled departure time when the use of the electric vehicle 100 for the movement of the user starts, based on the driving performance and the charging and discharging performance of the electric vehicle 100. This can also be used as the target charge completion time.

[0070] The target charge state estimation unit estimates the target charge state information from the actual value of the state of charge of the drive battery 102 when the electric vehicle 100 finishes the electrical connection with the house 200. The estimated target charge state may be set as the target charge state set by the user of the electric vehicle 100.

[0071] The battery state prediction unit predicts the changes in the battery temperature and the state of charge when the drive battery 102 performs charging and discharging based on the characteristic information of the drive battery 102. The detailed prediction method will be described later.

[0072] When the acquisition unit 2 can acquire the target charging completion time set by the user of the electric vehicle 100, the range setting unit 4 sets the target charging completion time information; otherwise, it sets the estimated departure time estimated by the estimation unit 3 as the time when the charging of the drive battery 102 should be completed. Further, the range setting unit 4 sets the upper limit charging state that permits the charging of the drive battery 102, the lower limit charging state that permits the discharging of the drive battery 102, and the reference charging state that becomes the charging state based on the target charging state information at the time when the drive battery 102 should complete charging, starting from the charging state of the drive battery 102 at the time when the control starts. The methods of these settings will be described later.

[0073] The command value generation unit 5 compares the upper limit charging state, the lower limit charging state, and the reference charging state set by the range setting unit 4 with the charging state of the drive battery 102, calculates the target value of the charge / discharge output when the in-vehicle charger 103 or the stationary charger 209 charges / discharges the drive battery 102, and commands it through the communication bus 107.

[0074] The control unit 6 commands the execution of each function constituting the charge / discharge control device 1.

[0075] [Details of the battery state prediction unit of the estimation unit 3] Regarding the battery temperature, as battery characteristic information, from the mass, specific heat, internal resistance, entropy change, surface area, heat transfer coefficient of the drive battery 102, and the environmental temperature in which the drive battery 102 is stored, the temperature change of the drive battery 102 accompanying charge / discharge is estimated by updating the temperature of the drive battery 102 according to the following formulas (i) to (vi).

[0076] Equation (1) is an equation for obtaining the heat inflow and outflow that updates the temperature of the drive battery 102, and calculates the heat inflow and outflow associated with heat generation due to the current flowing during charging and discharging of the drive battery 102 (Equation (3)), heat generation or heat absorption associated with the entropy change of the drive battery 102 (Equation (5)), and heat dissipation of the drive battery 102 (Equation (6)), respectively. Using Equation (2), the temperature of the drive battery 102 is updated with the heat generation amount obtained in Equation (1). The current I in Equation (3) is obtained using Equation (4) based on the charging and discharging output of the in-vehicle charger 103 or the stationary charger 209 during charging or discharging of the drive battery 102.

[0077] P in Equation (4) is the output when charging or discharging the drive battery 102, and V is the drive battery voltage. Since the entropy change in Equation (5) varies depending on the state of charge of the drive battery 102, it is preferable to measure the relationship between the state of charge and the entropy change in advance through experiments or the like and use it after organizing it in the form of a table function or the like.

[0078] An example of estimating the battery temperature change using Equations (1) to (6) has been shown, but it is not limited to this method and can be used as long as the temperature change of the battery is obtained.

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Number

[0081]

Number

[0082]

Number

[0083]

Number

[0084]

Number

[0085] Regarding the state of charge, when charging and discharging the drive battery 102 with the in-vehicle charger 103 or the stationary charger 209, the charge and discharge current is obtained from the charge and discharge output at that time and the drive battery voltage corresponding to the state of charge of the drive battery 102 in the same manner as in Equation (4). The current for a predetermined period is integrated as in Equation (7) to obtain the change amount of the state of charge with respect to the rated capacity of the drive battery 102, and the state of charge is updated to estimate the future state of charge of the drive battery 102. The voltage of the drive battery 102 has a correlation with the state of charge of the drive battery 102, and it is preferable to use the measurement result of the voltage of the drive battery 102 with respect to the state of charge of the drive battery 102 in the form of a table function or the like.

[0086]

Number

[0087] In Equation (7), ΔS is the change amount of the state of charge, I is the charge and discharge current, and C rated corresponds to the full charge capacity of the drive battery 102.

[0088] [Details of the Range Setting Unit 4] Using FIGS. 4A and 4B, the method for setting the upper limit state of charge, the lower limit state of charge, and the reference state of charge implemented by the range setting unit 4 will be described.

[0089] FIG. 4A is an example of the upper limit state of charge, the lower limit state of charge, and the reference state of charge (reference value) set in the procedure described below. The horizontal axis represents time, and the vertical axis represents the state of charge. FIG. 4B is an example of the temperature state of the drive battery 102 calculated in the process of setting each set value in FIG. 4A.

[0090] Time T0 in FIG. 4A corresponds to the time when the electric vehicle 100 and the house 200 are connected through the charging cable 106 or the stationary charger 209. Time T corresponds to the time when the electric vehicle 100 should complete charging, that is, the target charging completion time. The charging state indicated by the filled circle on time T0 corresponds to the charging state S0 at time T0. The charging state indicated by the filled circle on time T corresponds to the target charging state S dep corresponds to.

[0091] What is indicated by the dashed line in FIG. 4A is the upper limit charging state and the lower limit charging state, and what is indicated by the solid line connecting the filled circles on time T0 and time T corresponds to the reference charging state (reference value). In FIG. 4A, T s corresponds to the time when charging and discharging of the drive battery 102 is started by applying the present invention. When the electric vehicle 100 is electrically connected to the house 200 at time T0 and the drive battery 102 becomes in a chargeable / dischargeable state, by time T s the upper limit charging state, the lower limit charging state, and the reference charging state (reference value) are set.

[0092] In addition, when the target charging completion time and the target charging state corresponding to time T are not set, the target charging completion time is set to 24 hours later, and a predetermined value such as 0.5 or 0.7, the charging state of the drive battery 102 at time T0, or the charging state of the drive battery 102 when charging was completed in the past is set as the target charging state. Such a predetermined value can be adjusted and set by the user of the electric vehicle 100 through the HMI 108, or it may be configured to obtain the average value of the past target charging states from the charging performance of the electric vehicle 100 and set this value.

[0093] Such a past target state of charge may be referred to by looking back a certain number of times, such as the past 10 times or 100 times, or by looking back in time, such as for the past 10 days, 2 weeks, or 1 month. Information regarding the past target state of charge may be recorded in the storage within the integrated controller 101, or may also be recorded on an external server (not shown) via the communication unit 109. At this time, categorization may be performed according to day of the week, time zone, etc., and values corresponding to the day of the week and time zone close to the target charge completion time may be referred to.

[0094] The setting of the target charge / discharge range by the range setting unit 4 is executed until the electric vehicle 100 establishes an electrical connection with the house 200 at time T0 in FIG. 4A and the charge / discharge of the drive battery 102 starts. Thereafter, until the time reaches T, the electric vehicle 100 starts running between the times up to T, or the user of the electric vehicle 100 requests cancellation of the control, the range setting unit 4 compares the target charge / discharge range set by the range setting unit 4 with the state of charge of the drive battery 102, and determines the charge / discharge output of the in-vehicle charger 103 or the installed charger 209. s When the state of charge of the drive battery 102 is equal to or higher than the reference state of charge (reference value) and equal to or lower than the upper limit state of charge, a smaller charge output is selected compared to the case where the state of charge of the drive battery 102 is less than the reference state of charge (reference value) and equal to or higher than the lower limit state of charge. On the other hand, when the state of charge of the drive battery 102 is less than the reference state of charge (reference value) and equal to or higher than the lower limit state of charge, a smaller discharge output is selected compared to the case where the state of charge of the drive battery 102 is equal to or higher than the reference state of charge (reference value) and equal to or lower than the upper limit state of charge.

[0095] When the state of charge of the drive battery 102 is equal to or higher than the reference state of charge (reference value) and equal to or lower than the upper limit state of charge, a smaller charge output is selected compared to the case where the state of charge of the drive battery 102 is less than the reference state of charge (reference value) and equal to or higher than the lower limit state of charge. On the other hand, when the state of charge of the drive battery 102 is less than the reference state of charge (reference value) and equal to or higher than the lower limit state of charge, a smaller discharge output is selected compared to the case where the state of charge of the drive battery 102 is equal to or higher than the reference state of charge (reference value) and equal to or lower than the upper limit state of charge.

[0096] Depending on the state of charge of the drive battery 102, if it is not possible to charge or discharge the drive battery 102 with the selected charge and discharge output here, the charge and discharge of the drive battery 102 is performed with an output that allows charge and discharge, with the selected charge and discharge output here as the upper limit. For example, when the drive battery 102 is in the state of performing the CV charging described above, it may not be suitable to charge by increasing the charging output beyond the upper limit voltage of the drive battery 102. In such a case, a charging output that does not exceed the upper limit voltage may be selected.

[0097] In addition, when the electric vehicle 100 is left unused after the time T, a new target charge and discharge range is set in the same manner as when the target charge completion time or the target state of charge corresponding to the time T is not set, after a predetermined time such as 30 minutes, 1 hour, or 3 hours has elapsed from the time T.

[0098] <Setting of the upper limit state of charge> The upper limit state of charge is set to a value that is smaller than the full charge of the drive battery 102 and equal to or greater than the target state of charge based on the target state of charge information. In FIG. 4A, an example in which a value equal to the target state of charge is set is shown. The larger the value set for the upper limit state of charge, the more surplus power generated by the solar power generation system 205 provided in the house 200 can be charged to the drive battery 102. As a result, the utilization rate of renewable energy and the amount of electric power that can be used other than the running of the electric vehicle 100 increase, and the convenience such as the amount of electric power that can be used in the house 200 in the future increases. On the other hand, there is a trade-off that the effect of suppressing the storage deterioration of the drive battery 102 becomes smaller.

[0099] By setting the upper limit state of charge in this way, it acts to suppress the storage deterioration of the drive battery 102. The upper limit state of charge may be configured such that the user of the electric vehicle 100 can set or adjust the value through the HMI 108. In that case, it is also okay to configure the display means 117 of the HMI 108 to provide information regarding the trade-off between the convenience and the storage deterioration for setting the upper limit state of charge high, so that it can be used as a reference for setting.

[0100] <Setting of the lower charge state> The lower charge state is set based on the target charge state information, the target charge completion time information, and the charging output of the in-vehicle charger 103 or the stationary charger 209. At time T, it becomes a value equal to the target charge state, and starting from time T b backward, it is set so that charging can be started by the charging output of the drive battery 102 achievable by the in-vehicle charger 103 or the stationary charger 209 and the target charge state can be achieved at time T.

[0101] Also, from time T s backward, discharging is started by the discharging output of the drive battery 102 achievable by the in-vehicle charger 103 or the stationary charger 209 so that the lower charge state is reached at time T f is set. The lower charge state from time T f to time T b is set to satisfy the following formula (8).

[0102]

Equation

[0103] [[ID=**30**]]In formula (8), x is the value of the lower charge state to be obtained, Qlim is the charge and discharge power amount allowed per day, and for example, it can be set based on the charge and discharge power amount record of the electric vehicle 100, such as being the same power amount as the previous day's charge and discharge power amount or the average value of the charge and discharge power amount for one week. Alternatively, some predetermined value can be set, and it can be set in the form of 10%, 20%, 50% of the rated capacity, etc. It may be automatically set based on the charge and discharge power amount record, or the user of the electric vehicle 100 may set it through the HMI 108. In that case, information for reference in setting the power amount may be provided to the user while displaying the power amount record on the display means 117.

[0104] T - T s corresponds to the elapsed time from time T s to time T, S0 is the charge state of the drive battery 102 at time T0, Sdep corresponds to the target state of charge. Q rated corresponds to the rated capacity of the drive battery 102. By limiting the amount of charge and discharge power in this way, it acts to prevent an increase in unnecessary charge and discharge opportunities and suppress cycle degradation of the drive battery 102.

[0105] x in Equation (8) can be obtained by an iterative calculation algorithm such as a binary search algorithm.

[0106] <Setting of reference state of charge (reference value)> The reference state of charge (reference value) is set based on the target state of charge information, the target charge completion time information, and the charging output of the in-vehicle charger 103 or the stationary charger 209, in addition to the temperature outlook of the drive battery 102. From the temperature outlook of the drive battery 102 shown in Equations (1) to (6) and the state of charge outlook of the drive battery 102 obtained by Equations (4) and (7), the charging and discharging output of the in-vehicle charger 103 or the stationary charger 209 that minimizes the evaluation value of the following Equation (9) is set.

[0107]

Equation

[0108] S in Equation (9) is the output of the in-vehicle charger 103 or the stationary charger 209 that is desired to be obtained and the estimated value of the state of charge of the drive battery 102 obtained by Equations (4) and (7), and T bat is the temperature outlook of the drive battery 102 obtained by Equations (1) to (6).

[0109] a, b, and c in Equation (9) are weighting coefficients for each term on the right side of Equation (9), respectively. The first term on the right side of Equation (9) is a penalty term for storage degradation of the drive battery 102, and φ is a penalty function for storage degradation. The second term on the right side is a penalty term related to the electricity charge associated with charging and discharging, and the third term on the right side is the terminal cost, and it is evaluated whether the power reception state of the drive battery 102 at the end of control can reach the target state of charge.

[0110] By obtaining the output sequence of the in-vehicle charger 103 or the stationary charger 209 at which the evaluation value Z shown in formula (9) is minimized, the state of charge of the drive battery 102 when charging and discharging is performed according to this charging and discharging output becomes the reference state of charge (reference value).

[0111] [Charging and Discharging Control Flow] Fig. 5 shows the control flow of the charging and discharging control device 1 of this embodiment.

[0112] When control starts, first, in step S1, in order to perform charging and discharging by the in-vehicle charger 103, the charging cable 106 or the stationary charger 209 is connected to the electric vehicle 100, and it waits until an electrical connection between the electric vehicle 100 and the house 200 is established.

[0113] After an electrical connection between the electric vehicle 100 and the house 200 is established in step S1 (Yes), the control after step S2 is performed, and the setting of the target charging and discharging range by the range setting unit 4 is started.

[0114] Next, in step S2, the state of charge of the drive battery 102 is acquired. The acquired state of charge of the drive battery 102 corresponds to S0 in Fig. 4A.

[0115] Next, in step S3, the target state of charge is acquired. In addition to being set by the user of the electric vehicle 100 through the HMI 108, it may be connected to a setting website from an information terminal (such as a mobile phone, smartphone, or personal computer) not shown in the figure, and the one set on the website may be acquired and used through the communication unit 109. Alternatively, the target state of charge estimated by the estimation unit 3 may be set.

[0116] Next, in step S4, the target charge completion time is acquired. Similar to step S3, it may be acquired through the HMI 108, or there is no problem if it is acquired via an information terminal not shown in the figure, and the target charge completion time estimated by the estimation unit 3 may be set.

[0117] Next, in step S5, the target charge / discharge range is set by the range setting unit 4. At the same time, the control start time T for starting charge / discharge is set. S is set.

[0118] Next, in step S6, it waits until the current time t reaches the control start time T. Alternatively, even if a button operation or switch operation for notifying the user of the electric vehicle 100 to start the charge / discharge of the electric vehicle 100 is performed and the control start time T S is reached, it may be considered valid. S is reached.

[0119] Next, in step S7, it is determined whether there is an interruption request at time t. If there is an interruption request (Yes), it proceeds to step S8 and performs a process of interrupting the charge / discharge of the drive battery 102.

[0120] Specifically, the power exchange through the in-vehicle charger 103 or the installed charger 209 is terminated so that the AC charging port 105 and the DC charging port 118 are in a power-off state. In addition, the user of the electric vehicle 100 is notified through the HMI 108 that the charge / discharge of the drive battery 102 has been interrupted. In addition, information regarding the interruption of the charge / discharge of the drive battery 102 may be transmitted through the communication unit 109 and notified to the user of the electric vehicle 100 through an information terminal (not shown).

[0121] On the other hand, if there is no interruption request in step S7 (No), the processes after step S9 are continued.

[0122] In step S9, the charge state of the drive battery 102 at time t is acquired.

[0123] Next, in step S10, the upper limit charge state corresponding to time t is acquired.

[0124] Similarly, in steps S11 and S12, the reference charge state (reference value) and the lower limit charge state corresponding to time t are acquired.

[0125] The subsequent steps S13, S14, S15, and S16 compare the state of charge of the drive battery 102 obtained in step S9 with the upper limit state of charge, the reference state of charge (reference value), and the lower limit state of charge.

[0126] In step S13, it is determined whether the state of charge of the drive battery 102 exceeds the upper limit state of charge. If the state of charge of the drive battery 102 exceeds the upper limit state of charge (Yes), the subroutine designated as R1 is executed to discharge the drive battery 102. If it does not exceed the upper limit state of charge (No), the process proceeds to step S14.

[0127] Next, in step S14, it is determined whether the state of charge of the drive battery 102 is less than or equal to the upper limit state of charge and greater than or equal to the reference state of charge. If the state of charge of the drive battery 102 is less than or equal to the upper limit state of charge and greater than or equal to the reference state of charge (Yes), the subroutine designated as R2 is executed to charge and discharge the drive battery 102. If it is not less than or equal to the upper limit state of charge and greater than or equal to the reference state of charge (No), the process proceeds to step S15.

[0128] Next, in step S15, it is determined whether the state of charge of the drive battery 102 is less than the reference state of charge and greater than or equal to the lower limit state of charge. If the state of charge of the drive battery the reference state of charge and greater than or equal to the lower limit state of charge (Yes), the subroutine designated as R3 is executed to charge and discharge the drive battery 102. If it is not less than the reference state of charge and greater than or equal to the lower limit state of charge (No), the process proceeds to step S16.

[0129] Next, in step S16, it is determined whether the state of charge of the drive battery 102 is less than the lower limit state of charge. If the state of charge of the drive battery 102 is less than the lower limit state of charge (Yes), the subroutine designated as R4 is executed to charge the drive battery 102.

[0130] In step S16, if it is determined that none of steps S13 to S16 apply (No), it is determined that there is some problem in obtaining the charge state of the drive battery 102 or setting the target charge / discharge range by the range setting unit 4, and the process from step S2 is repeated. Alternatively, although not shown in the figure, the process may transition to step S8 to perform interruption processing and end the charge / discharge of the drive battery 102. Alternatively, the process from step S2 may be repeated until the number of times it is determined that none of steps up to S16 apply reaches a predetermined number of times, and when the predetermined number of times is reached, the process may transition to step S8. By repeating the process from step S2, the opportunity to attempt to implement the present invention can be reduced or prevented from being lost by transitioning to step S8.

[0131] Step S17 is a step performed after executing each of the above subroutines R1 to R4, and determines whether the current time t has reached the time T, that is, the target charge completion time. If it is a time before time T (No), the process returns to step S7 to continue charging and discharging the drive battery 102. In this way, the processes from step S7 to S17 are repeatedly executed until the current time t reaches the time T (target charge completion time). When it is determined that the current time t has reached the time T (target charge completion time) (Yes), the process proceeds to step S18 and ends.

[0132] Hereinafter, the movement of the charger in each of the subroutines R1 to R4 will be described. Each subroutine corresponds to an operation in the command value generation unit 5, and based on the generated command value, the in-vehicle charger 103 or the installed charger 209 charges and discharges the drive battery 102.

[0133] Figure 6 shows the control flow of the subroutine R1.

[0134] First, in step SR101, the power demand of the house 200 is obtained.

[0135] Next, in step SR102, an allowable output is calculated based on the state of charge and temperature of the drive battery 102 acquired from the BCU 104 and the outside air temperature acquired from the temperature detection means 120, which is the outside air sensor 119. The allowable output is calculated according to the flow shown in FIG. 7.

[0136] In steps SR201 to SR205, the state of charge of the battery, the battery voltage, the battery temperature, the battery resistance, and the outside air temperature are acquired.

[0137] By transforming Equation (1) as shown in Equation (10), Q total When is set to a predetermined value, the amount of heat generation Q p accompanying charge and discharge that is allowed is determined.

[0138]

Equation

[0139] Q p Based on, Equation (11) is obtained from Equations (3) and (4), and the allowable output P a can be obtained from the battery resistance and the battery voltage.

[0140]

Equation

[0141] After obtaining the allowable output in step SR206, the charge and discharge output of the battery that can be achieved by the charger used in step SR207 is acquired. In step SR208, the smaller output of the allowable output obtained in step SR206 and the charger output acquired in step SR207 is updated as the allowable output and output.

[0142] In this way, by setting the allowable output based on the temperature, it is possible to prevent the drive battery 102 from being overheated, and to suppress the progress of deterioration due to the rise in the battery temperature.

[0143] Next, in step SR103, a command is generated to discharge power from the drive battery 102 so as to satisfy the power demand of the house 200 acquired in step SR101, and the drive battery 102 is discharged through the in-vehicle charger 103 or the stationary charger 209.

[0144] Finally, in step SR104, the state of the charger is stored as "discharging".

[0145] Thereafter, subroutine R1 is terminated and the process proceeds to step S17.

[0146] Figure 8 shows the control flow of subroutine R2.

[0147] First, in step SR301, the power demand of the house 200 is acquired from the power adjustment means 203.

[0148] Next, in step SR302, if the house 200 is equipped with the solar power generation system 205, its power generation output is acquired. Here, the solar power generation system 205 is used, but it is not limited to the solar power generation system 205 as long as the facility has the ability to supply power to the house 200 from sources other than the power grid. For example, a fuel cell system or a wind power generation system may be used. If the house 200 does not have any of these facilities, assuming that the output of the solar power generation system 205 acquired in step SR302 to supply power from sources other than the power grid is zero, the process proceeds to the next step.

[0149] Next, in step SR303, the surplus power is calculated from the power demand of the house 200 and the output of the solar power generation system 205. The surplus power can be obtained by subtracting the power demand of the house 200 from the output of the solar power generation system 205. If the surplus power is positive, the output of the solar power generation system 205 exceeds the power demand of the house 200, and in addition to power consumption in the house 200, the drive battery 102 can be charged, the battery system 206 in the house 200 can be charged, or power can be sold to the power grid 204.

[0150] On the other hand, when the surplus power is negative, since the power consumption of the house 200 exceeds the output of the solar power generation system 205, power is purchased from the power grid 204, or power is discharged from the battery system 206 or the drive battery 102 to meet the demand.

[0151] Next, in step SR304, the allowable output is calculated according to the flow shown in FIG. 7.

[0152] Next, in step SR305, the charge and discharge of the drive battery 102 are determined based on the surplus power obtained in step SR303. When the surplus power is negative, that is, when the power is insufficient (Yes), the process proceeds to step SR306, and the drive battery 102 is discharged with the smaller of the power demand and the allowable output as the upper limit.

[0153] Thereafter, the process proceeds to step SR307, and the charge and discharge state is stored as "discharging". At this time, if the charging of the battery system 206 is included in the power demand of the house 200, the power adjustment means 203 may operate to stop the charging of the battery system 206 and reduce the power demand of the house 200.

[0154] On the other hand, when there is surplus power in step SR305 (No), the process proceeds to step SR308, and the charge and discharge of the drive battery 102 are determined based on the previous control state. In step SR308, if the previous charge and discharge control state is "charging" or there is no record of the previous charge and discharge state (Yes), the process proceeds to step SR309.

[0155] In step SR309, the charging power smaller than the surplus power is set by multiplying it by a value smaller than 1, such as a predetermined value of 0.5 or 0.8 that is smaller than 1, or a value smaller than 1 that becomes smaller as the difference between the reference charge state and the current drive battery charge state increases on the charging side.

[0156] Next, in step SR310, the drive battery 102 is charged with the smaller of the charging power obtained in step SR309 and the allowable power obtained in step SR304 as the upper limit.

[0157] Next, in step SR311, the charging state is set to "charging", and the process proceeds to step S17.

[0158] On the other hand, if the previous charge / discharge control state is "discharging" in step SR308 (No), the process proceeds to step SR312, the discharge from the drive battery 102 is stopped, and the charge / discharge output is set to zero.

[0159] Thereafter, the process proceeds to step SR313, and the charge / discharge state is set to remain "discharging" without change. The process proceeds to step S17.

[0160] FIG. 9 shows the control flow of subroutine R3.

[0161] The operations from step SR401 to step SR404 are almost the same as the operations from step SR301 to step SR304 of subroutine R2. However, in step SR403, if the house 200 does not have facilities corresponding to the solar power generation system 205, an alternative power target value is set as surplus power. Since the other operations are the same, the description is omitted, and only the method of setting the alternative power target value will be described.

[0162] The aforementioned alternative power target value is set to a value obtained by multiplying the power obtained by subtracting the power demand of the allowable power of the house 200 by a specified value such as 0.8 or 0.5. The allowable power of the house 200 is the power value at which an amperage breaker (not shown) of the house 200 operates, that is, the power demand at which the so-called breaker trips. That is, when the house 200 does not have a solar power generation system 205 or similar power generation facilities, the power available for charging the drive battery 102 is set as the alternative power target value so that the sum of the power demand of the house 200 and the power required for charging the drive battery 102 is within the range not exceeding the allowable power of the house 200.

[0163] In step SR405, the charging and discharging of the drive battery 102 are determined based on the surplus power obtained in step SR403. When the surplus power is positive, that is, when surplus power is generated (Yes), the process proceeds to step SR406, and the drive battery 102 is charged with the smaller of the surplus power and the allowable output as the upper limit.

[0164] Thereafter, the process proceeds to step SR407, the charging and discharging state is stored as "discharging", and the process transitions to step S17.

[0165] When charging and discharging the drive battery 102 to realize the surplus power or the shortage of power, it is not a problem even if there is some error in the output of the charger. It is difficult to make it completely consistent with the power measurement error and measurement delay, etc., and it is intended that it is in a state where the power that is generally consistent or surplus or insufficient is compensated for by charging and discharging the drive battery 102 approximately.

[0166] On the other hand, when there is a shortage of power in step SR405 (No), the process proceeds to step SR408, and the charging and discharging of the drive battery 102 are determined based on the previous control state.

[0167] In step SR408, when the previous charging and discharging control state is "discharging" or there is no record of the previous charging and discharging state (Yes), the process proceeds to step SR409.

[0168] In step SR409, a discharge output smaller than the power shortage obtained in step SR403 is calculated. Similar to step SR309 of subroutine R2, a discharge power smaller than the shortage power is set by multiplying it by a value smaller than 1, such as a predetermined value of 0.5 or 0.8, or a value smaller than 1 that becomes smaller as the difference between the reference charge state and the current drive battery charge state decreases on the discharge side and the difference from the reference charge state increases.

[0169] Next, in step SR410, the drive battery 102 is discharged with the smaller of the power shortage (discharge output) obtained in step SR409 and the allowable output obtained in step SR404 as the upper limit.

[0170] Thereafter, in step SR411, the charge / discharge state is set to "discharging", and the process proceeds to step S17.

[0171] On the other hand, if in step SR408 the previous charge / discharge control state is "charging" (No), the process proceeds to step SR412, the charging of the drive battery 102 is stopped, and the charge / discharge output is set to zero.

[0172] Thereafter, the process proceeds to step SR413, the charge / discharge state is set to remain "charging" without change, and the process proceeds to step S17.

[0173] Figure 10 shows the control flow of subroutine R4.

[0174] In subroutine R4, the drive battery 102 is charged to avoid a situation where the charge state of the drive battery 102 is insufficient and the target charge state cannot be achieved.

[0175] First, in step SR501, the allowable output is calculated according to the flow shown in FIG. 7, and in step SR502, the drive battery 102 is charged with the allowable output.

[0176] In the subsequent step SR503, the charge / discharge state is set to "charging", and the process proceeds to step S17.

[0177] In step SR312 and step SR313 in FIG. 8, or step SR412 and step SR413 in FIG. 9, the charge and discharge output is set to zero without changing the charge and discharge state, and only the charge and discharge is stopped. This is a measure to prevent the charge and discharge of the drive battery 102 from being frequently switched in a scene where surplus power is intermittently generated, and to suppress the progress of cycle degradation. If the charge state of the drive battery 102 is equal to or higher than the reference charge state, there is no need to rush the charging. On the other hand, if it is lower than the reference charge state, it is preferable to perform charging as much as possible when a surplus occurs.

[0178] According to this embodiment, by preferably maintaining the charge state of the drive battery 102 near the reference charge state between the upper limit charge state and the lower limit charge state, and suppressing the output (heat generation) so that the change in the charge state becomes gentle, while preferably suppressing both the storage degradation and the cycle degradation of the battery, it is possible to provide a charge and discharge control device and its control method that can suppress the loss of opportunities for V2X operations such as power supply to the house 200 or charging of surplus power from solar power generation through the in-vehicle charger 103 or the stationary charger 209.

Embodiment

[0179] With reference to FIGS. 11 to 13, the charge and discharge control device and its control method according to Embodiment 2 of the present invention will be described.

[0180] Embodiment 2 is a modification of the method for setting the upper limit charge state in Embodiment 1, and only the method for setting the upper limit charge state will be described. Otherwise, it has the same technical features as Embodiment 1.

[0181] <Setting of the upper limit charge state> The upper limit charge state is set so that the degradation of the drive battery 102 has an equal degradation rate based on the temperature outlook. For example, the upper limit charge state can be arranged as a map function that returns the target of the charge state at which the storage degradation of the battery corresponding to the temperature becomes an equal degradation rate, with the temperature and the reference upper limit charge state as arguments.

[0182] In creating the map function, when changing the state of charge and storage temperature during battery storage through experiments or simulations, the storage degradation is measured. Here, the storage degradation is evaluated by comparing the discharge capacity and resistance of the battery after storage under predetermined conditions with the characteristics obtained from a new battery. In experiments or simulations, the conditions for storing the battery (temperature, state of charge) are set, and the discharge capacity and resistance of the battery are measured every two weeks or one month.

[0183] As a result, characteristics as shown in FIG. 11 can be obtained, and the obtained results are converted into the amount of degradation per unit time. The amount of degradation per unit time corresponds to the slope when the plots in FIG. 11 are linearly approximated. By summarizing this according to the conditions for storage (temperature, state of charge), contour lines of the degradation rate as shown in FIG. 12 can be obtained.

[0184] In FIG. 11, each plot shows the capacity retention rate defined by Equation (12). As in Equation ( 12), the capacity retention rate is defined as the ratio of the discharge capacity after storage to the discharge capacity of a battery in a new state.

[0185]

Equation

[0186] When setting the upper limit state of charge as a reference using the relationship in FIG. 12, by investigating the points where the heights of the contour lines match, the state of charge with the same degradation rate can be obtained, and a map function as shown in FIG. 13 can be created. The map shown in FIG. 13 refers to the state of charge that results in the same degradation rate as when the drive battery 102 is stored at the given temperature and stored under the reference state of charge and at room temperature when the reference state of charge and temperature are given.

[0187] By taking the reference state of charge and temperature as arguments, it becomes a function that outputs the upper limit value of the state of charge to be set.

[0188] When setting the upper charge state in the range setting unit 4, the temperature outlook of the drive battery 102 predicted by the estimation unit 3 as the temperature, or the temperature outlook based on the weather information of the area acquired by the position detection means of the electric vehicle 100 through the communication unit 109 is used. When using the temperature estimated by the estimation unit 3, assuming that it will be stored after charging from the charge state of the drive battery 102 at the time of starting control to the reference upper charge state, the temperature change of the drive battery 102 is estimated.

Example

[0189] Referring to FIGS. 14 and 15, the charge and discharge control device and its control method according to Embodiment 3 of the present invention will be described.

[0190] Embodiment 3 is a modification of the method for setting the lower charge state in Embodiment 1, and only the method for setting the lower charge state will be described. Others have the same technical features as in Embodiment 1.

[0191] Regarding the setting of the lower charge state in Embodiment 1, when setting the time T shown in FIG. 4A b in response to the variation in the time when the electric vehicle 100 was actually used with respect to the time T (target charge completion time) when the electric vehicle 100 is assumed to start use, a backward amount is set so that the time T is virtually set to a time earlier than the original time T. Briefly speaking, the charge and discharge of the drive battery 102 are completed before the actual time T arrives.

[0192] For example, as shown in FIG. 14, by counting the error between the time zone when the target charge completion time (scheduled departure time) is set and the time when the electric vehicle 100 was actually used, and obtaining the variation for each time zone, the greater the variation with respect to the set target charge completion time, the more the virtual time T is set to a time earlier. As shown in FIG. 15, this can be used as a table function for calculating the backward amount for advancing the time T with the variation in the departure time as the input.

[0193] By setting a relationship like that in FIG. 14 for setting such a reverse amount for each day of the week, month, or location, etc., it is possible to prevent a power shortage (power outage) from occurring due to the electric vehicle 100 being used before the charging of the drive battery 102 is completed.

Embodiment

[0194] With reference to FIGS. 16 to 19, a charge-discharge control device and its control method according to Embodiment 4 of the present invention will be described.

[0195] Embodiment 4 sets the reference charge state in a band shape and adjusts the control method of the charge-discharge output. It is a modification of the reference charge state setting method and the control flow shown in FIG. 5 in Embodiment 1, and these will be described.

[0196] Regarding the reference charge state, a plurality of weights of the evaluation function shown in Equation (9) are set to generate a plurality of corresponding reference charge states, and the maximum value and minimum value of the plurality of reference charge states are joined together with respect to time to obtain a band-shaped reference charge state as shown by the dark shading in FIG. 16. Also, a band-shaped reference charge state can be obtained by adding and subtracting a predetermined value to the reference charge state shown in FIG. 4A.

[0197] First, it is assumed that the target charge-discharge range shown in FIG. 16 is composed of the upper charge state set by the upper charge state setting method shown in Embodiment 2 and the lower charge state set by the lower charge state setting method shown in Embodiment 3.

[0198] In Embodiment 4, control is performed according to the control flow shown in FIG. 17 by partially modifying the control flow shown in FIG. 5 according to the band-shaped reference charge state shown in FIG. 16.

[0199] In the control flow shown in FIG. 17, since the operations up to step S9 are the same as the control flow shown in FIG. 5, the movements after step S9 will be described.

[0200] After obtaining the state of charge of the drive battery 102 in step S9, in step S19, a subroutine to be executed as shown in FIG. 18 is selected according to whether the current state of charge is in any of the shaded areas shown in FIG. 16, or whether it exceeds the upper limit state of charge or is below the lower limit state of charge.

[0201] In FIG. 18, in step SR601, it is determined whether the state of charge of the drive battery 102 exceeds the upper limit state of charge. If it exceeds (Yes), subroutine R1 is executed in the same manner as in FIG. 5. Otherwise (No), the process proceeds to step SR602.

[0202] Next, in step SR602, if the state of charge of the drive battery 102 is the state of charge corresponding to area A1 shown in FIG. 16 (Yes), subroutine R2 shown in the flow of FIG. 8 is executed. Otherwise (No), the process proceeds to step SR603.

[0203] Next, in step SR603, if the state of charge of the drive battery 102 is the state of charge corresponding to area A2 shown in FIG. 16 (Yes), subroutine R5 shown in FIG. 19 is executed. Otherwise (No), the process proceeds to step SR604.

[0204] Next, in step SR604, if the state of charge of the drive battery 102 is the state of charge corresponding to area A3 shown in FIG. 16 (Yes), subroutine R3 shown in FIG. 9 is executed. Otherwise (No), the process proceeds to step SR605.

[0205] Finally, in step SR605, it is determined whether the state of charge of the drive battery 102 is below the lower limit state of charge. If it is below the lower limit state of charge (Yes), subroutine R4 shown in FIG. 10 is executed. Otherwise (No), similar to Example 1, the process transitions to step S2 to re - set the charging range and then transitions to E in FIG. 17 or to E' in FIG. 17. If it is assumed that some malfunction has occurred, interruption processing is executed in step S8.

[0206] The processing in steps S17 and S18 of FIG. 17 is the same as that in steps S17 and S18 of FIG. 5.

[0207] The subroutine R5 shown in FIG. 19 will be described.

[0208] Steps SR701 to SR704 are the same as steps SR301 to SR304 in FIG. 8, or steps SR401 to SR404 in FIG. 9.

[0209] After obtaining the allowable output in step SR704, the previous charge-discharge state is referred to in step SR705. If the previous charge-discharge state is charging or there is no charge-discharge state setting (Yes), the process proceeds to step SR706. On the other hand, if the previous charge-discharge state is discharging (No), the process proceeds to step SR711.

[0210] In step SR706, the surplus power of the house 200 is referred to. If there is surplus power (Yes), the process proceeds to step SR707, and the drive battery 102 is charged with the smaller of the surplus power and the allowable output as the upper limit. Then, the process proceeds to step SR708, the charge-discharge state is set to "charging", the subroutine R5 is terminated, and the process transitions to step S17 of FIG. 17.

[0211] On the other hand, if there is no surplus power in step SR706 (No), the process proceeds to step SR709, the charge-discharge output is set to zero, and charging is stopped. Then, in step SR710, the charge-discharge state is not updated, and in this case, the subroutine R5 is terminated while remaining in the "charging" state, and the process transitions to step S17 of FIG. 17.

[0212] Also, if in step SR705 the previous charge-discharge state is "discharging" (No), the process proceeds to step SR711 to determine whether the power demand of the house 200 exceeds the power generation output of the solar power generation system 205, that is, whether there is a power shortage. If there is a power shortage (Yes), the process proceeds to step SR712, and the drive battery 102 is discharged with the smaller output of the shortage and the allowable output as the upper limit. Then, in step SR713, the charge-discharge state is set to "discharging", subroutine R5 is terminated, and the process transitions to step S17 in FIG. 17.

[0213] On the other hand, if there is surplus power in step SR711 (No), the process proceeds to step SR709, the charge-discharge output is set to zero, and discharging is stopped. Then, in step SR710, the charge-discharge state is not updated. In this case, subroutine R5 is terminated while remaining in the "discharging" state, and the process transitions to step S17 in FIG. 17.

[0214] By doing so, the drive battery 102 can continue to charge or discharge at a charge state near the reference charge state. The reference charge state is determined based on equation (9), and charge-discharge with little impact on the degradation of the drive battery 102 can be continued.

[0215] Also, unlike subroutine R2 and subroutine R3, since the charge-discharge output during charge-discharge is not suppressed, a larger amount of power can be charged and discharged when the drive battery 102 is used for V2X operation.

[0216] In this way, by increasing the operating rate of the drive battery 102 in V2X operation, appropriately charging surplus power, and discharging the shortage from the drive battery 102, the effect of suitably reducing the power cost of the house 200 can be obtained.

[0217] Note that the present invention is not limited to the above-described embodiments, and various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible. [[ID='1']]

[0218] Also, the control lines and information lines show those considered necessary for explanation, and do not necessarily show all the control lines and information lines on the product. In fact, it may be considered that almost all the configurations are interconnected.

Explanation of Reference Numerals

[0219] 1... Charge and Discharge Control Device 2... Acquisition Unit 3... Estimation Unit 4... Range Setting Unit 5... Command Value Generation Unit 6... Control Unit 100... Electric Vehicle (Electric Automobile or Plug-in Hybrid Vehicle) 101... Integrated Controller 102... Drive Battery 103... On-vehicle Charger 104... BCU (Battery Control Unit) 105... AC Charging Port 106... Charging Cable 107... Communication Bus 108... HMI (Human Machine Interface) 109... Communication Unit 110... Vehicle Control Unit 111... Power Converter 112... Traction Motor 113... Power Conversion Unit 114... Power Sensing Unit 115... Power Conversion Control Unit 116... Input Means 117... Display Means 118… DC charging port 119… External sensor 120… Temperature detection means 121… Position detection means 200… House 201… Outlet 202… Distribution board 203… Power adjustment means 204… Power system 205… Photovoltaic power generation system 206… Battery system 207… Communication means 208… Stand-alone load 209… Installed charger.

Claims

1. External charging for charging the battery of an electric vehicle with an external power source, External discharging for discharging the power of the battery to an external device, A charge and discharge control device for controlling a charge and discharge device capable of performing the above, Based on the charge state of the battery, the target completion time, the target value of the charge state at the target completion time, and the output of the charge and discharge device, Setting a reference value of the charge state of the battery at a predetermined time from the start of control to the target completion time, Setting a target charge and discharge range defined by a charge state upper limit value at a predetermined time from the start of control to the target completion time, After the start of control, When the charge state of the battery is in the region between the charge state upper limit value and the reference value, when charging the battery, charging is performed with an output smaller than the charging output in other regions. A charge and discharge control device characterized by this.

2. The charge and discharge control device according to claim 1, Further setting a target charge and discharge range defined by a charge state lower limit value at a predetermined time from the start of control to the target completion time, When the charge state of the battery is in the region between the reference value and the charge state lower limit value, when discharging the battery, discharging is performed with an output smaller than the discharge output in other regions. A charge and discharge control device characterized by this.

3. The charge and discharge control device according to claim 1, The charge state upper limit value is set based on the temperature of the battery. A charge and discharge control device characterized by this.

4. The charge and discharge control device according to claim 2, The charge state lower limit value is set based on the target completion time. A charge and discharge control device characterized by this.

5. The charge and discharge control device according to claim 1, In the target charge and discharge range, a region where charging and discharging are not performed with the small output is further provided. A charge and discharge control device characterized by this.

6. External charging for charging the battery of an electric vehicle with an external power source, External discharging for discharging the power of the battery to an external device, A control method for a charge and discharge control device for controlling a charge and discharge device capable of performing the above, (a) Based on the charge state of the battery, the target completion time, the target value of the charge state at the target completion time, and the output of the charge and discharge device, setting a reference value of the charge state of the battery at a predetermined time from the start of control to the target completion time. Step of setting a target charge / discharge range defined by a charge state upper limit value at a predetermined time from the start of control to the target completion time based on the charge state of the battery, the target completion time, the target value of the charge state at the target completion time, and the output of the charge / discharge device; Step of, when charging the battery when the charge state of the battery is in a region between the charge state upper limit value and the reference value after the start of control, charging with an output smaller than the charging output in other regions; A control method for a charge / discharge control device, characterized by comprising the above steps.

7. A control method for a charge / discharge control device according to claim 6, further comprising: Step of setting a target charge / discharge range defined by a charge state lower limit value at a predetermined time from the start of control to the target completion time; Step of, when discharging the battery when the charge state of the battery is in a region between the reference value and the charge state lower limit value, discharging with an output smaller than the discharge output in other regions; A control method for a charge / discharge control device, characterized by comprising the above steps.

8. A control method for a charge / discharge control device according to claim 6, wherein the charge state upper limit value is set based on the temperature of the battery.

9. A control method for a charge / discharge control device according to claim 7, wherein the charge state lower limit value is set based on the target completion time.

10. A control method for a charge / discharge control device according to claim 6, further comprising: Step of providing a region in the target charge / discharge range where charging / discharging is not performed with the small output; A control method for a charge / discharge control device, characterized by comprising the above steps.

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