Charge / discharge control device and charge / discharge control method

Abstract

The invention provides a charge and discharge control device and a charge and discharge control method which can grasp the influence of battery degradation factors accompanying charge and discharge and suppress battery degradation. A charge / discharge control device for controlling charge / discharge of a storage battery connected to a load is provided with: a means for setting a reference operation mode for charge / discharge of the storage battery, and calculating a reference degradation amount, which is an amount of degradation of the storage battery in the reference operation mode; a means for calculating an actual operation degradation amount, which is the degradation amount of the storage battery in the actual operation mode, when the charging / discharging of the storage battery is operated in an actual operation mode different from the reference operation mode; a means for calculating a degradation amount difference, which is the difference between the reference degradation amount and the actually used degradation amount; and a means for calculating the degree of contribution of each of a plurality of deterioration factors, which are factors of deterioration of the storage battery, on the basis of the deterioration amount difference.

Description

Technical Field

[0001] This invention relates to a charge / discharge control device and a charge / discharge control method. Background Technology

[0002] In the cases of V2H (Vehicle to Home), V2G (Vehicle to G), V2L (Vehicle to Load), V2V (Vehicle to Vehicle), and V2X (Vehicle to Everything), which connect electric vehicles (EVs) to homes, electric vehicles (EVs) to power systems, electric vehicles (EVs) to loads, electric vehicles (EVs) to connect to each other, and V2X (Vehicle to Everything), which connects all devices that exchange electricity, the batteries mounted on the electric vehicles (EVs) are more prone to degradation due to the increased opportunities for charging and discharging.

[0003] Battery degradation is also highly dependent on usage methods. It is well known that even under the same temperature conditions and with the same total charge / discharge capacity, the degree of degradation will vary due to differences in factors such as cycle depth (indicating the rate of increase / decrease in State of Charge), average State of Charge (SOC), and charging time. To ensure the battery performs its intended function for V2X applications, appropriate charge / discharge control is necessary to minimize the decline in battery State of Health (SOH).

[0004] Previously, technologies for estimating the relationship between battery usage mode and state of health (SOH) in situations like V2X where usage modes are not uniform but continuously changing, such as those described in Patent Documents 1 and 2, have been used.

[0005] Patent Document 1 describes the following: It has a storage unit that stores a degradation line that represents the correspondence between the amount of battery used and the full charge capacity of the battery according to the battery usage method. It determines the battery usage method, and if it is determined that the usage method has been changed, it shifts the current battery degradation line so that the full charge capacity of the degradation line before the usage method change is consistent with that of the degradation line after the usage method change, thereby estimating the full charge capacity of the battery.

[0006] Patent document 2 describes a method for storing a specified current ratio distribution that represents the current ratio distribution when driving in each of a plurality of preset driving modes. The method derives a driving mode ratio based on the actual current ratio distribution and the specified current ratio distribution during actual operation. This driving mode ratio represents the proportion of each specified current ratio distribution when the actual current ratio distribution is represented by the synthesis of the plurality of specified current ratio distributions.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2020-159990

[0010] Patent Document 2: Japanese Patent Application Publication No. 2022-144152 Invention Summary

[0011] The problem that the invention aims to solve

[0012] Even in situations where the application mode is not uniform and changes continuously, such as V2X, it is necessary to leverage the role of batteries as energy storage devices on the grid and minimize the decline in battery health (SOH) through appropriate charge and discharge control.

[0013] In the technology described in Patent Document 1, it is necessary to prepare in advance a degradation line for the battery usage method corresponding to the number of envisioned charge and discharge modes. As in the EV tested for V2X, it is difficult to cope with charge and discharge modes that involve many aspects from driving to system connection.

[0014] In the technology described in Patent Document 2, by overlapping a specified current ratio distribution representing the current ratio distribution during driving in multiple pre-set driving modes, a fitting with the complex charging and discharging modes in reality is performed. This allows for the handling of a wide range of driving modes with a limited pre-stored mode. However, based on the results obtained, only the dominant driving mode is known, making it difficult to obtain a strategy for suppressing battery degradation.

[0015] As mentioned above, existing patent literature has the following problems: it cannot grasp the impact of battery degradation factors when the usage mode changes continuously, and it cannot make appropriate applications for long-term suppression of battery degradation.

[0016] In view of the above problems, the purpose of the present invention is to provide a charge-discharge control device and a charge-discharge control method that can control the influence of battery degradation factors accompanying charge-discharge to suppress battery degradation.

[0017] Methods for solving problems

[0018] As described above, the present invention is configured as: "A charge-discharge control device for controlling the charge-discharge of a battery connected to a load, the charge-discharge control device comprising the following units: a unit for setting a reference operating mode for the charge-discharge of the battery and calculating the amount of battery degradation, i.e., the reference degradation amount, under the reference operating mode; a unit for calculating the amount of battery degradation, i.e., the actual operating degradation amount, under the actual operating mode when the charge-discharge of the battery is performed in a different operating mode than the reference operating mode; a unit for calculating the difference between the reference degradation amount and the actual operating degradation amount, i.e., the degradation amount difference; and a unit for calculating the factors of battery degradation, i.e., the contribution of each of the multiple degradation factors, based on the degradation amount difference."

[0019] Furthermore, the present invention is defined as: "A charging and discharging control method, which uses a computer to control the charging and discharging of a battery connected to a load. The computer sets a reference operating mode for the charging and discharging of the battery, calculates the amount of battery degradation under the reference operating mode, i.e., the reference degradation amount, and calculates the amount of battery degradation under the actual operating mode, i.e., the actual degradation amount, when the charging and discharging of the battery is carried out in an actual operating mode different from the reference operating mode. The difference between the reference degradation amount and the actual degradation amount is calculated, i.e., the degradation amount difference. Based on the degradation amount difference, the factors of battery degradation, i.e., the contribution of each of the multiple degradation factors, are calculated."

[0020] The effects of the invention

[0021] According to the present invention, it is possible to accurately and quantitatively grasp the changes in battery degradation factors caused by differences in application methods, and to suppress battery degradation by applying a balanced load to the battery. Attached Figure Description

[0022] Figure 1 This diagram illustrates an example of the overall configuration of a charging system that enables V2H connectivity between vehicles.

[0023] Figure 2 This diagram illustrates an example of the overall configuration of a charging system that includes a V2H connection between a vehicle and a stationary DC charger.

[0024] Figure 3 The diagram shows an example of the configuration of the charge / discharge control device according to Embodiment 1 of the present invention.

[0025] Figure 4 A diagram showing a comparison between the benchmark application mode and the evaluation object application mode.

[0026] Figure 5 A graph showing examples of extracted deterioration factors.

[0027] Figure 6 A diagram illustrating an example of the input-output response of a battery degradation model.

[0028] Figure 7 A graph representing the base degradation amount, degradation amount difference, and contribution classification examples.

[0029] Figure 8 A flowchart illustrating an example of the control method of the charge / discharge control device according to Embodiment 2 of the present invention.

[0030] Figure 9 The diagram shows an example of the waveforms of current, voltage, and SOC when the battery is used in a fixed battery operating mode.

[0031] Figure 10A A chart that visualizes the accumulation of battery degradation factors when used in a fixed battery operating mode.

[0032] Figure 10B A graph showing the load applied to the battery in relation to cycle depth.

[0033] Figure 11 This diagram illustrates an example of the current, voltage, and SOC waveforms when the battery usage mode is changed periodically.

[0034] Figure 12A A chart that visualizes the accumulation of battery degradation factors when the battery usage mode is changed periodically.

[0035] Figure 12B A graph showing the impact of three degradation factors—cycle depth, charging time, and average SOC—on the battery. Detailed Implementation

[0036] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In this specification and the drawings, constituent elements that have substantially the same function or structure are given the same reference numerals and repeated descriptions are omitted.

[0037] Example 1

[0038] Hereinafter, a charge / discharge control device according to an embodiment of the present invention will be described. Furthermore, in each figure, common components are given the same reference numerals.

[0039] Figure 1 This is a hardware diagram showing the overall configuration of the charging system when connecting vehicles via V2H. Figure 1 In this system, household 2 is powered by power system 1, and vehicle 9, equipped with on-board charger 10, is powered by each household 2.

[0040] Each household 2 includes a HEMS 4, a distribution panel 4, and external equipment 7. Additionally, it may appropriately include a solar power generation device 5 and a household battery 6. Furthermore, this example uses a vehicle 9, which is either an electric vehicle or a plug-in hybrid, connected to a household 2, which is assumed to be a detached house. However, the household 2 is not necessarily limited to a detached house inhabited by the owner of the vehicle 9. For example, it could be a multi-family dwelling, and the facilities corresponding to the household 2 could be office space, a business location, or a parking lot. It could also be a configuration connecting multiple vehicles 9. Furthermore, from the perspective of onboard charging and discharging devices, household 2 can be referred to as an external power source.

[0041] In contrast, vehicle 9 includes an on-board charger 10, an integrated controller 15, batteries (HV battery 20, LV battery 21), a power conversion device 26, and internal equipment 27. Furthermore, the on-board charger 10 includes an AC charging port 11, a power conversion control unit 12, a battery sensor unit 13, and a power conversion unit 14. The integrated controller 15 includes a network communication unit 16, an ECM 17, a processing unit 18, and a battery management system (BMS) 19.

[0042] Through the settings of this device Figure 1 The charging and discharging system uses electricity supplied from an external power source (each household 2) to charge the batteries (HV battery 20, LV battery 21) mounted on the vehicle 9.

[0043] The main components constituting the charging and discharging system are described in detail below. First, the HV battery 20, mounted on the vehicle 9, is a battery module composed of multiple battery cells connected in series or parallel to achieve desired output characteristics. A lithium-ion battery is an example of the HV battery 20. The LV battery 21 is used to supply power to 12V-series devices in the vehicle; a lead-acid battery is an example of this. The HV battery 20 is connected to a power conversion device 26, and the internal equipment 27 utilizes the electrical energy in a desired manner. The power conversion device 26 converts the power discharged from the HV battery 20 and supplies it to the internal equipment 27.

[0044] To detect the state of the HV battery 20, the battery management system 19 within the integrated controller 15 includes a voltage measurement unit capable of detecting the voltage of the 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 HV battery 20. The voltage measurement unit is configured such that voltage lines are installed between the battery cells, allowing for individual measurement of the voltage at each terminal of the battery cell. The current measurement unit can detect current by measuring the voltage across the shunt resistor Rsht, but sensors such as Hall effect sensors can also be used. The temperature measurement unit can utilize a thermistor or a thermocouple.

[0045] In this way, BMS 19 converts the state of HV battery 20 into voltage information and detects it. Therefore, it can be constructed using general-purpose analog front-end ICs or semiconductor devices such as ASICs (Application Specific Integrated Circuits). By including an A / D converter, the value obtained by detecting the state of HV battery 20 as voltage can be converted into a digital value that can be used in program processing, etc.

[0046] The power conversion device 26 is, for example, a bidirectional converter, which drives the driving motor used in the movement of the vehicle 9. The bidirectional converter consists of a DC / DC converter and an inverter. The DC / DC converter converts the DC voltage of the HV battery 20 into the voltage required to drive the driving motor, and the inverter converts the DC power into AC power. This allows for frequency control corresponding to the rotational speed of the driving motor, enabling the driving motor to operate and thus obtaining the rotational force (driving torque) used to accelerate the vehicle. Alternatively, regenerative driving can be used when the vehicle decelerates, regenerating the vehicle's kinetic energy as electricity and charging the HV battery 20 via the DC / DC converter.

[0047] The internal device 27 is, for example, the aforementioned driving motor, which accelerates the vehicle 9 by using electricity as rotational force. In addition, while the vehicle 9 is in motion, the driving motor is driven as a generator in cooperation with a bidirectional converter, thereby regenerating the inertial force of the vehicle 9 into electricity.

[0048] To achieve this operation, the power conversion device 26 includes a controller (not shown) that adjusts the output voltage of the DC / DC converter by controlling the duty cycle of the switching elements of the DC / DC converter. Furthermore, it adjusts the driving force of the drive motor by adjusting the switching frequency and current phase of the inverter. Various sensors are installed on the internal device 27 so that the power conversion device 26 can control the internal device 27 into the desired configuration.

[0049] The power conversion device 26 is a converter different from, for example, the bidirectional converter used to drive the driving motor described above, and the internal device 27 is still a compressor drive motor. Thus, it drives the air conditioner used to regulate the air in the passenger compartment of the vehicle 9.

[0050] That is, the power conversion device 26 and the internal equipment 27 are units that consume the power of the HV battery 20; in other words, they are units that discharge the power of the HV battery 20. Multiple power conversion devices 26 and internal equipment 27 are provided on the vehicle 9. Furthermore, the HV battery 20 is connected to the on-board charger 10 and the DC charging port.

[0051] exist Figure 1The example shown is an on-board charger 10 with on-board charging function, but it can also be used in a non-on-board manner with charging and discharging function. Figure 2 This is a hardware diagram showing the overall configuration without onboard charging functionality. (Comparison) Figure 1 and Figure 2 It can be seen that, in Figure 2 In this design, a portion of the function of the on-board charger 10 is separated into a fixed DC charger 28, with a new DC charging port 29 and a DC-DC converter 25 installed inside the vehicle. This difference is due to... Figure 1 Charging with AC power Figure 2 This is due to the difference in charging methods, such as DC charging.

[0052] Thus, the present invention can handle both AC charging via the AC charging port 11 of the on-board charger 10 and charging via the charging and discharging system of the vehicle 9. Figure 2 The fixed charger 28 and DC charging port 29 shown are for DC charging. AC charging and DC charging are used exclusively within the vehicle-mounted charger 10 via relays or semiconductor switches (not shown). The vehicle-mounted charger 10 is mounted on the vehicle 9 and performs bidirectional power conversion between power supplied from an external power source such as the residence 2 and power discharged from the HV battery 20. The fixed charger 101 is located outside the vehicle 9 and the residence 2 and performs bidirectional power conversion between power supplied from a power source such as the residence 2 and power discharged from the HV battery 20.

[0053] During AC charging, the vehicle-mounted charger 10 is also connected to a charging cable via an AC charging port 11, and the charging cable is connected to the distribution panel 4 of the residence 2. The connection to the distribution panel 4 can be a direct connection via a residual current circuit breaker (RCCB) or a connection via an AC outlet in the residence 2. The distribution panel 4 is electrically connected to an ampere circuit breaker (not shown) and an electricity meter power system 1.

[0054] In DC charging, the fixed charger 101 is connected to the AC-DC power conversion unit of the fixed charger 28 via the DC charging port 26, and the fixed charger 101 is connected to the distribution panel 4 in the residence 2. It is then electrically connected to the power system 1 in the same manner as AC charging.

[0055] The vehicle-mounted charger 10 includes: a DC / DC converter capable of transforming DC voltage and converting DC voltage to AC voltage; and a power conversion unit 14 having an inverter unit that rectifies AC power from the distribution panel 4 into DC power and converts DC power output from the DC / DC converter unit into AC power. Additionally, it comprises a power conversion control unit 12 for controlling these components, an AC charging port 11 connected to AC power, and a battery sensor unit for measuring battery data based on these currents.

[0056] Like the vehicle-mounted charger 10, the stationary charger 28 also includes a power conversion unit 14 and a power conversion control unit 12.

[0057] When charging the HV battery 20, a so-called CC-CV (Constant Current, Constant Voltage) charging method is used, which combines constant current charging and constant voltage charging corresponding to the battery cells within the HV battery 20.

[0058] Specifically, constant current charging is performed when the HV battery 20 is at a low charge rate, adjusting the charging speed so that the current flowing through the battery cells within the HV battery 20 does not exceed a predetermined value. When excessive current flows through the battery cells, lithium ions will not enter the interlayer of the negative electrode active material within the battery cell, resulting in lithium metal deposition on the negative electrode. This can cause an internal short circuit, potentially leading to thermal runaway, accompanied by fire or rupture of the battery cell. To prevent this, it is necessary to control the charging speed, i.e., the current, in a way that prevents excessive current from flowing.

[0059] When charging the HV battery 20, as the voltage of the battery cell rises, the charging process switches to constant voltage charging. If the battery cell voltage rises excessively, lithium ions are extracted from the positive electrode active material, causing electrode embrittlement. Furthermore, the reactivity of the positive electrode increases, leading to electrolyte decomposition and the generation of gas within the battery cell. This electrolyte decomposition also generates heat. Since the gas and electrolyte generated within the battery cell are flammable, there is a possibility of fire due to their ignition, potentially causing damage such as battery cell ignition and rupture due to increased gas pressure. Similar to current, voltage also needs to be controlled to prevent it from becoming excessive.

[0060] Taking the on-board charger 10 as an example, the power conversion unit 14 rectifies the AC power obtained through the AC charging port 11 into DC power. By controlling the duty cycle of the switching element of the DC / DC converter inside the power conversion unit 14, the charging current and charging voltage flowing to the battery cell and then to the HV battery 20 are controlled. Similarly, the stationary charger 28 also uses a power conversion unit 14 to rectify the AC power obtained through the distribution panel 4 into DC power. By controlling the duty cycle of the switching element of the DC / DC converter inside the power conversion unit 14, the charging current and charging voltage flowing to the battery cell and then to the HV battery 20 are controlled.

[0061] As described above, the HV battery 20 can be charged via the on-board charger 10 or the stationary charger 28.

[0062] When power is supplied to the HV battery 20 in the residence 2, the DC / DC converter of the power conversion unit 14 of the vehicle charger 10 adjusts the voltage according to the AC power used in the residence 2.

[0063] The inverter section of the power conversion unit 14 generates AC power in a manner synchronized with the frequency and phase of the AC power used in the residence 2. In addition to adjusting the duty cycle of the switching signal for the switching element command of the DC / DC converter for voltage regulation, the power conversion control unit 12 also feeds back the frequency and phase of the AC power in the residence 2 in order to supply power to the residence 2, and adjusts the switching command of the inverter section in a manner synchronized with it.

[0064] The same applies when the power of the HV battery 20 is supplied to the residence 2 via the fixed charger 28, so that the DC / DC converter, inverter, and power conversion control unit 12 of the power conversion unit 14 operate in the same way as the DC / DC converter, inverter, and power conversion control unit 12 of the power conversion unit 14 of the vehicle charger 10.

[0065] With the on-board charger 10 and the stationary charger 28, the power of the HV battery 20 can be used in the residence 2. For example, it is possible to use the power of the HV battery 20 in the event of a disaster when there is no power supply from the power system 1, or to reduce the amount of electricity purchased from the power system 1 to reduce the electricity bill of the residence 2.

[0066] Residential building 2 may also be equipped with a solar power generation system 5 or a fuel cell system (not shown) as a power source to replace electrical system 1.

[0067] In addition to the aforementioned solar power generation system 5, an external device 7 is also connected to the distribution panel 4 of the residence 2. The external device 7 is residential equipment or any electrical product of the residence 2. For example, in addition to white goods such as air conditioners, hot water supply systems, lighting, cooking appliances, refrigerators, and washing machines used for air conditioning of the residence 2, other examples include black goods such as televisions or stereos, and information appliances such as personal computers or telephones.

[0068] Supplying power to the HV battery 20 via the vehicle-mounted charger 10 or the stationary charger 28 is another means of consuming the power of the HV battery 20, or in other words, discharging the power of the HV battery 20.

[0069] Residence 2 is equipped with a Home Energy Management System (HEMS) 3, which can adjust the heating time of the hot water supply system (as an external device 111), adjust the operation status of the air conditioner (as an external device 111), and sell surplus electricity from the solar power system 5 to the power system 1 based on the operating status, power generation, and electricity demand of residence 2 obtained from the electricity meter. HEMS 3 is configured to be able to query the electricity demand of residence 2 from the outside via a communication module (not shown). The integrated controller 27 of vehicle 9 can also be configured to obtain the electricity demand information of residence 2 maintained by HEMS 3 through the network communication unit 16 of vehicle 9.

[0070] The integrated controller 15 consists of a network communication unit 16, an engine control module (ECM) 17, an arithmetic processing unit 18, and a battery management system (BMS) as functional blocks. The operation of each functional block of the integrated controller 15 will be described in detail below.

[0071] The integrated controller 15 has an arithmetic processing unit 18 consisting of an arithmetic unit composed of a CPU or the like, and a storage unit composed of a memory such as RAM or ROM or a recording medium, and implements each functional block of the integrated controller 15 by executing the program stored in the storage unit.

[0072] The integrated controller 15 is configured to acquire the operating status of the power conversion device 26 and internal equipment 27, as well as the status of the HV battery 20, as needed. It can also communicate with the stationary charger 28 via the DC charging port 29. Furthermore, the integrated controller 15 can also communicate via the AC charging port 11 and the charging cable. Communication between the vehicle 9 and the residence 2 can utilize communication methods such as CAN (Controller Area Network) or LIN (Local Interconnect Network), Ethernet connection, etc., allowing for separate use, such as using CAN or LIN within the vehicle 9 and Ethernet-based communication within the residence 2. Alternatively, communication based on PLC (Power Line Communication) can also be used. Both wired and wireless communication are possible.

[0073] The above uses Figure 1 and Figure 2 An example of the configuration of a charging and discharging system to which the present invention can be applied is described. Next, the case of charging from an external power source while the vehicle 9 is stationary is investigated.

[0074] As described above, existing charging methods suffer from the inability to control the impact of battery degradation factors under continuously changing operating modes, hindering appropriate application for long-term suppression of battery degradation. Therefore, this invention describes a method for controlling the impact of battery degradation factors accompanying charging and discharging, and a method for suppressing degradation, within the charge / discharge control device of the present invention.

[0075] Battery degradation within the HV battery 20 cell is primarily due to structural changes in the positive and negative electrodes caused by charge-discharge cycles. For example, the negative electrode, made of graphite, deteriorates due to the operating environment and repeated expansion and contraction during charge-discharge cycles. Similarly, the positive electrode, made of ternary metals, deteriorates due to metal corrosion or the dissolution of binder components. If the same charge-discharge cycles are repeatedly performed in V2G operation mode, specific degradation patterns and localized degradation within the cell may occur. If a specific part of the battery is completely damaged, the battery's state of health (SOH) will decrease, rendering it unusable, even if other parts remain healthy. While it is necessary to avoid localized degradation within the battery, it is difficult to control the degradation sites individually. Therefore, degradation factors during operation are used as evaluation indicators to even out the load on the battery.

[0076] Figure 3 This is a diagram illustrating an example configuration of the charge / discharge control device according to Embodiment 1 of the present invention. The charge / discharge control device of Embodiment 1 of the present invention, for example, comprises... Figure 1 , Figure 2 The processing unit 18 within the integrated controller 15 is implemented, or it is configured in the cloud, and the processing results are stored and utilized within the integrated controller 15 via the network communication unit 16. Furthermore, in the following description, the implementation by the processing unit 18 will be used as an example.

[0077] The processing of charge and discharge control devices is generally implemented using computers, but if the processing content in this arithmetic unit is represented as processing functions, then... Figure 3 As illustrated, it has the processing functions of a battery health (SOH) calculation unit F301, a battery degradation factor calculation unit F305, and a charge / discharge plan control unit F316.

[0078] The battery health (SOH) calculation unit F301 consists of the following: an external communication unit F302 that obtains the battery degradation status of the vehicle from external degradation diagnostic devices such as a stationary charger 28, or a degradation diagnostic unit F303 that obtains the battery degradation status from vehicle degradation diagnostic devices such as an on-board charger 10, and a battery health (SOH) diagnostic unit F304 that estimates the battery health (SOH) based on this information.

[0079] The battery degradation factor calculation unit F305 quantifies the amount of battery degradation and the contribution of degradation factors when a battery is charged and discharged under a certain usage mode of the evaluation object. When evaluating the difference in degradation amount between two charging and discharging modes, since most of the degradation amount is a common baseline degradation amount and does not depend on usage differences, the difference in daily degradation amount caused by usage differences is very small. If the degradation amount of the evaluation object's usage mode is directly evaluated, there is a problem that the contribution calculation described later cannot be performed with high accuracy.

[0080] Therefore, in this invention, by defining a benchmark usage mode and a benchmark degradation amount, the difference between the degradation amount under the evaluation object's usage mode is obtained, thereby improving the extraction accuracy of changes in battery degradation factors caused by usage differences.

[0081] Specifically, the benchmark application mode is processed using F306, F307, and F308. In particular, by... Figure 3 The reference operating mode charge / discharge data acquisition unit F306 acquires the current, voltage, and temperature history under the reference operating mode. Next, in the reference degradation factor calculation unit F307, characteristic quantities related to battery degradation are extracted from the charge / discharge data. Using these as inputs, the battery degradation model is used, and the reference health (SOH) reduction calculation unit F308 calculates the battery health (SOH) reduction during the reference operating mode. The calculation of characteristic quantities related to battery degradation and the health (SOH) reduction will be described in detail later.

[0082] Similarly, the evaluation objects are processed using modes F310, F311, and F312. Specifically, by Figure 3 The evaluation object's usage mode charge / discharge data acquisition unit F310 acquires the current, voltage, and temperature history under the evaluation object's usage mode. Next, in the usage degradation factor calculation unit F311, characteristic quantities related to battery degradation are extracted from the charge / discharge data, and these are used as inputs. The usage health (SOH) reduction calculation unit F312 calculates the reduction in battery health (SOH) of the evaluation object during usage.

[0083] Then, in the additional degradation calculation unit F313, the additional degradation caused by the difference in battery health (SOH) is calculated by obtaining the difference between the baseline operating mode and the operating mode of the evaluation object.

[0084] Next, in the degradation factor sensitivity calculation unit F309, the sensitivity of the degradation factor is calculated using the gradient information of the battery degradation model used in the calculation of state of health (SOH) reduction. Details will be described later. In the degradation factor contribution calculation unit F314, the contribution of the degradation factor is quantified using the aforementioned additional degradation amount and degradation factor sensitivity. In the cumulative degradation factor storage unit F315, the calculated degradation factor contributions are accumulated and stored.

[0085] In the charge / discharge plan control unit F316, the cumulative degradation factor accumulation status evaluation unit F317 confirms whether there is a bias towards specific degradation factors among the accumulated degradation factors. In the charge / discharge plan correction unit F318, the charge / discharge plan is corrected to avoid biased accumulation of degradation factors.

[0086] use Figure 4 A comparative example is provided to illustrate the application of the benchmark model and the application model of the evaluation object. Figure 4 In the diagram, the horizontal axis represents 24 hours in a day, and the vertical axis from top to bottom represents the magnitudes of current, voltage, temperature, and SOC, respectively. Dashed lines represent the temporal changes of current, voltage, temperature, and SOC under the baseline operating mode, while solid lines represent the temporal changes of current, voltage, temperature, and SOC under the evaluation object's operating mode. The positive direction of the current indicates charging the battery, and the negative direction indicates discharging to the household. For simplicity, the CV charging curve for CCCV charging in the current distribution is not shown.

[0087] according to Figure 4 In the example of the solid line evaluation object application mode, electricity is purchased at point A at 0:00 AM to charge vehicle 9. Then, at point B, the SOC reaches the charging limit, and charging stops. Afterwards, no electricity is supplied to residence 2 before 6:00 AM, and the current value is zero. Starting from point C at 6:00 AM, electricity is supplied to residence 2 from vehicle 9 due to increased power consumption from heating and cooking appliances in residence 2. Starting from point D, the driver of vehicle 9 departs for the workplace, etc., and the HV battery 20 consumes power due to driving. After vehicle 9 finishes driving and arrives at the workplace or residence 2, it reconnects to the power line. Charging of electricity generated by solar power generation 5 begins from point E. Although the power generation of solar power generation varies depending on the season, weather, and region, the power generation is greatest around noon at point F. Then, as evening approaches, the sun's altitude decreases, and the amount of sunlight reaching the solar power generation 5 panels in the workplace or residence 2 decreases, and the charging current is zero at point G. Then, at point H, the driver drives the vehicle home from the workplace, and discharge begins at point I to cope with the peak electricity usage of residence 2 during the evening. Discharge continues until the battery SOC reaches a preset lower SOC limit, at which point the charging current is zero.

[0088] In addition, according to Figure 4 In the case of the dashed line reference application mode, the representative application mode in V2G was determined, and the current distribution was set based on the above event.

[0089] The benchmark application mode does not necessarily need to be similar to the application mode of the evaluation object. In addition, the benchmark application mode does not have to be the measured value; results obtained through simulation analysis can also be used.

[0090] Next, the extraction of feature quantities related to battery degradation will be explained. Figure 5 This is a graph illustrating examples of extracted degradation factors. In Figure 5 Nakaya and Figure 4 Similarly, the horizontal axis represents 24 hours in a day, and the vertical axis from top to bottom represents the current, voltage, temperature, and SOC, respectively. Here, as the charge and discharge data of HV battery 20, time-series data of current, voltage, and temperature are taken, so that the battery capacity at this time is known, and thus the SOC can be calculated. Degradation factor parameters are extracted from these data as input parameters for the battery degradation model.

[0091] Here, as an example of degradation factor parameters, the periods with positive current values ​​(i.e., charging time), the periods with negative current values ​​(i.e., discharging time), the average battery temperature, the cycle depth with calculated SOC increases and decreases, the upper limit of SOC, and the average SOC are defined.

[0092] Next, the calculation of the decrease in health status (SOH) and the sensitivity of degradation factors based on the battery degradation model will be explained. Figure 6 This is a diagram illustrating an example of the input-output response of a battery degradation model. The processing using this battery degradation model is... Figure 3 The baseline SOH reduction calculation unit F308 and the application SOH reduction calculation unit F312 are executed. In processing step S601, battery degradation factors extracted from the charge and discharge data of HV battery 20 are prepared as input parameters. Then, in processing step S602, the battery degradation prediction model is used to calculate the amount of battery health (SOH) reduction caused by this application. Then, in processing step S603, the change in battery health (SOH) (dSOH) is obtained.

[0093] Here, the battery degradation model can be a database using the results of charge-discharge tests with actual batteries, or it can be a simulation model. The battery degradation model in this embodiment is a multivariate function with six input parameters, but these parameters are factors that influence the cyclic degradation of the battery. The degradation caused by these input factors is relatively rarely non-linear. If two parameters are used to represent the relationship with state of health (SOH), then the following description is provided. Figure 6The response surface 30 shows the smoothed predicted battery degradation values. Additionally, Figure 6 This example illustrates a battery degradation model with discharge time and cycle depth as input parameters. The relationship between discharge time, cycle depth, and the change in battery health (SOH), dSOH, is defined in three dimensions within the battery degradation model. The battery degradation model represents the difference between the baseline operating mode and the operating mode of the evaluated object.

[0094] Here, if we perform partial differential analysis on the response surface 30 of the battery degradation prediction value for each degradation factor, we obtain the partial differential coefficients for each factor. The partial differential coefficients are equivalent to the gradient of the response surface; the larger the gradient, the greater the impact of that degradation factor on the degree of degradation. Therefore, based on the gradient ratio of each degradation factor, the degradation amount difference caused by this operation is allocated, thereby quantifying the contribution of each degradation factor.

[0095] Figure 7 This is a graph representing the base degradation level, the degradation difference, and contribution classification examples. Figure 7 The baseline degradation amount dSOH under the benchmark application mode on the left. base Using this as a baseline, the degradation amount dSOH under the evaluation object's operating mode is represented on its right. In this invention, the focus is on obtaining the degradation amount dSOH and the baseline degradation amount dSOH. base The degradation of the difference.

[0096] Based on this, the magnitude of the impact of each major cause of the degradation difference (charging time, discharging time, battery average temperature, cycle depth, upper limit of SOC, and average SOC) is quantified. This quantification of the magnitude of impact is based on... Figure 6 The gradient ratio of the response surface 30 is assigned, thereby enabling high-precision extraction of the amount of degradation caused by application differences, and enabling quantification of each degradation factor.

[0097] Furthermore, when fast charging is performed with a charging current exceeding 1C (1C is the current value at which the capacity of HV battery 20 can be fully charged in 1 hour), nonlinear degradation such as lithium deposition occurs within the battery, which may produce maxima or minima on the response surface 30 of the battery degradation model. To account for the effects of fast charging, it is preferable to use the peak current value during charging or its time integral value as input values, and to prepare a degradation model for fast charging to correct the response surface 30 of the battery degradation model.

[0098] Example 2

[0099] In Example 1, the charge / discharge control device was described, but in Example 2, the charge / discharge control method is described.

[0100] Figure 8 This is a flowchart illustrating an example of the control method for the charging and discharging device according to Embodiment 2 of the present invention. In this process, firstly in processing step S801, baseline operating conditions and baseline degradation amounts are calculated. These baseline conditions are appropriately updated when the vehicle owner changes or when the driver's driving style changes.

[0101] In processing step S802, it is determined whether it is time to perform degradation diagnosis. Degradation diagnosis is performed at midnight, 0:00, etc. If degradation diagnosis is performed, degradation calculation using the usage data of that day begins. Specifically, in processing step S803, the degradation status of the vehicle battery is obtained from an external degradation diagnosis device such as a fixed charger 28, or the battery degradation status is obtained from a vehicle-mounted charger 10 or other vehicle-mounted degradation diagnosis device.

[0102] Next, in processing step S804, degradation factors are calculated based on the charge / discharge data (current, voltage, temperature, SOC) during operation. In processing step S805, the degradation amount and degradation factor sensitivity during operation are calculated based on the battery degradation model. In processing step S806, the degradation amount difference between the operation time and the baseline operation time is calculated using the output information of the degradation model. Then, in processing step S807, the degradation amount difference is allocated according to the sensitivity ratio of the degradation factors, and the degradation factors are quantified and accumulated for storage.

[0103] Finally, in processing step S808, the charge / discharge plan for the next iteration is revised to avoid the accumulation of specific degradation factors. In processing step S809, it is determined whether to update the baseline operating mode, and in processing step S810, it is determined whether to continue the degradation accumulation calculation.

[0104] Figure 9 This is an example of simulated waveforms representing the current, voltage, and SOC when the battery is used in a fixed operating mode. Assuming a V2G environment connecting vehicle 9 and residence 2, a charge-discharge pattern is established. Starting from a fully charged state, discharge is first performed to the residence from time zero. Next, charging based on solar power is implemented. However, if the SOC reaches its upper limit during charging, charging is stopped during this period. Then, discharge is performed to residence 2 in the latter half of the charging process. In this embodiment, the same charge-discharge pattern is repeated for 30 days.

[0105] Figure 10A This is a chart visualizing the accumulation of battery degradation factors when used under a fixed battery operating mode. When calculating the accumulation of degradation factors according to the method of the present invention, it can be seen that the influence of cycle depth accounts for 98.1% and the influence is amplified. This is because the degradation of battery cells leads to a reduction in battery capacity, but despite this, the same charge-discharge mode is still implemented, resulting in an increased change in battery SOC with each charge-discharge cycle, such as... Figure 10BAs shown, the load related to the cycle depth is applied to the battery.

[0106] Figure 11 This example illustrates the waveforms of current, voltage, and SOC when the battery usage mode is changed periodically. In this case, a charge / discharge plan is developed by periodically changing the upper limit SOC during charging and discharging and the lower limit SOC during discharging. It can be seen that the historical changes in voltage and SOC over time are multifaceted.

[0107] Figure 12A This is a chart showing the accumulation of battery degradation factors when the battery is used in a way that involves periodically changing the battery usage mode according to the first embodiment of the present invention. By changing the battery usage mode midway through the process (changing the actual usage mode in subsequent uses to avoid the accumulation of specific degradation factors), the types and impact of the accumulated degradation factors change, such as... Figure 12B As shown, three degradation factors—cycle depth, charging time, and average state of charge (SOC)—affect the battery. Therefore, by controlling charge and discharge in a way that prevents degradation factors from favoring any particular factor and instead allows them to accumulate evenly, battery degradation can be suppressed.

[0108] like Figure 10A and Figure 12A As shown, the visualization results of battery degradation factors can be communicated via in-vehicle displays, the driver's smartphone, etc. Furthermore, by simultaneously notifying users of recommended charging and discharging modes, users can be encouraged to connect vehicle 9 to the electrical system at appropriate times. For vehicle 9, this not only facilitates ideal charging and discharging control but also improves the utilization rate of on-board battery resources.

[0109] In this embodiment, a lithium-ion battery is used as an example, but it can also be applied to various types of batteries, such as all-cell batteries. The same degradation factor visualization and charge / discharge control can also be applied to LV batteries such as lead-acid batteries.

[0110] In this embodiment, the following was used Figure 5 The factors listed are considered degradation factors, but in addition, vehicle mileage, driving time, and cumulative vehicle vibration can also be used as degradation factors. Furthermore, the battery degradation model can be updated with the latest battery information through wired or wireless external vehicle communication, allowing for the correction or modification of the degradation model. Moreover, inter-vehicle communication can be used to share model information between specific manufacturing batches of batteries, improving accuracy.

[0111] Furthermore, the present invention is not limited to the above embodiments. As long as it does not depart from the spirit of the present invention as described in the claims, various other application examples and modifications may be adopted.

[0112] For example, the above embodiments have been described in detail and specifically to facilitate understanding of the present invention, and are not necessarily limited to having all the described configurations. Furthermore, for a portion of the configuration of this embodiment, other configurations may be added, deleted, or substituted.

[0113] Furthermore, control lines and information lines refer to lines deemed necessary in the specifications, but not all control lines and information lines may be represented on the product. In reality, almost all components can be considered interconnected.

[0114] Explanation of symbols

[0115] 1…Power System

[0116] 2…residential

[0117] 3…HEMS

[0118] 4…Distribution panel

[0119] 5…Solar power generation

[0120] 6… Household storage batteries.

[0121] 7…External devices

[0122] 9… Vehicles (electric vehicles or plug-in hybrid vehicles)

[0123] 10…On-board charger

[0124] 11…AC charging port

[0125] 12…Power Conversion Control Department

[0126] 13…Battery Sensing Section

[0127] 14…Power Conversion Department

[0128] 15…Integrated Controller

[0129] 16…Network Communications Department

[0130] 17…ECM

[0131] 18…Computational Processing Unit

[0132] 19… Battery Management System

[0133] 20…HV battery (high voltage)

[0134] 21…LV battery (low voltage)

[0135] 22…AC connection section

[0136] 25…DC-DC converter

[0137] 26…Power conversion device

[0138] 27…Internal Equipment

[0139] 28… Fixed DC Charger

[0140] 29…DC charging port

[0141] Response surface of 30… battery degradation prediction value.

Claims

1. A charge / discharge control device for controlling the charging and discharging of a storage battery connected to a load. The charging and discharging control device is characterized by comprising the following units: A unit is configured to set a reference operating mode for charging and discharging the battery and calculate the amount of battery degradation, i.e., the reference degradation amount, under the reference operating mode; a unit is configured to calculate the amount of battery degradation, i.e., the actual operating degradation amount, when the battery is charged and discharged in an actual operating mode different from the reference operating mode; a unit is configured to calculate the difference between the reference degradation amount and the actual operating degradation amount, i.e., the degradation amount difference; and a unit is configured to calculate the factors contributing to the degradation of the battery, i.e., the contribution of each of the multiple degradation factors, based on the degradation amount difference.

2. The charging and discharging control device according to claim 1, characterized in that, A unit capable of changing the actual operating mode after the next change to avoid the accumulation of a specific degradation factor among the multiple degradation factors.

3. The charging and discharging control device according to claim 1, characterized in that, The benchmark application mode and the benchmark degradation amount are calculated or recorded based on the results of battery degradation tests or simulation analysis.

4. The charging and discharging control device according to claim 1, characterized in that, The degradation factors include at least one of the following: the period with a positive current value, i.e., charging time; the period with a negative current value, i.e., discharging time; the average battery temperature; the depth of cycle with calculated SOC increases or decreases; the upper limit of SOC; and the average SOC.

5. The charging and discharging control device according to claim 1, characterized in that, The baseline operating mode and the baseline degradation level are updated periodically based on the user's past operating history and charging / discharging patterns.

6. The charge / discharge control device according to claim 1, characterized in that, The system will notify the driver via in-vehicle display or their smartphone of the accumulation of degradation factors, recommended EV connection times, and other charging / discharging plan information.

7. A charging and discharging control method, which uses a computer to control the charging and discharging of a battery connected to a load. The charging and discharging control method is characterized in that... The computer sets a baseline operating mode for charging and discharging the battery, calculates the amount of battery degradation under the baseline operating mode, i.e., the baseline degradation amount, and calculates the amount of battery degradation under the actual operating mode, i.e., the actual usage degradation amount, when the battery is charged and discharged in an actual operating mode different from the baseline operating mode. The difference between the baseline degradation amount and the actual usage degradation amount is calculated, i.e., the degradation amount difference. Based on the degradation amount difference, the factors contributing to the degradation of the battery, i.e., the contribution of each of the multiple degradation factors, are calculated.

8. The charging and discharging control method according to claim 7, characterized in that, Change the actual usage pattern in the future to avoid the accumulation of specific degradation factors among the multiple degradation factors.

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