Method and system for estimating state of health of rechargeable battery, in particular for vehicle

Abstract

To solve the following problems: known methods assume different definitions of the SoH, being indeed not comparable, and customized charging stations are required for solutions based on extrapolation of a nominal internal resistance of a battery.SOLUTION: A method for estimating the State of Health SoH of a rechargeable battery, in particular for a vehicle, comprises the steps of: obtaining a first value of State of Charge of the battery; charging the battery with DC power; after the DC power charging, obtaining a second value of State of Charge of the battery; computing energy supplied to the battery; and computing the State of Health using the following formula: SoH=(DE) / (SoCEND-SoCSTART), DE being the energy supplied to the battery during the DC power charging, SoCSTART being the first value of state of charge of the battery, and SoCEND being the second value of state of charge of the battery.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method and system for estimating the state of health of a rechargeable battery, in particular a rechargeable battery for a vehicle such as an electric vehicle. [Background technology]

[0002] Vehicle batteries are subject to aging which affects their chemical and electrical properties.

[0003] In particular, the capacity of a battery is specified in ampere-hours (Ah) and indicates the amount of charge that the battery contains. For a given battery voltage, a higher capacity means that the battery can store more energy.

[0004] As a result of aging, the capacity of a vehicle battery gradually decreases over its useful life.

[0005] At the same time, the internal resistance increases, so the energy content, expressed as a percentage, is less than the capacity.

[0006] The figure of merit of the actual state of the battery compared to its nominal state is called the "State of Health" (SoH).

[0007] Unlike the "state of charge" (SoC), which can be determined by measuring the battery's actual charge, there is no absolute definition of SoH.

[0008] Instead, SoH is an important quality indicator that can be related to various performance parameters of the battery.

[0009] Theoretically, a new battery should have SoH=100%.

[0010] SoH is important for warranties, used car certification, etc.

[0011] Diagnostic tools usually have access to some battery parameters, depending on the car manufacturer. The SoH is not usually provided by the diagnostic device.

[0012] Document US 2015 / 0102818 A1 describes a method and device for determining the SoH of a vehicle battery, comprising the following steps: - a step of complete discharge of the vehicle battery by the vehicle's internal loads; - the steps of fully charging the vehicle battery; - measuring the capacity and / or energy content of the vehicle battery while the vehicle battery is being charged; - determining the battery condition according to the capacity and / or energy content of the vehicle battery.

[0013] Document CN109001636 discloses a method for estimating the SoH of a battery, where the SoH depends on a capacity value, a remaining power variation and a preset value.

[0014] Document CN102866361 discloses a method for estimating the SoH of a battery, where the SoH is a function of the voltage, current and state of charge SoC.

[0015] In fact, the known methods assume different definitions of the SoH that are not really comparable.

[0016] Solutions based on extrapolation of the nominal internal resistance of the battery are also known. These solutions require customized charging stations. Furthermore, the methods are lengthy and provide only a statistical indication, not a real measurement of the internal resistance. Summary of the Invention

[0017] In this context, the technical problem underlying the present invention is to propose a method and a system for estimating the state of health of a rechargeable battery, in particular a rechargeable battery for vehicles, which overcomes the above-mentioned drawbacks of the prior art.

[0018] In particular, it is an object of the present invention to provide a method and a system for estimating the state of health of a rechargeable battery, in particular a rechargeable battery for vehicles, that is applicable to any battery, regardless of manufacturer.

[0019] The stated technical problem and the particular object are substantially achieved by a method for estimating the State of Health (SoH) of a rechargeable battery, in particular a rechargeable battery for a vehicle, the method comprising: obtaining a first value of a state of charge of a battery; - charging a battery with DC power; obtaining a second value of the state of charge of the battery after performing a DC power charge; - calculating the energy supplied to the battery; - The following formula: SoH = (DE) / (SoC END -SoC START ) calculating the state of health using where DE is the energy delivered to the battery during DC power charging, and SoC START is the first value of the battery's state of charge, SoC END is a second value of the state of charge of the battery.

[0020] According to one aspect of the invention, the first and second values ​​of the state of charge of the battery are obtained from an electronic control unit of the vehicle.

[0021] According to one embodiment of the present invention, the method further comprises: - measuring the DC current supplied to the battery during DC power charging; - obtaining a voltage value of the battery.

[0022] A step of calculating the energy supplied to the battery is performed depending on the measured direct current and voltage values.

[0023] In particular, the battery voltage value is obtained from said electronic control unit.

[0024] According to one embodiment of the present invention, the method further comprises: - obtaining a first value of the energy of the battery prior to a direct current charging; - obtaining a second value of the energy of the battery after performing the DC power charging.

[0025] The step of calculating the energy supplied to the battery comprises calculating a difference between the second value of the energy of the battery and the first value of the energy.

[0026] In particular, the first value and the second value of the energy of the battery are obtained from said electronic control unit of the vehicle.

[0027] The stated technical problem and particular object are substantially achieved by a system for estimating the State of Health (SoH) of a rechargeable battery, in particular a rechargeable battery for a vehicle, the system comprising: - a fast charging station configured to provide DC power to the battery; - a DC logger having an inlet connected to a rapid charging station and an outlet connectable to a battery, the DC logger being configured to measure a DC current or power supplied by the rapid charging station to the battery; a diagnostic device configured to obtain at least a first value and a second value of a state of charge of the battery at two different states of charge of the battery, and a voltage value of the battery; The diagnostic device is - communicate with a DC logger to obtain DC current or DC power; - calculating the energy DE delivered to the battery by the fast charging station according to the measured DC current or DC power from the DC logger, - The following formula: SoH = (DE) / (SoC END -SoC START) to calculate the SoH, where DE is the energy delivered to the battery during DC power charging, and SoC STARTは The first value of the battery's state of charge, SoC END is a second value of the battery's state of charge.

[0028] According to one embodiment, the fast charging station is a portable charging station configured to provide 20 kW to 60 kW of DC power to the battery.

[0029] According to one embodiment, the fast charging station is a fixed charging station configured to provide more than 50 kW of DC power to the battery.

[0030] In one embodiment, the DC logger is a DC ammeter.

[0031] In another embodiment, the DC logger is a DC power meter.

[0032] According to one aspect of the invention, the DC logger inlet is a Type 2 socket compatible for connection to a quick charging station, and the DC logger outlet is a Type 2 plug compatible for connection to a vehicle. [Brief description of the drawings]

[0033] Additional features and advantages of the present invention will become more apparent from the non-limiting description of preferred but non-limiting embodiments of a method and system for estimating the state of health of a rechargeable battery, in particular a rechargeable battery for a vehicle, as illustrated in the accompanying drawings. [Figure 1] 1 is a flowchart of a method for estimating the state of health of a rechargeable battery, in particular a rechargeable battery for a vehicle, according to a first embodiment of the present invention; [Diagram 2] 5 is a flowchart of a method for estimating the state of health of a rechargeable battery, in particular a rechargeable battery for a vehicle, according to a second embodiment of the present invention. [Diagram 3]1 shows a schematic diagram of a system for estimating the state of health of a rechargeable battery, in particular a rechargeable battery for a vehicle, according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Referring to FIG. 1, the numeral 100 indicates a first embodiment of a method for estimating the State of Health (SoH) of a rechargeable battery, indicated as 2 .

[0035] In this context, the term "battery" may refer to a single storage cell or a battery pack containing multiple storage cells.

[0036] The method 100 includes the step of charging the battery 2 with DC power. This step is shown as 103 in FIG.

[0037] This step is carried out by connecting the battery 2 to a fast charging station 3 arranged to supply DC power.

[0038] According to one example, the fast charging station 3 is a portable charging station configured to supply 20 kW to 60 kW of DC power to the battery 2 .

[0039] According to another example, the fast charging station 3 is a fixed charging station configured to supply the battery 2 with more than 50 kW DC power.

[0040] It may be useful to recall that, according to the prior art, two basic charging modes are known for rechargeable batteries in vehicles: conventional charging and fast charging.

[0041] In conventional charging, also called slow charging, the current can be direct current (portable DC machines) or single-phase AC (110V-250V) and three-phase AC (380V). The charging current is typically in the range of 8-32A and the charging power is typically in the range of 1.5-21kW.

[0042] Conversely, fast charging (also called ground charging) is a direct current power method for charging vehicle batteries. In particular, fast charging is characterized by currents in the range of 150-400 A, voltages in the range of 200-750 V, and charging powers in excess of 50 kW.

[0043] The main advantage of the fast charging mode is that the charging time is reduced, since the voltage is generally higher than the battery voltage. Inside the fast charging station there is a rectifier that converts AC power to DC power.

[0044] According to a first embodiment of the method, before charging the battery 2 with DC power (step 103), the following steps are carried out: Step 101: A first value of the state of charge (SoC) of the battery 2 is obtained. - step 102: a first value of the energy of the battery 2 is obtained.

[0045] In particular, the first value of SoC (SoC START ) and the first value of the energy (E START ) is obtained from the vehicle's electronic control unit (ECU).

[0046] Preferably, the first value of SoC and the first value of energy are read from a diagnostic device 4 arranged to communicate with an ECU of the vehicle.

[0047] The diagnostic device 4 is of a known type and will not be described further.

[0048] After performing steps 101 and 102 , the method 100 proceeds to perform step 103 .

[0049] After performing DC power charging (step 103), the following steps are performed. Step 104: At the end of charging, a second value of the SoC of battery 2 is obtained. Step 105: At the end of the charging, a second value of the energy of the battery 2 is obtained.

[0050] In particular, the second value of the SoC (SoC END ) and a second value of the energy (E END ) is obtained from the vehicle's ECU.

[0051] Preferably, the second value of SoC and the second value of energy are read from the diagnostic device 4 .

[0052] Next, in step 106, the SoH is calculated using the following formula:

[0053] SoH=(E END -E START ) / (SoC END -SoC START ) Preferably, the diagnostic device 4 is configured to perform step 106 .

[0054] Referring to FIG. 2, numeral 200 indicates a second embodiment of a method for estimating the state of health (SoH) of a rechargeable battery.

[0055] The method 200 includes a step of charging the battery 2 with DC power. This step is shown as 203 in Figure 2. It is exactly the same as step 103 of the first embodiment of the method (see Figure 1).

[0056] Step 203 is actually carried out by connecting the battery 2 to the fast charging station 3 .

[0057] According to the second embodiment of the present invention, before charging the battery with DC power (step 103), a first value of the SoC of the battery 2 is obtained. This step is indicated as 201. It is exactly the same as step 101 of the first embodiment of the present invention (see FIG. 1).

[0058] In particular, the first value of SoC (SoCSTART ) is obtained from the vehicle's ECU.

[0059] Preferably, the first value of the SoC is read from the diagnostic device 4 .

[0060] After performing step 201 , the method 200 proceeds to perform step 203 .

[0061] During step 203, the direct current supplied to the battery 2 by the fast charging station 3 is measured.

[0062] Measuring the DC current is shown as step 205 .

[0063] In particular, in a second embodiment of the method, a DC logger 5 is used.

[0064] The DC logger 5 has an inlet 5a configured to be connected to the quick charging station 3 and an outlet 5b configured to be connected to the battery 2 of the vehicle 10.

[0065] In particular, the inlet 5a is a type 2 socket compatible for connection to a rapid charging station, and the outlet 5b is a type 2 plug compatible for connection to a vehicle.

[0066] According to one example, the DC logger 5 is a DC ammeter configured to measure the DC current supplied to the battery 2 by the quick charging station 3 .

[0067] The method 200 also includes the following steps. - Step 207: The voltage value of battery 2 is obtained from the vehicle's ECU. Step 208: Calculate the energy supplied to the battery 2 as a function of the measured DC current (measured by the DC logger 5) and the voltage value of the battery 2.

[0068] In particular, the energy is calculated with reference to the time interval during which the battery 2 is charged by the fast charging station 3, using very well known formulas.

[0069] Power P(t)=V(t)×I(t) TIFF2024037701000002.tif1070

[0070] The energy supplied during charging is called DE, which is the difference between the energy of the battery 2 at the end of the DC charging and the energy of the battery 2 before charging.

[0071] After performing DC power charging (step 203), a second value of the SoC of the battery 2 is obtained. This step is indicated as 204. It is exactly the same as step 104 in the first embodiment of the present invention (see FIG. 1).

[0072] In particular, the second value of the SoC (SoC END ) is obtained from the vehicle's ECU.

[0073] Preferably, the second value of the SoC is read from the diagnostic device 4 .

[0074] Next, in step 206, the SoH is calculated using the following formula:

[0075] SoH=DE / (So CEND -SoC START ) For example, the DC logger 5 is configured to provide the measured DC current to the diagnostic device 4 .

[0076] The diagnostic device 4 is also configured to obtain a voltage value of the battery 2 from the ECU (step 207).

[0077] Finally, the diagnostic device 4 is arranged to calculate the energy DE (step 208) and to calculate the SoH (step 206).

[0078] Preferably, the SoH can be read out directly on the display of the diagnostic device 4, like other vehicle parameters.

[0079] In a variant, the method 200 envisages measuring the DC power supplied to the battery 2 by the fast charging station 3 instead of measuring the DC current.

[0080] In this case, the DC logger 5 is therefore a power meter arranged to measure the DC power supplied to the battery 2 by the quick charging station 3 .

[0081] In this variant, step 207 is absent and step 208 consists in calculating the energy supplied by the battery 2 depending on the DC power measured in the time interval of charging the battery 2 .

[0082] With reference to FIG. 3, number 1 indicates a system for estimating the SoH of a rechargeable battery.

[0083] System 1 - a fast charging station 3 configured to supply DC power to the battery 2; a DC logger 5 having an inlet 5a connected to a quick charging station (3) and an outlet 5b connectable to a battery 2; a diagnostic device 4 arranged to communicate with the DC logger 5 and connectable (preferably wirelessly) to the ECU of the vehicle 10;

[0084] In particular, the DC logger 5 is configured to measure the DC current or power supplied to the battery 2 by the fast charging station 3 .

[0085] The diagnostic device 4 is adapted to obtain the following values: - A first value of the SoC of battery 2 (i.e., SoC START ), - A second value of the battery's SoC (i.e., SoC END ), - configured to acquire a voltage value of battery 2.

[0086] In an embodiment using the system of FIG. 3, the diagnostic device 4 also - calculating the energy DE delivered to the battery 2 by the fast charging station 3 according to the measured direct current received from the direct current logger 5, - configured to calculate the SoH according to the following formula:

[0087] SoH = DE / (SoC END -SoC START ).

[0088] In fact, in the first embodiment, two instantaneous energy values ​​E START , E END is acquired by the diagnostic device 4, whereas in a second embodiment the delivered energy DE is calculated based on measurements of either the DC current or the DC power measured by the DC logger 5.

[0089] In either case, DE=E END -E START Therefore, it can be said that the formula for obtaining the SoH is identical in the two embodiments.

[0090] The features of the method and system for estimating the state of health of a rechargeable battery, in particular a vehicular rechargeable battery, according to the invention, as well as the advantages emerge clearly from the above description.

[0091] In particular, the method makes it possible to determine the amount of SoH of any battery starting from parameters obtained directly from a diagnostic device.

[0092] In a specific embodiment, the system uses a universal DC logger that can measure the DC current delivered to the battery, which is transmitted to a diagnostic device, allowing the SoH of any vehicle battery to be calculated.

[0093] The method is simple, fast and easy to implement as it uses fast charging stations already available on the market and does not require a customized charging station, as is the case with methods based on extrapolation of the internal resistance (a parameter that is usually not published by the manufacturers). [Prior art documents] [Patent documents]

[0094] [Patent Document 1] US 2015 / 0102818 A1 [Patent Document 2] CN109001636 [Patent Document 3] CN102866361

Claims

1. A method (100, 200) for estimating the state of health (SoH) of a rechargeable battery, particularly a rechargeable battery for vehicles, - A step of obtaining a first value of the charge state of the battery (101, 201), - The step of charging the battery with DC power (103, 203), - After performing the DC power charging, the step of obtaining a second value of the battery's charge state (104, 204) - A step (208) of calculating the energy supplied to the battery, - The following equation, namely SoH = (DE) / (SoC) ＥＮＤ -SoC ＳＴＡＲＴ A step (106, 206) of calculating the healthy state using ), Here, DE is the energy supplied to the battery during the DC power charging, and SoC ＳＴＡＲＴ This is the first value of the battery's charge state, and SoC ＥＮＤ A method (100, 200) comprising the step of the charge state of the battery being the second value.

2. The method according to claim 1 (100, 200), wherein the first and second values ​​of the battery charge state are obtained from the vehicle's electronic control unit.

3. - A step (205) of measuring the DC current supplied to the battery during DC power charging, - Further includes the step of obtaining the voltage value of the battery (207), The method of claim 2 (200), wherein the step (208) of calculating the energy supplied to the battery is performed according to the measured DC current and the voltage value.

4. The method according to claim 3 (200), wherein the voltage value of the battery is obtained from the electronic control unit.

5. - The step (102) of obtaining a first value of the battery's energy before the DC power charging, - The step (105) of obtaining a second value of the battery's energy after performing the DC power charging, The method according to claim 2 (100), wherein the step of calculating the energy supplied to the battery comprises calculating the difference between the second value of the battery's energy and the first value of the energy.

6. The method according to claim 5 (100), wherein the first and second values ​​of the battery energy are obtained from the electronic control unit of the vehicle.

7. A system (1) for estimating the state of health (SoH) of a rechargeable battery (2), particularly a rechargeable battery (2) for a vehicle (10), - A rapid charging station (3) configured to supply DC power to the battery (2), - A DC logger (5) having an inlet (5a) connected to the rapid charging station (3) and an outlet (5b) connectable to the battery (2), the DC logger (5) configured to measure the DC current or DC power supplied to the battery (2) by the rapid charging station (3), - A diagnostic device (4) configured to acquire at least a first value and a second value of the charge state of the battery (2) in two different charge states of the battery (2), and the voltage value of the battery (2), The diagnostic device (4) is - Communicates with the DC logger (5) to obtain the DC current or DC power, -Calculate the energy DE supplied to the battery (2) by the rapid charging station (3) according to the measured DC current or DC power from the DC logger (5), - The following equation, namely SoH = (DE) / (SoC) ＥＮＤ -SoC ＳＴＡＲＴ It is configured to calculate SoH using ) Here, DE is the energy supplied to the battery (2) during the DC power charging, and SoC ＳＴＡＲＴ This is the first value of the charge state of the battery (2), and SoC ＥＮＤ The system (1) is the second value of the charge state of the battery (2).

8. The system (1) according to claim 7, wherein the rapid charging station (3) is a portable charging station configured to supply 20 kW to 60 kW of DC power to the battery (2).

9. The system (1) according to claim 7, wherein the rapid charging station (3) is a fixed charging station configured to supply DC power exceeding 50 kW to the battery (2).

10. The system (1) according to any one of claims 7 to 9, wherein the DC logger (5) is a DC ammeter.

11. The system (1) according to any one of claims 7 to 9, wherein the DC logger (5) is a DC power meter.

12. The system (1) according to any one of claims 7 to 9, wherein the inlet (5a) of the DC logger (5) is a Type 2 socket conforming to the connection with the fast charging station (3), and the outlet (5b) of the DC logger (5) is a Type 2 plug conforming to the connection with the vehicle (10).

13. A computer program having, when executed by a computer device or system, an instruction causing the computer device or system to perform the method described in any one of claims 1 to 6.

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