Deterioration detection method

Abstract

To provide a deterioration detection method capable of detecting deterioration of storage batteries with high accuracy even on batteries that have a flat region.SOLUTION: A deterioration detection method for detecting the deterioration of a storage battery mounted on a vehicle includes the steps: flowing a detection current from the storage battery to a predetermined load mounted on a vehicle when the vehicle starts or when the vehicle is parked; observing the waveform of the detection current flowing through the predetermined load; and determining whether or not the storage battery has deteriorated based on the waveform of the detection current observed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for detecting deterioration of a storage battery mounted on a vehicle. [Background technology]

[0002] Patent Document 1 discloses a method for detecting deterioration of an auxiliary battery (storage battery) mounted on a vehicle. In the method described in Patent Document 1, the auxiliary battery is discharged, the time required for the voltage of the auxiliary battery to reach a predetermined voltage from a starting voltage is measured, and if the measured time is equal to or less than a predetermined threshold, it is determined that the auxiliary battery is deteriorated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-029182 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method described in the above Patent Document 1, the determination of whether the storage battery has deteriorated or not depends on the voltage change of the storage battery. Therefore, for example, when an iron phosphate lithium ion battery (LFP battery) having a so-called flat region in which the voltage change is small in the SOC-OCV characteristic curve is used as the storage battery, the voltage change may be too small to detect the deterioration of the storage battery with high accuracy.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a deterioration detection method that can detect deterioration of a storage battery with high accuracy, even for a storage battery that has a flat region. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the disclosed technology is a degradation detection method for detecting degradation of a storage battery mounted on a vehicle, the degradation detection method including the steps of: flowing a detection current from the storage battery to a specified load mounted on the vehicle when the vehicle is started or parked; observing the waveform of the detection current flowing through the specified load; and determining whether or not the storage battery has deteriorated based on the observed waveform of the detection current. Effect of the Invention

[0007] According to the deterioration detection method of the present disclosure, deterioration of a storage battery is detected based on the waveform of the current flowing through the vehicle-mounted load, so that deterioration of the storage battery can be detected with high accuracy even for a storage battery having a flat region. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a vehicle system in which a deterioration detection method according to an embodiment of the present disclosure is performed; [Figure 2A] A process flow chart of the deterioration detection method according to the present embodiment. [Figure 2B] A process flow chart of the deterioration detection method according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Embodiment> [composition] Fig. 1 is a block diagram of a vehicle system 10 in which a deterioration detection method according to an embodiment of the present disclosure is executed. The vehicle system 10 illustrated in Fig. 1 includes a generator 100, a storage battery 200, a battery ECU 300, a plurality of on-board loads 400, and a deterioration detection device 500. In Fig. 1, connection lines through which power flows are indicated by solid lines, and connection lines through which detection signals, control signals, etc. flow are indicated by dotted lines.

[0010] 1 is mounted on a vehicle equipped with an autonomous driving system. In the following embodiment, the deterioration detection method according to the present embodiment will be described using as an example a case in which the vehicle system 10 is mounted on a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV) that uses an electric motor as a power source.

[0011] The generator 100 is a power source that supplies power to the storage battery 200. Examples of this generator 100 include an alternator that generates power in response to the drive of a power source (not shown), and a DC-DC converter that converts the power of a secondary battery configured to be chargeable and dischargeable or input power from an external charger into a predetermined voltage and outputs it.

[0012] The storage battery 200 is a secondary battery configured to be chargeable and dischargeable, such as a lithium ion battery. The storage battery 200 is connected to the generator 100 and a plurality of on-board loads 400, and is charged with power output from the generator 100 via the generator 100, and supplies its own stored power to the plurality of on-board loads 400. In addition to functioning as a power source for the plurality of on-board loads 400, the storage battery 200 also functions as a sub-battery that supplies backup power required for evacuation actions in place of a main battery (not shown) in a situation where an emergency occurs while the vehicle is traveling in an autonomous driving mode and a predetermined evacuation action must be taken.

[0013] The battery ECU 300 is an electronic control unit (ECU) for monitoring and controlling the storage battery 200. Specifically, the battery ECU 300 can acquire physical quantities such as voltage, current, and temperature as the state of the storage battery 200. These physical quantities are acquired, for example, via detection elements (not shown) such as a voltage sensor, a current sensor, and a temperature sensor provided in the storage battery 200. The battery ECU 300 can also instruct a predetermined in-vehicle load 400 to drive based on the state of the vehicle door detected by a device (not shown) provided in the vehicle system 10. In this drive instruction, an instruction is given to cause a current (detection current) required for detecting a deterioration state of the storage battery 200 to flow through the predetermined in-vehicle load 400.

[0014] The on-vehicle load 400 is configured with an electronic control unit (ECU), actuators (systems), etc. mounted on a vehicle. The on-vehicle load 400 includes, for example, ECUs and actuators (systems) such as electric power steering, advanced driving assistance, shift-by-wire, and electric brakes that are necessary to realize an evacuation action in a situation where the vehicle is driving autonomously.

[0015] The deterioration detection device 500 is configured to detect deterioration of the storage battery 200. The deterioration detection device 500 determines whether or not the storage battery 200 has deteriorated, based on the state of the storage battery 200 monitored by the battery ECU 300.

[0016] [control] Next, a deterioration detection method according to an embodiment of the present disclosure will be described with further reference to Figures 2A and 2B. Figures 2A and 2B are flowcharts showing the procedure of a deterioration detection process executed by the vehicle system 10. The process in Figure 2A and the process in Figure 2B are connected by connectors X and Y, respectively.

[0017] (Step S201) The vehicle system 10 determines whether or not an action to close the vehicle door (door CLOSE) has been performed. This determination is made in order to determine whether or not the vehicle is in a parked state. The parked state of the vehicle can be determined based on whether or not an action to close the vehicle door has been performed when an occupant gets out of the vehicle. If the vehicle system 10 determines that an action to close the vehicle door (door CLOSE) has been performed (step S201, Yes), the process proceeds to step S202.

[0018] (Step S202) The battery ECU 300 instructs one or more predetermined in-vehicle loads 400 to drive. The in-vehicle loads 400 to be instructed to drive are actuators that can be operated during parking, and an example of such an actuator is a brake actuator. When the battery ECU 300 instructs one or more in-vehicle loads 400 to drive, the process proceeds to step S203.

[0019] (Step S203) The battery ECU 300 measures, as a detection current, an "actuator draw current" which is a current flowing from the storage battery 200 to the vehicle-mounted load 400 due to the driving of the one or more vehicle-mounted loads 400 (actuators) instructed in step S202 above. When the detection current (actuator draw current) is measured by the battery ECU 300, the process proceeds to step S204.

[0020] (Step S204) The deterioration detection device 500 detects deterioration of the storage battery 200 (during parking) based on the waveform of the detection current (current drawn by the actuator) measured by driving the actuator in step S203 above. This deterioration detection of the storage battery 200 can be performed, for example, by analyzing the waveform of the detection current to determine whether the storage battery 200 can stably flow a predetermined current value for a predetermined period of time. When the deterioration detection device 500 detects deterioration of the storage battery 200, the process proceeds to step S205.

[0021] (Step S205) Based on the result of the deterioration detection of the storage battery 200 in step S204, the vehicle system 10 determines whether or not a "backup permission condition" that allows the vehicle's driving mode to be shifted from a driver-led manual driving mode to a system-led autonomous driving mode is satisfied. The backup permission condition includes, for example, that the storage battery 200 is capable of supplying power that allows at least a predetermined evacuation action to be performed in an emergency during autonomous driving. If the vehicle system 10 determines that the backup permission condition is satisfied (step S205, Yes), the process proceeds to step S206. On the other hand, if the vehicle system 10 determines that the backup permission condition is not satisfied (step S205, No), the process proceeds to step S208.

[0022] (Step S206) The vehicle system 10 determines whether or not an action to open the vehicle door (DOOR OPEN) has been performed. This determination is made in order to determine whether or not the parked vehicle is ready for use. The use state of the vehicle can be determined based on whether or not an action to open the vehicle door has been performed when a user gets in the vehicle. If the vehicle system 10 determines that an action to open the vehicle door (DOOR OPEN) has been performed (step S206, YES), the process proceeds to step S207.

[0023] (Step S207) The vehicle system 10 judges whether the state of the vehicle has deteriorated at the time of judging the boarding in the above step S206. Examples of the case where the state of the vehicle has deteriorated include a case where the charge rate (SOC: State Of Charge) of the storage battery 200 is below a predetermined threshold, and a case where the temperature of the storage battery 200 (ambient temperature) is lower than a predetermined threshold. If the vehicle system 10 judges that the state of the vehicle has not deteriorated (step S207, Yes), the process proceeds to step S215. In this case, it can be judged that the transition to the automatic driving mode described later is permitted based on the result of the deterioration detection of the storage battery 200 during parking, and the deterioration detection of the storage battery 200 during boarding when the vehicle is started next time is not required. On the other hand, if the vehicle system 10 judges that the state of the vehicle has deteriorated (step S207, No), the process proceeds to step S208.

[0024] (Step S208) The vehicle system 10 starts the power supply of the vehicle (for example, Ready-ON). This starts the vehicle. When the power supply of the vehicle is started by the vehicle system 10, the process proceeds to step S209.

[0025] (Step S209) The vehicle system 10 performs a predetermined initial check of the vehicle. A well-known technique can be used for the initial check. After the initial check is performed by the vehicle system 10, the process proceeds to step S210.

[0026] (Step S210) The battery ECU 300 measures, as a detection current, a "current drawn by motor drive," which is a current that flows from the storage battery 200 to a vehicle motor (not shown) when the motor is driven. When the detection current (current drawn by motor drive) is measured by the battery ECU 300, the process proceeds to step S211.

[0027] (Step S211) The deterioration detection device 500 detects deterioration of the storage battery 200 (when riding) based on the waveform of the detection current (current drawn by motor drive) measured by performing the initial check in step S210. This deterioration detection of the storage battery 200 can be performed, for example, by analyzing the waveform of the detection current to determine whether the storage battery 200 can stably flow a predetermined current value for a predetermined period of time. When the deterioration detection device 500 detects deterioration of the storage battery 200, the process proceeds to step S212.

[0028] (Step S212) The vehicle system 10 determines whether or not the above-mentioned backup permission condition is satisfied based on the result of the deterioration detection of the storage battery 200 in step S211. If the vehicle system 10 determines that the backup permission condition is satisfied (step S212, Yes), the process proceeds to step S215. On the other hand, if the vehicle system 10 determines that the backup permission condition is not satisfied (step S212, No), the process proceeds to step S213.

[0029] (Step S213) The vehicle system 10 determines whether or not a transition from the manual driving mode to the automatic driving mode is possible, that is, whether or not backup is permitted, based on the current waveform of the in-vehicle load 400 that can be acquired. This determination is performed because there may be a special situation in which backup may be permitted even if the backup permission condition is not satisfied. This special situation can be determined, for example, based on an arbitrary load waveform flowing from the storage battery 200 that can be acquired by the battery ECU 300. When the vehicle system 10 determines whether backup is permitted, the process proceeds to step S214.

[0030] (Step S214) If the vehicle system 10 determines in step S213 that backup permission is possible (step S214, Yes), the process proceeds to step S215. On the other hand, if the vehicle system 10 determines that backup permission is not possible (step S214, No), the process proceeds to step S216.

[0031] (Step S215) The vehicle system 10 permits the vehicle's driving mode to be shifted from the manual driving mode to the automatic driving mode. When the vehicle system 10 permits the vehicle to be shifted to the automatic driving mode, the process returns to step S201.

[0032] (Step S216) The vehicle system 10 prohibits the transition of the vehicle's driving mode from the manual driving mode to the automatic driving mode. When the transition to the automatic driving mode is prohibited by the vehicle system 10, the process returns to step S201.

[0033] <Actions and Effects> As described above, according to the deterioration detection method of one embodiment of the present disclosure, when the vehicle is started or parked, a detection current is passed from the storage battery to a load mounted on the vehicle, the waveform of the detection current flowing through the load mounted on the vehicle is observed, and the presence or absence of deterioration of the storage battery is determined based on the observed waveform of the detection current.

[0034] In this way, the deterioration detection method disclosed herein detects deterioration of a storage battery based on the waveform of the current flowing through a load mounted on a vehicle, so that deterioration detection of the storage battery can be performed with high accuracy even for storage batteries that have a flat region (such as LFP batteries). [Industrial Applicability]

[0035] The deterioration detection method disclosed herein can be used, for example, to detect deterioration of a storage battery mounted on a vehicle. [Explanation of symbols]

[0036] 10 Vehicle Systems 100 Generator 200 Battery 300 battery ECU 400 Vehicle load 500 Deterioration detection device

Claims

[Claim 1] A deterioration detection method for detecting deterioration of a storage battery mounted on a vehicle, comprising: When the vehicle is started or when the vehicle is parked, a detection current is caused to flow from the storage battery to a predetermined load mounted on the vehicle; Observing a waveform of the detection current flowing through the predetermined load; and determining whether or not the storage battery has deteriorated based on the waveform of the observed detection current.

Images