Deterioration prediction device

Abstract

To provide a deterioration prediction method capable of predicting the deterioration time of a battery cell in a battery pack.SOLUTION: A vehicle ECU 13 acquires the respective voltages of a plurality of battery cells BC and vehicle information related to a vehicle, calculates a voltage difference for each prescribed voltage range in a battery pack based on the respective voltages of the plurality of battery cells, counts the voltage difference for each voltage range, and predicts the deterioration time of the battery pack based on the count number of the voltage difference and the vehicle information.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a deterioration prediction device. [Background technology]

[0002] In Patent Document 1, the internal resistance of each battery cell is repeatedly calculated based on the measurement results of the current flowing through a battery pack in which multiple battery cells are connected in series and the measurement results of the cell voltage across each battery cell, and a battery cell in which the change in internal resistance from the previous time to the current time exceeds a judgment value is judged to be a faulty cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-046942 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, since Patent Document 1 merely determines the current state of failure of the battery cell, there has been a demand for a technology that can predict when the battery cells in a battery pack will deteriorate.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide a deterioration prediction device capable of predicting the time when a battery cell in a battery pack will deteriorate. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objective, the deterioration prediction device of the present disclosure is a deterioration prediction device that predicts when a battery pack in which multiple battery cells are connected in series will deteriorate, and is equipped with a processor, wherein the processor acquires the voltage of each of the multiple battery cells and vehicle information related to the vehicle, calculates a voltage difference for each specified voltage range within the battery pack based on the voltage of each of the multiple battery cells, counts the voltage differences for each voltage range, and predicts when the battery pack will deteriorate based on the number of voltage differences counted and the vehicle information. Effect of the Invention

[0007] According to the present disclosure, an effect is achieved in that it is possible to predict when a battery cell in a battery pack will deteriorate. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a vehicle according to an embodiment. [Diagram 2] FIG. 2 is a flowchart showing an overview of a deterioration prediction process for a battery cell BC executed by a vehicle ECU provided in a vehicle according to one embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an overview when a counting unit of a vehicle ECU provided in a vehicle according to one embodiment counts a voltage difference for each voltage range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A vehicle equipped with a deterioration prediction device according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same. Also, each figure referred to in the following description merely shows the shape, size, and positional relationship in a schematic manner to the extent that the contents of the present disclosure can be understood. In other words, the present disclosure is not limited to only the shape, size, and positional relationship exemplified in each figure.

[0010] [Overall vehicle configuration] Fig. 1 is a diagram showing a schematic configuration of a vehicle according to an embodiment. The vehicle 1 shown in Fig. 1 is assumed to be a hybrid electric vehicle (HEV) or plug-in hybrid electric vehicle (PHEV) equipped with a motor and an engine. Note that the vehicle 1 may also be a battery electric vehicle (BEV) or fuel cell electric vehicle (FCEV) equipped with only a motor as a power source.

[0011] As shown in FIG. 1, vehicle 1 includes an engine 2, a motor 3, a transmission 4 (hereinafter simply referred to as "TM4"), an engine ECU (Electronic Control Unit) 5, an inverter 6, a battery pack 7, an equalization circuit 8, an integrated circuit 9 (hereinafter simply referred to as "IC9") that drives the equalization circuit 8 and measures cell voltage values, a current sensor 10, a battery ECU 11, a motor ECU 12, and a vehicle ECU 13.

[0012] The engine 2 is a known internal combustion engine. Under the control of an engine ECU 5, the engine 2 outputs driving force to the TM 4 using fuel supplied from a fuel tank (not shown).

[0013] The motor 3 is configured using a permanent magnet motor or a magnetless motor. The motor 3 has the functions of driving the vehicle, starting the engine, generating electricity, and regenerative braking. When the vehicle is traveling, the motor 3 outputs driving force based on electric power from the battery pack 7 to the TM4 via the inverter 6. In addition, when regenerating electricity, the motor 3 generates electricity using an external force transmitted via the TM4. The generated electric power is output to the battery pack 7 via the inverter 6.

[0014] TM4 transmits the driving force of the engine 2 and the motor 3 to driving wheels (not shown). In addition, TM4 transmits an external force from the driving wheels to the motor 3 during regeneration.

[0015] The engine ECU 5 is configured using a processor having hardware such as a memory and a CPU (Central Processing Unit). The engine ECU 5 controls the driving force of the engine 2 under the control of the vehicle ECU 13. Specifically, the engine ECU 5 controls the torque and rotation speed of the engine 2 based on a torque signal indicating the amount of torque input from the vehicle ECU 13, and controls operation and stopping of the engine 2.

[0016] The inverter 6 has a function of converting DC power supplied from the battery pack 7 into AC power and supplying it to drive, for example, the motor 3, which serves as a power source for traveling, and a function of converting AC power supplied from the motor 3 into DC power for charging the battery. Specifically, the inverter 6 converts the DC power of the battery pack 7 into AC power and supplies it to the motor 3, causing the motor 3 to generate a driving force for traveling. The inverter 6 also inversely converts the regenerative AC power of the motor 3 into DC power to charge the battery pack 7. The inverter 6 may further have a DC / DC conversion function of increasing or decreasing the voltage of the DC power.

[0017] The battery pack 7 is an assembled battery formed by connecting multiple battery cells BC1, BC2, BC3, ..., BCn (where n is an integer of 4 or more) in series. In the following, when the battery cells BC1, BC2, BC3, ..., BCn are referred to without distinction, they will simply be referred to as battery cells BC. In the following, an example in which four or more battery cells BC are included will be described, but two or more cells will suffice. Each of the battery cells BC is a secondary battery that can be charged and discharged, such as a lithium ion battery. An inverter 6 is electrically connected to the battery pack 7 via a positive line PL1 and a negative line NL1.

[0018] System main relays SMR1, SMR2 ​​are provided in the positive line PL1 and the negative line NL1 between the battery pack 7 and the inverter 6. The system main relays SMR1, SMR2 ​​are turned on by the battery ECU 11 to enable power supply from the battery pack 7 to the inverter 6 (i.e., the motor 3). That is, the system main relays SMR1, SMR2 ​​are controlled to be turned on and off by receiving a control signal from the battery ECU 11.

[0019] The equalization circuit 8 is connected to each of the battery cells BC that make up the battery pack 7. The equalization circuit 8 has discharge resistors R1, R2, a switching element FET, a voltage sensor 81, and a capacitor C1.

[0020] The discharge resistor R1 is electrically connected to the positive electrode terminal of each battery cell BC, and the discharge resistor R2 is electrically connected to the negative electrode terminal of each battery cell BC.

[0021] The switching element FET is electrically connected between the discharge resistor R1 and the discharge resistor R2. A field effect transistor such as a MOSFET can be suitably used as the switching element FET. The switching element FET is on / off controlled by receiving a control signal from the battery ECU 11. Specifically, the switching element FET is turned on by receiving a gate-on signal from the battery ECU 11. A short circuit is formed in the battery cell BC corresponding to the turned-on switching element FET, in which a current flows through the discharge resistor R1, the switching element FET, and the discharge resistor R2 in that order. As a result, the power of the battery cell BC in which the switching element FET is turned on is consumed by the discharge resistors R1 and R2. As a result, an equalization process can be performed in which the SOC or voltage of a specific battery cell BC is reduced to match the SOC or voltage of the other battery cells BC.

[0022] The voltage sensor 81 is electrically connected in parallel to the battery cell BC. The voltage sensor 81 detects the open end voltage (cell voltage) of the battery cell BC, and outputs this detection result to the battery ECU 11 and the vehicle ECU 13. In one embodiment, the switching element FET and the voltage sensor 81 of each equalization circuit 8 are configured as an IC 9 covered by a resin mold 20. In addition, the voltage sensor 81 detects the capacitor voltage of the capacitor C1, and outputs this detection result to the battery ECU 11 and the vehicle ECU 13.

[0023] The capacitor C1 has a function of stabilizing the voltage of the battery cell BC detected by the voltage sensor 81. The capacitor C1 is electrically connected to the battery cell BC and the voltage sensor 81 in parallel.

[0024] The current sensor 10 is electrically connected in series to the battery pack 7. The current sensor 10 detects the current value of the battery pack 7, and outputs the detection result to the vehicle ECU 13. The current sensor 10 is configured using an operational amplifier and the like.

[0025] The battery ECU 11 is configured using a processor having hardware such as a memory and a CPU, etc. The battery ECU 11 controls charging and discharging of the battery pack 7 under the control of the vehicle ECU 13.

[0026] The motor ECU 12 is configured using a processor having hardware such as a memory and a CPU (Central Processing Unit), etc. Under the control of the vehicle ECU 13, the motor ECU 12 controls the voltage and current of the motor 3 via the inverter 6, and controls the torque and rotation speed of the motor 3.

[0027] The vehicle ECU 13 is configured using a processor having hardware such as a memory and a CPU. The vehicle ECU 13 acquires vehicle information, calculates the driving force of the vehicle 1 based on the acquired vehicle information, and generates and outputs a torque signal including a torque command for driving the engine 2 and the motor 3. Here, the vehicle information includes the vehicle speed of the vehicle 1 from the speed sensor, the shift position of the transmission, the depression pressure of the brake pedal, the accelerator opening of the accelerator pedal, the mileage from the odometer, the current position of the vehicle 1 from the navigation system, date data from the clock, and the like. The vehicle ECU 13 also controls the engine ECU 5 to control the operation and stop, torque, and rotation speed of the engine 2, and controls the motor ECU 12 to control the operation and stop, torque, and rotation speed of the motor 3. The vehicle ECU 13 also includes an acquisition unit 131, a calculation unit 132, a count unit 133, a determination unit 134, a prediction unit 135, and an output control unit 136. In one embodiment, the vehicle ECU 13 functions as a deterioration prediction device.

[0028] The acquisition unit 131 acquires the voltage and vehicle information of each of the battery cells BC. Specifically, the acquisition unit 131 acquires the voltage (voltage value) from the voltage sensor 81 of each of the battery cells BC. Furthermore, the acquisition unit 131 acquires vehicle information from an accelerator pedal (not shown) or the like.

[0029] The calculation unit 132 calculates a voltage difference in the battery pack 7 based on the voltages of the plurality of battery cells BC acquired by the acquisition unit 131.

[0030] The counting unit 133 counts the voltage difference for each predetermined voltage range based on the voltage difference calculated by the calculation unit 132.

[0031] The determination unit 134 determines whether the count number is increasing based on the count number of the voltage difference for each voltage range counted by the count unit 133 and the travel distance of the vehicle 1.

[0032] The prediction unit 135 predicts the deterioration time of the battery pack 7 based on the count number for each voltage difference and the vehicle information.

[0033] The output control unit 136 outputs the deterioration timing of the battery pack 7 predicted by the prediction unit 135 to a display monitor (not shown) or an external server that manages the vehicle 1, etc.

[0034] [Battery cell BC deterioration prediction process] Next, a description will be given of the deterioration prediction process for the battery cells BC executed by the vehicle ECU 13. Fig. 2 is a flowchart showing an overview of the deterioration prediction process for the battery cells BC executed by the vehicle ECU 13.

[0035] 2, first, the acquisition unit 131 acquires the voltage of each of the multiple battery cells BC and vehicle information (step S101). Specifically, the acquisition unit 131 acquires the voltage (voltage value) from the voltage sensor 81 of each of the multiple battery cells BC. Furthermore, the acquisition unit 131 acquires vehicle information including the accelerator opening from an accelerator pedal (not shown), the mileage from an odometer, the speed from a speed sensor, the current position of the vehicle 1 from a navigation system, and date data from a clock.

[0036] Next, the calculation unit 132 calculates a voltage difference in the battery pack 7 based on the voltages of the plurality of battery cells BC acquired by the acquisition unit 131 (step S102).

[0037] The counting unit 133 counts the voltage difference for each voltage range based on the voltage difference calculated by the calculation unit 132 (step S103).

[0038] FIG. 3 is a diagram showing a schematic overview of the counting unit 133 counting the voltage difference for each voltage range. In FIG. 3, the horizontal axis indicates the time or the travel distance of the vehicle 1 included in the vehicle information, and the vertical axis indicates the number of counts. Also, in FIG. 3, lines L1 to L6 indicate the count of the voltage difference for each voltage range, and line L7 indicates the total count value of the count of the voltage difference for each voltage range. Here, the predetermined voltage range is, for example, every 0.0050 (v), as shown by lines L1 and L2 in FIG. 3. The voltage range can be changed as appropriate. Line L5 in FIG. 3 is the total of the count numbers of lines L3 and L4.

[0039] 3, the counting unit 133 counts the voltage difference for each voltage range based on the voltage difference calculated by the calculation unit 132. After step S103, the vehicle ECU 13 proceeds to step S104, which will be described later.

[0040] Returning to FIG. 2, the description of step S104 and subsequent steps will be continued. The determination unit 134 determines whether the count number is increasing based on the count number of the voltage difference for each voltage range counted by the count unit 133 and the travel distance of the vehicle 1. Normally, the battery pack 7 is subjected to an equalization process to match the voltage of each battery cell BC with that of the other battery cells BC in order to prevent a voltage difference from occurring in each battery cell BC by the equalization circuit 8. However, if an abnormality occurs in any of the battery cells BC, a voltage difference occurs. For this reason, as shown by the straight lines L3 and L4 in FIG. 3, the determination unit 134 determines that the count number is increasing at the timing t1 because the count number counted by the count unit 133 increases as the travel distance of the vehicle 1 increases. If the determination unit 134 determines that the count number is increasing (step S104: Yes), the vehicle ECU 13 proceeds to step S105 described later. On the other hand, if the determination unit 134 determines that the count number is not increasing (step S104: No), the vehicle ECU 13 ends this process.

[0041] In step S105, the prediction unit 135 predicts the deterioration time of the battery pack 7 based on the count number for each voltage difference and the vehicle information. Here, the deterioration timing (criteria area) of the battery pack 7 correlates with a value (area) obtained by multiplying the count number of the voltage difference for each voltage range counted by the count unit 133 by the travel distance included in the vehicle information. For this reason, the prediction unit 135 calculates the slope of each straight line indicating the cumulative total of the count number for each voltage range based on the count number of the voltage difference for each voltage range counted by the count unit 133 up to the timing t1 at which the count number was increased by the determination unit 134 and the travel distance included in the vehicle information up to the timing t1 at which the count number was increased by the determination unit 134. Then, the prediction unit 135 predicts the deterioration time of the battery pack 7 from the slope of each straight line. 3, the prediction unit 135 estimates the mileage from the count number estimated from the gradient of lines L1 to L6 based on the count numbers of the voltage differences for each voltage range at the timing t1 at which the determination unit 134 determines that the count number is increasing for the preset criteria area, and from the preset criteria area, and estimates the estimated mileage as the deterioration time (failure timing t2) of the battery pack 7. Note that the prediction unit 135 may predict the deterioration time of the battery pack 7 by dividing the estimated mileage by the average mileage of the vehicle 1 in one day.

[0042] Next, the output control unit 136 outputs the deterioration result of the battery pack 7 predicted by the prediction unit 135 (the timing of the mileage estimated in step S105) to a display monitor (not shown) or an external server that manages the vehicle 1 (step S106). This allows the user to know the deterioration timing of the battery pack 7. After step S106, the vehicle ECU 13 ends this process.

[0043] According to the embodiment described above, the prediction unit 135 predicts the deterioration time of the battery pack 7 based on the number of counts for each voltage difference and the mileage of the vehicle 1 included in the vehicle information, so that the user can know the deterioration time of the battery pack 7.

[0044] According to the embodiment described above, the prediction unit 135 predicted the deterioration time of the battery pack 7 based on the number of counts for each voltage difference and the mileage of the vehicle 1 included in the vehicle information. However, instead of the mileage of the vehicle 1 included in the vehicle information, the prediction unit 135 may estimate the number of days from a preset criteria area based on the number of days measured by the judgment unit 134 up to the timing t1 at which the count number was increased by the judgment unit 134, and may predict the deterioration time of the battery pack 7 by inferring the date based on this estimated number of days as the deterioration time of the battery pack 7 (failure timing t2).

[0045] Furthermore, in the deterioration prediction device according to one embodiment, the above-mentioned "ECU" can be read as a "control circuit," a "control means," a "control device," and the like.

[0046] In the description of the flowcharts in this specification, the order of processing between steps is clearly indicated using expressions such as "first," "then," and "continue," but the order of processing required to implement this embodiment is not uniquely determined by these expressions. In other words, the order of processing in the flowcharts described in this specification can be changed as long as there is no contradiction.

[0047] Further advantages and modifications may readily occur to those skilled in the art. The invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Thus, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

[0048] Although some of the embodiments of the present application have been described in detail above with reference to the drawings, these are merely examples, and the present invention can be embodied in other forms that incorporate various modifications and improvements based on the knowledge of those skilled in the art, including the forms described in the disclosure of the present invention. [Explanation of symbols]

[0049] 1 vehicle 2 Engine 3 Motor 4. Transmission 5. Engine ECU 6 Inverter 7 Battery Pack 8 Equalization circuit 9 Integrated Circuits 10 Current Sensor 11 Battery ECU 12 Motor ECU 13 Vehicle ECU 20 Resin mold 81 Voltage Sensor 131 Acquisition Department 132 Calculation section 133 Counting Department 134 Judgment section 135 Prediction Department 136 Output control section BC Battery Cell

Claims

1. A deterioration prediction device for predicting a deterioration time of a battery pack in which a plurality of battery cells are connected in series, comprising: A processor is provided. The processor, acquiring a voltage of each of the plurality of battery cells and vehicle information related to the vehicle; calculating a voltage difference for each predetermined voltage range in the battery pack based on the voltages of the respective battery cells; Counting the voltage difference for each of the voltage ranges; predicting a deterioration time of the battery pack based on the count number of the voltage difference and the vehicle information; Deterioration prediction device.

2. The deterioration prediction device according to claim 1, The processor, determining whether the count number is increasing based on the count number and the vehicle information; When it is determined that the count number is increasing, the deterioration time is predicted. Deterioration prediction device.

3. The deterioration prediction device according to claim 2, The vehicle information includes: A distance traveled by the vehicle up until a time when it is determined that the count number is increasing. Deterioration prediction device.

4. The deterioration prediction device according to claim 2, The vehicle information includes: The number of days that have passed since the vehicle was in operation until the time when it is determined that the count number has increased. Deterioration prediction device.

5. The deterioration prediction device according to claim 2, The processor, outputting the deterioration time to an external device; Deterioration prediction device.

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