Electric vehicle and method for diagnosing deterioration of vehicle battery

Abstract

To diagnose whether a battery undergoes rapid deterioration when large electric current is applied to the battery due to counter-electromotive force.SOLUTION: When a PCU (inverter) of an electric vehicle fails, whether a battery undergoes rapid deterioration is determined using a first map with a battery temperature TB and electric current IB as parameters or a second map with the temperature TB and a change rate ΔVB of battery voltage VB as parameters (S12 and S13). When the battery is determined to undergo the rapid deterioration, a battery replacement warning lamp is illuminated (S14).SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle and a method for diagnosing degradation of a vehicle battery.

Background Art

[0002] As electric vehicles equipped with a battery as a power source, battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), etc. are known. In an electric vehicle, the electric power stored in the battery is supplied to a motor generator (MG) that drives the drive wheels using a power control unit (PCU) as a power conversion device, and the drive wheels are driven.

[0003] In Japanese Patent Application Laid-Open No. 2021-83188 (Patent Document 1), in an electric vehicle equipped with two MGs, when an abnormality in an inverter that drives one MG and peripheral devices of the inverter is detected, the gate command of the inverter is cut off, and the other MG is driven to perform a retreat running. At the same time, when the back electromotive voltage (back electromotive force) due to the regeneration of one MG becomes higher than the battery voltage, the main relay of the battery is opened to enable the retreat running of the electric vehicle to continue.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The MG includes windings (coils). When an abnormality or failure occurs in the device that controls the MG, at the same time as the occurrence of the abnormality or failure, a counter electromotive force is generated by the induced voltage of the coil, and there is a possibility that the counter electromotive force is applied to the battery. When this counter electromotive force occurs, a large current is instantaneously generated, so there is a possibility that the large current is applied to the battery before the protection function such as shutting off the main relay operates.

[0006] When a large current is applied to the battery, the damage to the battery is significant, and the battery may deteriorate rapidly. Hereinafter, the rapid deterioration of the battery is also referred to as "rapid degradation". Patent Document 1 does not mention that the battery rapidly deteriorates due to the counter electromotive force.

[0007] The object of the present disclosure is to diagnose whether the battery has rapidly deteriorated when a large current due to the counter electromotive force is applied to the battery.

Means for Solving the Problem

[0008] The electric vehicle of the present disclosure is an electric vehicle including a battery, a motor generator driven by the electric power stored in the battery, and a diagnostic device that diagnoses the deterioration of the battery. The diagnostic device is configured to determine whether rapid deterioration has occurred in the battery based on the temperature of the battery and the current value input to the battery when a counter electromotive force is applied to the battery, or based on the temperature of the battery and the rate of change of the battery voltage.

[0009] When a counter electromotive force is applied to the battery and a large current is input, for example, lithium precipitation occurs in a lithium-ion battery. In particular, the lower the battery temperature, the easier it is for lithium precipitation to occur. Also, when a large current is input to the battery, the voltage of the battery rises rapidly, and the rate of change of the voltage (the amount of voltage change per unit time) increases. When the rate of change of the battery voltage is large, the internal resistance deteriorates (increases) rapidly. In particular, the higher the battery temperature, the greater the increase in the internal resistance.

[0010] According to this configuration, when a counter electromotive force is applied to the battery, the diagnostic device for the electric vehicle determines whether or not rapid deterioration has occurred in the battery based on the temperature of the battery and the current value input to the battery. Alternatively, when a counter electromotive force is applied to the battery, the diagnostic device determines whether or not rapid deterioration has occurred in the battery based on the temperature of the battery and the rate of change of the battery voltage. Thereby, when a large current due to the counter electromotive force is applied to the battery, it is possible to diagnose whether or not the battery has deteriorated rapidly.

[0011] Preferably, the electric vehicle further includes a power control unit that supplies the power stored in the battery to the motor generator and controls the motor generator. When the diagnostic device determines that the power control unit has failed, it determines that the counter electromotive force is applied to the battery. The diagnostic device may determine whether or not rapid deterioration has occurred in the battery based on the temperature of the battery and the current value input to the battery, or based on the temperature of the battery and the rate of change of the battery voltage.

[0012] When the power control unit fails, there is a possibility that a counter electromotive force is generated by the induced voltage of the coil (winding) of the motor generator simultaneously with the failure. According to this configuration, when this counter electromotive force occurs and a large current is input to the battery, it is possible to determine whether or not rapid deterioration has occurred in the battery.

[0013] Preferably, the diagnostic device has a first map using the temperature of the battery and the current value input to the battery as parameters, and a second map using the temperature of the battery and the rate of change of the battery voltage as parameters, and determines whether or not rapid deterioration of the battery has occurred using the first map or the second map. In this case, the first map may be set to determine that rapid deterioration of the battery has occurred in a region where the temperature of the battery is low and the current value input to the battery is large, and the second map may be set to determine that rapid deterioration of the battery has occurred in a region where the temperature of the battery is high and the rate of change of the battery voltage is large.

[0014] According to this configuration, by performing map search (map matching) using the first map or the second map, rapid deterioration of the battery can be detected (judged). The first map or the second map can be created (set) in advance according to, for example, the specifications (characteristics) and types of the battery, and can preferably detect rapid deterioration.

[0015] Preferably, when the diagnostic device determines that rapid deterioration has occurred in the battery based on the temperature of the battery and the current value input to the battery, or when it determines that rapid deterioration has occurred in the battery based on the temperature of the battery and the rate of change of the battery voltage, the diagnostic device may diagnose that the battery needs to be replaced.

[0016] According to this configuration, when it is determined that rapid deterioration has occurred in the battery, since it is diagnosed that the battery needs to be replaced, it becomes possible to preferably determine whether the battery needs to be replaced when a counter electromotive force is applied to the battery.

[0017] Preferably, when the diagnostic device determines that rapid deterioration has occurred in the battery based on the temperature of the battery and the current value input to the battery, and also determines that rapid deterioration has occurred in the battery based on the temperature of the battery and the rate of change of the battery voltage, the diagnostic device may diagnose that the battery needs to be replaced.

[0018] According to this configuration, when it is determined that rapid deterioration has occurred in the battery by using the parameter of the current value input to the battery and the rate of change of the battery voltage, since it is diagnosed that the battery needs to be replaced, it becomes possible to preferably determine whether the battery needs to be replaced when a counter electromotive force is applied to the battery.

[0019] The method for diagnosing the deterioration of a battery for an electric vehicle according to the present disclosure is a method for diagnosing the deterioration of a vehicle battery mounted as a power source in an electric vehicle. The method for diagnosing the vehicle battery includes a step of determining whether a counter electromotive force is applied to the battery, and a step of determining whether rapid deterioration has occurred in the vehicle battery based on the temperature of the vehicle battery and the current value input to the vehicle battery when the counter electromotive force is applied to the vehicle battery.

[0020] According to this method, when it is determined that a counter electromotive force is applied to the vehicle battery, it is determined whether rapid deterioration has occurred in the vehicle battery based on the temperature of the vehicle battery and the current value input to the vehicle battery. Thereby, when a large current due to the counter electromotive force is applied to the vehicle battery, it is possible to diagnose whether the vehicle battery has rapidly deteriorated.

[0021] Preferably, the method for diagnosing the deterioration of the vehicle battery may further include a step of determining whether rapid deterioration has occurred in the vehicle battery based on the temperature of the vehicle battery and the rate of change of the voltage of the vehicle battery when the counter electromotive force is applied to the vehicle battery.

[0022] According to this method, when it is determined that a counter electromotive force is applied to the vehicle battery, it is determined whether rapid deterioration has occurred in the vehicle battery based on the temperature of the vehicle battery and the rate of change of the voltage of the vehicle battery. Thereby, when a large current due to the counter electromotive force is applied to the vehicle battery, it is also possible to diagnose whether the vehicle battery has rapidly deteriorated based on the temperature of the vehicle battery and the rate of change of the voltage of the vehicle battery.

Advantages of the Invention

[0023] According to the present disclosure, when a large current due to a counter electromotive force is applied to the battery, it is possible to diagnose whether the battery has rapidly deteriorated.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions are not repeated.

[0026] FIG. 1 is an overall configuration diagram of an electric vehicle according to the present embodiment. In the present embodiment, the electric vehicle 1 is, for example, an electric car. The electric vehicle 1 includes a motor generator (MG) 10 that is a rotary electric machine, a power transmission gear 20, drive wheels 30, a power control unit (PCU) 40, a system main relay (SMR) 50, a battery 100, a monitoring unit 200, and an electronic control unit (ECU) 300 that controls the electric vehicle 1.

[0027] The MG 10 is, for example, an interior permanent magnet synchronous motor (IPM motor), and has a function as an electric motor (motor) and a function as a generator (generator). The output torque of the MG 10 is transmitted to the drive wheels 30 via a power transmission gear 20 configured to include a speed reducer, a differential device, and the like.

[0028] When the electric vehicle 1 is braking, the MG10 is driven by the drive wheels 30, and the MG10 operates as a generator. Thereby, the MG10 also functions as a braking device that performs regenerative braking to convert the kinetic energy of the electric vehicle 1 into electric power. The regenerative power generated by the regenerative braking force in the MG10 is stored in the battery 100.

[0029] The PCU 40 is a power conversion device that converts power bidirectionally between the MG10 and the battery 100. The PCU 40 includes an inverter (three-phase inverter) that converts the DC power of the battery 100 into AC power to drive the MG10. The inverter converts the AC power (regenerative power) generated by the MG10 into DC power and supplies it to the battery 100. Note that the PCU 40 may include a DC / DC converter that steps up and down the DC power.

[0030] The SMR 50 is electrically connected to the power line connecting the battery 100 and the PCU 40. When the SMR 50 is closed (ON) in response to a control signal from the ECU 300 (i.e., in a conductive state), power can be transferred between the battery 100 and the PCU 40. On the other hand, when the SMR 50 is opened (OFF) in response to a control signal from the ECU 300 (i.e., in a cut-off state), the electrical connection between the battery 100 and the PCU 40 is cut off.

[0031] The battery 100 stores power for driving the MG10. The battery 100 is a rechargeable DC power source (secondary battery), and a plurality of single cells (battery cells) are stacked and configured, for example, to be electrically connected in series. In the present embodiment, the single cell of the battery 100 is composed of a lithium-ion battery. The electric vehicle 1 is provided with a charging inlet, a charging circuit, etc. (not shown), and the battery 100 is charged using an external power source.

[0032] The monitoring unit 200 includes a voltage sensor 210, a current sensor 220, and a temperature sensor 230. The voltage sensor 210 detects the voltage VB of the battery 100 (single battery (cell)). The current sensor 220 detects the current IB input to and output from the battery 100. The temperature sensor 230 detects the temperature TB of the battery 100. Each sensor outputs its detection result to the battery ECU (BT-ECU) 400.

[0033] The ECU 300 includes a CPU (Central Processing Unit) 301 and a memory 302 (including, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory), etc.). The ECU 300 controls each device so that the electric vehicle 1 is in a desired state based on the state of the battery 100 transmitted from the BT-ECU 400, signals from various sensors (not shown) (such as an accelerator opening signal, a vehicle speed signal, etc.), etc., and information such as maps and programs stored in the memory 302.

[0034] The BT-ECU 400 includes a CPU, a memory (not shown), and calculates the SOC (State Of Charge) indicating the power storage amount of the battery 100 based on the current IB and / or the voltage VB output from the monitoring unit 200. The SOC is represented as a percentage of the current power storage amount with respect to the full charge capacity of the battery 100. Then, the BT-ECU 400 outputs the calculated SOC to the ECU 300.

[0035] The MG-ECU 500 includes a CPU, a memory, a drive circuit for driving the PCU 40 (not shown), etc., and performs drive control of, for example, the switching elements of the inverter based on a drive command transmitted from the ECU 300.

[0036] The HMI-ECU 600 includes a CPU and a memory (not shown), and controls the HMI (Human Machine Interface) device 700. The HMI device 700 may be, for example, a multi-information display provided on the dashboard of the electric vehicle 1. In the present embodiment, the HMI device 700 is provided with a PCU failure display section (PCU failure warning lamp) 701 and a battery replacement display section (battery replacement warning lamp) 702.

[0037] MG10 includes a winding (coil). When an abnormality occurs in the PCU 40, for example, when an abnormality occurs in the switching element of the inverter, when an abnormality occurs in each phase current sensor of MG10, when an abnormality occurs in the circuit (for example, ECU) of the MG-ECU 5 00, etc., when an abnormality occurs in the PCU 40 or its peripheral devices and malfunctions, at the same time as the occurrence of the abnormality or failure, a back electromotive force is generated by the induced voltage of the coil, and there is a possibility that the back electromotive force is applied to the battery 100. When this back electromotive force occurs, a large current is instantaneously generated, so there is a possibility that a large current is applied to the battery 100 before the protection function such as shutting off the SMR50 operates.

[0038] When a large current is applied to the battery 100, the damage to the battery 100 is significant, and the battery 100 may deteriorate rapidly (rapid deterioration). When the battery 100 deteriorates rapidly, the capacity may be significantly reduced or there may be significant heat generation during charging and discharging, so it is preferable to replace the battery 100.

[0039] In the present embodiment, when a large current due to the back electromotive force is applied to the battery 100, it is diagnosed whether the battery 100 has deteriorated rapidly. And when the battery 100 has deteriorated rapidly, by notifying that the battery 100 needs to be replaced, it becomes possible to suitably determine whether the battery 100 needs to be replaced when the back electromotive force is applied to the battery 100.

[0040] FIG. 2 is a diagram showing an example of the diagnostic device Dd in the present embodiment. In the present embodiment, the diagnostic device Dd is a functional block configured by an ECU 300, a BT-ECU 400, and an MG-ECU 500. The INV failure determination unit 510 is a functional block configured in the MG-ECU 500, and determines whether or not the PCU 40 has failed. The INV failure determination unit 510 determines that the PCU 40 has failed when an abnormality occurs in the inverter of the PCU 40. In addition to when an abnormality occurs in the inverter, the INV failure determination unit 510 may determine that the PCU 40 has failed when the MG 10 cannot be normally controlled by the PCU 40. For example, when an abnormality occurs in each phase current sensor of the MG 10 or when an abnormality occurs in the CPU of the MG-ECU 5 00, etc. When the INV failure determination unit 510 determines that the PCU 40 has failed, it outputs a failure signal to the HMI control unit 310 and the rapid deterioration diagnosis unit 410. Thus, in the present embodiment, when an event occurs in which the MG 10 cannot be normally controlled by the PCU 40, it is estimated that a large current is applied to the battery 100, the damage to the battery 100 increases, and the battery 100 may rapidly deteriorate (rapid deterioration).

[0041] The HMI control unit 310 is a functional block configured in the ECU 300, and outputs a notification command to the HMI-ECU 6 00. When the HMI control unit 310 receives a failure signal from the INV failure determination unit 510, it outputs a notification command to the HMI-ECU 600 to perform a failure notification. When the HMI-ECU 600 receives a notification command for a failure notification, it performs a failure display (lights up the PCU failure warning lamp) on the PCU failure display unit 701.

[0042] The rapid deterioration diagnosis unit 410 is a functional block configured in the BT-ECU 400. When the rapid deterioration diagnosis unit 410 receives a failure signal from the INV failure determination unit 510, it determines whether or not the battery 100 has rapidly deteriorated. In the present embodiment, the rapid deterioration diagnosis unit 410 receives a failure signal via the ECU 300, but it may also receive it directly from the MG-ECU 500 without going through the ECU 300.

[0043] When the rapid degradation diagnosis unit 410 receives a failure signal from the INV failure determination unit 510, it determines whether the battery 100 has rapidly degraded based on the current IB and the temperature TB. FIG. 3 is a diagram showing an example of a first map for determining the rapid degradation of the battery 100. In FIG. 3, the horizontal axis represents the current IB, and the vertical axis represents the temperature TB. When a back electromotive force is applied to the battery 100, the current IB is input to the battery 100. In FIG. 3, the current value in the direction input to the battery 100 is defined as positive. In the first map shown in FIG. 3, "○" indicates a region where no rapid degradation of the battery 100 has occurred, and "×" indicates a region where rapid degradation of the battery 100 has occurred. The region where rapid degradation of the battery 100 occurs varies depending on the specifications (characteristics), type, etc. of the battery 100, and the first map is set in advance through experiments or the like. In the present embodiment, as shown in FIG. 3, in the first map, the region where rapid degradation of the battery 100 occurs is set in a region where the temperature TB is low and the current IB is large. This is because the lower the temperature TB and the larger the current IB (input current), the easier it is for lithium to precipitate.

[0044] When the rapid degradation diagnosis unit 410 receives a failure signal from the INV failure determination unit 510, it monitors the current IB and the temperature TB for several seconds from the time of receiving the failure signal. Then, when the current IB and the temperature TB enter the "×" region of the first map, the rapid degradation diagnosis unit 410 determines that rapid degradation has occurred in the battery 100.

[0045] Further, when the rapid deterioration diagnosis unit 410 receives a failure signal from the INV failure determination unit 510, it determines whether the battery 100 has rapidly deteriorated based on the change rate ΔVB of the voltage VB and the temperature TB. FIG. 4 is a diagram showing an example of a second map for determining the rapid deterioration of the battery 100. In FIG. 4, the horizontal axis is the change rate ΔVB of the voltage VB, and the vertical axis is the temperature TB. The change rate ΔVB of the voltage VB is the time derivative of the voltage VB (V / sec) and is the amount of change in the voltage VB per unit time. For example, the BT-ECU 400 calculates the change rate ΔVb of the voltage VB by dividing the detected value (voltage VB) of the voltage sensor 210 by the operation period at every predetermined operation period (for example, every several msec to several tens of msec). Then, the simple moving average of the change rate ΔVb calculated for each operation period is obtained as the change rate ΔVB. For example, the average value of the latest 10 change rates ΔVb may be obtained as the change rate ΔVB.

[0046] In the second map shown in FIG. 4, "○" indicates a region where rapid deterioration of the battery 100 has not occurred, and "×" indicates a region where rapid deterioration of the battery 100 has occurred. The region where rapid deterioration occurs in the battery 100 varies depending on the specifications (characteristics), type, etc. of the battery 100, and the second map is set in advance by experiments or the like. In the present embodiment, as shown in FIG. 4, in the second map, the region where rapid deterioration of the battery 100 occurs is set in a region where the temperature TB is high and the change rate ΔVB is large. This is to cope with the increase in overvoltage due to the increase in internal resistance caused by the deterioration of the battery 100.

[0047] When the rapid deterioration diagnosis unit 410 receives a failure signal from the INV failure determination unit 510, it monitors the change rate ΔVB of the temperature TB and the voltage VB for several seconds from the time of receiving the failure signal. When the temperature TB and the change rate ΔVB fall within the "×" area of the second map, the rapid deterioration diagnosis unit 410 determines that rapid deterioration has occurred in the battery 100. In the present embodiment, the voltage VB is the voltage (cell voltage) of a single battery (battery cell) of the battery 100, and the monitoring unit 200 detects the cell voltage of each single battery. When the change rate ΔVB of the cell voltage of at least one single battery falls within the "×" area of the second map, the rapid deterioration diagnosis unit 410 determines that rapid deterioration has occurred in the battery 100.

[0048] When the rapid deterioration diagnosis unit 410 determines that rapid deterioration has occurred in the battery 100, it outputs a deterioration signal to the HMI control unit 310. When the HMI control unit 310 receives the deterioration signal from the rapid deterioration diagnosis unit 410, it outputs a notification command to the HMI-ECU 600 to notify the replacement of the battery 100. When the HMI-ECU 600 receives the notification command for replacement notification, it displays on the battery replacement display unit 702 (turns on the battery replacement warning light).

[0049] FIG. 5 is a flowchart showing an example of the rapid deterioration diagnosis process executed by the diagnostic device Dd. This flowchart is executed at regular intervals. In step (hereinafter, step is abbreviated as "S") 10, it is determined whether an abnormality has occurred in the inverter and the inverter has failed. If it is determined that the inverter has failed, an affirmative determination is made and the process proceeds to S11. When it is determined that the inverter has not failed, a negative determination is made and the current routine ends. In the present embodiment, when an event occurs in which the MG10 cannot be normally controlled by the PCU 40, a large current is applied to the battery 100, the damage to the battery 100 increases, and it is estimated that the battery 100 may deteriorate rapidly (rapid deterioration). Therefore, in S10, as described above, in addition to the occurrence of an abnormality in the inverter, when the MG10 cannot be normally controlled by the PCU 40, it may be determined that a failure has occurred in the inverter.

[0050] In S11, after turning on the PCU failure warning lamp (after the failure display is performed by the PCU failure display unit 701), the process proceeds to S12. In S12, the current IB and the temperature TB are monitored for several seconds since the positive determination in S10, and it is determined whether the current IB and the temperature TB enter the "×" area of the first map. When the current IB and the temperature TB enter the "×" area of the first map and a positive determination is made, the process proceeds to S14. If the current IB and the temperature TB do not enter the "×" area of the first map, a negative determination is made and the process proceeds to S13.

[0051] In S13, the change rate ΔVB of the current IB and the voltage VB is monitored for several seconds since the positive determination in S10, and it is determined whether the temperature TB and the change rate ΔVB enter the "×" area of the second map. When the temperature TB and the change rate ΔVB enter the "×" area of the second map and a positive determination is made, the process proceeds to S14. If the temperature TB and the change rate ΔVB do not enter the "×" area of the second map, a negative determination is made and the current routine ends.

[0052] In S14, it is determined that rapid deterioration has occurred in the battery 100. Also, in S14, after turning on the battery replacement warning lamp (after the display of the battery replacement display unit 702), the current routine ends.

[0053] According to the present embodiment, when the PCU 40 fails and a counter electromotive force is applied to the battery 100, the diagnostic device Dd determines whether rapid deterioration has occurred in the battery 100 based on the temperature TB of the battery 100 and the current IB input to the battery, or based on the temperature TB and the change rate ΔVB of the voltage VB of the battery 100. Then, when the diagnostic device Dd determines that rapid deterioration has occurred in the battery 100, the diagnostic device Dd performs the display of the battery replacement display unit 702 (turns on the battery replacement warning lamp) and notifies that it is necessary to replace the battery 100. Thereby, when a large current due to the counter electromotive force is applied to the battery 100, it is possible to diagnose whether the battery 100 has rapidly deteriorated, and it is possible to suitably determine whether the battery 100 needs to be replaced.

[0054] In the above-described embodiment, the diagnostic device Dd has been described as a functional block configured by the ECU 300, the BT-ECU 400, and the MG-ECU 500. However, each functional block of the diagnostic device Dd may be configured in any of the ECUs. For example, the diagnostic device Dd may be configured as a functional block of the ECU 300 or may be configured as a functional block of the BT-ECU 400.

[0055] In the above-described embodiment, the rapid deterioration of the battery 100 has been determined using the first map and the second map. However, the rapid deterioration of the battery 100 may be determined using only one of the maps. For example, in the flowchart of FIG. 5, S12 may be omitted, or S13 may be omitted.

[0056] (Modification example) FIG. 6 is a flowchart showing an example of rapid deterioration diagnosis processing executed by the diagnostic device Dd in the modification example. The flowchart of this modification example is obtained by replacing S12 in the flowchart of FIG. 5 with S20. In S20 of the modification example, the current IB and the temperature TB are monitored for several seconds from when an affirmative determination is made in S10, and it is determined whether the current IB and the temperature TB have entered the "×" region of the first map. When the current IB and the temperature TB enter the "×" region of the first map and an affirmative determination is made, the process proceeds to S13. When the current IB and the temperature TB do not enter the "×" region of the first map, a negative determination is made and the current routine ends.

[0057] According to this modification example, when it is determined that rapid deterioration has occurred in the battery 100 based on the temperature TB of the battery 100 and the current IB input to the battery (positive determination in S20), and when it is determined that rapid deterioration has occurred in the battery 100 based on the temperature TB and the rate of change ΔVB of the voltage VB of the battery 100 (positive determination in S13), it is diagnosed (determined) that rapid deterioration has occurred in the battery 100, the display of the battery replacement display unit 702 is performed (the battery replacement warning light is turned on), and it is notified that the battery 100 needs to be replaced (S14). Therefore, by using the first map and the second map, when it is determined that rapid deterioration has occurred, it is diagnosed that rapid deterioration has occurred in the battery 100, and it is notified that the battery 100 needs to be replaced. Thus, it is possible to more strictly determine whether the battery 100 needs to be replaced.

[0058] Note that although the electric vehicle 1 shown in FIG. 1 is a BEV, it may be a PHEV or an HEV. It may also be an industrial vehicle such as a forklift.

[0059] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown by the claims rather than the description of the above-described embodiments, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0060] 1 Electric vehicle, 10 Motor generator (MG), 20 Drive transmission gear, 30 Drive wheels, 40 PCU, 50 SMR, 100 Battery, 200 Monitoring unit, 210 Voltage sensor, 220 Current sensor, 230 Temperature sensor, 300 ECU, 310 HMI control unit, 400 BT-ECU, 410 Rapid deterioration diagnosis unit, 500 MG-ECU, 510 INV failure determination unit, 600 HMI-ECU, 700 HMI device, 701 PCU failure display unit, 702 Battery replacement display unit, Dd Diagnostic device.

Claims

1. An electric vehicle comprising a battery, a motor generator driven by electric power stored in the battery, and a diagnostic device for diagnosing degradation of the battery, wherein the diagnostic device, when a counter electromotive force is applied to the battery, determines whether rapid degradation has occurred in the battery based on the temperature of the battery and the current value input to the battery, or based on the temperature of the battery and the rate of change of the voltage of the battery, the diagnostic device, has a first map using the temperature of the battery and the current value input to the battery as parameters, and a second map using the temperature of the battery and the rate of change of the voltage of the battery as parameters, and determines whether rapid degradation has occurred in the battery using the first map or the second map, the first map is set to determine that rapid degradation has occurred in the battery in a region where the temperature of the battery is low and the current value input to the battery is large, the second map is set to determine that rapid degradation has occurred in the battery in a region where the temperature of the battery is high and the rate of change of the voltage of the battery is large. An electric vehicle.

2. further comprising a power control unit that supplies the electric power stored in the battery to the motor generator and controls the motor generator, wherein the diagnostic device, when the power control unit fails, determines that it is a case where the counter electromotive force is applied to the battery, and determines whether rapid degradation has occurred in the battery based on the temperature of the battery and the current value input to the battery, or based on the temperature of the battery and the rate of change of the voltage of the battery. The electric vehicle according to claim 1.

3. wherein the diagnostic device, When it is determined that rapid deterioration has occurred in the battery based on the temperature of the battery and the current value input to the battery, or when it is determined that rapid deterioration has occurred in the battery based on the temperature of the battery and the rate of change of the voltage of the battery, it is diagnosed that the battery needs to be replaced. The electric vehicle according to claim 1 or claim 2.

4. The diagnostic device When it is determined that rapid deterioration has occurred in the battery based on the temperature of the battery and the current value input to the battery, and when it is determined that rapid deterioration has occurred in the battery based on the temperature of the battery and the rate of change of the voltage of the battery, it is diagnosed that the battery needs to be replaced. The electric vehicle according to claim 1 or claim 2.

5. A method for diagnosing deterioration of a vehicle battery mounted as a power source in an electric vehicle, A step of determining whether or not a counter electromotive force is applied to the vehicle battery, When a counter electromotive force is applied to the vehicle battery, using a first map based on the temperature of the vehicle battery and the current value input to the vehicle battery, or using a second map based on the temperature of the vehicle battery and the rate of change of the voltage of the vehicle battery, determining whether or not rapid deterioration has occurred in the vehicle battery. The first map is a map using the temperature of the vehicle battery and the current value input to the vehicle battery as parameters, The first map is set to determine that rapid deterioration has occurred in the vehicle battery in a region where the temperature of the vehicle battery is low and the current value input to the vehicle battery is large. The second map is a map using the temperature of the vehicle battery and the rate of change of the voltage of the vehicle battery as parameters, The second map is set to determine that rapid deterioration of the vehicle battery has occurred in a region where the temperature of the vehicle battery is high and the rate of change of the voltage of the vehicle battery is large, in a method for diagnosing deterioration of a vehicle battery.

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