Electric vehicle control method and electric vehicle system
The control method optimizes power distribution between high- and low-power batteries in electric vehicles by adjusting voltage conversion based on battery degradation, preventing battery deterioration and enhancing cruising range.
Patent Information
- Application Number
- JP2024006278
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-01-18
- Publication Date
- 2025-07-31
AI Technical Summary
Existing electric vehicle power supply systems face issues where supplying power to auxiliary equipment from a low-power battery leads to battery deterioration, while supplying from a high-power battery reduces cruising range when its SOC is low.
A control method that adjusts power supply based on the degradation state of the low-power battery, using normal voltage control, low-voltage control, or stop control to manage power distribution between high- and low-power batteries, optimizing voltage conversion through a DC/DC converter.
This method prevents battery deterioration and extends cruising range by dynamically managing power distribution, ensuring efficient use of both batteries based on their states.
Smart Images
Figure 2025112152000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a control method for an electric vehicle and an electric vehicle system. [Background technology]
[0002] Patent Document 1 discloses an electric vehicle power supply device that includes a low-power battery (auxiliary equipment battery) that supplies power to the auxiliary equipment, and a charger that supplies charging power to the low-power battery via a DC / DC converter and also supplies power to the auxiliary equipment. In this electric vehicle power supply device, when the SOC of the low-power battery is within a predetermined range, the DC / DC converter is stopped and the power supply from the charger to the low-power battery and the auxiliary equipment is stopped. Therefore, in this case, power is supplied to the auxiliary equipment only from the low-power battery. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-80689 Summary of the Invention [Problem to be solved by the invention]
[0004] In the electric vehicle power supply device described in Patent Document 1, when the SOC of the low-power battery is within a predetermined range, the DC / DC converter is always stopped and power is supplied to the auxiliary equipment from the low-power battery. This makes the low-power battery prone to deterioration, which may lead to the battery running out.
[0005] On the other hand, it is also possible to supply power to the auxiliary equipment from the high-power battery for the vehicle drive motor, but if power is supplied to the auxiliary equipment from the high-power battery, for example, when the SOC of the high-power battery is low, there is a risk that the vehicle's cruising range (the distance that can be traveled on a single charge) will be reduced.
[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide an electric vehicle control method and an electric vehicle system that improve the cruising range while preventing the low-power battery from running out. [Means for solving the problem]
[0007] According to one aspect of the present invention, there is provided a control method for an electric vehicle including a high-power battery that supplies power to a drive motor and accessories, a DC / DC converter interposed between the high-power battery and the accessories that converts power from the high-power battery and supplies it to the accessories, and a low-power battery that supplies power to the accessories. The control method for an electric vehicle executes one of the following based on a degradation state of the low-power battery: normal voltage control, in which the DC / DC converter is controlled to convert power from the high-power battery to a first voltage value higher than the voltage of the low-power battery, and power is supplied to the accessories only from the high-power battery; low voltage control, in which the DC / DC converter is controlled to convert power from the high-power battery to a voltage value lower than the first voltage value, and power is supplied to the accessories only from the high-power battery or from both the high-power battery and the low-power battery; or stop control, in which the DC / DC converter is stopped and power is supplied to the accessories only from the low-power battery. [Effects of the Invention]
[0008] According to the present invention, based on the degradation state of the low-power battery, one of the following is executed: normal voltage control, in which power is supplied to the auxiliary equipment only from the high-power battery; low-voltage control, in which power is supplied to the auxiliary equipment only from the high-power battery or from both the high-power battery and the low-power battery; and stop control, in which power is supplied to the auxiliary equipment only from the low-power battery. In this way, voltage control is executed according to the degradation state of the low-power battery, so that the cruising range can be improved while preventing the battery from running out, etc. That is, when the low-power battery is degraded, normal voltage control can be executed to prevent the low-power battery from running out, etc., and when the low-power battery is not degraded or has only a small degree of degradation, stop control or low-voltage control can be executed to improve the cruising range. [Brief explanation of the drawings]
[0009]
Figure 1
Figure 2
Figure 3
Figure 4
DETAILED DESCRIPTION OF THE INVENTION
[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like.
[0011] (Embodiment) FIG. 1 is a schematic configuration diagram of an electric vehicle system 100 in which a control method for an electric vehicle according to an embodiment of the present invention is used. As shown in FIG. 1, the electric vehicle system 100 includes a high-voltage battery 1, a drive motor 2, drive wheels 3, a DC / DC converter 4, a low-voltage battery 5, auxiliary equipment 6, and a controller 10. Note that the electric vehicle system 100 is mounted on an electric vehicle, and the electric vehicle here includes not only a BEV (Battery Electric Vehicle) but also an HEV (Hybrid Electric Vehicle) and the like.
[0012] The high-voltage battery 1 is connected to the drive motor 2 and supplies drive power to the drive motor 2 via an inverter (not shown) during vehicle driving or the like. Also, during vehicle braking, the high-voltage battery 1 is supplied with the regenerative current generated by the drive motor 2 via the inverter, and thereby the high-voltage battery 1 is charged. Further, the high-voltage battery 1 is also connected to be able to supply power to the low-voltage battery 5 and the auxiliary equipment 6 via the DC / DC converter 4 described later. That is, the high-voltage battery 1 supplies charging power to the low-voltage battery 5 and supplies power for driving the auxiliary equipment 6 to the auxiliary equipment 6. Thus, the high-voltage battery 1 is configured to be able to supply power to the drive motor 2, the low-voltage battery 5, and the auxiliary equipment 6.
[0013] The drive motor 2 is connected to the drive wheels 3 via a shaft, receives power supply from the high-voltage battery 1, and rotates to drive. The rotational torque generated in the drive motor 2 is transmitted to the drive wheels 3 via the shaft, and thereby the electric vehicle runs.
[0014] The DC / DC converter 4 is interposed between the high-voltage battery 1 and the low-voltage battery 5 and the auxiliary machine 6. Specifically, the DC / DC converter 4 is connected to a line connected to the high-voltage battery 1 and a line branched and connected to the low-voltage battery 5 and the auxiliary machine 6. The DC / DC converter 4 converts the power (DC voltage) from the high-voltage battery 1 based on the control of the controller 10 described later and supplies it to the low-voltage battery 5 and the auxiliary machine 6.
[0015] The low-voltage battery 5 is a battery with a voltage lower than that of the high-voltage battery 1 and supplies power to the auxiliary machine 6. The low-voltage battery 5 is connected to a line branched and connected to the auxiliary machine 6 and the high-voltage battery 1, and the DC / DC converter 4 is interposed between the low-voltage battery 5 and the high-voltage battery 1. When the DC / DC converter 4 is stopped, or when the power output from the high-voltage battery 1 is stepped down to a voltage lower than that of the low-voltage battery 5 by the DC / DC converter 4, power is supplied from the low-voltage battery 5 to the auxiliary machine 6. On the other hand, when the power output from the high-voltage battery 1 is adjusted to a voltage higher than that of the low-voltage battery 5 by the DC / DC converter 4, the power of the high-voltage battery 1 is supplied to the low-voltage battery 5 and the low-voltage battery 5 is charged. Note that the low-voltage battery 5 is provided with various sensors capable of detecting the SOC, current, voltage, temperature, etc. of the low-voltage battery 5, and the values detected by the various sensors are transmitted to the controller 10 described later.
[0016] The accessories 6 include, for example, wipers, lights, an air conditioner, an audio system, and the like. The accessories 6 operate by receiving power from one or both of the high-power battery 1 and the low-power battery 5. A current sensor (not shown) that detects the current supplied to the accessories 6 is provided on a line that branches off from the line connecting the high-power battery 1 (DC / DC converter 4) and the low-power battery 5 and connects to the accessories 6. The current value detected by the current sensor is sent to a controller 10 (described later).
[0017] The controller 10 is configured by a computer that includes a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface) and is programmed to be able to execute the processes described below. Note that the controller 10 can also be configured by multiple computer hardware that executes the processes in a distributed manner.
[0018] The controller 10 controls the operation of the DC / DC converter 4 and performs voltage control to convert the voltage of the power output from the high-power battery 1 into a desired voltage. Specifically, based on the deterioration state of the low-power battery 5, the controller 10 performs one of the following control operations: normal voltage control, low voltage control, and stop control.
[0019] Normal voltage control is a control used when the deterioration of the weak power battery 5 is most advanced. In normal voltage control, the controller 10 controls the DC / DC converter 4 to convert the power from the strong power battery 1 to a predetermined voltage value (first voltage value) V1 that is higher than the voltage of the weak power battery 5. As a result, power is supplied to the auxiliary equipment 6 only from the strong power battery 1. Therefore, the deterioration of the weak power battery 5 is suppressed. Furthermore, in normal voltage control, power is also supplied from the strong power battery 1 to the weak power battery 5, and the weak power battery 5 is charged.
[0020] In this embodiment, when the SOC of the high-power battery 1 has a margin, such as when the high-power battery 1 is nearly fully charged, normal voltage control is executed regardless of the degradation state of the low-power battery 5. That is, in a normal state where the SOC of the high-power battery 1 has a margin, normal voltage control is executed. This further suppresses the progression of degradation of the low-power battery 5. On the other hand, when the SOC of the high-power battery 1 is low and the degradation of the low-power battery 5 has not progressed very far, low voltage control or stop control is executed to suppress the power supply from the high-power battery 1 to the auxiliary equipment 6. This improves the cruising range of the vehicle. Whether or not the SOC of the high-power battery 1 has a margin can be determined, for example, by setting the SOC of the high-power battery 1 at a threshold (predetermined value) SOC th The SOC of the high-power battery 1 is set to the threshold SOC th The determination is made based on whether or not the value is equal to or greater than this.
[0021] In this embodiment, the current value (actual current) I r is the predetermined current value I th In the above cases, normal voltage control is performed regardless of the deterioration state of the low-power battery 5. Here, the predetermined current value I th is set to a value equal to or less than the current value that can be normally output from the low-power battery 5 based on the output current of the low-power battery 5. For example, when an actuator such as a wiper included in the auxiliary device 6 is operating, the auxiliary device 6 is supplied with a predetermined current value I th In this case, if power is supplied to the auxiliary device 6 only from the low-power battery 5, there is a risk of a power shortage and a delay in the response of the actuator. Therefore, the current value (actual current) I supplied to the auxiliary device 6 is r is the predetermined current value I th In the above cases, normal voltage control is executed to supply power from the high-power battery 1 to the auxiliary device 6. This prevents a shortage of power supplied to the auxiliary device 6 and prevents a delay in the response of the actuator.
[0022] Low-voltage control is a control used when the weak-power battery 5 is deteriorating. In low-voltage control, the controller 10 controls the DC / DC converter 4 to convert power from the strong-power battery 1 to a voltage value (hereinafter also referred to as a low-voltage control voltage value) V2 that is lower than the first voltage value V1. Here, when the low-voltage control voltage value V2 is higher than the voltage of the weak-power battery 5, power is supplied to the auxiliary equipment 6 only from the strong-power battery 1. This suppresses the progression of deterioration of the weak-power battery 5. On the other hand, when the low-voltage control voltage value V2 is equal to or lower than the voltage of the weak-power battery 5, power is supplied to the auxiliary equipment 6 from both the strong-power battery 1 and the weak-power battery 5. In this case, when the SOC of the weak-power battery 5 decreases and the voltage of the weak-power battery 5 becomes lower than the low-voltage control voltage value V2, power supply from the weak-power battery 5 to the auxiliary equipment 6 is stopped, and power is supplied to the auxiliary equipment 6 only from the strong-power battery 1. That is, the power of the low-power battery 5 is used only until the voltage of the low-power battery 5 becomes smaller than the low-voltage control voltage value V2, thereby suppressing the progression of deterioration of the low-power battery 5. Note that in the low-voltage control, the specific value of V to which the low-voltage control voltage value V2 is set can be determined based on, for example, the operating state of the auxiliary equipment 6.
[0023] The stop control is used when the low-power battery 5 is not deteriorated. In the stop control, the controller 10 stops the DC / DC converter 4. As a result, the auxiliary equipment 6 is supplied with power only from the low-power battery 5. By executing the stop control, the power supply from the high-power battery 1 to the auxiliary equipment 6 is stopped, so that the cruising distance can be improved, for example, when the SOC of the high-power battery 1 is low.
[0024] In this embodiment, the degradation state of the low-power battery 5 can be estimated based on at least one of the SOC, current, voltage, temperature, charge / discharge power amount, charge / discharge cumulative time, and operating time of the low-power battery 5. Specifically, the degradation state is estimated using, for example, one or more of a map of the voltage at full charge of the low-power battery 5 and degradation rate, a map of the charge / discharge power amount and degradation rate of the low-power battery 5, a map of the charge / discharge cumulative time and degradation rate, an operating time and degradation rate, and a map of the battery temperature and degradation rate of the low-power battery 5. FIG. 2 shows an example of the map of the charge / discharge power amount and degradation rate, and FIG. 3 shows an example of the map of the charge / discharge cumulative time and degradation rate. For example, in FIG. 2, when the repeated charge / discharge power amount (lifetime cumulative value) is 300 kWh, the degradation rate d of the low-power battery 5 is 50%, and in FIG. 3, when the charge / discharge cumulative time is 10,000 h, the degradation rate d of the low-power battery 5 is 10%. In this embodiment, when the estimated deterioration rate d of the weak battery 5 is equal to or greater than a first threshold (first predetermined value) d1, normal voltage control is executed, and when the deterioration rate d of the weak battery 5 is smaller than the first threshold d1 and equal to or greater than a second threshold (second predetermined value) d2 that is smaller than the first threshold d1, low voltage control is executed. That is, normal voltage control is executed when the deterioration of the weak battery 5 is most advanced, and low voltage control is executed when the weak battery 5 is deteriorating. Furthermore, when the deterioration rate d of the weak battery 5 is smaller than the second threshold (second predetermined value) d2 and the weak battery 5 is hardly degraded, stop control is executed. However, the above-described method of estimating the deterioration state of the weak battery 5 is merely an example and is not limited thereto.
[0025] As described above, the electric vehicle system 100 performs either normal voltage control, in which power is supplied to the auxiliary equipment 6 only from the high-power battery 1, low voltage control, in which power is supplied to the auxiliary equipment 6 only from the high-power battery 1 or from both the high-power battery 1 and the low-power battery 5, or stop control, in which power is supplied to the auxiliary equipment 6 only from the low-power battery 5.
[0026] Incidentally, in an electric vehicle system, if power to the accessories is always supplied from a low-power battery, the low-power battery is likely to deteriorate, and there is a risk of the battery running out, etc. On the other hand, it is also possible to supply power to the accessories from a high-power battery for the drive motor, but if the high-power battery has a low SOC, for example, supplying power to the accessories from the high-power battery may reduce the vehicle's cruising range.
[0027] In contrast, in this embodiment, based on the degradation state of the low-power battery 5, one of the following is executed: normal voltage control, in which power is supplied to the auxiliary device 6 only from the high-power battery 1; low-voltage control, in which power is supplied to the auxiliary device 6 only from the high-power battery 1 or from both the high-power battery 1 and the low-power battery 5; or stop control, in which power is supplied to the auxiliary device 6 only from the low-power battery 5. In this way, voltage control is executed according to the degradation state of the low-power battery 5, so that the cruising range can be improved while preventing the battery from running out, etc. That is, when the low-power battery 5 is degraded, normal voltage control can be executed to prevent the low-power battery 5 from running out, etc., and when the low-power battery 5 is not degraded or has only a small degree of degradation, stop control or low-voltage control can be executed to improve the cruising range.
[0028] 4 is a flowchart illustrating voltage control. The following controls are all repeatedly executed at predetermined time intervals by the controller 10. The controller 10 also acquires detection values detected by various sensors as appropriate.
[0029] When the electric vehicle system 100 is activated (activated state) by turning on the ignition switch, for example, the controller 10 starts voltage control. The activated state here refers to a state in which power can be supplied from the high-power battery 1 to the DC / DC converter 4 and the drive motor 2, and does not include a state in which only the accessories 6, such as the air conditioner and audio, are operating (accessory mode). In accessory mode, power is supplied to the accessories 6 only from the low-power battery 5.
[0030] In step S11, the controller 10 calculates the current value (actual current) I supplied to the auxiliary device 6 in this embodiment. r is the predetermined current value I th As described above, it is determined whether the predetermined current value I th is set based on the output current of the low-power battery 5. The current value (actual current) I supplied to the auxiliary device 6 r is the predetermined current value I th In the above cases, the controller 10 executes the process of step S18. On the other hand, the current value (actual current) I r is the predetermined current value I th If it is smaller, the controller 10 executes the process of step S12.
[0031] A predetermined current value I th If a current greater than the predetermined current value I is being supplied, the controller 10 controls the DC / DC converter 4 in step S18 to convert the power from the high-power battery 1 to a first voltage value V1 higher than the voltage of the low-power battery 5. That is, normal voltage control is executed. As a result, charging power is supplied from the high-power battery 1 to the low-power battery 5 via the DC / DC converter 4, and operating power is supplied to the auxiliary equipment 6. In this way, the auxiliary equipment 6 is supplied with a predetermined current value I th If the above current is being supplied, normal voltage control is executed to supply power from the high-power battery 1 to the auxiliary device 6. This prevents a delay in the response of the actuator. After executing normal voltage control, the controller 10 executes the process from step S11 again.
[0032] On the other hand, the current value (actual current) I supplied to the auxiliary device 6 r is the predetermined current value I thIn the following cases, the controller 10 estimates the degradation state of the low-voltage battery 5 in step S12. Specifically, as described above, the degradation rate d of the low-voltage battery 5 is estimated based on at least one or more of the SOC, current, voltage, temperature, charge-discharge power amount, charge-discharge integration time, and operation time of the low-voltage battery 5. When the degradation rate d of the low-voltage battery 5 is estimated, the controller 10 executes the process of step S13.
[0033] In step S13, the controller 10 determines whether the estimated degradation rate d of the low-voltage battery 5 is less than the first threshold value d1. The first threshold value d1 is, for example, a value such that if the low-voltage battery 5 is used further, there is a risk of inducing battery exhaustion or the like, and it can be preset by experiments or the like, but is not limited thereto. When the degradation rate d of the low-voltage battery 5 is greater than or equal to the first threshold value d1, the controller 10 executes the process of step S18, that is, normal voltage control. Thereby, the progress of the degradation of the low-voltage battery 5 is suppressed. When normal voltage control is executed, the controller 10 executes the process from step S11 again.
[0034] On the other hand, in step S13, when the degradation rate d of the low-voltage battery 5 is less than the first threshold value d1, the controller 10 executes the process of step S14.
[0035] In step S14, the controller 10 determines whether there is a margin in the SOC of the high-voltage battery 1. Specifically, it is determined whether the SOC of the high-voltage battery 1 is less than the threshold value SOC th Here, the threshold value SOC th is a value of SOC such that by switching the power supply source to the auxiliary machine 6 from the high-voltage battery 1 to the low-voltage battery 5, the cruising range is improved to a certain extent (for example, a significant difference occurs in the cruising range), and it can be preset by experiments or the like. When the SOC of the high-voltage battery 1 is the threshold value SOC thThe above being the case, when there is a certain margin in the SOC of the high-voltage battery 1, the controller 10 executes the process of step S18, that is, normal voltage control. As a result, the usage frequency of the low-voltage battery 5 decreases, and the progress of deterioration of the low-voltage battery 5 is further suppressed. When executing the normal voltage control, the controller 10 starts the process from step S11 again.
[0036] On the other hand, when the SOC of the high-voltage battery 1 is smaller than the threshold SOC th the controller 10 executes the process of step S15.
[0037] In step S15, the controller 10 determines whether the estimated deterioration rate d of the low-voltage battery 5 is smaller than the second threshold d2. The second threshold d2 is a value that does not induce, for example, battery overcharge, etc., but is such that the low-voltage battery 5 is deteriorating, and can be preset in advance by experiments or the like. When the deterioration rate d of the low-voltage battery 5 is smaller than the second threshold d2, the controller 10 executes the process of step S16. On the other hand, when the deterioration rate d of the low-voltage battery 5 is equal to or greater than the second threshold d2, the controller 10 executes the process of step S17.
[0038] When the deterioration rate d of the low-voltage battery 5 is smaller than the second threshold d2, that is, when the low-voltage battery 5 is hardly deteriorated, the controller 10 executes stop control to stop the DC / DC converter 4 in step S16. As a result, power is supplied to the auxiliary machine 6 only from the low-voltage battery 5. In step S16, since the SOC of the high-voltage battery 1 is smaller than the threshold SOC th (see step S14), by supplying power to the auxiliary machine 6 only from the low-voltage battery 5 and stopping the power supply from the high-voltage battery 1 to the auxiliary machine 6, the cruising range of the vehicle is improved. When executing the stop control in step S16, the controller 10 executes the process from step S11 again.
[0039] When the deterioration rate d of the low-voltage battery 5 is equal to or higher than the second threshold value d2, that is, when the low-voltage battery 5 is deteriorating, the controller 10 performs low-voltage control to control the DC / DC converter 4 to convert the power from the high-voltage battery 1 to a low-voltage control voltage value V2 that is lower than the first voltage value V1. As a result, when the low-voltage control voltage value V2 is higher than the voltage of the low-voltage battery 5, power is supplied to the auxiliary machine 6 only from the high-voltage battery 1, and when the low-voltage control voltage value V2 is equal to or lower than the voltage of the low-voltage battery 5, power is supplied to the auxiliary machine 6 from both the high-voltage battery 1 and the low-voltage battery 5. In step S17, since the SOC of the high-voltage battery 1 is smaller than the threshold SOC (see step S14), while the voltage of the low-voltage battery 5 is equal to or higher than the low-voltage control voltage value V2, by supplying power to the auxiliary machine 6 from both the high-voltage battery 1 and the low-voltage battery 5, the power supply from the high-voltage battery 1 to the auxiliary machine 6 is suppressed, and the cruising range of the vehicle is improved. On the other hand, when the low-voltage control voltage value V2 is higher than the voltage of the low-voltage battery 5, since power is supplied to the auxiliary machine 6 only from the high-voltage battery 1, the deterioration of the low-voltage battery 5 is suppressed. As described above, specifically, the low-voltage control voltage value V2 can be determined based on, for example, the operating state of the auxiliary machine 6. When performing the low-voltage control in step S17, the controller 10 executes the processing from step S11 again. th Since it is smaller than (see step S14), while the voltage of the low-voltage battery 5 is equal to or higher than the low-voltage control voltage value V2, by supplying power to the auxiliary machine 6 from both the high-voltage battery 1 and the low-voltage battery 5, the power supply from the high-voltage battery 1 to the auxiliary machine 6 is suppressed, and the cruising range of the vehicle is improved. On the other hand, when the low-voltage control voltage value V2 is higher than the voltage of the low-voltage battery 5, since power is supplied to the auxiliary machine 6 only from the high-voltage battery 1, the deterioration of the low-voltage battery 5 is suppressed. As described above, specifically, the low-voltage control voltage value V2 can be determined based on, for example, the operating state of the auxiliary machine 6. When performing the low-voltage control in step S17, the controller 10 executes the processing from step S11 again.
[0040] Note that the voltage control by the controller 10 ends at any time when the electric vehicle system 100 is not in the startup state, such as when the ignition switch is turned off.
[0041] According to the control method of the electric vehicle of the above-described embodiment, the following effects can be obtained.
[0042] According to the control method of the electric vehicle of this embodiment, based on the deterioration state of the low-voltage battery 5, normal voltage control for supplying power to the auxiliary machine 6 only from the high-voltage battery 1, low-voltage control for supplying power to the auxiliary machine 6 only from the high-voltage battery 1 or both the high-voltage battery 1 and the low-voltage battery 5, or stop control for supplying power to the auxiliary machine 6 only from the low-voltage battery 5 is executed. In this way, since voltage control is executed according to the deterioration state of the low-voltage battery 5, it is possible to improve the cruising range while preventing overcharging of the battery. That is, when the low-voltage battery 5 is deteriorated, normal voltage control can be executed to prevent overcharging of the low-voltage battery 5, and when the low-voltage battery 5 is not deteriorated or the deterioration is small, stop control or low-voltage control can be executed to improve the cruising range.
[0043] According to the control method of the electric vehicle of this embodiment, based on the SOC of the high-voltage battery 1 and the deterioration state of the low-voltage battery 5, either normal voltage control, low-voltage control, or stop control is executed. In this way, since voltage control is executed according to the SOC of the high-voltage battery 1 and the deterioration state of the low-voltage battery 5, it is possible to further improve the cruising range while preventing overcharging of the battery. That is, when there is a margin in the SOC of the high-voltage battery 1, by executing normal voltage control for supplying power from the high-voltage battery 1 to the auxiliary machine 6, the progress of deterioration of the low-voltage battery 5 can be suppressed. On the other hand, when the SOC of the high-voltage battery 1 is low and the deterioration of the low-voltage battery 5 has not progressed so much, by executing low-voltage control or stop control, the power supply from the high-voltage battery 1 to the auxiliary machine 6 can be suppressed, and the cruising range of the vehicle can be improved.
[0044] According to the control method of the electric vehicle of this embodiment, the current value I supplied to the auxiliary machine 6 r is equal to or greater than a predetermined current value I set based on the output current of the low-voltage battery 5 th In this case, normal voltage control is executed. Thereby, insufficient supply power to the auxiliary machine 6 can be prevented, and response delay of the actuator can be prevented.
[0045] According to the control method of the electric vehicle of this embodiment, when the SOC of the high-voltage battery 1 is equal to or higher than the threshold value (predetermined value) SOC th above, normal voltage control is executed. When the SOC of the high-voltage battery 1 is less than the threshold value (predetermined value) SOC th smaller, either low-voltage control or stop control is executed based on the deterioration state of the low-voltage battery 5. That is, when the SOC of the high-voltage battery 1 is equal to or higher than the threshold value (predetermined value) SOC th above and there is a margin in the SOC of the high-voltage battery 1, normal voltage control for supplying power from the high-voltage battery 1 to the auxiliary machine 6 is executed. Thereby, the progress of the deterioration of the low-voltage battery 5 is further suppressed. On the other hand, when the SOC of the high-voltage battery 1 is smaller than the predetermined threshold value SOC th and the SOC of the high-voltage battery 1 is low, when the deterioration of the low-voltage battery 5 has not progressed so much, low-voltage control or stop control is executed. Thereby, the power supply from the high-voltage battery 1 to the auxiliary machine 6 is suppressed, and the cruising range of the vehicle is improved. Therefore, it is possible to further improve the cruising range while preventing battery overheating and the like.
[0046] According to the control method of the electric vehicle of this embodiment, the deterioration state of the low-voltage battery 5 is the deterioration rate d calculated based on at least one or more of the SOC, current, voltage, temperature, charge and discharge power amount, charge and discharge integration time, and operation time of the low-voltage battery 5. When the deterioration rate d of the low-voltage battery 5 is equal to or higher than the first threshold value (first predetermined value) d1, normal voltage control is executed. When the deterioration rate d of the low-voltage battery 5 is smaller than the first threshold value (first predetermined value) d1 and equal to or higher than the second threshold value (second predetermined value) d2 smaller than the first threshold value (first predetermined value) d1, low-voltage control is executed. When the deterioration rate d of the low-voltage battery 5 is smaller than the second threshold value (second predetermined value) d2, stop control is executed. That is, normal voltage control is executed when the deterioration of the low-voltage battery 5 is progressing most (that is, d?d1), low-voltage control is executed when the low-voltage battery 5 is deteriorating (that is, d2≦d<d1), and stop control is executed when the low-voltage battery 5 is hardly deteriorated (that is, d<d2). Thereby, the progress of the deterioration of the low-voltage battery 5 can be suppressed, and the cruising range can be improved while preventing battery overheating and the like.
[0047] According to the control method for an electric vehicle of this embodiment, the current value I r is a predetermined current value I that is set based on the output current of the low-power battery 5. th In the above cases, normal voltage control is performed. The current value I r is a predetermined current value I that is set based on the output current of the low-power battery 5. th If the deterioration rate d of the weak power battery 5 is smaller than the first threshold (first predetermined value) d1, normal voltage control is executed. If the deterioration rate d of the weak power battery 5 is smaller than the first threshold (first predetermined value) d1 and the SOC of the strong power battery 1 is equal to or larger than the threshold (predetermined value) SOC th In the above cases, normal voltage control is executed. When the deterioration rate d of the low-power battery 5 is smaller than the first threshold (first predetermined value) d1 and the SOC of the high-power battery 1 is equal to or lower than the threshold (predetermined value) SOC th If the deterioration rate d of the low-power battery 5 is smaller than the first threshold (first predetermined value) d1, low voltage control is executed when the deterioration rate d of the low-power battery 5 is equal to or greater than a second threshold (second predetermined value) d2 that is smaller than the first threshold (first predetermined value) d1, and stop control is executed when the deterioration rate d of the low-power battery 5 is smaller than the second threshold (second predetermined value) d2. This prevents a delay in the response of the actuator, suppresses the progression of deterioration of the low-power battery 5, and improves the cruising range while preventing the battery from running out, etc.
[0048] In this embodiment, when the SOC of the high-power battery 1 has a margin, it is preferable to execute normal voltage control regardless of the degradation state of the low-power battery 5, but this is not necessarily limited to this. That is, any of normal voltage control, low voltage control, and stop control may be executed based only on the degradation state of the low-power battery 5.
[0049] In addition, as in this embodiment, the current value (actual current) I supplied to the auxiliary device 6 r is the predetermined current value I thIn the above case, it is preferable to execute normal voltage control regardless of the deterioration state of the low-voltage battery 5, but it is not necessarily limited to this. That is, any one of normal voltage control, low voltage control, or stop control may be executed based only on the deterioration state of the low-voltage battery 5.
[0050] Also, the schematic configuration diagram of the electric vehicle system 100 shown in FIG. 1 is merely an example and is not necessarily limited to this. That is, as long as the high-voltage battery 1 can supply power to the auxiliary machine 6 via the DC / DC converter 4 and the low-voltage battery 5 is configured to be able to supply power to the auxiliary machine 6, other configurations can be appropriately changed.
[0051] The embodiments of the present invention have been described above. However, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.
Explanation of Reference Numerals
[0052] 1, high-voltage battery, 2, drive motor, 3, drive wheel, 4, DC / DC converter, 5, low-voltage battery, 6, auxiliary machine, 10, controller, 100, electric vehicle system
Claims
1. A control method for an electric vehicle, comprising: a high-voltage battery that supplies power to a drive motor and auxiliary equipment; a DC / DC converter that is interposed between the high-voltage battery and the auxiliary equipment and converts the power from the high-voltage battery to supply it to the auxiliary equipment; and a low-voltage battery that supplies power to the auxiliary equipment, wherein, based on the degradation state of the low-voltage battery, the DC / DC converter is controlled to convert the power from the high-voltage battery to a first voltage value higher than the voltage of the low-voltage battery, so as to perform normal voltage control to supply power to the auxiliary equipment only from the high-voltage battery; the DC / DC converter is controlled to convert the power from the high-voltage battery to a voltage value lower than the first voltage value, so as to perform low-voltage control to supply power to the auxiliary equipment only from the high-voltage battery or from both the high-voltage battery and the low-voltage battery; or the DC / DC converter is stopped to perform stop control to supply power to the auxiliary equipment only from the low-voltage battery. A control method for an electric vehicle.
2. The control method for an electric vehicle according to claim 1, wherein the degradation state of the low-voltage battery is estimated based on at least one or more of the SOC, current, voltage, temperature, charge and discharge power amount, charge and discharge integration time, and operation time of the low-voltage battery. A control method for an electric vehicle.
3. The control method for an electric vehicle according to claim 1 or 2, wherein, based on the SOC of the high-voltage battery and the degradation state of the low-voltage battery, any one of the normal voltage control, the low-voltage control, and the stop control is executed. A control method for an electric vehicle.
4. The control method for an electric vehicle according to claim 1 or 2, wherein when the current value supplied to the auxiliary equipment is equal to or greater than a predetermined current value set based on the output current of the low-voltage battery, the normal voltage control is executed; when the current value supplied to the auxiliary equipment is less than the predetermined current value, any one of the normal voltage control, the low-voltage control, and the stop control is executed based on the degradation state of the low-voltage battery. A control method for an electric vehicle.
5. The control method for an electric vehicle according to claim 3, wherein when the SOC of the high-voltage battery is equal to or greater than a predetermined value, the normal voltage control is executed; when the SOC of the high-voltage battery is less than the predetermined value, any one of the low-voltage control and the stop control is executed based on the degradation state of the low-voltage battery. A control method for an electric vehicle.
6. The control method for an electric vehicle according to claim 3, wherein the deterioration state of the low-voltage battery is a deterioration rate calculated based on at least one or more of the SOC, current, voltage, temperature, charge-discharge power amount, charge-discharge integrated time, and operation time of the low-voltage battery, when the deterioration rate of the low-voltage battery is equal to or greater than a first predetermined value, the normal voltage control is executed, when the deterioration rate of the low-voltage battery is less than the first predetermined value and the SOC of the high-voltage battery is equal to or greater than a predetermined value, the normal voltage control is executed, when the deterioration rate of the low-voltage battery is less than the first predetermined value and the SOC of the high-voltage battery is less than the predetermined value, when the deterioration rate of the low-voltage battery is equal to or greater than a second predetermined value that is less than the first predetermined value, the low-voltage control is executed, when the deterioration rate of the low-voltage battery is less than the second predetermined value, the stop control is executed, A control method for an electric vehicle.
7. The control method for an electric vehicle according to claim 6, wherein when the current value supplied to the auxiliary machine is equal to or greater than a predetermined current value set based on the output current of the low-voltage battery, the normal voltage control is executed, when the current value supplied to the auxiliary machine is less than the predetermined current value, when the deterioration rate of the low-voltage battery is equal to or greater than a first predetermined value, the normal voltage control is executed, when the deterioration rate of the low-voltage battery is less than the first predetermined value and the SOC of the high-voltage battery is equal to or greater than a predetermined value, the normal voltage control is executed, when the deterioration rate of the low-voltage battery is less than the first predetermined value and the SOC of the high-voltage battery is less than the predetermined value, when the deterioration rate of the low-voltage battery is equal to or greater than a second predetermined value that is less than the first predetermined value, the low-voltage control is executed, when the deterioration rate of the low-voltage battery is less than the second predetermined value, the stop control is executed, A control method for an electric vehicle.
8. A high-voltage battery that supplies power to a drive motor and an auxiliary machine, a DC / DC converter interposed between the high-voltage battery and the auxiliary machine, which converts the power from the high-voltage battery and supplies it to the auxiliary machine, a low-voltage battery that supplies power to the auxiliary machine, an electric vehicle system including a controller that controls the DC / DC converter. The controller controls the DC / DC converter to convert the power from the high-voltage battery to a first voltage value higher than the voltage of the low-voltage battery based on the degradation state of the low-voltage battery, and performs normal voltage control to supply power to the auxiliary machine only from the high-voltage battery; controls the DC / DC converter to convert the power from the high-voltage battery to a voltage value lower than the first voltage value, and performs low-voltage control to supply power to the auxiliary machine only from the high-voltage battery or from both the high-voltage battery and the low-voltage battery; or stops the DC / DC converter and performs stop control to supply power to the auxiliary machine only from the low-voltage battery. Electric vehicle system.
Citation Information
Patent Citations
Power supply unit for electric vehicle
JP2012080689A