Low voltage energy management system

Abstract

According to one aspect of the present application, a low voltage energy management system for a vehicle is provided. The system includes a low voltage battery, a battery sensor connected to the low voltage battery, a high voltage battery, a controller configured to wake up the controller and the battery sensor from a sleep state in response to a wake-up condition, recalibrate the battery sensor in response to a recalibration condition, charge the low voltage battery with the high voltage battery in response to a charge-in condition, and place the controller and the battery sensor in the sleep state and stop charging the low voltage battery in response to a charge-out condition.

Description

Technical Field

[0001] This disclosure relates to the field of battery energy management, and particularly to low-voltage battery energy management for vehicles. Background Technology

[0002] Traditional automobiles use low-voltage (LV) batteries, such as 12V, 9V, 6V, and 48V batteries, to power onboard electronics. Vehicles equipped with internal combustion engines charge the LV batteries using an alternator powered by the engine while the engine is running. When the engine is not running, the vehicle cannot charge the LV batteries, and therefore cannot continue operating the electronics while maintaining the battery's state of charge (SoC). As a result, internal combustion engine vehicles typically shut down their electronics after a predetermined time following engine shutdown. Vehicles equipped with high-voltage (HV) batteries to power the electric powertrain can use HV batteries to charge LV batteries. HV batteries typically have a larger capacity than LV batteries, which allows the LV batteries to be continuously charged and thus maintain their SoC while powering the electronics. This allows the electronics to operate for longer periods when the vehicle's powertrain is not in operation. However, this extended use of LV batteries can have negative consequences. For example, extended charging of LV batteries with HV batteries will cause a decrease in the HV battery's SoC, often referred to as "ghost charging." Drivers may return to the vehicle dissatisfied and find that the HV battery's SoC has significantly decreased. In addition, the continuous charging and discharging of LV batteries maintains the load on the LV batteries, which may degrade the state of health (SoH) of the LV batteries and / or cause the sensors monitoring the batteries to go out of calibration. Summary of the Invention

[0003] According to one aspect of the present invention, a low-voltage energy management system for a vehicle includes: a low-voltage battery; a battery sensor connected to the low-voltage battery; a high-voltage battery; and a controller configured to: wake up the controller and the battery sensor from a sleep state in response to a wake-up condition; recalibrate the battery sensor in response to a recalibration condition; charge the low-voltage battery with the high-voltage battery in response to a charging start condition; and stop charging the low-voltage battery and put the controller and the battery sensor into a sleep state in response to a charging stop condition.

[0004] According to another aspect of the present invention, a low-voltage energy management method for a vehicle includes the following steps: waking up a controller and a battery sensor from a sleep state in response to a wake-up condition; recalibrating the battery sensor in response to a recalibration condition; charging a low-voltage battery with a high-voltage battery in response to a charging start condition; and stopping charging the low-voltage battery and putting the controller and battery sensor into a sleep state in response to a charging stop condition.

[0005] The above aspects achieve a more reliable LV battery SoC, reduce LV battery SoH degradation, and minimize HV battery SoC consumption. These and other objects, features, and advantages of the invention will become more apparent when read in conjunction with the accompanying drawings in the following description. Attached Figure Description

[0006] Figure 1 This is an illustration of an exemplary embodiment of a low-pressure energy management system.

[0007] Figure 2 This is an illustration of an exemplary embodiment of the low-voltage energy management operation of a low-voltage energy management system. Detailed Implementation

[0008] Figure 1 The diagram illustrates a low-voltage energy management system 100 for an electric vehicle. System 100 includes a low-voltage (LV) battery 110, a high-voltage (HV) battery 120, a controller 130, an HV powertrain 140, auxiliary electronics 150, and a DC-DC converter 160. The LV battery 110 is a conventional battery with a low voltage, such as 12V, 9V, 6V, or 48V, and includes conventional battery chemistry such as AGM (Absorbed Glass Fiber Separator), lead-acid, or lithium-ion. One or more battery sensors 111 are attached to the LV battery 110 and measure battery parameters such as current load, voltage, internal resistance, SoC, and SoH. The battery sensor 111 may be an intelligent battery sensor (IBS) that measures multiple parameters. The HV powertrain 140 includes one or more electric motors powered by the HV battery 120. The auxiliary electronics 150 may include additional controllers, network components, displays, vehicle actuators, HVAC systems, etc., powered by the LV battery 110. In some embodiments, the auxiliary electronics 150 may be an additional controller operating cockpit functions such as infotainment. DC-DC converter 160 is positioned between LV battery 110 and HV battery 120 and is controlled by controller 130 to charge LV battery 110.

[0009] Controller 130 is programmed as operating system 100. Controller 130 may be a standalone control unit, a control unit controlling multiple vehicle functions, or a module within or virtualized within another control unit in the vehicle. Controller 130 may include a processor, random access memory (RAM), storage devices, and input and output ports. The processor may be one or more microprocessors. RAM serves as working memory for temporarily storing data to be processed by the processor. The storage devices are capable of storing information placed therein. The storage devices may include read-only memory (ROM) and rewritable non-volatile memory. Various types of control are performed when the processor executes programs stored in the storage devices. Additional controllers include hardware configurations similar to controller 130.

[0010] Figure 2 The diagram illustrates low-voltage energy management operation 200 of the low-voltage energy management system 100 performed by controller 130. Operation 200 begins when the vehicle is in sleep mode (step 201). In sleep mode, controller 130 and auxiliary electronics 150 operate in a very low-power mode. The vehicle enters sleep mode when it will not be operated for an extended period of time, such as during long-term parking or when the driver is not detected to have reached a predetermined time. Maintaining sleep mode reduces the discharge of LV and HV batteries; however, even in sleep mode, controller 130 and auxiliary electronics 150 may still consume LV batteries. Therefore, it is necessary to charge the LV batteries even when the vehicle is in sleep mode. When the wake-up condition is met (step 210), operation 200 continues and controller 130 and battery sensor 111 are awakened (step 211). The wake-up condition may be a predetermined time elapsed since the last wake-up, such as 60-65 minutes. When the wake-up condition is not met, controller 130 and auxiliary electronics 150 remain in sleep mode.

[0011] Operation 200 continues to check whether the recalibration conditions for recalibrating battery sensor 111 are met (step 220). Some battery sensors, such as IBS, require a long period of quiescent current for calibration. When a battery sensor is maintained at an effective current level for an extended period, it may become out of calibration, resulting in erroneous readings, such as incorrect battery voltage. The recalibration condition may be when the charge cycle counter exceeds a predetermined threshold. When the recalibration condition is met, controller 130 executes a preparation phase (step 221). In the preparation phase, LV battery 110 is charged to substantially full capacity with a low charging current (e.g., below 2.5A). When the LV battery can no longer accept charging current, such as when the charging current drops below a low charging current, or when the battery reaches a substantially full SoC, such as 95%, controller 130 can determine that the LV battery is substantially full. After the preparation phase is complete, operation 200 sets the LV charging entry conditions such that LV battery 110 is not charged for a predetermined number of wake-ups, or until the LV battery SoC or voltage falls below a low threshold, such as below 70% SoC or 11.5V. Pausing LV battery charging allows battery sensor 111 time to recalibrate. Once the entry conditions have been set, the vehicle returns to sleep mode (step 201).

[0012] If the recalibration conditions are not met, operation 200 checks whether the LV charging entry conditions are met (step 230). When the entry conditions are met, the LV battery 110 is charged by the HV battery 120 via the DC-DC converter 160 (step 231). The controller 130 can control the charging voltage based on the measured SoC and battery temperature. For example, the charging voltage when the SoC is low and / or the temperature is low can be higher than the charging voltage when the SoC is high and / or the temperature is high. The entry conditions are based on measurements from the battery sensor 111, such as battery voltage, SoC, charging current, SoH, and total available capacity. When the LV battery 110 is charging, operation 200 checks whether the LV charging exit conditions are met (step 232) to stop charging. The exit conditions are based on measurements from the battery sensor 111, such as battery voltage, SoC, charging current, SoH, total available capacity, and capacity loss. Making the entry and exit conditions based on multiple parameters, rather than just voltage, reduces the influence of the uncalibrated battery sensor 111. For example, even when the reading from battery sensor 111 has degraded, or when the battery capacity's SoH has degraded, controller 130 can determine that the LV battery 110 has reached its upper limit threshold when the charging current drops below a threshold or the battery voltage reaches an upper limit threshold. When the exit condition is met, the vehicle returns to sleep mode (step 201). When the exit condition is not met, operation 200 checks whether the maximum timeout has elapsed since charging began. When the maximum timeout has elapsed, the vehicle returns to sleep mode (step 201). When the maximum timeout has not elapsed, the LV battery 110 continues to be charged. Setting a maximum timeout prevents the LV battery 110 from charging for an extended period of time and keeps the vehicle awake if the exit condition is not met. This may happen if the battery's SoH has degraded to the point that the battery cannot reach the threshold voltage or SoH. The maximum timeout can be based on ambient temperature, as the LV battery 110 may require more time to charge in a cold environment than in a warm environment. When the entry condition is not met (step 230), the vehicle returns to sleep mode (step 201).

[0013] Low-voltage energy management operation 200 aims to keep the vehicle in a sleep state as much as possible to reduce the consumption of the HV battery 120, while ensuring that the LV battery remains fully charged. Operation 200 further considers the limitations of sensor accuracy and the potential degradation of the LV battery 110 in the charging strategy, resulting in a more reliable vehicle.

[0014] The included description and accompanying drawings depict specific embodiments to teach those skilled in the art how to manufacture and use the optimal mode. For the purpose of teaching the principles of the invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand variations of these embodiments that fall within the scope of this invention. They will also understand that the above features can be combined in various ways to form multiple embodiments. Therefore, the invention is not limited to the specific embodiments described above, but is limited only by the claims and their equivalents.

Claims

1. A low-voltage energy management system for a vehicle, the system comprising: Low-voltage batteries; A battery sensor connected to the low-voltage battery; High-voltage batteries; as well as The controller is configured to: In response to a wake-up condition, the controller and battery sensor are woken up from sleep mode; In response to recalibration conditions, the battery sensor is recalibrated; In response to a charging condition, the low-voltage battery is charged using the high-voltage battery. as well as In response to the charging exit condition, charging of the low-voltage battery is stopped and the controller and battery sensor are placed in the sleep state.

2. The low-voltage energy management system according to claim 1, wherein the wake-up condition is based on the elapsed time of a predetermined period.

3. The low-voltage energy management system of claim 1, wherein charging the low-voltage battery with the high-voltage battery is via a DC-DC converter.

4. The low-voltage energy management system of claim 1, wherein the recalibration condition is based on the number of charging cycles.

5. The low-voltage energy management system of claim 1, wherein recalibrating the battery sensor comprises charging the low-voltage battery to a substantially fully charged state of charge at a predetermined charging rate.

6. The low-voltage energy management system of claim 5, wherein recalibrating the battery sensor further includes preventing the low-voltage battery from being charged until a predetermined time has elapsed or the state of charge of the low-voltage battery is below a predetermined critical state of charge.

7. The low-voltage energy management system of claim 1, wherein the entry condition is based on at least one of low-voltage battery voltage, state of charge, state of health, charging current, total capacity, and capacity loss.

8. The low-voltage energy management system of claim 1, wherein the exit condition is based on at least one of low-voltage battery voltage, state of charge, state of health, charging current, total capacity, and capacity loss.

9. The low-voltage energy management system of claim 1, wherein the controller is further configured to stop charging the low-voltage battery and place the controller and battery sensor into the sleep state in response to the elapsed maximum timeout.

10. The low-pressure energy management system of claim 9, wherein the maximum timeout is based on ambient temperature.

11. A low-voltage energy management method for a vehicle, the method comprising the following steps: In response to a wake-up condition, the controller and battery sensors are woken up from sleep mode; In response to recalibration conditions, the battery sensor is recalibrated; In response to charging conditions, the low-voltage battery is charged using the high-voltage battery. as well as In response to the charging exit condition, charging of the low-voltage battery is stopped and the controller and battery sensor are placed in the sleep state.

12. The low-voltage energy management method according to claim 11, wherein the wake-up condition is based on the elapsed time of a predetermined period.

13. The low-voltage energy management system of claim 11, wherein charging the low-voltage battery with the high-voltage battery is via a DC-DC converter.

14. The low-voltage energy management method of claim 11, wherein the recalibration condition is based on the number of charging cycles.

15. The low-voltage energy management method of claim 11, wherein recalibrating the battery sensor comprises charging the low-voltage battery to a substantially fully charged state of charge at a predetermined charging rate.

16. The low-voltage energy management method of claim 15, wherein recalibrating the battery sensor further includes preventing the low-voltage battery from being charged until a predetermined time has elapsed or the state of charge of the low-voltage battery is below a predetermined critical state of charge.

17. The low-voltage energy management method of claim 11, wherein the entry condition is based on at least one of low-voltage battery voltage, state of charge, state of health, charging current, total capacity, and capacity loss.

18. The low-voltage energy management method of claim 11, wherein the exit condition is based on at least one of low-voltage battery voltage, state of charge, state of health, charging current, total capacity, and capacity loss.

19. The low-voltage energy management method of claim 11, further comprising, in response to the elapsed maximum timeout, stopping charging of the low-voltage battery and placing the controller and battery sensor into the sleep state.

20. The low-pressure energy management method of claim 19, wherein the maximum timeout is based on ambient temperature.

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