A new energy vehicle low-voltage power supply system control device and method

Abstract

This invention provides a control device and method for a low-voltage power supply system in new energy vehicles. The device includes a vehicle status monitoring module and a dynamic control module for DC-DC output voltage. The vehicle status monitoring module is used to obtain monitoring information; the dynamic control module for DC-DC output voltage is used to obtain dynamically changing DC-DC output voltage values ​​based on the monitoring information. This invention optimizes the low-voltage power supply system scheme. By monitoring the relevant states of the vehicle and dynamically adjusting the DC-DC output voltage, it reduces low-voltage battery float charging losses, significantly lowering low-voltage energy consumption compared to existing DC-DC constant voltage output schemes. Furthermore, this invention eliminates the need for additional IBS (Intelligent Battery Management System) components, significantly reducing overall vehicle costs compared to existing IBS intelligent battery management system solutions.

Description

Technical Field

[0001] This invention belongs to the field of new energy vehicles, specifically relating to a control device and method for a low-voltage power supply system of new energy vehicles. Background Technology

[0002] In new energy vehicles, the power battery is the sole source of power. Its energy management scheme directly determines the performance of its high-voltage components and the overall energy consumption of the vehicle. Currently, numerous high-voltage energy management schemes and technologies have been applied to new energy vehicles, enabling the rational allocation and management of battery power within the high-voltage system. However, for low-voltage energy management, because its energy consumption is not high, and the time and money spent on technical research into low-voltage energy management is often disproportionate to the returns, many new energy vehicles adopt simple low-voltage energy management schemes. The basic logic and shortcomings of these schemes are as follows:

[0003] like Figure 1 As shown, the DC-DC constant voltage output system includes a vehicle control unit (VCU), a power battery (with a battery management system (BMS)), a DC-DC converter (DCDC), a low-voltage battery, and low-voltage electrical appliances. The power battery powers the DCDC. The DCDC, BMS, and VCU work together to convert the high-voltage electricity from the power battery into 12-16V low-voltage electricity, which then powers the low-voltage electrical appliances and charges the low-voltage battery. This solution does not differentiate between vehicle operating conditions and scenarios; the VCU uniformly controls the constant voltage output of the DCDC, meaning the DCDC output voltage is fixed. The advantages of this solution are simple control and low cost; the disadvantages are that it cannot precisely control the voltage output, and the low-voltage section has higher energy consumption. Therefore, this solution is commonly used in mid-to-low-end vehicles.

[0004] IBS intelligent battery management system, such as Figure 2 As shown, compared to the DC-DC constant voltage output solution, this solution adds an intelligent battery sensor (IBS) between the positive and negative terminals of the low-voltage battery. The IBS monitors the battery's voltage, current, SOC, SOH, and temperature in real time and feeds this information back to the VCU to control the DC-DC output voltage. This low-voltage energy management solution can effectively reduce energy consumption in the low-voltage section. However, this solution has two drawbacks: firstly, it requires the addition of a dedicated component, the IBS, increasing component costs; secondly, the system is more complex, increasing the time and cost of software development and testing. Therefore, this solution is suitable for mid-to-high-end new energy vehicle models. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and provide a control device and method for a low-voltage power supply system of new energy vehicles, optimize the low-voltage energy management system, and enable low- and mid-range models to have good low-voltage energy consumption performance without increasing the cost of parts.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a control device for a low-voltage power supply system of a new energy vehicle, the device comprising: a vehicle status monitoring module and a dynamic control module for DC-DC output voltage;

[0008] The vehicle status monitoring module is used to obtain monitoring information;

[0009] The DC-DC output voltage dynamic control module is used to obtain the dynamically changing DC-DC output voltage value based on monitoring information.

[0010] A further improvement of the present invention is that:

[0011] The monitoring information obtained by the vehicle status monitoring module includes:

[0012] Vehicle operating conditions monitored in real time by the VCU;

[0013] The output voltage and current of the DC-DC converter are monitored in real time.

[0014] The BMS monitors the SOC and current of the power battery in real time.

[0015] The ambient temperature is monitored in real time by a temperature sensor.

[0016] A further improvement of the present invention is that:

[0017] The operation of the vehicle condition monitoring module to obtain the dynamically changing DC-DC output voltage value based on the monitoring information includes:

[0018] (1) Obtain the first output voltage value U1 based on the ambient temperature:

[0019] (2) Obtain the second output voltage value U2 based on the SOC of the power battery;

[0020] (3) Obtain the third output voltage value U3 based on the current of the power battery;

[0021] (4) Obtain the fourth output voltage value U4 based on the output current of the DC-DC converter;

[0022] (5) Obtain the fifth output voltage value U5 based on the vehicle operating conditions;

[0023] (6) Obtain the dynamically changing DC-DC output voltage value.

[0024] A further improvement of the present invention is that:

[0025] The operation of obtaining the dynamically changing DC-DC output voltage value includes:

[0026] The maximum value among the first output voltage value U1 to the fifth output voltage value U5 is taken and processed to obtain the dynamically changing DC-DC output voltage value.

[0027] A further improvement of the present invention is that:

[0028] The processing refers to filtering based on the maximum value among the real-time changing first output voltage value U1 to fifth output voltage value U5 to obtain the current voltage value, and using the current voltage value as the DC-DC output voltage value.

[0029] The rate of change of the DC-DC output voltage is less than or equal to the set rate of change.

[0030] A further improvement of the present invention is that the set change rate is 0.25V / s.

[0031] A second aspect of the present invention provides a control method for a low-voltage power supply system of a new energy vehicle, the method comprising:

[0032] (1) High voltage on the vehicle;

[0033] (2) Vehicle status monitoring, obtaining the first to the fifth output voltage values;

[0034] (3) Obtain the dynamically changing DC-DC output voltage value based on the first output voltage value to the fifth output voltage value.

[0035] A further improvement of the present invention is that:

[0036] The operations in step (2) to obtain the first to fifth output voltage values ​​include:

[0037] The first output voltage value U1 is obtained based on the ambient temperature monitored in real time by the temperature sensor.

[0038] The second output voltage value U2 is obtained based on the SOC of the power battery monitored in real time by the BMS;

[0039] The third output voltage value U3 is obtained based on the current of the power battery monitored in real time by the BMS.

[0040] The fourth output voltage value U4 is obtained based on the output current of the DC-DC converter monitored in real time.

[0041] The fifth output voltage value U5 is obtained based on the vehicle operating conditions monitored in real time by the VCU.

[0042] A further improvement of the present invention is that:

[0043] Step (3) includes the following operations:

[0044] Take the maximum value among the first and fifth output voltage values, then perform filtering based on the real-time changing maximum value among the first and fifth output voltage values ​​to obtain the current voltage value, and use the current voltage value as the DC-DC output voltage value.

[0045] A further improvement of the present invention is that the rate of change of the DC-DC output voltage is less than or equal to 0.25V / s.

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] 1) This invention optimizes the low-voltage power supply system scheme. By monitoring the relevant status of the vehicle and dynamically adjusting the output voltage of the DC-DC converter, it reduces the float charging loss of the low-voltage battery and significantly reduces the low-voltage energy consumption compared with the existing DC-DC constant voltage output scheme.

[0048] 2) This invention does not require the addition of IBS or other components, and significantly reduces the overall vehicle cost compared to existing IBS intelligent battery management system solutions. Attached Figure Description

[0049] Figure 1 A schematic diagram of the existing DC-DC constant voltage output scheme;

[0050] Figure 2 A schematic diagram of the existing IBS intelligent battery management system solution;

[0051] Figure 3 A flowchart of the control method for a low-voltage power supply system of a new energy vehicle according to the present invention;

[0052] Figure 4 A schematic diagram of the structure of the control device for the low-voltage power supply system of new energy vehicles according to the present invention;

[0053] Figure 5 This invention provides a schematic diagram of the control method for a low-voltage power supply system of a new energy vehicle, which obtains dynamically changing DC-DC output voltage values ​​based on the first output voltage value to the fifth output voltage value. Detailed Implementation

[0054] The present invention will now be described in further detail with reference to the accompanying drawings:

[0055] like Figure 4 As shown, this invention provides a control device for a low-voltage power supply system of a new energy vehicle, the structure of which is similar to... Figure 1Similarly, it also includes a vehicle control unit (VCU), a power battery (with a battery management system (BMS)), a DC-DC converter (DCDC), a low-voltage battery, and low-voltage electrical appliances. The power battery powers the DCDC, and the DCDC, BMS, and VCU work together to convert the high-voltage electricity from the power battery into 12-16V low-voltage electricity, which then powers the low-voltage electrical appliances and charges the low-voltage battery via the DCDC. To better illustrate the specific state information that needs to be monitored in the "vehicle state monitoring" involved in this invention, and the way the monitoring module transmits the monitored information, Figure 4 The power battery and BMS are drawn separately, and two VCUs and two DC-DC converters are drawn. In fact, the two VCUs represent the same VCU. Figure 4 The arrow from VCU to VCU does not indicate that VCU sends the recognized information to VCU, but rather that VCU needs the vehicle operating conditions, and the vehicle operating conditions recognized by VCU can be processed in VCU's own software logic without additional transmission. The two DC-DC converters represent the same DC-DC converter. Figure 4 The first arrow from the DC-DC converter to the VCU indicates that the DC-DC converter sends voltage and current to the VCU, and the arrow from the VCU to the second DC-DC converter indicates that the VCU sends voltage to the DC-DC converter (used to control the DC-DC converter's output voltage value). Figure 1 same.

[0056] This invention will Figure 4 The device shown is divided into two functional modules: a vehicle condition monitoring module and a DC-DC output voltage dynamic control module. The vehicle condition monitoring module acquires monitoring information, and the DC-DC output voltage dynamic control module acquires dynamically changing DC-DC output voltage values ​​based on the monitoring information. Functionally, the vehicle condition monitoring module can be understood as including... Figure 4 The VCU, DCDC, BMS, and temperature sensor in the DCDC output voltage dynamic control module can be understood as including... Figure 4 The device includes a VCU, DC-DC converter, power battery, low-voltage electrical appliances, and low-voltage storage battery. The DC-DC output voltage in this invention's device is dynamically changing, thus reducing unnecessary energy consumption in the low-voltage system while ensuring its normal operation.

[0057] The monitoring information obtained by the vehicle status monitoring module includes:

[0058] Vehicle operating conditions monitored in real time by the VCU;

[0059] The output voltage and current of the DC-DC converter are monitored in real time.

[0060] The BMS monitors the SOC and current of the power battery in real time.

[0061] The ambient temperature is monitored in real time by a temperature sensor.

[0062] The monitoring information mentioned above is all that the existing devices can monitor, and will not be described in detail here.

[0063] The operation of the vehicle condition monitoring module to obtain the dynamically changing DC-DC output voltage value based on the monitoring information includes:

[0064] (1) Obtain the first output voltage value U1 based on the ambient temperature:

[0065] The VCU obtains the first output voltage value U1 based on the ambient temperature monitored in real time by the temperature sensor. Ambient temperature has a significant impact on the system efficiency and charge loss of low-voltage batteries, and the impact is more pronounced at low temperatures. Therefore, U1 should decrease as the ambient temperature increases.

[0066] Specifically, a lookup table between ambient temperature and U1 is pre-set, in which different ambient temperatures correspond to different U1 values. The VCU retrieves the corresponding U1 value from the ambient temperature and U1 lookup table based on the real-time monitored ambient temperature.

[0067] (2) Obtain the second output voltage value U2 based on the SOC of the power battery:

[0068] The VCU obtains the second output voltage value U2 based on the SOC of the power battery monitored in real time by the BMS. When the power battery has a high SOC (above 90%), it is usually in a state where charging has just been completed. Because the power battery has just finished charging, the low-voltage battery is also being charged during the charging process. At this time, the low-voltage battery has a high charge and voltage, and there is no need for the DC-DC converter to output a high voltage value to charge the low-voltage battery. Therefore, the U2 value can be appropriately reduced. When the power battery has a low SOC (below 20%), the vehicle usually needs to be charged, that is, the driver will charge the power battery. While the power battery is being charged, the low-voltage battery is also being charged. At this time, the U2 value can also be appropriately reduced.

[0069] Specifically, a lookup table between SOC and U2 is pre-set. In this lookup table, different SOCs correspond to different U2s. The VCU retrieves the corresponding U2 from the SOC and U2 lookup table based on the SOC monitored in real time.

[0070] (3) Obtain the third output voltage value U3 based on the current of the power battery:

[0071] The VCU obtains the third output voltage value U3 based on the real-time monitoring of the power battery current by the BMS. When the power battery output current is negative during non-plug-in charging, the vehicle is in kinetic energy recovery mode, and the U3 value needs to be increased so that more of the recovered energy from the drive motor is stored in the low-voltage battery after DC-DC conversion.

[0072] Specifically, a lookup table between the power battery current and U3 is pre-set. In this lookup table, different current values ​​correspond to different U3 values. The VCU retrieves the corresponding U3 from the lookup table of power battery current and U3 based on the power battery current monitored in real time.

[0073] (4) Obtain the fourth output voltage value U4 based on the output current of the DC-DC converter:

[0074] The VCU obtains the fourth output voltage value U4 based on the real-time output current of the DC-DC converter. When the DC-DC converter's output current is high, there are usually two states: one is that the vehicle's low-voltage system is operating under heavy load, and the other is that the low-voltage battery is too low and is in a high-power charging state. In both cases, the DC-DC converter needs to have a larger power output, and U4 needs to be increased until the DC-DC converter's output current is lower than the set value or the time exceeds the set value.

[0075] Specifically, a lookup table between the output current of the DC-DC converter and U4 is pre-set. In this lookup table, different current values ​​correspond to different U4 values. The VCU retrieves the corresponding U4 from the lookup table of the output current of the DC-DC converter and U4 based on the real-time monitored output current of the DC-DC converter.

[0076] (5) Obtain the fifth output voltage value U5 based on the vehicle operating conditions.

[0077] The VCU obtains the fifth output voltage value U5 based on its real-time monitoring of vehicle operating conditions. When the vehicle is charging, U5 should be increased to prevent the low-voltage battery from failing to charge due to a small voltage difference. When the vehicle is discharging externally or driving, U5 should be decreased to avoid energy loss from low-voltage components.

[0078] Specifically, a lookup table of vehicle operating conditions and U5 is pre-set. In this lookup table, different vehicle operating conditions correspond to different U5s. The VCU retrieves the corresponding U5 from the lookup table of vehicle operating conditions and U5s based on the real-time monitored vehicle operating conditions.

[0079] (6) Obtain the dynamically changing DC-DC output voltage value:

[0080] The VCU takes the maximum value from the first output voltage value U1 to the fifth output voltage value U5, and after processing, obtains the dynamically changing DC-DC output voltage value.

[0081] Because the first output voltage value U1 to the fifth output voltage value U5 all change in real time, and the maximum value obtained from them also changes in real time and very quickly, since this value will change dynamically with the vehicle status, but the voltage change is too fast (i.e., a large voltage difference) will impact the low-voltage electrical appliances of the vehicle, that is, it will have a negative impact on the normal operation of the low-voltage electrical appliances. Therefore, in this invention, the VCU needs to limit the rate of change of the DC-DC output voltage value. Specifically, the rate of change of the DC-DC output voltage value is limited to less than or equal to a set rate of change through filtering, for example, the rate of change ≤ 0.25V / s (unit is volts per second), that is, the change of the DC-DC output voltage value is limited to a maximum change of 0.25 volts per second.

[0082] For example: Suppose that the maximum value taken from U1 to U5 changes from 12V to 14V in 1 second, and assume that the DC-DC output voltage has already reached 12V. After filtering and limiting the rate of change, it will take 8 seconds to complete the change ((14-12) / 0.25=8). That is, within these 8 seconds, the DC-DC output voltage needs to slowly rise from 12V to 14V, with a rise slope of 0.25V / s, and a total time of 8 seconds. The filtering mentioned above actually controls the slope of the DC-DC output voltage. The slope is divided into rising and falling, with slopes of 0.25V / s and -0.25V / s respectively. The maximum value among U1 to U5 can be taken as the target voltage value, and the voltage value after filtering (i.e., the slope limit) can be taken as the current voltage value, i.e., the DC-DC output voltage value U. Since the maximum value among U1 to U5 changes in real time, the target voltage value also changes in real time. At every moment, the DC-DC output voltage value changes towards the target voltage value according to the rising or falling slope, based on the current voltage value. The changed DC-DC output voltage is then taken as the new current voltage value and changes towards the new target voltage value. This cycle repeats continuously, constantly updating the current voltage value and the target voltage value.

[0083] like Figure 3 As shown, the present invention also provides a control method for a low-voltage power supply system of a new energy vehicle, the method comprising:

[0084] (1) High voltage on the vehicle;

[0085] (2) Vehicle status monitoring, obtaining the first to the fifth output voltage values;

[0086] Based on the existing low-voltage control system architecture of mid-to-low-end vehicles (such as...) Figure 4 As shown), the system utilizes existing components within the architecture to monitor the vehicle's relevant status. After acquiring the monitoring information, the VCU dynamically adjusts the DC-DC output voltage value, specifically as follows:

[0087] The VCU obtains the first output voltage value U1 based on the ambient temperature monitored in real time by the temperature sensor.

[0088] The VCU obtains the second output voltage value U2 based on the SOC of the power battery monitored in real time by the BMS;

[0089] The VCU obtains the third output voltage value U3 based on the current of the power battery monitored in real time by the BMS.

[0090] The VCU obtains the fourth output voltage value U4 based on the output current of the DC-DC converter monitored in real time.

[0091] The VCU obtains the fifth output voltage value U5 based on its real-time monitoring of vehicle operating conditions.

[0092] (3) Obtain the dynamically changing DC-DC output voltage value based on the first output voltage value to the fifth output voltage value:

[0093] like Figure 5 As shown, the VCU takes the maximum value among the first output voltage value to the fifth output voltage value, and then performs filtering based on the real-time changing maximum value among the first output voltage value to the fifth output voltage value to obtain the current voltage value, and uses the current voltage value as the DC-DC output voltage value.

[0094] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0095] In the description of this invention, unless otherwise stated, the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0096] The above technical solution is only one embodiment of the present invention. For those skilled in the art, based on the principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the technical solutions described in the specific embodiments of the present invention. Therefore, the foregoing description is only preferred and not restrictive.

Claims

1. A new energy vehicle low-voltage power supply system control device, characterized in that: The device does not require a smart battery sensor (IBS) and includes: a vehicle condition monitoring module and a DC-DC output voltage dynamic control module. The vehicle status monitoring module is used to obtain monitoring information, which includes: vehicle operating conditions monitored in real time by the VCU; output voltage and current of the DC-DC converter monitored in real time by the DC-DC converter; SOC and current of the power battery monitored in real time by the BMS; and ambient temperature monitored in real time by the temperature sensor. The DC-DC output voltage dynamic control module is used to obtain the dynamically changing DC-DC output voltage value based on monitoring information; The dynamic control module for the output voltage value of the DC-DC converter is specifically used for: Obtaining a first output voltage value U according to the ambient temperature 1； The second output voltage value U2 is obtained based on the SOC of the power battery; The third output voltage value U3 is obtained based on the current of the power battery; The fourth output voltage value U4 is obtained based on the output current of the DC-DC converter. The fifth output voltage value U5 is obtained based on the vehicle operating conditions; To obtain a dynamically changing DC-DC output voltage value: take the maximum value among the first output voltage value U1 to the fifth output voltage value U5, and obtain the dynamically changing DC-DC output voltage value after filtering; the rate of change of the DC-DC output voltage value is less than or equal to the set rate of change.

2. The new energy vehicle low-voltage power supply system control device according to claim 1, characterized in that: The processing refers to filtering based on the maximum value among the real-time changing first output voltage value U1 to the fifth output voltage value U5 to obtain the current voltage value, and using the current voltage value as the DC-DC output voltage value.

3. The new energy vehicle low-voltage power supply system control device according to claim 1, characterized in that: The set change rate is 0.25V / s.

4. A control method for a low-voltage power supply system of a new energy vehicle, implemented using the control device for a low-voltage power supply system of a new energy vehicle as described in any one of claims 1-3, characterized in that: The method includes: (1) High voltage on the vehicle; (2) Vehicle status monitoring to obtain the first to the fifth output voltage values; (3) Obtain the dynamically changing DC-DC output voltage value based on the first output voltage value to the fifth output voltage value.

5. The new energy vehicle low-voltage power supply system control method according to claim 4, characterized in that: The operations in step (2) to obtain the first to fifth output voltage values ​​include: The first output voltage value U1 is obtained based on the ambient temperature monitored in real time by the temperature sensor. The second output voltage value U2 is obtained based on the SOC of the power battery monitored in real time by the BMS; The third output voltage value U3 is obtained based on the current of the power battery monitored in real time by the BMS. The fourth output voltage value U4 is obtained based on the output current of the DC-DC converter monitored in real time. The fifth output voltage value U5 is obtained based on the vehicle operating conditions monitored in real time by the VCU.

6. The new energy vehicle low-voltage power supply system control method according to claim 5, characterized in that: Step (3) includes the following operations: Take the maximum value among the first and fifth output voltage values, then perform filtering based on the real-time changing maximum value among the first and fifth output voltage values ​​to obtain the current voltage value, and use the current voltage value as the DC-DC output voltage value.

7. The new energy vehicle low-voltage power supply system control method according to claim 6, characterized in that: The rate of change of the DC-DC output voltage is less than or equal to 0.25V / s.

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