Control device and method for low-voltage power supply system of new energy automobile

Abstract

The invention provides a control device and method for a low-voltage power supply system of a new energy automobile. The device comprises a vehicle state monitoring module and a DCDC output voltage value dynamic control module. The vehicle state monitoring module is used for obtaining monitoring information; and the DCDC output voltage value dynamic control module is used for obtaining a dynamically changing DCDC output voltage value according to the monitoring information. The low-voltage power supply system scheme is optimized, the floating charge loss of the low-voltage storage battery is reduced by monitoring the related state of the whole vehicle and dynamically adjusting the DCDC output voltage value, and compared with an existing DCDC constant-voltage output scheme, the low-voltage energy consumption is remarkably reduced; parts such as an IBS do not need to be added, and compared with an existing IBS intelligent battery management system scheme, the cost of the whole vehicle is remarkably reduced.

Description

Technical Field

[0001] The present invention belongs to the field of new energy vehicles, and specifically relates to a control device and method for a low-voltage power supply system of a new energy vehicle. Background Art

[0002] In new energy vehicles, power batteries are the only source of power energy. Their energy management solutions directly determine the working performance of their high-voltage components and the energy consumption of the entire vehicle. Currently, many high-voltage energy management solutions and technologies have been applied to new energy vehicles, so that battery power can be reasonably distributed and managed in the high-voltage system. However, for the energy management of the low-voltage part, since its own energy consumption is not high, and the time and money spent on technical low-voltage energy management research is often not proportional to the benefits, many new energy vehicles use simple low-voltage energy management solutions. Its basic logic and shortcomings are as follows:

[0003] like Figure 1 As shown in the figure, the DCDC 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 is used to power the DCDC. The DCDC, BMS, and VCU work together to convert the high voltage electricity of the power battery into a low voltage electricity of 12-16V, and power the low-voltage electrical appliances through the DCDC, and charge the low-voltage battery through the DCDC. This solution does not distinguish between vehicle operating conditions and scenarios, and the constant voltage output of the DCDC is uniformly controlled by the VCU, that is, the voltage output of the DCDC is fixed. The advantages of this solution are simple control and low cost; the disadvantages are that the voltage output cannot be accurately controlled, and the energy consumption of the low-voltage part is high. Therefore, this solution is often used in mid- and low-end models.

[0004] IBS intelligent battery management system Figure 2 As shown in the figure, compared with the DCDC constant voltage output solution, this solution adds an intelligent battery sensor (IBS) between the positive and negative electrodes of the low-voltage battery. The IBS detects the voltage, current, SOC, SOH, temperature and other status information of the low-voltage battery in real time, and feeds this information back to the VCU to control the DCDC output voltage value. This low-voltage energy management solution can effectively reduce the energy consumption of the low-voltage part, but this solution has two disadvantages. On the one hand, the disadvantage is that a special component IBS needs to be added, resulting in an increase in component costs. On the other hand, the disadvantage is that the system solution is more complicated, involving an increase in the time cost of software development and test verification. Therefore, this solution is suitable for mid-to-high-end new energy vehicle models. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, to provide a new energy vehicle low-voltage power supply system control device and method, to optimize the low-voltage energy management system, so that mid- and low-end models can also have good low-voltage energy consumption performance without increasing the cost of components.

[0006] The present invention is achieved through the following technical solutions:

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

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

[0009] The DCDC output voltage value dynamic control module is used to obtain a dynamically changing DCDC output voltage value according to monitoring information.

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

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

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

[0013] The output voltage and current of DCDC monitored in real time by DCDC;

[0014] The SOC and current of the power battery monitored in real time by the BMS;

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

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

[0017] The operation of the vehicle state monitoring module obtaining the dynamically changing DCDC output voltage value according to the monitoring information includes:

[0018] (1) Obtaining the first output voltage value U according to the ambient temperature 1 :

[0019] (2) Obtaining the second output voltage value U according to the SOC of the power battery 2 ;

[0020] (3) Obtaining the third output voltage value U according to the current of the power battery 3 ;

[0021] (4) Obtaining the fourth output voltage value U according to the output current of the DCDC 4 ;

[0022] (5) Obtain the fifth output voltage value U according to the vehicle operating conditions5 ;

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

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

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

[0026] Take the first output voltage value U 1 To the fifth output voltage value U 5 The maximum value in the output voltage is obtained after processing, and the dynamically changing DCDC output voltage value is obtained.

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

[0028] The processing refers to the first output voltage value U that changes in real time 1 To the fifth output voltage value U 5 The maximum value in is filtered to obtain the current voltage value, and the current voltage value is used as the DCDC output voltage value;

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

[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 method for controlling 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 a first output voltage value to a fifth output voltage value;

[0034] (3) A dynamically changing DCDC output voltage value is obtained according to the first output voltage value to the fifth output voltage value.

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

[0036] The operation of obtaining the first output voltage value to the fifth output voltage value in step (2) includes:

[0037] The first output voltage value U is obtained according to the ambient temperature monitored in real time by the temperature sensor 1 ;

[0038] The second output voltage value U is obtained according to the SOC of the power battery monitored in real time by the BMS. 2 ;

[0039] The third output voltage value U is obtained according to the current of the power battery monitored in real time by the BMS. 3 ;

[0040] The fourth output voltage value U is obtained according to the output current of the DCDC monitored in real time by the DCDC 4 ;

[0041] The fifth output voltage value U is obtained according to the vehicle operating conditions monitored in real time by the VCU 5 .

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

[0043] The operation of step (3) includes:

[0044] The maximum value among the first output voltage value to the fifth output voltage value is taken, and then filtering is performed according to the maximum value among the first output voltage value to the fifth output voltage value that changes in real time to obtain the current voltage value, and the current voltage value is used as the DCDC output voltage value.

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

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1) The present invention optimizes the low-voltage power supply system solution, reduces the floating charge loss of the low-voltage battery by monitoring the relevant status of the whole vehicle and dynamically adjusting the DCDC output voltage value, and significantly reduces the low-voltage energy consumption compared with the existing DCDC constant voltage output solution;

[0048] 2) The present invention does not require additional components such as IBS, and significantly reduces the cost of the entire vehicle compared to the existing IBS intelligent battery management system solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 System structure diagram of existing DCDC constant voltage output solution;

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

[0051] Figure 3 Flow chart of the control method of the low-voltage power supply system of a new energy vehicle of the present invention;

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

[0053] Figure 5A schematic diagram of obtaining a dynamically changing DCDC output voltage value according to a first output voltage value to a fifth output voltage value in a method for controlling a low-voltage power supply system for a new energy vehicle of the present invention. DETAILED DESCRIPTION

[0054] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0055] like Figure 4 As shown, the present invention provides a new energy vehicle low voltage power supply system control device, the structure of which is similar to Figure 1 Similarly, 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 is used to power the DCDC. The DCDC, BMS, and VCU work together to convert the high-voltage electricity of the power battery into a low-voltage electricity of 12-16V, and power the low-voltage electrical appliances through the DCDC, while charging the low-voltage battery through the DCDC. In order to better demonstrate the specific status information that needs to be monitored in the "vehicle status monitoring" involved in the present invention and the way the module responsible for monitoring transmits the monitoring information, Figure 4 The power battery and BMS are drawn separately, and two VCUs and two DCDCs are drawn. In fact, the two VCUs represent the same VCU ( Figure 4 The arrow from VCU to VCU does not mean that VCU sends the identified information to VCU, but that VCU needs the vehicle working condition, and the vehicle working condition identified by VCU can be processed in VCU's own software logic without additional transmission). The two DCDCs represent the same DCDC ( Figure 4 The arrow from the first DCDC to the VCU indicates that the DCDC sends the voltage and current to the VCU, and the arrow from the VCU to the second DCDC indicates that the VCU sends the voltage to the DCDC for controlling the DCDC output voltage value). Figure 1 same.

[0056] The present invention will Figure 4 The device shown is divided into two functional modules, namely a vehicle state monitoring module and a DCDC output voltage value dynamic control module, wherein the vehicle state monitoring module is used to obtain monitoring information, and the DCDC output voltage value dynamic control module is used to obtain a dynamically changing DCDC output voltage value according to the monitoring information. From a functional point of view, the vehicle state monitoring module can be understood as including Figure 4 The VCU, DCDC, BMS, and temperature sensor in the DCDC output voltage value dynamic control module are understood as including Figure 4The VCU, DCDC, power battery, low-voltage electrical appliances, and low-voltage storage battery in the device of the present invention. The DCDC output voltage value in the device of the present invention changes dynamically, so it can reduce unnecessary energy consumption of the low-voltage system on the basis of satisfying the normal operation of the vehicle low-voltage system.

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

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

[0059] The output voltage and current of DCDC monitored in real time by DCDC;

[0060] The SOC and current of the power battery monitored in real time by the BMS;

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

[0062] The above monitoring information can all be monitored by existing devices and will not be described in detail here.

[0063] The operation of the vehicle state monitoring module obtaining the dynamically changing DCDC output voltage value according to the monitoring information includes:

[0064] (1) Obtaining the first output voltage value U according to the ambient temperature 1 :

[0065] The VCU obtains the first output voltage value U according to the ambient temperature monitored in real time by the temperature sensor. 1 The ambient temperature has a great influence on the system efficiency and power loss of low-voltage batteries, and the influence is more obvious at low temperatures. 1 It should decrease as the ambient temperature increases.

[0066] Specifically, preset the ambient temperature and U 1 In this table, different ambient temperatures correspond to different U 1 VCU monitors the ambient temperature in real time and the ambient temperature and U 1 Take out the corresponding U from the comparison table 1 .

[0067] (2) Obtaining the second output voltage value U according to the SOC of the power battery 2 :

[0068] The VCU obtains the second output voltage value U according to the SOC of the power battery monitored in real time by the BMS. 2When the power battery has a high SOC (above 90%), it is usually in the state of just completing charging. Because the power battery has just been charged, the low-voltage battery will also be charged during the charging process. At this time, the low-voltage battery has a high power and voltage, and does not require DCDC to output a high voltage value to charge the battery. Therefore, U can be appropriately reduced. 2 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, and when charging the power battery, the low-voltage battery is also charged. At this time, the U 2 value.

[0069] Specifically, pre-set SOC and U 2 In this comparison table, different SOCs correspond to different U 2 , VCU monitors the SOC in real time to determine the SOC and U 2 Take out the corresponding U from the comparison table 2 .

[0070] (3) Obtaining the third output voltage value U according to the current of the power battery 3 :

[0071] The VCU obtains the third output voltage value U according to the current of the power battery monitored in real time by the BMS. 3 When the power battery output current is negative in the non-plug charging state, the vehicle is in the kinetic energy recovery state and needs to increase U 3 value, so that more of the recovered electricity of the drive motor can be stored in the low-voltage battery after DCDC conversion.

[0072] Specifically, the current of the power battery and U 3 In this table, different current values ​​correspond to different U 3 The VCU calculates the current of the power battery and the U value according to the current of the power battery monitored in real time. 3 Take out the corresponding U from the comparison table 3 .

[0073] (4) Obtaining the fourth output voltage value U according to the output current of the DCDC 4 :

[0074] The VCU obtains the fourth output voltage value U according to the output current of the DCDC monitored in real time by the DCDC 4 When the output current of DCDC is large, there are usually two states: one is that the vehicle's low-voltage system is in a high-load operation state, and the other is that the low-voltage battery is too low and is in a high-power charging state. In both cases, DCDC needs to have a large power output, and U needs to be increased. 4, until the output current of DCDC is lower than the set value or the time exceeds the set value.

[0075] Specifically, the output current of DCDC is preset to be 4 In this comparison table, different current values ​​correspond to different U 4 , VCU monitors the output current of DCDC in real time and compares the output current of DCDC with U 4 Take out the corresponding U from the comparison table 4 .

[0076] (5) Obtain the fifth output voltage value U according to the vehicle operating conditions 5

[0077] The VCU obtains the fifth output voltage value U according to the vehicle operating conditions monitored in real time by itself. 5 When the vehicle is in charging condition, U 5 , to prevent the low-voltage battery from being unable to charge due to the small pressure difference. When the vehicle is in external discharge or driving condition, the U 5 , avoiding energy loss in low-voltage components.

[0078] Specifically, the vehicle operating conditions and U 5 In this comparison table, different vehicle operating conditions correspond to different U 5 VCU monitors the vehicle usage conditions in real time and compares the vehicle usage conditions with the U 5 Take out the corresponding U from the comparison table 5 .

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

[0080] VCU takes the first output voltage value U 1 To the fifth output voltage value U 5 The maximum value in the output voltage is obtained after processing, and the dynamically changing DCDC output voltage value is obtained.

[0081] Because the first output voltage value U 1 To the fifth output voltage value U 5All of them change in real time, and the maximum value obtained from them also changes in real time, and changes very quickly. Since the value will change dynamically with the vehicle state, but the voltage changes too quickly (i.e., a large voltage difference) will have an impact on the low-voltage electrical appliances of the vehicle, that is, a negative impact on the normal operation of the low-voltage electrical appliances. Therefore, in the present invention, the VCU needs to limit the speed of change of the DCDC output voltage value. Specifically, the change rate of the DCDC output voltage value is limited to be less than or equal to the set change rate through filtering processing, for example, the change rate is ≤0.25V / s (the unit is volts per second), that is, the change amount of the DCDC output voltage value is limited to a maximum of 0.25 volts per second.

[0082] An example is as follows: Assume that from U 1 To U 5 The maximum value obtained from the value changes from 12V to 14V within 1 second, and assuming that the DCDC output voltage has reached 12V, after the change rate is limited by filtering, it takes 8s to complete the change ((14-12) / 0.25=8), that is, within these 8s, the DCDC output voltage value needs to slowly rise from 12V to 14V, and the rising slope is 0.25V / s, which takes a total of 8s. The filtering mentioned above actually controls the change slope of the DCDC output voltage value. The change slope is divided into rising and falling, and the slopes are 0.25V / s and -0.25V / s respectively. 1 To U 5 The maximum value of the value is taken as the target voltage value, and the voltage value output after filtering, that is, the change slope limit, is taken as the current voltage value, that is, the DCDC output voltage value U, because U 1 To U 5 The maximum value taken from the value changes in real time, so the target voltage value also changes in real time. The current voltage value is used as the benchmark at all times, and the DCDC output voltage value changes toward the target voltage value according to the rising or falling slope. The changed DCDC output voltage is used as the new current voltage value and changes toward the new target voltage value. This cycle repeats and continuously updates the current voltage value and the target voltage value.

[0083] like Figure 3 As shown, the present invention also provides a method for controlling 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 a first output voltage value to a fifth output voltage value;

[0086] Based on the existing low-voltage control system architecture of mid- and low-end models (such as Figure 4As shown in the figure, the existing components in the architecture are used to monitor the relevant status of the vehicle. After the VCU obtains the monitoring information, it dynamically adjusts the DCDC output voltage value, specifically:

[0087] The VCU obtains the first output voltage value U according to the ambient temperature monitored in real time by the temperature sensor. 1 ;

[0088] The VCU obtains the second output voltage value U according to the SOC of the power battery monitored in real time by the BMS. 2 ;

[0089] The VCU obtains the third output voltage value U according to the current of the power battery monitored in real time by the BMS. 3 ;

[0090] The VCU obtains the fourth output voltage value U according to the output current of the DCDC monitored in real time by the DCDC 4 ;

[0091] The VCU obtains the fifth output voltage value U according to the vehicle operating conditions monitored in real time by itself. 5

[0092] (3) Obtaining a dynamically changing DCDC output voltage value according to the first output voltage value to the fifth output voltage value:

[0093] like Figure 5 As shown, the VCU takes the maximum value from the first output voltage value to the fifth output voltage value, and then performs filtering processing based on the maximum value from the first output voltage value to the fifth output voltage value that changes in real time to obtain the current voltage value, and uses the current voltage value as the DCDC output voltage value.

[0094] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0095] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

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

Claims

1. A low-voltage power supply system control device for new energy vehicles, characterized in that: The device comprises: a vehicle state monitoring module and a DCDC output voltage value dynamic control module; The vehicle status monitoring module is used to obtain monitoring information; The DCDC output voltage value dynamic control module is used to obtain a dynamically changing DCDC output voltage value according to monitoring information.

2. The low-voltage power supply system control device for new energy vehicles according to claim 1 is characterized in that: The monitoring information obtained by the vehicle status monitoring module includes: Vehicle operating conditions monitored in real time by VCU; The output voltage and current of DCDC monitored in real time by DCDC; The SOC and current of the power battery monitored in real time by the BMS; The ambient temperature is monitored in real time by the temperature sensor.

3. The low-voltage power supply system control device for new energy vehicles according to claim 2 is characterized in that: The operation of the vehicle state monitoring module obtaining the dynamically changing DCDC output voltage value according to the monitoring information includes: (1) Obtaining the first output voltage value U1 according to the ambient temperature: (2) obtaining a second output voltage value U2 according to the SOC of the power battery; (3) obtaining a third output voltage value U3 according to the current of the power battery; (4) obtaining a fourth output voltage value U4 according to the output current of the DCDC; (5) obtaining a fifth output voltage value U5 according to the vehicle operating condition; (6) Obtain the dynamically changing DCDC output voltage value.

4. The low-voltage power supply system control device for new energy vehicles according to claim 3 is characterized in that: The operation of obtaining the dynamically changing DCDC output voltage value includes: The maximum value among the first output voltage value U1 to the fifth output voltage value U5 is taken, and after processing, a dynamically changing DCDC output voltage value is obtained.

5. The low-voltage power supply system control device for new energy vehicles according to claim 4 is characterized in that: The processing refers to filtering the maximum value among the first output voltage value U1 to the fifth output voltage value U5 which changes in real time, obtaining the current voltage value, and using the current voltage value as the DCDC output voltage value; The change rate of the DCDC output voltage value is less than or equal to the set change rate.

6. The low-voltage power supply system control device for new energy vehicles according to claim 5 is characterized in that: The set change rate is 0.25V / s.

7. A method for controlling a low-voltage power supply system for a new energy vehicle, characterized in that: The method comprises: (1) High voltage on the vehicle; (2) vehicle status monitoring, obtaining a first output voltage value to a fifth output voltage value; (3) A dynamically changing DCDC output voltage value is obtained according to the first output voltage value to the fifth output voltage value.

8. The method for controlling a low-voltage power supply system for a new energy vehicle according to claim 7, characterized in that: The operation of obtaining the first output voltage value to the fifth output voltage value in step (2) includes: Obtaining a first output voltage value U1 according to the ambient temperature monitored in real time by the temperature sensor; Obtaining a second output voltage value U2 according to the SOC of the power battery monitored in real time by the BMS; Obtaining a third output voltage value U3 according to the current of the power battery monitored in real time by the BMS; Obtaining a fourth output voltage value U4 according to the output current of the DCDC monitored in real time by the DCDC; The fifth output voltage value U5 is obtained according to the vehicle operating condition monitored in real time by the VCU.

9. The method for controlling a low-voltage power supply system for a new energy vehicle according to claim 7, characterized in that: The operation of step (3) includes: The maximum value among the first output voltage value to the fifth output voltage value is taken, and then filtering is performed according to the maximum value among the first output voltage value to the fifth output voltage value that changes in real time to obtain the current voltage value, and the current voltage value is used as the DCDC output voltage value.

10. The method for controlling a low-voltage power supply system for a new energy vehicle according to claim 9, characterized in that: The change rate of the DCDC output voltage value is less than or equal to 0.25V / s.

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