Low-voltage power supply method for new energy vehicles

Abstract

The present invention discloses a low-voltage power supply method for new energy vehicles. The main design concept of the present invention is to divide low-voltage electrical appliances into a first electrical load and a second electrical load, connect the first electrical load in parallel with a DC-DC converter, and connect the second electrical load in parallel with a battery, so that the second electrical load has two power supply sources. The power demand is determined in real time based on the activation status of the low-voltage electrical appliances. Based on the power demand and the battery status, the operating power combination of the DC-DC converter is actively controlled to maintain a high-efficiency operating state of the DC-DC converter. The reasonable low-voltage power supply mode provided by the present invention is applicable to new energy passenger cars and commercial vehicles equipped with a DC-DC converter. Only simple modifications to the vehicle power supply wiring harness and electrical components are required to effectively reduce the loss of the DC-DC converter and improve the endurance performance of the entire vehicle. This effectively compensates for the shortcomings of the existing DC-DC converter operating power control strategy and establishes a control mechanism for efficient DC-DC operation.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a low-voltage power supply method for new energy vehicles. Background Art

[0002] New energy vehicles, including plug-in hybrid vehicles and pure electric vehicles, are gaining increasing market acceptance and maintaining a growing market share. The driving range of new energy vehicles directly impacts the overall driving experience, prompting automakers to research control technologies for all aspects of vehicle energy transmission to improve overall vehicle energy efficiency. The DC-DC converter, a high-voltage to low-voltage converter that powers low-voltage electrical appliances, significantly impacts vehicle energy consumption.

[0003] The low-voltage system power supply logic of new energy vehicles in the current market is divided into the following situations:

[0004] 1) The vehicle is on high voltage ("Ready"), and low voltage electrical appliances are powered by DCDC;

[0005] 2) The vehicle is under high voltage, and the low voltage electrical appliances are powered by 12V or 24V batteries;

[0006] 3) After the vehicle is powered on, when the battery voltage is lower than the limit (for example, 11.5V), the DCDC will charge the battery.

[0007] The DCDC output power is controlled by the VCU, which calculates the DCDC working power according to the low-voltage electrical appliance on-state. The DCDC efficiency ranges from 85% to 95%, and the DCDC working efficiency directly affects the energy consumption of the entire vehicle. Its working power and conversion efficiency are as follows: Figure 1 As shown, it can be seen that controlling the operating power of DCDC in the medium and high load area will effectively reduce DCDC loss.

[0008] The current low-voltage system power supply method has the following problems:

[0009] 1) The operating power of the DCDC is determined by the low-voltage electrical appliances turned on in the vehicle;

[0010] 2) The DC-DC converter is connected in parallel with the low-voltage electrical appliances, and the battery is directly connected to the DC-DC converter, making it impossible to actively control the charging and discharging of the battery. Summary of the Invention

[0011] In view of the above, the present invention aims to provide a low-voltage power supply method for new energy vehicles to solve the above-mentioned technical problems.

[0012] The technical solution adopted in the present invention is as follows:

[0013] The present invention provides a low-voltage power supply method for new energy vehicles, comprising:

[0014] Dividing the low-voltage electrical appliances in the vehicle into a first electrical load and a second electrical load;

[0015] On the basis of the parallel connection between the DCDC and the battery, the first electrical load is connected in parallel with the DCDC, and the second electrical load is connected in parallel with the battery, so that the second electrical load has two power supply sources;

[0016] Determine the power demand for DCDC in real time based on the power-on status of low-voltage electrical appliances; the power demand is used to determine the working efficiency of DCDC;

[0017] Based on the working efficiency and in combination with the voltage state of the battery, the working power combination of the DCDC is determined.

[0018] In at least one possible implementation manner, the power requirement is determined by determining a load of the first electrical load.

[0019] In at least one possible implementation, the determining the operating power combination of the DCDC includes:

[0020] When the load of the first electrical load is less than a preset power demand threshold, detecting whether the voltage of the battery is lower than a preset full-charge voltage;

[0021] If the battery voltage is lower than the fully charged voltage, the operating power of the DCDC is the sum of the power required by the first electrical load, the power required by the second electrical load, and the battery charging power;

[0022] If the voltage of the battery is higher than the fully charged voltage, the operating power of the DCDC is the sum of the power required by the first electrical load and the power required by the second electrical load.

[0023] In at least one possible implementation, the determining the operating power combination of the DCDC includes:

[0024] When the load of the first electrical load is greater than a preset power demand threshold, detecting whether the voltage of the battery is higher than a preset maximum voltage of the battery feeding state;

[0025] If the battery voltage is higher than the maximum voltage, the operating power of the DCDC is the power required by the first electrical load;

[0026] If the voltage of the battery is lower than the maximum voltage, the operating power of the DCDC is the sum of the power required by the first electrical load and the power required by the second electrical load.

[0027] In at least one possible implementation, the work efficiency includes:

[0028] The efficiency distribution of DCDC is calibrated in advance based on the two dimensions of load ratio and efficiency;

[0029] According to the efficiency distribution, a lower efficiency area and a higher efficiency area related to the power demand are obtained.

[0030] In at least one possible implementation manner, the second electrical load is an electrical appliance that must work after the vehicle is started.

[0031] In at least one possible implementation manner, a power supply line of the second electrical load is integrated into a low-voltage power harness.

[0032] Compared with the prior art, the main design concept of the present invention is to divide low-voltage electrical appliances into a first electrical load and a second electrical load, connect the first electrical load in parallel with the DC-DC converter, and connect the second electrical load in parallel with the battery, so that the second electrical load has two power supply sources. The power demand is determined in real time based on the activation status of the low-voltage electrical appliances. Based on the power demand and battery status, the DC-DC converter's operating power combination is actively controlled to maintain a highly efficient operating state. The reasonable low-voltage power supply mode provided by the present invention is applicable to new energy passenger cars and commercial vehicles equipped with DC-DC converters. Only simple modifications to the vehicle's power supply wiring harness and electrical components are required to effectively reduce DC-DC converter losses and improve vehicle endurance performance. This effectively compensates for the shortcomings of existing DC-CDC operating power control strategies and establishes a control mechanism for efficient DC-CDC operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described below with reference to the accompanying drawings, in which:

[0034] Figure 1 Schematic diagram of the relationship between DCDC efficiency and load (percentage);

[0035] Figure 2 A schematic diagram of a flow chart of a low-voltage power supply method for a new energy vehicle provided by an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the circuit connections between low-voltage electrical appliances, DCDC, batteries and relays provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0038] The present invention proposes an embodiment of a low-voltage power supply method for new energy vehicles. Specifically, Figure 2 shown, including:

[0039] Step S1, dividing the low-voltage electrical appliances in the vehicle into a first electrical load and a second electrical load;

[0040] Step S2: On the basis of the parallel connection between the DC-DC converter and the battery, the first electrical load is connected in parallel with the DC-DC converter, and the second electrical load is connected in parallel with the battery, so that the second electrical load has two power sources (battery and DC-DC converter);

[0041] Step S3: Determine the power demand for the DCDC in real time based on the start-up status of the low-voltage electrical appliances. The power demand is used to determine the working efficiency of the DCDC. In actual operation, the power demand can be determined by calculating the load of the first electrical load.

[0042] The working efficiency described here includes: pre-calibrating the efficiency distribution of the DCDC based on the two dimensions of load ratio and efficiency; obtaining a lower efficiency zone and a higher efficiency zone related to the power demand based on the efficiency distribution; it can be understood that the higher efficiency zone corresponds to the preset medium and high loads of the DCDC, and the lower efficiency zone corresponds to the preset low load and high load of the DCDC.

[0043] Step S4: Based on the working efficiency and the voltage state of the battery, determine the working power combination of the DCDC.

[0044] That is, when formulating a reasonable control of the DCDC output power, the present invention also takes into account whether the battery has the conditions to assist in power supply and whether it needs to be charged. Based on this integrated consideration, the corresponding power supply line is controlled to form a combination of different DCDC output working power values.

[0045] Specifically, when the load of the first electrical load is less than a preset power demand threshold, detecting whether the voltage of the battery is lower than a preset full-charge voltage;

[0046] If it is lower than the full-charge voltage, the operating power of the DCDC is the sum of the power required by the first electrical load, the power required by the second electrical load, and the battery charging power;

[0047] If it is higher than the full-charge voltage, the operating power of the DCDC is the sum of the power required by the first electrical load and the power required by the second electrical load.

[0048] In another case, when the load of the first electrical load is greater than a preset power demand threshold, detecting whether the voltage of the battery is higher than a preset maximum voltage of the battery feeding state;

[0049] If it is higher than the maximum voltage, the operating power of the DCDC is the power required by the first electrical load;

[0050] If it is lower than the maximum voltage, the operating power of the DCDC is the sum of the power required by the first electrical load and the power required by the second electrical load.

[0051] To facilitate understanding of the aforementioned embodiments, Figure 3 As shown, a relay K2 can be installed between the connection line between the DCDC and the battery C to independently control the on / off of the battery, so that the battery can be used as the power load of the DCDC, thereby adjusting the working power (work load) of the DCDC; and a part of the vehicle's basic low-voltage electrical appliances (such as headlights, etc.) can be separated from the original load concept, such as into power load A (first power load) and power load B (second power load), where power load B is the separated part of the basic low-voltage electrical appliances, which is independently connected in parallel with the battery, and a relay K1 is added to control the on / off of the power supply circuit composed of the battery and power load B.

[0052] Corresponding to the above-mentioned hardware system changes, the VCU control logic for adjusting the DCDC operating power was further designed, thereby achieving a higher probability of the DCDC operating in the aforementioned high-efficiency area of ​​medium and high loads.

[0053] The specific logic is as follows:

[0054] (1) When the voltage and power consumption of the entire vehicle are at the medium or low load of the DCDC (lower efficiency zone), K1 is triggered to close and K2 is closed, the DCDC charges the battery, and the electrical load B is powered by the DCDC (of course, it can be understood that the power supply mechanism of the electrical load A is the same as before the improvement), thereby increasing the working power of the DCDC;

[0055] (2) When the voltage and power consumption of the vehicle are in the medium-high load (higher efficiency zone) of the DCDC, K1 is triggered to close and K2 is disconnected. The DCDC does not charge the battery, and the power load B is powered by the DCDC, thereby ensuring the efficient operation of the DCDC.

[0056] (3) When the voltage and power consumption of the vehicle are at the high load (low efficiency zone) of the DCDC, K1 is triggered to open and K2 is closed, and the battery supplies power to the load B, reducing the working power of the DCDC (at this time, the DCDC only supplies power to the load A);

[0057] (4) When the battery voltage is detected to be lower than the limit (such as 11.8V), K1 is triggered to close and K2 is triggered to open, which plays a protective role.

[0058] Following the aforementioned principle, the present invention further illustrates this: Adjusting the power supply circuits for low-voltage loads allows the power circuits of some loads to be connected in parallel with the battery. This increases the DC-DC load adjustment range and enhances energy savings. This allows a separate portion of loads B to be powered either by DC-DC or by the battery. Loads B are preferably essential vehicle electrical appliances, i.e., those that must operate after the vehicle is started, such as the running lights, instrument panel, and body controls. Furthermore, in actual operation, the power supply circuits for loads B can be integrated into the low-voltage wiring harness.

[0059] On this basis, combined with Figure 3 The following example provides a more detailed explanation: Select the running light power supply circuit, separate it, and connect it to the battery. The battery and running lights are connected as a power circuit to the DC-DC output. Connect two relays to the battery power circuit and the combined battery and running light circuit, respectively. For reference, select K1 (12V, 50W) and K2 (12V, 200W).

[0060] According to the low-voltage electrical appliance turned on, calculate the load P of the first electrical load A , determine the power requirement (operating power) of DCDC:

[0061] (1) When P A Less than 0.5kw

[0062] Determine the battery voltage. If the battery voltage is lower than 13V, close K1 and K2 to charge the battery. The working power of DCDC is P A +P B +P C , where P C is the battery charging power; if the battery voltage is higher than 13V, close K1 and open K2. At this time, there is no need to charge the battery. The working power of DCDC is P A +P B ;

[0063] It should be noted that the 0.5 kW mentioned in this example is approximately 25% of the vehicle's DC / DC rated power, and 13 V is approximately the fully charged voltage of a typical vehicle battery.

[0064] (2) When P A When greater than 0.5kw

[0065] Determine the battery voltage. If the battery voltage is higher than 11.8V, disconnect K1 and close K2. The working power of DCDC is only P A If the battery voltage is lower than 11.8V, close K1 and open K2. At this time, the working power of DCDC is P A+P B .

[0066] The 11.8V here is approximately the highest voltage of a general vehicle battery in the feeding state.

[0067] In summary, the main design concept of the present invention is to divide low-voltage electrical appliances into a first electrical load and a second electrical load, connect the first electrical load in parallel with the DC-DC converter, and connect the second electrical load in parallel with the battery, so that the second electrical load has two power supply sources. The power demand is determined in real time according to the activation status of the low-voltage electrical appliances, and based on the power demand and battery status, the working power combination of the DC-DC converter is actively controlled to maintain a high-efficiency working state of the DC-DC converter. The reasonable low-voltage power supply mode provided by the present invention is applicable to new energy passenger cars and commercial vehicles equipped with DC-DC converters. Only simple modifications to the vehicle power supply wiring harness and electrical components are required to effectively reduce the loss of the DC-DC converter and improve the endurance performance of the entire vehicle, thereby effectively compensating for the shortcomings of the existing DC-DC converter working power control strategy and establishing a control mechanism for the efficient operation of the DC-DC converter.

[0068] In the embodiment of the present invention, "at least one" refers to one or more, and "more" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, a and b, a and c, b and c, or a, b and c, where a, b, c can be single or multiple.

[0069] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings, but the above is only a preferred embodiment of the present invention. It should be noted that the technical features involved in the above embodiments and their preferred modes can be reasonably combined and matched into a variety of equivalent schemes by those skilled in the art without departing from or changing the design ideas and technical effects of the present invention; therefore, the scope of implementation of the present invention is not limited to what is shown in the drawings. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the scope of protection of the present invention.

Claims

1. A low-voltage power supply method for new energy vehicles, characterized in that: include: Dividing the low-voltage electrical loads in the vehicle into a first electrical load and a second electrical load, wherein the second electrical load is an electrical load that must work after the vehicle is started; On the basis of the parallel connection of the DC-DC converter and the battery, a first electrical load is connected in parallel with the DC-DC converter, and a second electrical load is connected in parallel with the battery, so that the second electrical load has two power supply sources; including: installing a relay between the connection line between the DC-DC converter and the battery to independently control the on / off of the battery to adjust the working power of the DC-DC converter, and the second electrical load is independently connected in parallel with the battery, and adding a relay to control the on / off of the power supply circuit composed of the battery and the second electrical load; Determining the power demand for the DC-DC system in real time based on the start-up status of the low-voltage electrical appliances, including obtaining the load of the first electrical load; the power demand is used to determine the working efficiency of the DC-DC system; Based on the working efficiency and the voltage state of the battery, the working power combination of the DCDC is determined, including: When the load of the first electrical load is less than a preset power demand threshold, detecting whether the voltage of the battery is lower than a preset full-charge voltage; If the battery voltage is lower than the fully charged voltage, the operating power of the DCDC is the sum of the power required by the first electrical load, the power required by the second electrical load, and the battery charging power; If the voltage of the battery is higher than the fully charged voltage, the operating power of the DCDC is the sum of the power required by the first electrical load and the power required by the second electrical load.

2. The low-voltage power supply method for new energy vehicles according to claim 1, characterized in that: The working power combination of the decision DCDC includes: When the load of the first electrical load is greater than a preset power demand threshold, detecting whether the voltage of the battery is higher than a preset maximum voltage of the battery feeding state; If the battery voltage is higher than the maximum voltage, the operating power of the DCDC is the power required by the first electrical load; If the voltage of the battery is lower than the maximum voltage, the operating power of the DCDC is the sum of the power required by the first electrical load and the power required by the second electrical load.

3. The low-voltage power supply method for new energy vehicles according to claim 1, characterized in that: The work efficiency includes: The efficiency distribution of DCDC is calibrated in advance based on the two dimensions of load ratio and efficiency; According to the efficiency distribution, a lower efficiency area and a higher efficiency area related to the power demand are obtained.

4. The low-voltage power supply method for new energy vehicles according to any one of claims 1 to 3, characterized in that: The power supply line of the second electrical load is integrated into the low-voltage electrical wiring harness.

Images