A method and system for extending the driving range of low-voltage new energy vehicle lithium batteries when the battery is low

Abstract

A low-voltage new energy vehicle lithium battery low-power endurance extension method and system, wherein the method comprises the following steps: collecting the voltage, current, temperature and other original operation data of the lithium battery through a single-chip microcomputer; judging whether the remaining power of the lithium battery meets the preset condition: when the remaining power of the lithium battery is less than or equal to 30%, triggering the power controller; when 15%<=SOC<=30%, generating a control signal with a starting current slope <=30A / ms and a running power gradually changing to 50%; when SOC<15%, generating a control signal with a forced starting current slope <=20A / ms and a locked 50% power; during power limitation, dynamically improving the under-voltage protection threshold compensation coefficient, and the compensation amount is +0.5V; the power control signal generated by the power controller is transmitted to the motor through the motor driving instruction, and the actual output power of the motor is changed. The application can solve the problem of false power shortage shutdown, greatly improve the utilization rate of residual power, improve the problem of rapid reduction of endurance at low power, and prolong the service life of the lithium battery.

Description

TECHNICAL FIELD

[0001] The application relates to the field of new energy vehicle control technology, in particular to a low-voltage new energy vehicle lithium battery low-charge range extension method and system. BACKGROUND

[0002] In the field of low-voltage new energy vehicles, lithium batteries serve as the core power source, and their performance directly affects the overall operation of the vehicle. With the rapid development of the new energy vehicle market, users have increasingly stringent requirements for the vehicle's range capability, especially in the low-charge state. The range performance in this state has become a key indicator of the vehicle's practicality and reliability. However, there are still many problems to be solved when the low-voltage new energy vehicle lithium battery is in a low-charge state.

[0003] First, false power loss shutdown occurs frequently. When the lithium battery is in a low-charge state (i.e., SOC < 30%), the vehicle's large current start-up will cause the battery voltage to drop sharply, often by more than 20%. This sharp voltage drop easily triggers the vehicle's under-voltage protection mechanism, resulting in the remaining 15%-20% of the battery's power being unable to be effectively utilized. For example, in some actual driving scenarios, the vehicle attempts to start when the battery is low, but is forced to shut down due to the sharp voltage drop. Even though there is still some power reserve in the battery, it cannot support the vehicle to continue driving, severely affecting the user's travel experience.

[0004] Second, the range sharply decreases. Traditional battery management schemes still allow the vehicle to output at 100% power when the lithium battery is in a low-charge state. This causes the battery's power to be quickly depleted in a short time, greatly reducing the vehicle's range. For example, when driving on urban roads, if the vehicle's battery is low, it will still run at the regular power output, which will greatly reduce the actual range compared to when the battery is high, causing great inconvenience to the user's travel planning.

[0005] Third, the battery is severely damaged. When the lithium battery works at a large current in the deep discharge area, it will accelerate the aging process, not only reducing the battery's service life, but also causing the battery's capacity to gradually decrease, thereby affecting the vehicle's overall range capability and performance. The internal resistance of the lithium battery in this working state will gradually increase, reducing the charging and discharging efficiency, and eventually requiring the battery to be replaced prematurely, increasing the user's usage cost. SUMMARY

[0006] To overcome the defects of the prior art, the application provides a low-voltage new energy vehicle lithium battery low-charge range extension method and system, which at least partially solves the problems raised in the background art.

[0007] The technical solution adopted by the application is as follows:

[0008] The application provides a low-voltage new energy vehicle lithium battery low-charge endurance extension method.

[0009] S1, collecting voltage, current and temperature original operation data of the lithium battery through a single-chip microcomputer (MCU);

[0010] S2, judging whether the remaining charge (SOC) of the lithium battery meets a preset condition:

[0011] When the remaining charge (SOC) of the lithium battery is less than or equal to 30%, triggering a power control signal of a power grading controller:

[0012] When 15%≤SOC≤30%, generating a control signal of a starting current slope ≤30A / ms and a running power gradually changing to 50%;

[0013] When SOC<15%, generating a control signal of a forced starting current slope ≤20A / ms and a locked 50% power;

[0014] During power limitation, dynamically improving an under-voltage protection threshold compensation coefficient, and the compensation amount is +0.5V.

[0015] S3, the power control signal generated by the power grading controller is transmitted to a motor through a motor driving instruction, and the actual output power of the motor is changed.

[0016] Further, in the step S2, when the remaining charge (SOC) of the lithium battery is less than or equal to 30%, triggering a safety coordination mechanism:

[0017] When the vehicle is in a starting state, immediately enabling soft starting;

[0018] When the vehicle is in a non-starting state, performing a running power gradual change;

[0019] Both the soft starting and the running power gradual change meet the condition that the instantaneous power is greater than 50%, so as to realize that the voltage fluctuation is less than 10%.

[0020] As a preferred technical solution, the power gradual change in the step S2 is realized through linear adjustment of a PWM duty ratio, and the adjustment mode is:

[0021] Duty_new=Duty_old×(1-0.05×t)

[0022] Wherein, Duty_old is the initial PWM duty ratio before adjustment, Duty_new is the target duty ratio after adjustment, t is time, and 0≤t≤10s.

[0023] Further, when the vehicle driving slope is greater than 8%, temporarily releasing the power limitation to 70%;

[0024] The power limit will be automatically reset once the slope returns to normal.

[0025] As a preferred technical solution, the microcontroller in step S1 is the MCU XMC1302 model.

[0026] The XMC1302 MCU features efficient data processing capabilities and real-time response performance, enabling it to meet the system's real-time acquisition and calculation requirements for parameters such as lithium battery voltage, current, and slope. It also provides hardware support for the stable operation of modules such as the dynamic SOC calculation engine and power curve optimization engine.

[0027] Secondly, the present invention provides a system for extending the driving range of low-voltage new energy vehicle lithium batteries when the battery is low, the system comprising:

[0028] A. Lithium batteries, as the energy source of the entire system, are used to provide the electrical energy required for the power output of low-voltage new energy vehicles;

[0029] B. The MCU XMC1302 is used to collect raw operating data of lithium battery voltage, current and temperature in real time, and realizes command issuance and status control to downstream engine through the built-in communication and computing modules.

[0030] C. Dynamic SOC calculation engine: Combining real-time current and temperature data transmitted by the MCU, it uses a dynamic correction algorithm to eliminate the interference of voltage fluctuations on SOC calculation under low battery conditions, and accurately outputs the actual remaining battery power.

[0031] D. Power curve optimization engine, used to build a power output model in the low power range and generate power limiting instructions based on the real-time power data output by the dynamic SOC calculation engine;

[0032] E. Hierarchical power controller, used to convert the power limiting instructions generated by the power curve optimization engine into specific hardware control signals;

[0033] F. Motor drive command, used to transmit the hardware control signals generated by the graded power controller to the motor.

[0034] Furthermore, when the remaining charge (SOC) of the lithium battery is less than or equal to 30%, the graded power controller performs the following control:

[0035] When 15%≤SOC≤30%, output a control signal with a starting current slope ≤30A / ms and a running power gradually increasing to 50%;

[0036] When SOC < 15%, output a control signal with a forced start current slope ≤ 20A / ms and lock 50% power.

[0037] In a further embodiment, the hierarchical power controller dynamically increases the under-voltage protection threshold compensation coefficient by 0.5V during power limitation.

[0038] In a further embodiment, the hierarchical power controller temporarily removes the power limitation to 70% when the vehicle is driving on a slope > 8%, and automatically resets the power limitation when the slope returns to normal.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] By means of the dynamic SOC calculation engine, the actual remaining power of the battery can be accurately perceived, and in combination with the limitation of the hierarchical power controller on large current output, voltage drop caused by large current starting at low power (SOC < 30%) can be avoided, thereby preventing the under-voltage protection mechanism from being triggered by mistake, effectively solving the problem of false power loss shutdown, and greatly improving the utilization rate of residual power.

[0041] By means of the power curve optimization engine, a corresponding power limitation curve is generated according to the SOC gradient in the low power interval, replacing the mode of allowing 100% power output in the traditional scheme, and the power gradient ensured by the linear regulation of the PWM duty cycle realizes smooth transition of power output, further reducing unnecessary power loss, and effectively improving the problem of sudden reduction of endurance at low power.

[0042] By means of the hierarchical power controller, the current output is strictly controlled in the deep discharge area, especially in the area with low SOC, to avoid the impact of large current work on the battery; the dynamic soft start strategy reduces the current fluctuation in the starting stage, and reduces the cycle damage of lithium batteries in the deep discharge state. The synergistic effect of the two can effectively alleviate the battery aging problem caused by large current work in the deep discharge area, and prolong the service life of lithium batteries.

[0043] By means of the synergistic control of software algorithm optimization and existing hardware architecture, the function is improved without additional hardware cost, breaking through the low power endurance bottleneck under the premise of zero cost. At the same time, its architecture design does not need to rely on a complex battery management system (BMS), and is especially suitable for low-voltage electric vehicles without BMS, such as mountain logistics vehicles, sanitation vehicles, and old-age walking vehicles, which can provide a practical solution for the endurance performance improvement of such vehicles, and has high practical value and market application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0045] Figure 1 A hierarchical power limiting strategy diagram in the embodiment of the present application;

[0046] Figure 2 A low-voltage new energy vehicle lithium battery low-power range extension system architecture diagram in the embodiment of the present application;

[0047] Figure 3 A safety coordination mechanism diagram proposed in the embodiment of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application belongs. In addition, any method and material similar or equivalent to those described herein can be used in the present application. The preferred methods and materials described herein are only used as examples, but cannot limit the content of the present application.

[0050] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values and should be understood as including values approximately near these ranges and values within these ranges. For ranges of values, the endpoints of the ranges are combined with the individual points to form new ranges that are within the scope of the present application.

[0051] When the lithium battery is in a low-power state, the vehicle's large-current starting will cause the battery voltage to drop suddenly, and the drop is often more than 20%. This voltage drop easily triggers the vehicle's under-voltage protection mechanism, which causes the remaining 15%-20% of the battery power to be unable to be effectively utilized. When the range is suddenly reduced, the vehicle is still allowed to output at 100% power. This makes the battery power be quickly depleted in a short time, greatly shortening the vehicle's range. When the lithium battery works in a large current in the deep discharge area, it will accelerate the aging process of itself, not only reducing the service life of the battery, but also causing the battery capacity to gradually decay, thereby affecting the overall range and performance of the vehicle. The lithium battery in this working state for a long time, its internal resistance will gradually increase, the charging and discharging efficiency will decrease, and eventually the battery may need to be replaced in advance, increasing the user's use cost.

[0052] In view of the above problems, the application proposes and discloses a low-voltage new energy vehicle lithium battery low-charge endurance extension method and system to solve the problem of false power loss shutdown, greatly improve the utilization rate of residual power, improve the problem of endurance reduction when the power is low, and prolong the service life of the lithium battery.

[0053] Referring to Figure 1 , in a first aspect, the embodiment provides a low-voltage new energy vehicle lithium battery low-charge endurance extension method, which comprises the following steps:

[0054] S1, collecting voltage, current, and temperature original operation data of the lithium battery through an MCUXMC1302 single-chip microcomputer;

[0055] S2, judging whether the battery residual power (SOC) meets a preset condition:

[0056] When the lithium battery residual power (SOC) is less than or equal to 30%, a power grading power controller is triggered:

[0057] When 15%≤SOC≤30%, a control signal with a starting current slope ≤30A / ms and a running power gradually changing to 50% is generated;

[0058] When SOC<15%, a control signal with a forced starting current slope ≤20A / ms and a locked 50% power is generated;

[0059] A dynamic improvement of an under-voltage protection threshold compensation coefficient is performed during power limitation, and the compensation amount is +0.5V.

[0060] S3, the power control signal generated by the power grading power controller is transmitted to the motor through a motor driving instruction to change the actual output power of the motor.

[0061] For example, in a 48V system operation process:

[0062] Scenario one:

[0063] When the dynamic SOC calculation engine obtains SOC=25%, immediately:

[0064] The starting current slope is limited to 30A / ms (the original value is 50A / ms)

[0065] The power is linearly reduced from 100% to 50% (for 10 seconds)

[0066] Result: the voltage is reduced from 40V to 38.5V (38V protection is not triggered)

[0067] Scenario two:

[0068] When the dynamic SOC calculation engine obtains SOC=12%:

[0069] - Enforcement measures:

[0070] - All start event slopes ≤ 20A / ms

[0071] - Maximum power permanent lock 50%

[0072] - Effects:

[0073] - Voltage stabilizes at 37.2-38.1V

[0074] - Range increases by 7km (to SOC=5%)

[0075] By comparing the measured data, the low power range of the traditional scheme is 19km, the number of false triggering of the under-voltage protection is 3.2 times per vehicle, and the battery cycle life is 500 times. The low power range of the present application is 26km, the number of false triggering of the under-voltage protection is 0 times, and the battery cycle life is 500 times. The low power range of the lithium battery is significantly improved, the number of under-voltage protection mechanisms triggered by voltage drop is reduced, and the service life of the battery is improved.

[0076] In one specific embodiment, in step S2, when the remaining power (SOC) of the lithium battery is less than or equal to 30%, the safety coordination mechanism is triggered:

[0077] When the vehicle is in a starting state, soft start is immediately enabled;

[0078] When the vehicle is in a non-starting state, runtime power ramping is performed;

[0079] Both soft start and runtime power ramping meet the prohibition of instantaneous power > 50% to achieve voltage fluctuation < 10%.

[0080] Specifically, referring to Figure 3 , the safety coordination mechanism triggering logic is:

[0081] A [power detection SOC ≤ 30%] --> B {is the starting state?}

[0082] B -->|Yes| C [immediately enable soft start]

[0083] B -->|No| D [runtime power ramping]

[0084] C & D --> E [prohibit instantaneous power > 50%]

[0085] E --> F [voltage fluctuation < 10%]

[0086] The core logic is that in the low power (SOC≤30%) scenario, according to whether the vehicle is in the starting state, the power output is limited (instantaneous power> 50%) through "soft start" or "runtime power gradient" respectively, and finally the control target of voltage fluctuation<10% is realized.

[0087] For example, in the 48V system operation process:

[0088] SOC=25% starting state, in the traditional scheme, the voltage drops 18V to trigger protection, and the application realizes voltage drop≤8V through soft start+power gradient, avoiding vehicle misstop and releasing 12% of the power;

[0089] SOC=15% climbing state, in the traditional scheme, large current causes rapid voltage drop, and the application stabilizes the voltage above 40V through 50% power locking, increasing the endurance by 7km;

[0090] Low temperature and low power-10℃ state, in the traditional scheme, the battery capacity is virtually reduced by 40%, and the application realizes real power utilization rate increase of 28% through power limitation+temperature compensation collaborative control.

[0091] In a specific embodiment, the power gradient in S2 is realized by linear adjustment of PWM duty ratio, and the adjustment formula is:

[0092] Duty_new=Duty_old×(1-0.05×t) (t is time, 0≤t≤10s).

[0093] PWM (Pulse Width Modulation) is a technology that adjusts output voltage or power by changing the duty ratio of pulse signals. In the field of electronic control, it is widely used to precisely control the output intensity of devices such as motors and power supplies. The higher the duty ratio, the more energy is output in a unit of time, and the greater the power output of the corresponding device; conversely, the lower the duty ratio, the lower the power output.

[0094] In this method, linear adjustment of PWM duty ratio can realize smooth transition of power in low power state, avoiding impact on battery and vehicle operation caused by power mutation.

[0095] In the above implementation formula, Duty_old represents the initial PWM duty ratio before adjustment, and Duty_new is the target duty ratio after adjustment. As time t increases from 0 seconds to 10 seconds, the coefficient of (1-0.05×t) decreases linearly from 1 to 0.5, meaning that the duty ratio decreases uniformly at a rate of 5% per second within 10 seconds, eventually decreasing to 50% of the initial value. This linear change directly translates into linear decay of motor power.

[0096] For example, when the initial power corresponds to a duty cycle of 80% (i.e., Duty_old = 80%), the duty cycle becomes 76% after 1 second (the power is reduced to 76% synchronously), and stabilizes at 40% after 10 seconds, realizing a smooth transition from 80% to 40% of the power.

[0097] This adjustment method avoids the sudden change in vehicle power caused by the "step reduction in power" in traditional power limitation, ensuring smooth driving. On the other hand, by gradually reducing the power, the battery voltage gradually adapts to the load change at low power, reducing voltage fluctuations caused by sudden power reduction, further reducing the risk of false power loss shutdown. At the same time, during the linear adjustment process, the current intensity is reduced smoothly and synchronously with the power, which can reduce the impact of large current surges on lithium batteries, and in combination with the graded power control logic, it can more effectively protect the safety of the battery in the deep discharge area.

[0098] In a specific embodiment, when the vehicle is driving on a slope > 8%, temporarily remove the power limit to 70%;

[0099] When the slope returns to normal, the power limit is automatically reset.

[0100] In this embodiment, the temporary power limit of 70% is still lower than the 100% power output of the traditional scheme, and is triggered only when the slope > 8%, which can reduce the damage to the battery caused by continuous output of large current, and balance the power demand and battery protection; on the other hand, the "automatic reset" mechanism ensures that the vehicle can quickly return to the low power limit state after leaving the climbing scene, avoiding excessive consumption of power due to the lack of manual intervention, and improving the traffic capacity of the vehicle under the premise of ensuring the safety and endurance of the battery.

[0101] Referring to Figure 2 , in a second aspect, the embodiment provides a low-voltage new energy vehicle lithium battery low-power endurance extension system, which comprises:

[0102] A, lithium battery, as the energy source of the whole system, used to provide the power output required by the low-voltage new energy vehicle.

[0103] B, MCU XMC1302, used to collect the voltage, current, and temperature raw operation data of the lithium battery in real time, and realize the instruction issuing and state regulation of the downstream engine through the built-in communication and operation module.

[0104] MCU XMC1302 as the core control and data processing hub, its efficient data processing capability provides real-time support for dynamic SOC calculation and power optimization, ensuring that the response delay of the whole system is within milliseconds, meeting the real-time adjustment requirements in the dynamic operation of the vehicle.

[0105] C. Dynamic SOC calculation engine, combined with real-time current and temperature data transmitted by MCU, eliminates the interference of voltage fluctuation on SOC calculation at low power through dynamic correction algorithm, accurately outputs the actual remaining power of the current battery, and provides a reliable basis for subsequent power control, avoiding false triggering of protection mechanism due to power misjudgment.

[0106] D. Power curve optimization engine, used to build a power output model in the low power interval based on the real-time power data output by the dynamic SOC calculation engine and generate power limit instructions.

[0107] When SOC<30%, the engine will automatically generate the corresponding power limit curve according to the power gradient. For example, allow 80% rated power output when SOC is 20%-30%, limit to 50% rated power when 10%-20%, avoid sudden power consumption caused by 100% power output in traditional scheme through hierarchical regulation. At the same time, the engine also combines historical discharge data to predict the remaining power supported by the endurance mileage, providing a quantitative reference for power adjustment.

[0108] E. Hierarchical power controller, used to convert the power limit instructions generated by the power curve optimization engine into specific hardware control signals.

[0109] The hierarchical power controller realizes hierarchical control of output power by adjusting the current threshold of the motor drive circuit: when detecting high power demand, such as sudden acceleration, if the current is in the low power interval, the controller will automatically reduce the output current to the safe threshold to avoid voltage drop caused by large current; In low-power scenarios such as smooth driving, the restriction is appropriately relaxed to ensure basic power demand. This dynamic hierarchical control not only solves the problem of false power loss shutdown, but also reduces the large current impact in deep discharge area.

[0110] F. Motor drive instruction, the connection node of the system and the execution terminal, the hardware control signal generated by the hierarchical power controller is transmitted to the motor through the instruction, which directly determines the actual output power of the motor. Through the dynamic adjustment of the instruction, the smooth running of the motor at low power is finally realized, achieving the dual goals of endurance extension and battery protection.

[0111] In the low-voltage new energy vehicle lithium battery low-power endurance extension system of the present application, each core module forms a complete control link through orderly data transmission and instruction interaction, and the specific architecture process can be further supplemented as follows:

[0112] The system takes lithium battery (A) as the energy source, and the real-time operation data such as voltage, current and temperature are first transmitted to MCU XMC1302 (B). As the core control center, MCU XMC1302 synchronizes the raw data to the dynamic SOC calculation engine (C) after preliminary processing. The dynamic SOC calculation engine eliminates the interference of voltage fluctuation under low power through dynamic correction algorithm, accurately outputs the real-time power information of the battery, and transmits the data to the power curve optimization engine (D).

[0113] The power curve optimization engine constructs a hierarchical control logic based on real-time power data, generates targeted power limit instructions and issues them to the hierarchical power controller (E). The core control strategy of the hierarchical power controller includes: when the remaining battery power SOC≤30% is detected, the soft ramp power regulation mode is started immediately, and the power output is limited through smooth transition; when SOC<15%, the maximum power is permanently locked to 50% to avoid rapid consumption of power in the deep discharge area.

[0114] Finally, the hierarchical power controller converts the above control strategy into specific hardware drive signals, transmits them to the motor through motor drive instructions (F), and realizes the dynamic regulation and control of motor output power. This architecture not only embodies the closed-loop logic of "data collection-accurate perception-intelligent decision-making-execution control", but also takes into account the battery safety and vehicle running smoothness while ensuring low power endurance extension through the differentiated strategy of the hierarchical power controller.

[0115] For example, in the scenario where SOC is 25%, after the dynamic SOC calculation engine outputs the real-time power, the power curve optimization engine triggers the soft ramp adjustment of the hierarchical power controller, realizes the smooth transition of power through PWM duty cycle linear adjustment (Duty_new=Duty_old×(1-0.05×t)); when SOC drops to 12%, the hierarchical power controller automatically switches to the 50% power lock mode, combined with the under-voltage protection threshold compensation (+0.5V), to ensure that the voltage is stable in the 37.2-38.1V interval, finally realizing the dual goals of endurance extension and battery protection.

[0116] It is noted that, in the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0117] Although the embodiments have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit thereof, and the scope of the present embodiments is defined by the appended claims and their equivalents.

[0118] The above describes the embodiments, which is not limited, and the drawings shown is only one of the embodiments, the actual structure is not limited. In general, if the person skilled in the art is inspired, without departing from the creative purpose, without creative design, similar structure and embodiments of the technical solution, which should belong to the protection scope.

Claims

1. A method for prolonging the endurance of a low-voltage new energy vehicle lithium battery with low power, characterized in that, The method comprises: S1, collecting the voltage, current and temperature of the lithium battery by a single-chip microcomputer (MCU); S2, judging whether the remaining power (SOC) of the lithium battery meets the preset condition: When the remaining power (SOC) of the lithium battery is less than or equal to 30%, the power grading controller is triggered: When 15%≤SOC≤30%, a control signal with a starting current slope ≤30A / ms and a running power gradually changing to 50% is generated; When SOC<15%, a control signal with a forced starting current slope ≤20A / ms and a locked 50% power is generated; During power limitation, the dynamic under-voltage protection threshold compensation coefficient is improved, and the compensation amount is +0.5V; S3, the power control signal generated by the power grading controller is transmitted to the motor through the motor driving instruction to change the actual output power of the motor; In the step S2, when the remaining power (SOC) of the lithium battery is less than or equal to 30%, a safety coordination mechanism is triggered: When the vehicle is in a starting state, soft start is immediately enabled; When the vehicle is in a non-starting state, running power is gradually changed; Both the soft start and the running power gradually changing meet the condition that the instantaneous power is greater than 50% to realize that the voltage fluctuation is less than 10%; The power gradually changing in the step S2 is realized by linear adjustment of the PWM duty ratio, and the adjustment formula is: Duty_new=Duty_old×(1-0.05×t) Wherein, Duty_old is the initial PWM duty ratio before adjustment, Duty_new is the target duty ratio after adjustment, t is time, and 0≤t≤10s.

2. The method for extending the driving range of a low-voltage new energy vehicle lithium battery when the battery is low, as described in claim 1, is characterized in that... Further comprising: When the vehicle driving slope is greater than 8%, the power limitation is temporarily released to 70%; When the slope returns to normal, the power limitation is automatically reset.

3. A system for implementing the method for prolonging the endurance of a low-voltage new energy vehicle lithium battery with low power according to claim 1, characterized in that, It comprises: A lithium battery for providing the required power for the power output of a low-voltage new energy vehicle; An MCU XMC1302 single-chip microcomputer for collecting the voltage, current and temperature of the lithium battery in real time, and realizing the instruction issuing and state regulation of the downstream engine; A dynamic SOC calculation engine for accurately outputting the actual remaining power of the current battery in combination with the real-time current and temperature data transmitted by the single-chip microcomputer; A power curve optimization engine for constructing a power output model in the low power interval and generating a power limitation instruction based on the real-time power data output by the dynamic SOC calculation engine; A grading power controller for converting the power limitation instruction generated by the power curve optimization engine into a specific hardware control signal; A motor driving instruction for transmitting the hardware control signal generated by the grading power controller to the motor.

4. The low-voltage new energy vehicle lithium battery low-charge range extension system according to claim 3, characterized in that, The grading power controller temporarily releases the power limitation to 70% when the vehicle driving slope is greater than 8%; when the slope returns to normal, the power limitation is automatically reset.

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