Novel control method for changing lead acid into lithium battery and intelligently adapting to electric quantity display of display screen of original vehicle

Abstract

The invention discloses a novel control method for changing lead acid into a lithium battery and intelligently adapting to electric quantity display of an original vehicle display screen. The control method is suitable for the scene that lead acid batteries of two-wheeled vehicles and three-wheeled vehicles are changed into lithium batteries. A lead-acid battery 0%-100% SOC-total voltage accurate array table is constructed, target voltage is obtained through real-time table look-up of a lithium battery management system (BMS), a Boost circuit is integrated in the BMS, output of the boost circuit is controlled in a closed-loop mode by combining AD sampling (+ / -0.3 V) and a PID algorithm, a display screen of an original vehicle collects voltage simulating lead-acid characteristics, and the electric quantity / voltage of the lithium battery is accurately displayed. An original vehicle display screen does not need to be replaced, an independent correction module does not need to be additionally arranged, the advantages of high voltage simulation precision, no delay, system structure simplification, modification cost reduction, lithium battery high energy density reservation and the like are achieved, the problems of low precision and complex structure in the prior art are solved, and the industrial application value is high.

Description

Technical Field

[0001] This invention relates to the field of vehicle battery modification and power display control technology, specifically to a novel control method for converting lead-acid batteries to lithium batteries that is intelligently adapted to the original vehicle display screen for power display in two-wheeled and three-wheeled vehicles. Background Technology

[0002] Traditional electric two-wheelers and three-wheelers generally use lead-acid batteries as their power source. While these batteries are technologically mature and low-cost, they suffer from drawbacks such as large size, heavy weight, short cycle life, and susceptibility to heavy metal pollution, making them unable to meet users' demands for lightweight vehicles, longer range, and environmental friendliness. Lithium-ion batteries, with their advantages of high energy density, long cycle life, fast charging, and low environmental impact, have become the mainstream alternative to lead-acid batteries, and the shift from lead-acid to lithium-ion batteries is a growing trend in the electric vehicle industry.

[0003] However, the original display screens in traditional lead-acid battery vehicles are designed specifically for lead-acid batteries and lack lithium battery BMS adaptation functions. They directly collect the total voltage of the lead-acid battery and convert it to display the charge based on its voltage-charge (SOC) non-linear characteristics. Lead-acid and lithium batteries have significant differences in chemical properties, and the actual charge can deviate by more than 20% at the same voltage. If the lead-acid battery is not compatible with lithium batteries after conversion, the display screen will show problems such as distorted charge and inconsistent voltage display, which seriously affects the user experience.

[0004] The current mainstream adaptation solution involves adding an independent power correction module between the vehicle controller and the instrument cluster. This module calculates the simulated lead-acid voltage output. However, this solution has significant drawbacks: adding an independent module increases system complexity and modification costs, and occupies installation space; simple voltage calculation without closed-loop control results in low simulation accuracy and display delay and distortion; communication delays occur when multiple modules work together, leading to poor system energy efficiency. Furthermore, replacing the original vehicle display screen would significantly increase costs, and modifying the entire vehicle's electrical system poses safety hazards.

[0005] Therefore, how to achieve high-precision, real-time, and distortion-free display of lithium battery power / voltage according to lead-acid characteristics without replacing the original vehicle display screen or adding an independent power correction module, while simplifying the structure, reducing costs, and improving energy efficiency, has become a core technical challenge that urgently needs to be addressed in the field of converting lead-acid batteries to lithium batteries for vehicles. Summary of the Invention

[0006] To address the shortcomings and pain points of existing technologies, the present invention aims to provide a novel control method for converting lead-acid batteries to lithium batteries that intelligently adapts to the original vehicle display screen for battery level display. This method solves the problems of complex system structure, high conversion cost, low voltage simulation accuracy, display delay, and poor energy efficiency in existing solutions. It achieves accurate real-time display of lithium battery power / voltage according to the characteristics of lead-acid batteries without replacing the screen or adding independent modules, retaining all the performance advantages of lithium batteries, simplifying the conversion process, reducing costs, and improving system compatibility and energy efficiency.

[0007] A novel control method for intelligently adapting to the original vehicle display screen's battery level display when converting lead-acid batteries to lithium batteries is proposed. This method is applicable to scenarios where lead-acid batteries in two-wheeled and three-wheeled vehicles are being replaced with lithium batteries in vehicles where the original vehicle display screen directly converts voltage data into battery level information without a battery management system adaptation function. The method includes the following steps:

[0008] Step 1: Construct a precise array table of lead-acid battery SOC-total voltage: Select a lead-acid battery that is compatible with the original vehicle, measure the total voltage VOL of the battery at 1% intervals within the range of SOC from 0% to 100%, obtain 101 continuous data points, generate a one-dimensional array table Table_VOL_SOC of the lead-acid battery total voltage as the battery capacity changes, and burn the array table into the storage module of the battery management system (BMS) of the lithium battery. Step 2: Real-time table lookup of the lithium battery BMS to obtain the target voltage: After the vehicle lead-acid battery is replaced with a lithium battery, the lithium battery BMS obtains the current SOC of the lithium battery in real time through its own voltage and current detection modules. By querying the Table_VOL_SOC, the total voltage of the lead-acid battery that uniquely corresponds to the current SOC of the lithium battery is obtained, and this total voltage is set as the target output voltage Vobj of the boost circuit. Step 3: Integrate the Boost topology boost circuit and establish a display connection: Integrate the Boost topology boost circuit inside the BMS of the lithium battery. The power input terminal of the boost circuit is connected to a +12V DC power supply, and the voltage output terminal is Vout. Connect Vout to the voltage acquisition terminal of the original vehicle display screen so that the original vehicle display screen only acquires the output voltage Vout of the boost circuit as the total battery voltage for display. Step 4: AD sampling + PID algorithm closed-loop control of boost circuit output: The output voltage Vout of the boost circuit is sampled in real time by the AD sampling module with a sampling accuracy of ±0.3V. The difference Err = Vobj - Vout between the target voltage Vobj and the actual sampled voltage Vout is calculated. The difference Err is input to the PID algorithm controller. The duty cycle of the power transistor of the boost circuit is dynamically adjusted by the PID algorithm to realize closed-loop control of Vout, so that Vout is infinitely close to Vobj. The proportional gain Kp, integral gain Ki, and derivative gain Kd of the PID algorithm are all in the range of 0≤Kp≤1, 0≤Ki≤1, and 0≤Kd≤1. Step 5, Synchronous Dynamic Adaptation Display of Battery Power: When the SOC of the lithium battery changes dynamically during use, the BMS of the lithium battery updates the SOC in real time and repeats steps 2-4 above, continuously and dynamically adjusting the output voltage Vout of the boost circuit. This ensures that the Vout collected by the original vehicle display changes synchronously with the SOC of the lithium battery, enabling the original vehicle display to accurately display the actual voltage and power of the lithium battery without delay or distortion, based on the voltage-power characteristics of the lead-acid battery.

[0009] Furthermore, in step 2, the SOC detection accuracy of the lithium battery BMS is consistent with that of the lead-acid battery SOC measurement accuracy, and the BMS lookup response time is ≤10ms, ensuring the real-time performance of the target voltage Vobj.

[0010] Furthermore, the Boost topology boost circuit in step 3 consists of inductor L2, capacitor EC1, resistor R377, resistor R378, MOSFET power transistor Qn10, bidirectional Zener diode SD1, and output filter capacitors C94, EC2, and EC3. The Boost topology boost circuit is directly integrated on the circuit board of the lithium battery BMS and shares the power supply module with the BMS, without the need for an additional independent power supply circuit.

[0011] Furthermore, the PID algorithm control logic in step 4 is as follows: the direction of the boost circuit output voltage adjustment is determined according to the sign of the difference Err, and the adjustment range of the boost circuit power transistor conduction duty cycle is determined according to the absolute value of the difference Err, so as to realize the linear and overshoot-free following of Vout to Vobj.

[0012] In step 1, the measurement of the total voltage VOL of the lead-acid battery is completed under standard operating conditions of room temperature and rated load. The accuracy of the measuring equipment is ≤ ±0.01V to ensure the accuracy of Table_VOL_SOC.

[0013] The control method eliminates the need for a separate power correction module between the vehicle controller and the original vehicle display screen. Instead, it directly integrates table lookup, calculation, and control through the lithium battery BMS, simplifying the system structure.

[0014] The output voltage adjustment range of the Boost topology boost circuit is consistent with the total voltage range corresponding to 0%~100% SOC of the lead-acid battery, and the ripple coefficient of the output voltage is ≤0.5%, ensuring the stability of the voltage collected by the original vehicle display screen.

[0015] Beneficial effects Compared with existing technologies, the technical solution of this invention has outstanding substantive features and significant progress, solving several core pain points of existing technologies and possessing extremely high practical and industrial promotion value. This invention integrates the Boost converter circuit within the BMS, enabling integrated operation through the BMS without the need for any additional modules. This simplifies the system structure, saves installation space, reduces modification material and labor costs, avoids communication delays between multiple modules, and improves system energy efficiency. Furthermore, by constructing a precise array table of 101 data points under standard operating conditions, combined with precise AD sampling and PID closed-loop control, it achieves linear, overshoot-free tracking of the output voltage to the target voltage, ensuring that the deviation between the displayed value and the actual state of the lithium battery is ≤1%. This completely solves the problems of low accuracy and distortion in existing technologies. In addition, the BMS lookup response time is ≤10ms, and the entire process of AD sampling, PID calculation, and voltage adjustment is a real-time continuous closed-loop operation. The output voltage can be adjusted synchronously when the SOC changes, and the display has no display delay, further enhancing the user experience.

[0016] Furthermore, this invention requires no replacement of original vehicle parts, no modification to the vehicle controller or wiring harness, and the modification process is simple and easy to operate. It avoids the safety hazards of circuit modifications and is compatible with most two-wheeled / three-wheeled vehicles with voltage acquisition displays, offering a wide range of compatibility. The entire process does not affect the performance of the lithium battery, fully preserving its advantages of high energy density, fast charging, long cycle life, environmental friendliness, and lightweight design. This results in a 20%-30% increase in vehicle mileage, a 50% or more reduction in charging time, and a 3-5 times increase in battery life for the same capacity. The integrated design also avoids problems such as loose wiring and malfunctions in independent modules, improving system structural stability and operational reliability, and making subsequent maintenance and repair more convenient, effectively reducing later maintenance costs. Attached Figure Description

[0017] Figure 1 This is a block diagram showing the connection between the Boost topology boost circuit of this invention and the original vehicle display screen; Figure 2 This is a detailed circuit diagram of the Boost topology boost circuit of the present invention.

[0018] Figure 3 This is a schematic diagram illustrating the working principle of the closed-loop control of the PID algorithm of this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This control method is applicable to the original displays of two-wheeled and three-wheeled vehicles that do not have a battery management system adaptation function and directly convert the collected voltage into power display. For scenarios where lead-acid batteries are being replaced with lithium batteries, there is no need to modify the vehicle controller or add an independent power correction module. The lithium battery BMS is integrated to complete the lookup table, calculation, and closed-loop control, so that the original vehicle display can display the actual power of the lithium battery according to the voltage-power characteristics of the lead-acid battery, without delay or distortion, thus balancing the convenience of modification and the accuracy of display.

[0021] Step 1: Construct a precise array table of SOC-total voltage for lead-acid batteries. A standard lead-acid battery compatible with the original vehicle was selected, and measurements were conducted under normal temperature and rated load conditions. Professional measuring equipment with an accuracy of ≤±0.01V was used to collect the total battery voltage (VOL) at 1% intervals within the range of 0% to 100% SOC, obtaining 101 continuous data points. A one-dimensional array table Table_VOL_SOC was generated to show the change of total lead-acid battery voltage with charge, and this array table was burned into the lithium battery BMS storage module.

[0022] To adapt to complex vehicle operating conditions, a multi-condition compensation array table is constructed simultaneously. Data corresponding to the SOC-total voltage of lead-acid batteries are collected in a wide temperature range of -10℃ to 45℃ and a discharge rate of 0.2C to 1C. Temperature drift coefficient and rate compensation coefficient are generated and incorporated into the BMS storage module to eliminate voltage-capacity characteristic offset errors under extreme operating conditions.

[0023] Step 2: The lithium battery BMS obtains the target voltage in real time by looking up the table. After the lead-acid battery in the vehicle is replaced with a lithium battery, the lithium battery BMS obtains the current state of charge (SOC) in real time through its own voltage and current detection modules. The SOC detection accuracy is consistent with that of the lead-acid battery SOC measurement accuracy, and the table lookup response time is ≤10ms (≤5ms after optimization). By querying the Table_VOL_SOC array, the total voltage of the lead-acid battery that uniquely corresponds to the current lithium battery SOC is obtained, and this total voltage is set as the target output voltage Vobj of the boost circuit.

[0024] The BMS collects ambient temperature and discharge current in real time and automatically calls multi-condition compensation parameters to correct the target voltage Vobj, ensuring that the power display accuracy is ≤±2% across all scenarios.

[0025] Step 3: Integrate the Boost topology boost circuit and establish a display connection. A Boost topology boost circuit is integrated on the lithium battery BMS circuit board. This circuit shares the power supply module with the BMS and does not require an additional independent power supply circuit. The power input terminal of the boost circuit is connected to a +12V DC power supply, and the voltage output terminal is Vout. Vout is electrically connected to the voltage acquisition terminal of the original vehicle display screen, so that the original vehicle display screen only acquires Vout as the total battery voltage for display.

[0026] The circuit output uses the same plug interface as the original vehicle, achieving wire-free and damage-free connection without disrupting the original vehicle wiring layout; the output voltage adjustment range of the Boost circuit is consistent with the total voltage range of the lead-acid battery from 0% to 100% SOC, and the output ripple coefficient is ≤0.5% (≤0.3% after optimization).

[0027] Step 4: AD sampling + PID algorithm closed-loop control of boost circuit output The output voltage Vout of the boost circuit is acquired in real time with a sampling accuracy of ±0.3V by an AD sampling module. The difference between the target voltage Vobj and the actual sampled voltage Vout is calculated as Err = Vobj - Vout. The difference is input into the PID algorithm controller to dynamically adjust the duty cycle of the power transistor in the boost circuit, thereby realizing closed-loop control of Vout and making Vout infinitely close to Vobj. The proportional gain Kp, integral gain Ki, and derivative gain Kd of the PID algorithm are all in the range of 0≤Kp≤1, 0≤Ki≤1, and 0≤Kd≤1.

[0028] Segmented variable parameter PID control is adopted, dividing the SOC into three ranges: 0%~20% (low battery), 20%~80% (normal battery), and 80%~100% (high battery), and matching differentiated PID parameters; dead zone control is added, and the PID stops fine-tuning when the absolute value of Err is ≤0.05V, reducing power transistor losses; AD sampling adopts a multi-sample averaging mechanism of 50 times per second to eliminate glitch data, cope with motor start-stop and braking shocks, and achieve linear tracking without overshoot and jitter.

[0029] Step 5: Dynamically adapt and display battery level. When the SOC of the lithium battery changes dynamically during use, the BMS updates the SOC value in real time and repeats steps 2 to 4 above, continuously and dynamically adjusting the output voltage Vout of the boost circuit, so that the voltage collected by the original vehicle display changes synchronously with the SOC of the lithium battery, achieving accurate display of power without delay or distortion.

[0030] The method disclosed in this invention solves several core pain points of existing technologies, and has extremely high practical and industrial application value: 1. Abandoning independent correction modules simplifies the structure and reduces costs: The Boost circuit is integrated into the BMS, and the BMS performs integrated operation without the need for any additional modules. This simplifies the system structure, saves installation space, reduces the cost of retrofit materials and labor, avoids communication delays between multiple modules, and improves system energy efficiency.

[0031] 2. Precise array table construction + PID closed-loop control to achieve high-precision and distortion-free display: Under standard operating conditions, a precise array table of 101 data points is constructed. Combined with AD precise sampling and PID closed-loop control, the output voltage follows the target voltage linearly without overshoot. The deviation between the display and the actual state of the lithium battery is ≤1%, solving the problems of low accuracy and distortion in existing technologies.

[0032] 3. No-delay dynamic adaptation and strong real-time display: BMS table lookup response time ≤10ms, AD sampling, PID calculation, and voltage adjustment are real-time continuous closed-loop operations, output voltage is adjusted synchronously when SOC changes, and the display screen has no display delay, improving the user experience.

[0033] 4. No screen replacement or circuit modification required, strong adaptability and high safety: No need to replace original vehicle parts, no need to modify the vehicle controller and wiring harness, the modification process is simple and easy to operate, avoiding the safety hazards of circuit modification, and is suitable for most two-wheeled and three-wheeled vehicles with voltage acquisition display screens, with a wide range of compatibility.

[0034] 5. Retain all the advantages of lithium batteries and improve vehicle performance: It does not affect the performance of lithium batteries, and fully retains their advantages of high energy density, fast charging, long cycle life, environmental protection and lightness. Under the same capacity, the vehicle's driving range is increased by 20%-30%, the charging time is shortened by more than 50%, and the battery life is increased by 3-5 times.

[0035] 6. Integrated design, high system stability and easy maintenance: The integrated design of the boost circuit and BMS avoids problems such as loose wiring and failure of independent modules, improves the structural stability and operational reliability of the system, makes subsequent maintenance and repair more convenient, and reduces later maintenance costs.

[0036] In this invention, when the lithium battery is first connected, the cell is replaced, or the factory is restored, the full charge display value will be automatically calibrated by allowing it to stand still for 30 minutes after full charge. After every 5 complete charge and discharge cycles, the SOC deviation can be automatically corrected to offset the display drift caused by cell aging and changes in internal resistance. At the hardware level, the Boost circuit is comprehensively optimized. The input end is connected in series with a reverse connection protection diode and a self-resetting fuse to achieve reverse connection protection and overcurrent protection. The output end is equipped with a dual-stage filter circuit to suppress ripple and eliminate screen flicker. At the same time, high-temperature resistant and high-precision special components are selected, and opto-isolation modules are used to block circuit interference and breakdown risks, thus building a solid hardware safety defense.

[0037] The solution is highly adaptable and fault-tolerant for different modification scenarios and complex operating conditions. The BMS reserves multiple array table spaces and supports one-click switching of mainstream lead-acid battery specifications such as 48V, 60V, and 72V. It can be adapted to multiple models without reprogramming. At the same time, it is equipped with a complete abnormal protection mechanism. Under operating conditions such as voltage exceeding the standard, excessive SOC deviation, and low temperature, the corresponding protection and calibration logic can be triggered to ensure display stability and cell safety.

[0038] The installation and after-sales service adopts the original vehicle interface, eliminating the need for wire cutting and ensuring a non-destructive design. Ordinary repair personnel can quickly complete the modification without altering any original vehicle hardware. The BMS has a built-in fault storage unit that can retain 30 days of operating data and supports serial port and Bluetooth debugging for easy and quick troubleshooting. The entire solution requires no additional calibration modules and achieves accurate power display through integrated BMS control, balancing modification costs, convenience, and mass production practicality. It perfectly solves the industry problem of screen display distortion after converting lead-acid batteries to lithium batteries.

[0039] Furthermore, in step 2, the SOC detection accuracy of the lithium battery BMS is consistent with that of the lead-acid battery SOC measurement accuracy, and the BMS lookup response time is ≤10ms, ensuring the real-time performance of the target voltage Vobj.

[0040] Furthermore, the Boost topology boost circuit consists of inductor L2, capacitor EC1, resistor R377, resistor R378, MOSFET power transistor Qn10, bidirectional Zener diode SD1, and output filter capacitors C94, EC2, and EC3. The Boost topology boost circuit is directly integrated on the circuit board of the lithium battery BMS and shares the power supply module with the BMS, eliminating the need for an additional independent power supply circuit.

[0041] Furthermore, the PID algorithm control logic in step 4 is as follows: the direction of the boost circuit output voltage adjustment is determined according to the sign of the difference Err, and the adjustment range of the boost circuit power transistor conduction duty cycle is determined according to the absolute value of the difference Err, so as to realize the linear and overshoot-free following of Vout to Vobj.

[0042] In step 1, the measurement of the total voltage VOL of the lead-acid battery is completed under standard operating conditions of room temperature and rated load. The accuracy of the measuring equipment is ≤ ±0.01V to ensure the accuracy of Table_VOL_SOC.

[0043] The control method eliminates the need for a separate power correction module between the vehicle controller and the original vehicle display screen. Instead, it directly integrates table lookup, calculation, and control through the lithium battery BMS, simplifying the system structure.

[0044] The output voltage adjustment range of the Boost topology boost circuit is consistent with the total voltage range corresponding to 0%~100% SOC of the lead-acid battery, and the ripple coefficient of the output voltage is ≤0.5%, ensuring the stability of the voltage collected by the original vehicle display screen.

[0045] Example 1 This embodiment 1 is applied to a project to convert a 12V / 20Ah electric tricycle from a lead-acid battery to a lithium battery. The original vehicle was equipped with a 12V / 20Ah lead-acid battery, and the display screen was a conventional voltage acquisition type without BMS adaptation function. Now, it is being replaced with a 12V / 20Ah lithium battery of the same specification. The method of this invention is used to achieve adaptation. The specific steps are as follows: 1. Construct a precise SOC-total voltage array table for a 12V lead-acid battery: Using the original vehicle-matched 12V / 20Ah lead-acid battery, under normal temperature and rated load conditions at 25℃, a testing device with an accuracy of ±0.005V was used to complete the test, obtaining 101 data points. The key data are: SOC100%=13.20V, SOC80%=12.80V, SOC50%=12.50V, SOC20%=11.80V, and SOC0%=10.80V. The Table_VOL_SOC was generated and burned into the BMS. The table lookup response time was adjusted to 8ms.

[0046] 2. BMS Real-time Table Lookup for Vobj: After removing the lead-acid battery and installing a lithium battery of the same specifications, with no additional modifications to the conventional connection circuit, when the lithium battery's SOC is 80% while the vehicle is in motion, the BMS looks up Vobj = 12.80V within 8ms.

[0047] 3. Integrate the boost circuit and establish the connection: Integrate the boost circuit on the BMS circuit board. The boost topology boost circuit consists of inductor L2, capacitor EC1, resistor R377, resistor R378, MOSFET Qn10, bidirectional Zener diode SD1, and output filter capacitors C94, EC2, and EC3. It shares a +12V power supply with the BMS, with an output adjustment range of 10.80V~13.20V and a ripple factor of 0.3%. Solder the output terminal Vout to the voltage acquisition terminal of the display screen.

[0048] 4. AD sampling + PID closed-loop control: The AD sampling module acquires Vout with an accuracy of ±0.3V. When the initial Vobj=12.80V, Vout=12.00V and Err=0.80V. The PID parameters are set to Kp=0.8, Ki=0.5, and Kd=0.2. The PID algorithm stabilizes Vout to 12.78V within 10ms, which is very close to the target voltage.

[0049] 5. Synchronous adaptation to dynamic changes in SOC: When the lithium battery SOC drops from 80% to 60%, the BMS looks up Vobj=12.60V within 8ms, and the PID algorithm stabilizes Vout to 12.59V within 8ms. The display accurately shows 60% battery level with a display deviation of 0.5%.

[0050] After modification in this embodiment, the vehicle does not need to replace the original vehicle display screen or modify the vehicle circuit. The display screen shows a complete match with the actual state of the lithium battery. After multiple tests, the system has been running continuously for 3000 hours without failure. The advantages of fast charging and long range of lithium batteries are fully retained. The charging time is shortened from 8 hours for the original lead-acid battery to 3 hours. The vehicle's driving range is increased by 25% for the same capacity.

[0051] Example 2 This Example 2 is applied to the conversion of a 48V / 12Ah electric two-wheeler from lead-acid to lithium battery. The original vehicle was equipped with a 48V / 12Ah lead-acid battery and the display screen was a voltage acquisition type. Now it is replaced with a 48V / 12Ah lithium battery. The implementation steps are the same as in Example 1, except that Table_VOL_SOC (key data: SOC100%=54.6V, SOC50%=51.2V, SOC0%=42.0V) is adjusted according to the characteristics of the 48V lead-acid battery to adapt the BMS parameters of the 48V lithium battery (PID: Kp=0.7, Ki=0.6, Kd=0.3). The output adjustment range of the boost circuit is 42.0V~54.6V.

[0052] After implementation, the original vehicle display screen accurately displays the lithium battery power / voltage with no delay, with a deviation of ≤1%. Charging time is reduced from 6 hours to 2 hours, driving range is increased by 30%, and the system operates stably without faults.

[0053] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A novel control method for intelligently adapting to the original vehicle display screen's power level display when converting lead-acid batteries to lithium batteries, applicable to scenarios where the original vehicle display screen for two-wheeled and three-wheeled vehicles lacks a battery management system adaptation function and directly converts voltage acquisition into power level display, is used to replace lithium batteries. Its features include: Includes the following steps: Step 1: Construct a precise array table of lead-acid battery SOC-total voltage: Select a lead-acid battery that is compatible with the original vehicle, measure the total voltage VOL of the battery at 1% intervals within the range of SOC of 0%-100%, obtain 101 continuous data points, generate a one-dimensional array table Table_VOL_SOC of lead-acid battery total voltage as the amount of charge changes, and burn the array table into the storage module of the battery management system (BMS) of the lithium battery; Step 2: Real-time table lookup of the lithium battery BMS to obtain the target voltage: After the vehicle lead-acid battery is replaced with a lithium battery, the lithium battery BMS obtains the current SOC of the lithium battery in real time through its own voltage and current detection modules. By querying the Table_VOL_SOC, the total voltage of the lead-acid battery that uniquely corresponds to the current SOC of the lithium battery is obtained, and this total voltage is set as the target output voltage Vobj of the boost circuit. Step 3: Integrate the Boost topology boost circuit and establish a display connection: Integrate the Boost topology boost circuit inside the BMS of the lithium battery. The power input terminal of the boost circuit is connected to a +12V DC power supply, and the voltage output terminal is Vout. Connect Vout to the voltage acquisition terminal of the original vehicle display screen so that the original vehicle display screen only acquires the output voltage Vout of the boost circuit as the total battery voltage for display. Step 4: AD sampling + PID algorithm closed-loop control of boost circuit output: The output voltage Vout of the boost circuit is sampled in real time by the AD sampling module with a sampling accuracy of ±0.3V. The difference Err = Vobj - Vout between the target voltage Vobj and the actual sampled voltage Vout is calculated. The difference Err is input to the PID algorithm controller. The duty cycle of the power transistor of the boost circuit is dynamically adjusted by the PID algorithm to realize closed-loop control of Vout, so that Vout is infinitely close to Vobj. The proportional gain Kp, integral gain Ki, and derivative gain Kd of the PID algorithm are all in the range of 0≤Kp≤1, 0≤Ki≤1, and 0≤Kd≤1. Step 5, Synchronous Dynamic Adaptation Display of Battery Power: When the SOC of the lithium battery changes dynamically during use, the BMS of the lithium battery updates the SOC in real time and repeats steps 2 to 4 above, continuously and dynamically adjusting the output voltage Vout of the boost circuit, so that the Vout collected by the original vehicle display screen changes synchronously with the SOC of the lithium battery. This enables the original vehicle display screen to accurately display the actual voltage and power of the lithium battery without delay or distortion, based on the voltage-power characteristics of the lead-acid battery.

2. The control method for intelligently adapting to the original vehicle display screen's power display for converting lead-acid batteries to lithium batteries according to claim 1, characterized in that: In step 2, the SOC detection accuracy of the lithium battery BMS is consistent with that of the lead-acid battery SOC measurement accuracy, and the BMS lookup response time is ≤10ms, ensuring the real-time performance of the target voltage Vobj.

3. The control method for intelligently adapting to the original vehicle display screen's power display for converting lead-acid batteries to lithium batteries according to claim 1, characterized in that: The Boost topology boost circuit in step 3 consists of inductor L2, capacitor EC1, resistor R377, resistor R378, MOSFET Qn10, bidirectional Zener diode SD1, and output filter capacitors C94, EC2, and EC3. The Boost topology boost circuit is directly integrated on the circuit board of the lithium battery BMS and shares the power supply module with the BMS, without the need for an additional independent power supply circuit.

4. The control method for intelligently adapting to the original vehicle display screen's power display for converting lead-acid batteries to lithium batteries according to claim 1, characterized in that: The PID algorithm control logic in step 4 is as follows: the direction of the boost circuit output voltage adjustment is determined by the sign of the difference Err, and the adjustment range of the boost circuit power transistor conduction duty cycle is determined by the absolute value of the difference Err, so as to achieve linear and overshoot-free following of Vout to Vobj.

5. A novel control method for intelligently adapting to the original vehicle display screen's battery level display when converting lead-acid batteries to lithium batteries, as described in claim 1, is characterized in that: In step 1, the measurement of the total voltage VOL of the lead-acid battery is completed under standard operating conditions of room temperature and rated load. The accuracy of the measuring equipment is ≤ ±0.01V to ensure the accuracy of Table_VOL_SOC.

6. The control method for intelligently adapting to the original vehicle display screen's power display for converting lead-acid batteries to lithium batteries according to claim 1, characterized in that: The control method eliminates the need for a separate power correction module between the vehicle controller and the original vehicle display screen. It directly integrates table lookup, calculation, and control through the lithium battery BMS, simplifying the system structure.

7. A novel control method for converting lead-acid batteries to lithium batteries that intelligently adapts to the original vehicle display screen's battery level, as described in claim 1, is characterized in that: The output voltage adjustment range of the Boost topology boost circuit is consistent with the total voltage range corresponding to 0%-100% SOC of the lead-acid battery, and the ripple coefficient of the output voltage is ≤0.5%, ensuring the stability of the voltage collected by the original vehicle display screen.

Images