A LED smooth dimming control method based on dynamic voltage tracking

Abstract

This invention provides an LED smooth dimming control method based on dynamic voltage tracking, comprising: setting a target voltage threshold, a lower boundary and an upper boundary of a voltage hysteresis window; monitoring the current voltage value of the battery in real time and determining whether the current voltage value is lower than the lower boundary of the voltage hysteresis window; if so, continuously reducing the maximum allowable brightness value of the LED through a dynamic smoothing adjustment function based on the real-time deviation between the current voltage value and the target voltage threshold; maintaining the current brightness value when the voltage rises back to the upper boundary of the voltage hysteresis window; repeating the above steps when the battery voltage falls below the lower boundary of the voltage hysteresis window again, until the brightness drops to the minimum allowable brightness threshold or the battery discharge terminates; this invention aims to establish a nonlinear smoothing adjustment model between voltage deviation and brightness decay, dynamically clamping the battery voltage near the target threshold, maximizing the utilization of residual battery energy while ensuring stable system operation, and eliminating visual abruptness during dimming.

Description

Technical Field

[0001] This invention relates to the field of energy-saving lighting technology, and in particular to a method for smooth dimming control of LEDs based on dynamic voltage tracking. Background Technology

[0002] With the maturity of semiconductor lighting technology and the in-depth promotion of energy conservation and emission reduction policies, portable lighting products with LED as the core light source (such as flashlights, headlamps, emergency lights, outdoor work lights, etc.) have occupied a dominant position in daily life, industrial inspection and emergency rescue. The core development trend of this type of product focuses on two aspects: first, maximizing the duration of light output under the constraint of limited battery capacity, that is, improving system-level energy efficiency and energy utilization rate; second, improving the human-computer interaction experience during dimming, that is, eliminating visual discomfort caused by sudden brightness changes. In battery-powered LED lighting systems, the battery voltage gradually drops towards the end of its discharge phase. To prevent battery over-discharge damage or system undervoltage reset, existing technologies generally employ a stepped downshifting scheme based on voltage comparison. This involves real-time monitoring of the battery terminal voltage using an ADC, and forcibly switching the LED driver duty cycle to a preset low level when the voltage falls below a certain preset threshold. However, this conventional approach has significant energy-saving drawbacks and user experience shortcomings. First, when the system is forced to downshift due to a voltage drop, the LED load current decreases significantly, and the ohmic voltage drop across the battery's internal resistance decreases sharply, leading to a significant false rebound in the battery terminal voltage. Under the existing stepped downshifting logic, even if the voltage has recovered to a safe range far above the threshold, this effect persists. The brightness is locked at a low level, resulting in a significant amount of idle and wasted battery energy. This leads to a low average brightness of the lighting device at the end of its discharge phase, making it impossible to fully utilize the battery's remaining capacity while ensuring system stability. Secondly, the fixed voltage threshold cannot adapt to batteries of different brands, internal resistance characteristics, and aging degradation levels. For older batteries with higher internal resistance, the voltage drop under load is more pronounced, often triggering the down-level protection prematurely, resulting in a sharp decline in user experience. On the other hand, for newer batteries with lower internal resistance, the down-level protection may be delayed, leading to the risk of over-discharge. Furthermore, the step-like jumps in brightness make users clearly perceive the sudden dimming of the lighting device, and this discontinuous flickering can cause visual discomfort.

[0003] Therefore, there is an urgent need in this field for an LED smooth dimming control method based on dynamic voltage tracking to solve the above problems. Summary of the Invention

[0004] This invention provides an LED smooth dimming control method based on dynamic voltage tracking, which aims to solve the problems of energy waste, voltage rebound and visual flicker caused by fixed threshold step-down in the prior art. By establishing a nonlinear smooth adjustment model between voltage deviation and brightness decay, the battery voltage is dynamically clamped to near the target threshold, maximizing the utilization of residual battery energy while ensuring stable system operation and eliminating visual abruptness in the dimming process.

[0005] This invention provides a method for smooth LED dimming control based on dynamic voltage tracking, comprising the following steps: Step S1: Set the target voltage threshold, the lower boundary of the voltage hysteresis window, and the upper boundary; Step S2: Monitor the current voltage value of the battery in real time and determine whether the current voltage value is lower than the lower boundary of the voltage hysteresis window; Step S3: If not, maintain the LED at the maximum allowable brightness value; if yes, proceed to step S4. Step S4: Execute the dynamic voltage tracking adjustment mode. Based on the real-time deviation between the current voltage value and the target voltage threshold, continuously reduce the maximum allowable brightness value of the LED through a dynamic smoothing adjustment function to dynamically clamp the battery voltage near the target voltage threshold. Step S5: Continuously monitor the adjusted battery voltage. When the voltage rises back to the upper boundary of the voltage hysteresis window, pause the reduction process of the maximum allowable brightness value and maintain the current brightness value. Step S6: When the battery voltage falls below the lower boundary of the voltage hysteresis window again, repeat steps S4 to S5 until the brightness drops to the preset minimum allowable brightness threshold or the battery discharge terminates.

[0006] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention abandons the traditional fixed threshold step-down logic and uses a dynamic voltage tracking adjustment mode to continuously reduce the upper limit of brightness in very small steps when the battery voltage is lower than the threshold. This step-by-step fine-tuning strategy allows the battery voltage to naturally recover and stabilize near the target threshold after the load is slightly reduced, avoiding energy idleness caused by a large rebound in voltage after downgrading.

[0007] 2. This invention introduces a feedforward compensation circuit based on equivalent internal resistance identification and a sensitivity dynamic correction algorithm based on voltage drop slope. This makes the dimming behavior no longer dependent on a fixed voltage threshold, but automatically adjusts the adjustment intensity according to the real-time discharge characteristics of the battery (internal resistance, aging degree, voltage drop rate). Whether it is a brand-new power battery with extremely low internal resistance or an old recycled battery with significantly increased internal resistance, it can automatically match the optimal power reduction curve, ensuring that the lighting device can achieve stable and long-lasting lighting output under different battery conditions.

[0008] 3. This invention converts the linear decrease in physical brightness into an approximately linear decrease in brightness perceived by the human eye. In the initial high-brightness range of adjustment, the algorithm forces adjustment with extremely small step sizes, so the user cannot perceive any change in brightness. At the end of the discharge period, the algorithm overcomes the voltage oscillation by dynamically widening the step size. Throughout the entire discharge cycle, the user will only feel that the lighting device naturally and slowly dims after prolonged use, completely eliminating the abrupt flickering sensation of sudden dimming.

[0009] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0010] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof; in the drawings: Figure 1 This is a flowchart illustrating an LED smooth dimming control method based on dynamic voltage tracking provided by the present invention. Detailed Implementation

[0011] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1:

[0012] This invention provides an LED smooth dimming control method based on dynamic voltage tracking. Please refer to [link to relevant documentation]. Figure 1 This includes the following steps: Step S1: Set the target voltage threshold, the lower boundary of the voltage hysteresis window, and the upper boundary; Step S2: Monitor the current voltage value of the battery in real time and determine whether the current voltage value is lower than the lower boundary of the voltage hysteresis window; Step S3: If not, maintain the LED at the maximum allowable brightness value; if yes, proceed to step S4. Step S4: Execute the dynamic voltage tracking adjustment mode. Based on the real-time deviation between the current voltage value and the target voltage threshold, continuously reduce the maximum allowable brightness value of the LED through a dynamic smoothing adjustment function to dynamically clamp the battery voltage near the target voltage threshold. Step S5: Continuously monitor the adjusted battery voltage. When the voltage rises back to the upper boundary of the voltage hysteresis window, pause the process of reducing the maximum allowable brightness value and maintain the current brightness value. Step S6: When the battery voltage falls below the lower boundary of the voltage hysteresis window again, repeat steps S4 to S5 until the brightness drops to the preset minimum allowable brightness threshold or the battery discharge terminates.

[0013] Specifically, step S1 is the initialization phase. The target voltage threshold (e.g., 3.0V) is the lowest stable voltage reference point for the battery to operate without triggering low-voltage protection. The lower boundary of the voltage hysteresis window (e.g., 2.94V) is used to trigger brightness adjustment to prevent further voltage drops, and the upper boundary (e.g., 3.04V) is used to lock the current brightness when the voltage recovers due to reduced load, avoiding unnecessary brightness fluctuations. Step S2 uses an analog-to-digital converter (ADC) to collect the voltage value of the battery after voltage division in real time and compares it with the lower boundary. Step S3 is used to determine the continuous full-power output state when no adjustment is triggered. Step S4... When the voltage drops beyond the limit, the system does not directly jump to a preset low level. Instead, based on the real-time voltage deviation, it uses a subsequent function model to gradually reduce the upper limit of the PWM duty cycle in fine steps. By utilizing the positive correlation between the battery internal resistance voltage drop and the load current, the battery voltage is forced to rise and remain near the target threshold. Step S5 is used to determine the adjustment pause conditions to prevent energy waste caused by excessive brightness reduction. Step S6 is used to implement the cyclic discharge management process until the battery is depleted. This embodiment is used to solve the problems of voltage false rise, energy waste, and visual flicker caused by fixed threshold step-down in existing methods.

[0014] In some implementations, the dynamic smoothing adjustment function in step S4 is: In the formula, This is the logic control value for the PWM duty cycle output during the current adjustment cycle; This is the PWM duty cycle logic control value for the previous adjustment cycle; The target voltage threshold; This refers to the current real-time monitored battery voltage. This represents the total width of the voltage hysteresis window; The sensitivity coefficient is the coefficient for a sharp drop. A voltage potential well constraint operator is constructed to accelerate brightness decay when the voltage deviates from the target threshold and slow down the adjustment rate when it approaches the target threshold. The cumulative duration for which the current voltage remains below the lower boundary of the voltage hysteresis window; This is a preset time normalization constant; The inertial coefficient is the energy decay coefficient. It constitutes a virtual rebound suppression factor, which is used to dynamically increase the dimming depth according to the duration of continuous power loss, so as to overcome the false voltage rebound caused by changes in battery internal resistance. This represents the maximum allowable brightness attenuation ratio for a single adjustment.

[0015] Specifically, the dynamic smoothing adjustment function is the core algorithm model of this embodiment, used to calculate the target brightness logical variable for the next cycle. In the model The PWM duty cycle logic control quantity is calculated for the current adjustment cycle, and its value ranges from 0 to 1 (corresponding to 0% to 100% brightness logic value). The logic control values ​​stored in the previous cycle are used as the base for this calculation; The target voltage threshold preset for step S1; This is the real-time battery voltage sample value after filtering in step 2; This is the total width of the hysteresis window, which is the width from the lower boundary to the upper boundary of the voltage hysteresis window, used to normalize the voltage deviation. The sensitivity coefficient drops sharply. Hyperbolic tangent function; this term Constructing a voltage potential well constraint operator, when far below When the drop depth is reached (i.e., a deep drop), the function value approaches 1, allowing for a faster rate of brightness decay. nearing recovery When the function value approaches 0, the decay is significantly slowed down or even stopped, thus smoothly pulling the voltage into the target threshold potential well and avoiding overshoot; The duration (in seconds) during which the voltage accumulated by the microcontroller's internal timer remains below the lower boundary of the voltage hysteresis window. The time normalization constant is a preset value. It should be noted that if the value is too short, the cumulative effect will be too fast and the brightness will decay abruptly. If the value is too long, it will not be able to effectively combat the severe false rebound after battery aging. The preferred range is 30s~120s. The inertial coefficient for energy decay was found to be optimally ranged from 0.3 to 1.5 through experiments. When <0.3, the inhibitory effect on the false rebound is weak. A time-cumulative effect of >1.5 is too aggressive and may cause the brightness to decrease too quickly; The virtual rebound suppression factor is based on the exponential cumulative effect. That is, the battery internal resistance increases at the end of the discharge period, the voltage rebound is large but the load-carrying capacity is extremely weak. This factor gradually increases with time, forcibly deepening the dimming depth to consume the virtual capacity corresponding to the virtual voltage, ensuring that the real voltage is clamped and preventing the LED from flickering under the false high voltage. This represents the single-step maximum decay ratio limit under dynamic constraints. The model decomposes the brightness decay amplitude into the product of a voltage deviation term (potential well constraint) and a time accumulation term (virtual rebound suppression), and then subjectes it to a single-step limit constraint. Without relying on battery model parameters (such as the precise value of internal resistance), it achieves smooth, stable, and adaptive power reduction regulation solely through voltage feedback and time sensing.

[0016] In some implementations, the sensitivity coefficient drops sharply. for: In the formula, The basic sensitivity constant; This represents the absolute value of the instantaneous rate of decrease in battery voltage. This is the preset reference voltage; The slope weighting factor is preset; this term makes the dynamic smoothing adjustment function respond more quickly when the voltage drops sharply at the end of the battery's high-current discharge, thus adapting to the discharge characteristics of batteries with different aging levels or different internal resistances.

[0017] Specifically, this embodiment is used to enable the adjustment sensitivity to adapt to the drastic changes at the end of battery discharge. In the formula, Based on the fundamental sensitivity constant, If the value is too small, the transition region of the tanh function will be too wide, and the dimming will continue even if the voltage drops slightly, resulting in a decrease in average brightness. If the value is too large, the tanh function will approach a step, losing its smooth adjustment characteristics. The preferred range is 1.5~4.0. It is the absolute value of the instantaneous rate of voltage drop, calculated by dividing the difference between two consecutive ADC samples by the sampling period; The preset reference voltage is usually the system rated voltage or the ADC reference voltage (such as 3.3V) and is used for dimensional normalization. The preset slope weighting factor is used to adjust the contribution of slope changes to sensitivity, with a preferred range of 0.05 to 0.3. This represents the reciprocal of the brightness value, i.e., when the brightness is already very low (i.e.) (Small), at this point, a slight drop in voltage actually means the battery is nearing depletion and requires a more aggressive response (increase). This is to quickly reduce the power consumption to the lowest level to protect the battery; conversely, when the brightness is high, the reciprocal term is close to 1, which does not affect the basic sensitivity. This embodiment can address the issue when the battery reaches the inflection point of its discharge curve, where the voltage drop slope increases sharply. As the internal resistance of the battery increases, the tanh function curve becomes steeper, and the adjustment action becomes more decisive, thus adapting to the nonlinear discharge characteristics after the internal resistance of the battery increases.

[0018] In some implementations, the output of the dynamic smoothing adjustment function is further processed by a logarithmic visual compensation mapping to generate the actual pulse width modulation control quantity used to drive the LED. : In the formula, This is the pulse width modulation count value corresponding to the maximum brightness; The value of the logical variable corresponding to the maximum brightness; The correction coefficient is given, and satisfies the following conditions: Actual pulse width modulation control quantity It is used to make the brightness decay process conform to the characteristics of human eye perception of brightness, and to provide a visually uniform and smooth darkening effect when the physical brightness decreases linearly; Specifically, this embodiment is used to establish a bridge between physical dimming output and subjective human visual perception; in the formula, This is for writing the final value into the microcontroller's timer compare register (e.g., the range for a 16-bit timer is 0~65535). This corresponds to the maximum count value for 100% duty cycle of the hardware (e.g., 65535). The logical brightness value calculated above; The maximum logical value is usually taken as a constant of 1.0; the correction coefficient. The preferred range is 1.8≤ ≤2.4, the optimal embodiment uses 2.2, because the human eye is sensitive to low brightness changes but insensitive to high brightness changes; if a direct linear output is used... When the logic value drops from 1.0 to 0.8, the human eye only perceives a slight dimming, but when it drops from 0.2 to 0.1, the human eye perceives a sudden dimming. This embodiment uses exponential mapping to convert the linear decrease in physical brightness into an approximately linear decrease in perceived brightness, achieving truly smooth and imperceptible dimming, thereby improving the comfort of lighting.

[0019] In some implementations, the maximum allowable brightness attenuation ratio limit for a single adjustment for: In the formula, The basic attenuation factor constant; The value of the logical variable corresponding to the minimum allowable brightness; This is used to automatically constrain the maximum allowable attenuation ratio to a minimum when the brightness is high, so as to ensure smooth and imperceptible dimming in the high brightness range; while gradually relaxing the maximum attenuation ratio when the brightness drops to close to the minimum allowable brightness, so as to allow a larger dimming step to overcome the voltage rebound caused by the increase in battery internal resistance, and prevent the system from voltage oscillation or premature shutdown due to insufficient adjustment step size in the low energy state.

[0020] Specifically, this embodiment provides a protection mechanism to prevent a precipitous drop in brightness. In the formula, The basic attenuation factor is used to define the maximum allowable single-step adjustment range in the low brightness range, with a preferred range of 0.15 to 0.30, so that the maximum allowable single reduction in brightness is about 15% to 30%, ensuring that the human eye cannot perceive the sudden change; The value of the brightness logic variable is calculated by the dynamic smoothing adjustment function at the end of the previous adjustment cycle; This is the preset minimum allowable brightness logic value (e.g., 0.05, which is 5% brightness). It is the maximum logical value (i.e., 1.0). when near (At full brightness) Approaching At this point, the maximum allowable attenuation ratio is forcibly constrained to zero, meaning the actual single-step reduction of the dynamic smoothing adjustment function will be limited by a minimum value; in the high brightness range, the human eye is extremely sensitive to changes in relative brightness, and any single-step brightness change exceeding 5% may be perceived by the user as a sudden dimming flicker; by... By constraining the PWM duty cycle to zero with extremely fine steps, and utilizing the precise relationship between the battery internal resistance voltage drop and the load current, the battery voltage is stably restored with minimal brightness sacrifice. This ensures that users cannot perceive any brightness change in the initial dimming stage, achieving truly smooth and imperceptible dimming. when Gradually decrease to near (In low brightness state) as the brightness logic value decreases, Approaching The maximum permissible single-step reduction is reached. In the low brightness range, the battery has entered a deep discharge stage, and its equivalent internal resistance increases significantly, exacerbating the voltage rebound phenomenon. At this point, the core challenge shifts from visual smoothness to voltage stability. If the extremely small step size constraint in the high brightness range is maintained, the battery voltage will rebound sharply after a slight decrease in brightness, causing the system to pause adjustment. After a short delay, the voltage drops again, triggering adjustment. This repeated cycle of adjustment-pause-adjustment creates a high-frequency oscillation, causing not only noticeable flickering of LED brightness in the low-end range but also potentially leading to unexpected lighting interruptions due to frequent undervoltage protection thresholds. This embodiment relaxes the... to It is allowed to perform a large brightness decay within a single cycle to decisively reduce the load current, overcome the interference of the virtual rebound voltage in one go, and quickly pull the battery operating point into the stable range, thereby eliminating voltage oscillation and ensuring continuous and stable lighting under low energy conditions.

[0021] In some implementations, step S4 further includes a feedforward compensation step based on equivalent internal resistance identification, including: Each time the brightness reduction process is paused and the voltage recovers to the upper boundary of the voltage hysteresis window, the peak value of the recovered voltage is recorded. With corresponding load current ; Calculate the estimated equivalent DC internal resistance of the current battery. ; The equivalent DC internal resistance is estimated. Used to correct the steep drop in sensitivity coefficient in the next round of dynamic voltage tracking regulation mode. It adapts to the health status and aging degree of the battery.

[0022] Specifically, this embodiment is used to automatically adapt to differences in internal resistance between new and old batteries or batteries from different brands; wherein, This represents the stable voltage recovery value monitored by the ADC after the adjustment is paused in step S5; the corresponding load current. The acquisition can be achieved by integrating a battery fuel gauge chip. You can directly purchase the chip from the market and install it, which is a mature existing method. Given the target voltage; the calculated... The larger the value, the greater the internal resistance of the battery or the more severe the aging. Mapped to a correction factor, and with Multiplication (e.g.) , These are preset mapping coefficients, in Ω. -1 This is a correction factor used to convert the physical dimension of internal resistance into a dimensionless value (ranging from 0.01 to 0.05). Batteries with high internal resistance experience severe voltage fluctuations, increasing the risk of voltage reversal. This allows the algorithm to more aggressively reduce power and prevent the system from oscillating repeatedly on virtual voltages; this step enables the lighting device to be plug-and-play, without the need to write firmware with fixed parameters for specific battery models.

[0023] In some implementations, the lower and upper boundaries of the voltage hysteresis window in step S1 are set as asymmetric windows with respect to the target voltage threshold, and the hysteresis depth of the lower boundary is greater than that of the upper boundary, forming an anti-rebound hysteresis comparison mechanism to avoid frequent switching of dimming state and brightness flicker caused by load current fluctuations.

[0024] Specifically, during the dynamic adjustment of battery voltage, due to the slight fluctuations in the PWM load, the voltage sampling value has high-frequency ripple. If the window is symmetrical, it is very easy for frequent trigger-pause-trigger logic jitter to occur at the threshold critical point, causing the LED brightness to flicker slightly. A deeper lower boundary means that the system is more cautious in deciding to start dimming, and must wait until the voltage has indeed dropped to the dangerous edge before taking action. A shallower upper boundary means that the system responds very quickly to stopping dimming, and locks the brightness as soon as the voltage stabilizes slightly. This setting prioritizes the stability of brightness and the maximum energy output.

[0025] In some implementations, if the battery voltage recovers to above the upper boundary of the voltage hysteresis window after the brightness drops to a preset minimum allowable brightness threshold due to external power supply or battery replacement, a brightness recovery procedure is executed. The maximum permissible brightness value is slowly increased at a second recovery slope that is at least an order of magnitude lower than the power reduction adjustment rate, and the voltage stability is continuously monitored during the increase. If the voltage drops again, the recovery process is stopped, thereby avoiding repeated oscillations in lighting brightness caused by battery depletion.

[0026] Specifically, the power reduction adjustment rate is to decrease the logic brightness value by about 1% to 5% every 100ms; the second recovery slope is to increase the logic brightness value by 0.1% every second, or to use a more conservative step. This is because if the battery voltage is only slightly high after a short rest (old batteries that are replaced before being fully charged), if the brightness is quickly increased to full, the instantaneous large current will cause the voltage to drop immediately back to the low-voltage protection state, causing brightness oscillation (flickering-brightening-flickering). Using an extremely slow recovery slope is equivalent to applying a slowly increasing stress test to the battery, ensuring that the battery has the ability to continuously support the current brightness before continuing to increase the brightness. This avoids wasting energy on ineffective brightness oscillations.

[0027] In some implementations, the method is applied to battery-powered lighting devices that include a boost LED driver topology. During operation in dynamic voltage tracking mode, the LED load current is reduced by decreasing the PWM duty cycle, thereby reducing the battery output current. This causes the battery terminal voltage to naturally rise back to near the target voltage threshold due to the reduction in internal resistance voltage drop.

[0028] Specifically, boost-type driver topologies are commonly used in lighting scenarios where low-voltage batteries drive high-voltage LED strings. During system operation, the battery output current is positively correlated with the LED load current. When entering dynamic voltage tracking regulation mode, the controller gradually reduces the PWM duty cycle to smoothly reduce the LED load current, thereby reducing the battery output current. The decrease in battery output current leads to a corresponding decrease in internal resistance voltage drop, and the battery terminal voltage naturally rises. Through the coupling relationship between the load current and terminal voltage, the battery voltage can be stably clamped near the target voltage threshold, which avoids over-discharge of the battery, achieves smooth dimming and energy-saving lighting, makes full use of the remaining battery energy, and extends the duration of high-brightness lighting.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for smooth LED dimming control based on dynamic voltage tracking, characterized in that, Includes the following steps: Step S1: Set the target voltage threshold, the lower boundary of the voltage hysteresis window, and the upper boundary; Step S2: Monitor the current voltage value of the battery in real time and determine whether the current voltage value is lower than the lower boundary of the voltage hysteresis window; Step S3: If not, then maintain the LED operating at the maximum allowable brightness value; If so, proceed to step S4; Step S4: Execute the dynamic voltage tracking adjustment mode. Based on the real-time deviation between the current voltage value and the target voltage threshold, continuously reduce the maximum allowable brightness value of the LED through a dynamic smoothing adjustment function to dynamically clamp the battery voltage near the target voltage threshold. Step S5: Continuously monitor the adjusted battery voltage. When the voltage rises back to the upper boundary of the voltage hysteresis window, pause the reduction process of the maximum allowable brightness value and maintain the current brightness value. Step S6: When the battery voltage falls below the lower boundary of the voltage hysteresis window again, repeat steps S4 to S5 until the brightness drops to the preset minimum allowable brightness threshold or the battery discharge terminates.

2. The LED smooth dimming control method based on dynamic voltage tracking according to claim 1, characterized in that, The dynamic smoothing adjustment function mentioned in step S4 is: In the formula, This is the logic control value for the PWM duty cycle output during the current adjustment cycle; This is the PWM duty cycle logic control value for the previous adjustment cycle; The target voltage threshold; This refers to the current real-time monitored battery voltage. The total width of the voltage hysteresis window; The sensitivity coefficient is the coefficient for a sharp drop. A voltage potential well constraint operator is constructed to accelerate brightness decay when the voltage deviates from the target threshold and slow down the adjustment rate when it approaches the target threshold. The cumulative duration for which the current voltage remains below the lower boundary of the voltage hysteresis window; This is a preset time normalization constant; The inertial coefficient is the energy decay coefficient. The aforementioned virtual rebound suppression factor is used to dynamically increase the dimming depth based on the duration of continuous power loss, in order to overcome the false voltage rebound caused by changes in battery internal resistance. This represents the maximum allowable brightness attenuation ratio for a single adjustment.

3. The LED smooth dimming control method based on dynamic voltage tracking according to claim 2, characterized in that, The steep drop sensitivity coefficient for: In the formula, The basic sensitivity constant; This represents the absolute value of the instantaneous rate of decrease in battery voltage. This is the preset reference voltage; The slope weighting factor is preset; this term makes the dynamic smoothing adjustment function respond more quickly when the voltage drops sharply at the end of the battery's high-current discharge, thereby adapting to the discharge characteristics of batteries with different aging levels or different internal resistances.

4. The LED smooth dimming control method based on dynamic voltage tracking according to claim 2, characterized in that, The output of the dynamic smoothing adjustment function is further processed by logarithmic visual compensation mapping to generate the actual pulse width modulation control quantity used to drive the LED. : In the formula, This is the pulse width modulation count value corresponding to the maximum brightness; The value of the logical variable corresponding to the maximum brightness; The correction coefficient is given, and satisfies the following conditions: Actual pulse width modulation control quantity It is used to make the brightness decay process conform to the characteristics of human eye perception of brightness, and to provide a visually uniform and smooth darkening effect when the physical brightness decreases linearly.

5. The LED smooth dimming control method based on dynamic voltage tracking according to claim 2, characterized in that, The maximum allowable brightness attenuation ratio limit for a single adjustment for: In the formula, The basic attenuation factor constant; The value of the logical variable corresponding to the minimum allowable brightness; This is used to automatically constrain the maximum allowable attenuation ratio to a minimum when the brightness is high, so as to ensure smooth and imperceptible dimming in the high brightness range; while gradually relaxing the maximum attenuation ratio when the brightness drops to close to the minimum allowable brightness, so as to allow a larger dimming step to overcome the voltage rebound caused by the increase in battery internal resistance, and to prevent voltage oscillation or premature shutdown due to insufficient adjustment step size in the low energy state.

6. The LED smooth dimming control method based on dynamic voltage tracking according to claim 3, characterized in that, Step S4 also includes a feedforward compensation stage based on equivalent internal resistance identification, including: Each time the brightness reduction process is paused and the voltage recovers to the upper boundary of the voltage hysteresis window, the peak value of the recovered voltage is recorded. With corresponding load current ; Calculate the estimated equivalent DC internal resistance of the current battery. ; And estimate the equivalent DC internal resistance The steep drop sensitivity coefficient used to correct the next round of dynamic voltage tracking adjustment mode It adapts to the health status and aging degree of the battery.

7. The LED smooth dimming control method based on dynamic voltage tracking according to claim 1, characterized in that, In step S1, the lower and upper boundaries of the voltage hysteresis window are set as asymmetric windows with respect to the target voltage threshold, and the hysteresis depth of the lower boundary is greater than that of the upper boundary, thus forming an anti-rebound hysteresis comparison mechanism to avoid frequent switching of dimming state and brightness flicker caused by load current fluctuations.

8. The LED smooth dimming control method based on dynamic voltage tracking according to claim 1, characterized in that, When the brightness drops to the preset minimum allowable brightness threshold, if the battery voltage recovers to above the upper boundary of the voltage hysteresis window due to external power supply or battery replacement, then a brightness recovery procedure is executed: The maximum allowable brightness value is slowly increased at a second recovery slope that is at least an order of magnitude lower than the power reduction adjustment rate, and the voltage stability is continuously monitored during the increase. If the voltage drops again, the recovery process is stopped, thereby avoiding repeated oscillations in lighting brightness caused by battery depletion.

9. The LED smooth dimming control method based on dynamic voltage tracking according to claim 1, characterized in that, The method is applied to a battery-powered lighting device that includes a boost LED driver topology. During operation of the dynamic voltage tracking regulation mode, the LED load current is reduced by decreasing the PWM duty cycle, thereby reducing the battery output current. This causes the battery terminal voltage to naturally rise back to near the target voltage threshold due to the reduction in internal resistance voltage drop.

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