Active heat dissipation system and method for LED lamp beads

Abstract

The invention relates to the technical field of lamp bead active heat dissipation, and discloses an LED lamp bead active heat dissipation system and method, and the method comprises the steps: injecting a micro-current pulse into a PN junction of an LED chip through a constant current source, collecting a forward voltage drop sampling value, and collecting a substrate temperature sampling value; calculating a junction temperature value based on the forward voltage drop sampling value, and calculating a junction-to-case temperature difference value and a substrate temperature rise rate value; setting an early-warning state identifier when the junction-to-case temperature difference value exceeds an early-warning threshold value and the duration meets a preset duration, setting an alarm state identifier when the junction-to-case temperature difference value exceeds an alarm threshold value, and shielding thermal runaway detection when the substrate temperature rise rate value exceeds an environment thermal shock threshold value and the junction-to-case temperature difference value is smaller than an environment exclusion threshold value; when the state identification is the normal state identification, calculating a first compensation current value; and when the state identification is the early warning state identification, a second compensation current value is calculated, and when the state identification is the alarm state identification, an alarm current limiting value is calculated, so that the working stability and long-term reliability of the LED in a wide temperature range are ensured.

Description

Technical Field

[0001] This invention relates to the field of active heat dissipation technology for LED chips, and more particularly to an active heat dissipation system and method for LED chips. Background Technology

[0002] LED chips face thermal runaway failures due to junction temperature accumulation in high-density display and lighting applications. Traditional heat dissipation methods mainly rely on passive heat dissipation structures or simple temperature threshold protection, which are difficult to achieve precise thermal management. Existing technologies typically employ single-point temperature monitoring schemes, placing temperature sensors only on the LED package shell or substrate, which cannot directly obtain the real-time temperature status of the chip's PN junction, resulting in significant response lag in thermal runaway detection. Existing active heat dissipation control methods use fixed temperature threshold triggering mechanisms, directly reducing the drive current or shutting down the LED when the detected temperature exceeds a preset value. This method cannot distinguish between the chip's internal self-heating and the influence of external ambient temperature fluctuations, and is prone to false triggering when the ambient temperature changes rapidly, causing frequent LED start-stop and unstable light output. In addition, existing current regulation methods mostly use level switching or direct current limiting, lacking the ability to dynamically and continuously adjust according to temperature conditions. In other words, the accuracy of active heat dissipation for LED chips in existing technologies is low. Summary of the Invention

[0003] This invention provides an active heat dissipation system and method for LED beads, which ensures the working stability and long-term reliability of LEDs over a wide temperature range.

[0004] In a first aspect, the present invention provides an active heat dissipation method for LED chips, the active heat dissipation method for LED chips comprising: A micro-current pulse is injected into the PN junction of the LED chip by a constant current source, the forward voltage drop is sampled, and the substrate temperature is sampled by an NTC thermistor. The junction temperature is calculated based on the positive pressure drop sampling value, and the junction-shell temperature difference and the substrate temperature rise rate are calculated based on the junction temperature and the substrate temperature sampling value. When the temperature difference between the junction and the shell exceeds the warning threshold and the duration meets the preset duration, a warning status indicator is set; when the temperature difference between the junction and the shell exceeds the alarm threshold, an alarm status indicator is set; when the base temperature rise rate exceeds the environmental thermal shock threshold and the temperature difference between the junction and the shell is less than the environmental exclusion threshold, thermal runaway detection is shielded. When the status is normal, calculate the first compensation current value; when the status is warning, calculate the second compensation current value; and when the status is alarm, calculate the alarm current limit value.

[0005] In conjunction with the first aspect, in a first implementation of the first aspect of the present invention, the step of injecting a micro-current pulse into the PN junction of the LED chip through a constant current source, acquiring a forward voltage drop sampling value, and acquiring a substrate temperature sampling value through an NTC thermistor includes: After the main drive current of the LED is turned off, a micro-current pulse is injected into the PN junction of the LED chip, and the forward voltage drop sampling value of the PN junction is collected during the micro-current pulse. An NTC thermistor is connected to a reference resistor to form a voltage divider circuit. The voltage divider circuit outputs the voltage value at the package substrate, and the substrate temperature sampling value is calculated based on the voltage divider value.

[0006] In conjunction with the first aspect, in a second implementation of the first aspect of the present invention, the step of calculating the junction temperature value based on the forward voltage drop sampling value, and calculating the junction-shell temperature difference value and the substrate temperature rise rate value based on the junction temperature value and the substrate temperature sampling value, includes: The positive voltage drop sampling value is substituted into the linear temperature relationship to perform junction temperature conversion calculation, and the junction temperature value is obtained; The difference between the junction temperature value and the sampled substrate temperature value is calculated to obtain the junction-shell temperature difference value. Read the base temperature sample value at time i and time in, which are within a preset time interval n. Calculate the difference between the base temperature sample value at time i and time in and divide it by the preset time interval n to obtain the base temperature rise rate value.

[0007] In conjunction with the first aspect, in a third implementation of the first aspect of the present invention, the step of setting a warning status indicator when the junction temperature difference exceeds a warning threshold and the duration meets a preset duration, setting an alarm status indicator when the junction temperature difference exceeds an alarm threshold, and shielding thermal runaway detection when the substrate temperature rise rate exceeds an environmental thermal shock threshold and the junction temperature difference is less than an environmental exclusion threshold includes: When the temperature difference between the crust and the junction exceeds the warning threshold, the current timestamp is recorded and the warning timer is started. Within the preset monitoring time, it is continuously judged whether the temperature difference between the crust and the junction exceeds the warning threshold and whether the temperature increment exceeds the preset increment threshold. When the conditions are met, the warning status indicator is set. Determine whether the junction temperature difference exceeds the alarm threshold or whether the junction temperature exceeds the absolute temperature limit. If either condition is met, immediately set an alarm status indicator. When the substrate temperature rise rate exceeds the environmental thermal shock threshold and the junction temperature difference is less than the environmental exclusion threshold, an environmental interference flag is set and thermal runaway detection is blocked. When the substrate temperature rise rate drops below the recovery threshold and is continuously confirmed for a preset duration, the environmental interference flag is cleared.

[0008] In conjunction with the first aspect, in a fourth implementation of the first aspect of the present invention, the step of setting an environmental interference flag and shielding thermal runaway detection when the substrate temperature rise rate exceeds the environmental thermal shock threshold and the junction-shell temperature difference is less than the environmental exclusion threshold, and clearing the environmental interference flag after the substrate temperature rise rate drops below the recovery threshold and continues for a preset confirmation period, includes: Determine whether the substrate temperature rise rate exceeds the environmental thermal shock threshold and whether the junction temperature difference is less than the environmental exclusion threshold. If both conditions are met, set an environmental interference flag. During the effective period of the environmental interference indicator, the setting logic of the early warning status indicator and the alarm status indicator is blocked, and the current working state remains unchanged; The system continuously monitors the substrate temperature rise rate and determines whether it has decreased below the recovery threshold. Once the preset confirmation time is met, the environmental interference flag is cleared and the thermal runaway detection logic is restored.

[0009] In conjunction with the first aspect, in a fifth implementation of the first aspect of the present invention, the step of calculating a first compensation current value when the status is normal, calculating a second compensation current value when the status is warning, and calculating an alarm current limit value when the status is alarm, includes: When the normal state is indicated, the ambient temperature compensation coefficient is calculated based on the difference between the sampled base temperature and the reference temperature, and the ambient temperature compensation coefficient is multiplied by the rated current value to obtain the first compensation current value. When the warning status is indicated, the junction temperature compensation coefficient is calculated based on the difference between the junction temperature difference value and the warning threshold. The first compensation current value is multiplied by the junction temperature compensation coefficient to obtain the second compensation current value. When the alarm status is indicated, the second compensation current value is multiplied by the preset reduction ratio to obtain the alarm current limit value.

[0010] In conjunction with the first aspect, in the sixth implementation of the first aspect of the present invention, the active heat dissipation method for LED beads further includes: Divide the alarm current limit value by the rated current value to obtain the target duty cycle, and determine whether the difference between the target duty cycle and the current duty cycle exceeds the duty cycle change threshold. When the difference exceeds the duty cycle change threshold, the current duty cycle is adjusted to the target duty cycle in multiple sampling periods according to a preset adjustment step size; Based on the adjusted target duty cycle and preset PWM frequency, the timer is configured to generate a pulse width modulation signal, and the pulse width modulation signal is output to the dimming port of the LED chip to output the drive current.

[0011] In conjunction with the first aspect, in the seventh implementation of the first aspect of the present invention, the step of adjusting the current duty cycle to the target duty cycle in multiple sampling periods according to a preset adjustment step size when the difference exceeds the duty cycle change threshold includes: Calculate the absolute value of the difference between the target duty cycle and the current duty cycle, and divide it by the preset adjustment step size to obtain the number of cycles that need to be adjusted; Within each sampling period, the adjustment direction is determined based on whether the target duty cycle is greater than or less than the current duty cycle, and the current duty cycle is incremented or decremented according to the preset adjustment step size; Determine whether the adjusted current duty cycle has reached the target duty cycle. If not, continue the adjustment operation in the next sampling period until the current duty cycle equals the target duty cycle.

[0012] In conjunction with the first aspect, in the eighth implementation of the first aspect of the present invention, the active heat dissipation method for LED beads further includes: Determine whether the junction temperature value is less than the junction temperature recovery threshold and whether the junction-shell temperature difference value is less than the temperature difference recovery threshold. If both conditions are met, start the recovery confirmation timer. Verify whether the condition is continuously met cycle by cycle within the recovery confirmation time. If any parameter exceeds the recovery threshold, reset the recovery confirmation timer. When the recovery confirmation timer reaches the recovery confirmation duration, the operating state segment to be entered is determined based on the current range of the junction temperature value and the junction-shell temperature difference value, and the target operating segment current value of the corresponding operating state segment is calculated. The alarm current limit value is incremented by a fixed increment in each sampling period according to a preset current recovery rate. The rate of increase of the junction temperature value and the incremental change of the junction-shell temperature difference value are monitored simultaneously. When the rate of increase of the junction temperature value exceeds the temperature rise rate threshold or the increment of the junction-shell temperature difference value exceeds the temperature difference increment threshold, the increment is paused and the alarm current limit value is maintained.

[0013] Secondly, the present invention provides an active heat dissipation system for LED chips, the active heat dissipation system for LED chips comprising: The acquisition module is used to inject micro-current pulses into the PN junction of the LED chip through a constant current source, acquire the forward voltage drop sampling value, and acquire the substrate temperature sampling value through an NTC thermistor. The first calculation module is used to calculate the junction temperature value based on the positive pressure drop sampling value, and to calculate the junction-shell temperature difference value and the substrate temperature rise rate value based on the junction temperature value and the substrate temperature sampling value. The setting module is used to set an early warning status indicator when the temperature difference between the junction and the shell exceeds the early warning threshold and the duration meets the preset duration, set an alarm status indicator when the temperature difference between the junction and the shell exceeds the alarm threshold, and shield thermal runaway detection when the base temperature rise rate exceeds the environmental thermal shock threshold and the temperature difference between the junction and the shell is less than the environmental exclusion threshold. The second calculation module is used to calculate the first compensation current value when the status is normal, to calculate the second compensation current value when the status is warning, and to calculate the alarm current limit value when the status is alarm.

[0014] The technical solution provided by this invention monitors the PN junction temperature of the LED chip and the temperature of the packaging substrate separately, achieving physical decoupling between chip self-heating and environmental thermal interference. The junction-to-substrate temperature difference is calculated to reflect the thermal conduction state from the chip to the substrate. Combined with the substrate temperature rise rate, rapid thermal shocks from the external environment are identified, constructing a dual-criteria thermal runaway detection mechanism. When the substrate temperature rise rate exceeds the environmental thermal shock threshold and the junction-to-substrate temperature difference is less than the environmental exclusion threshold, temperature disturbances from the external environment can be accurately identified and shielded, effectively reducing the false trigger rate. Corresponding compensation current values ​​are calculated based on normal, warning, and alarm states. During normal operation, ambient temperature compensation maintains light output stability; during the warning operation, junction temperature compensation is superimposed to suppress further temperature increases; and during the alarm protection stage, current is forcibly reduced to achieve rapid heat dissipation protection, achieving precise matching between the drive current and the thermal state. A PWM duty cycle progressive adjustment mechanism avoids luminous flux jumps caused by sudden current changes. During the thermal runaway recovery phase, a progressive recovery strategy of periodic verification and fixed incremental increases is adopted, combined with real-time temperature rise rate monitoring to prevent secondary thermal shocks, ensuring the LED's operational stability and long-term reliability over a wide temperature range. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the steps of the active heat dissipation method for LED beads in an embodiment of the present invention; Figure 2 This is a schematic diagram of the active heat dissipation system for LED beads in an embodiment of the present invention. Detailed Implementation

[0017] This invention provides an active heat dissipation system and method for LED beads. The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0018] For ease of understanding, the specific process of the embodiments of the present invention is described below. Please refer to [link / reference]. Figure 1 One embodiment of the active heat dissipation method for LED beads in this invention includes: Step S1: Inject a micro-current pulse into the PN junction of the LED chip through a constant current source, collect the forward voltage drop sampling value, and collect the substrate temperature sampling value through an NTC thermistor; Specifically, within the carrier release stabilization window after the LED main drive current is turned off, a micro-current pulse with an amplitude of 1mA and a pulse width of 5ms is injected into the PN junction of the LED chip by a constant current source module. Since the LED chip can eliminate the stored charge effect within 100μs after the main drive current is turned off, the forward voltage drop sampled during the duration of the micro-current pulse can accurately reflect the inherent temperature characteristics of the PN junction. At the same time, the forward voltage drop is sampled by an ADC with a resolution of 0.8mV, and the voltage drop signal under micro-current excitation is completely and synchronously collected into the circulating buffer. An NTC thermistor with a resistance of 10kΩ (25℃) and a B value of 3950K is glued to the bottom of the aluminum substrate of the LED bead, about 3mm from the center of the chip and about 0.5mm vertically. This thermistor is connected to a 10kΩ reference resistor to form a stable voltage divider circuit, so that the resistance change of the NTC resistor with temperature is converted into a voltage divider signal between 0 and 3.3V in real time. Within the same sampling cycle of completing the PN junction pulse sampling, the microcontroller reads the voltage divider value and calculates the real-time NTC resistance value based on the voltage divider ratio. Then, it converts the resistance value into a substrate temperature sampling value using lookup data from -40℃ to 125℃ with a resolution of 0.5℃ stored in Flash, forming a dual-channel temperature data pair of junction temperature and substrate temperature.

[0019] Step S2: Calculate the junction temperature value based on the forward voltage drop sampling value, and calculate the junction-shell temperature difference value and the substrate temperature rise rate value based on the junction temperature value and the substrate temperature sampling value; Specifically, the microcontroller, based on the typical forward voltage drop of 2.85V for the LED chip at 25℃ and the temperature coefficient of 0.0023V / ℃ obtained through constant temperature chamber calibration, substitutes the collected forward voltage drop sampling value into the linear temperature relationship. By proportionally converting the voltage difference, it calculates the junction temperature conversion, obtaining the real-time junction temperature value, which is then stored in the real-time temperature register. The microcontroller reads the substrate temperature sampling value collected in the same period, subtracts the substrate temperature sampling value from the junction temperature value to obtain the junction-to-substrate temperature difference, reflecting the temperature gradient change along the path from the LED chip to the packaging substrate. The temperature gradient remains between 35℃ and 45℃ when the LED is operating stably, but increases significantly when the chip's self-heating accumulation tends to increase. To reflect dynamic changes in the environment or heat dissipation channels, the substrate temperature rise rate is calculated. The microcontroller continuously stores approximately 50 sets of historical temperature data in a circular buffer, allowing simultaneous acquisition of the substrate temperature sampling value at time i and time in any sampling period. The preset time interval n is designed to correspond to a 5-second historical window. The difference between the substrate temperature at time i and the substrate temperature at time in is calculated, and the difference is divided by the actual duration corresponding to the time interval n. The substrate temperature rise rate is obtained by calculating the ratio, expressed in °C / s, to characterize whether the external environment or heat dissipation structure is experiencing rapid temperature rise. When the temperature rise rate is significantly greater than 1.5 °C / s and the junction-to-shell temperature difference is still at a low level, it is determined that the temperature rise is not due to internal thermal runaway of the chip but rather an external temperature shock.

[0020] Step S3: When the temperature difference between the junction and the shell exceeds the warning threshold and the duration meets the preset duration, set the warning status indicator; when the temperature difference between the junction and the shell exceeds the alarm threshold, set the alarm status indicator; when the base temperature rise rate exceeds the environmental thermal shock threshold and the temperature difference between the junction and the shell is less than the environmental exclusion threshold, shield the thermal runaway detection. Specifically, when the junction temperature difference first exceeds the warning threshold, the system timestamp corresponding to the current moment is recorded and the warning timer is started, making the judgment process continuous over time. Within a preset monitoring period, such as a 2-second window, the junction temperature difference is continuously judged at a sampling period of 100ms to see if it continuously exceeds the warning threshold. The junction temperature increment between the start time of the monitoring window and the current time is calculated simultaneously. When the junction temperature increment is greater than the preset increment threshold of 3℃ and the junction temperature difference does not decrease throughout the monitoring window, this stable and continuous increase in temperature difference is used as the basis for the internal heat accumulation trend. This sets the warning status indicator and clears the normal status indicator, allowing the LED driver module to enter the warning adjustment range. If the junction temperature difference decreases or the junction temperature increment is insufficient at any sampling point within the preset monitoring period, it is judged as a transient disturbance, and the normal status indicator is maintained without triggering the warning. In each sampling cycle, a second-level alarm criterion detection is performed, which determines whether the junction-to-shell temperature difference exceeds the alarm threshold of 55°C or whether the junction temperature exceeds the absolute temperature limit of 100°C. When either condition is met, without waiting for verification, an alarm status flag is immediately set, both the warning and normal flags are cleared, and the driver stage enters a forced current-limiting protection state to prevent the chip temperature from continuing to rise and causing irreversible thermal damage. To avoid misinterpreting thermal runaway within the chip due to external factors such as rapid rise in ambient temperature, blocked airflow, or sudden heating of the heat sink, an environmental thermal shock elimination mechanism based on the substrate temperature rise rate is constructed. When the substrate temperature rise rate exceeds the environmental thermal shock threshold of 1.5℃ / s, and the junction-to-shell temperature difference is below the environmental exclusion threshold of 50℃, it is determined that the rapid temperature rise is caused by the external environment rather than the internal heat accumulation of the chip. At this time, an environmental interference flag is set and all thermal runaway detection logic is paused to prevent the system from entering a falsely triggered warning or alarm state. The environmental interference flag is cleared and the normal thermal runaway detection process is resumed only when the substrate temperature rise rate drops below 1.0℃ / s and remains stable for a preset confirmation time, such as 3 seconds.

[0021] Step S4: When the status is normal, calculate the first compensation current value; when the status is warning, calculate the second compensation current value; when the status is alarm, calculate the alarm current limit value.

[0022] Specifically, when the system is in a normal state, it indicates that the internal thermal behavior of the LED chip is within a controllable range, and the junction-to-case temperature difference is stable within the normal operating range. The focus of the compensation calculation is to offset the attenuation of LED luminous efficacy caused by changes in ambient temperature. Therefore, the microcontroller reads the currently collected substrate temperature sample value, calculates the difference between the substrate temperature value and the reference temperature of 25°C, and constructs an ambient temperature compensation coefficient based on the characteristic that the luminous flux of the LED chip decreases by 0.5% for every 1°C increase in ambient temperature. This ambient temperature compensation coefficient decreases linearly with the increase in substrate temperature. The ambient temperature compensation coefficient is multiplied by the rated current value of 350mA to obtain the first compensation current value. This ensures that when the ambient temperature is between 25°C and 45°C, the first compensation current value can smoothly decrease from 350mA to 315mA, thereby maintaining the stability of light output. When the system is in a warning state, it indicates that the junction-to-case temperature difference has exceeded 48°C and has a continuing trend of increasing. This means that the internal thermal path of the chip is approaching its heat dissipation limit. Therefore, the compensation strategy is no longer only aimed at the ambient temperature, but also needs to reduce the current to limit the chip's self-heating. Based on the first compensation current value, a junction temperature compensation coefficient is constructed according to the difference between the current junction-to-case temperature difference and the warning threshold of 48°C. This coefficient linearly decreases to approximately 0.6 within the junction-to-case temperature difference range of 45°C to 55°C. Multiplying the junction temperature compensation coefficient by the first compensation current value yields the second compensation current value, which actively reduces the operating current by approximately 40%. For example, when the substrate temperature is 40°C and the junction-to-case temperature difference is 50°C, the second compensation current value is approximately 259mA, effectively suppressing further junction temperature accumulation while reducing the impact on light output. When the system enters an alarm state, it indicates that the junction-to-case temperature difference has exceeded 55°C or the junction temperature is approaching the risk boundary of 100°C. Forced current limiting is implemented to prevent thermal runaway from evolving into irreversible chip damage. A preset reduction ratio, such as 50%, is directly applied to the second compensation current value to obtain the alarm current limit value. For example, when the substrate temperature is 50°C, the alarm current limit value can be reduced to 153mA to quickly reduce chip power consumption and slow down the PN junction temperature rise rate.

[0023] In one specific embodiment, the process of performing step S1 may specifically include the following steps: After the main drive current of the LED is turned off, a micro-current pulse is injected into the PN junction of the LED chip, and the forward voltage drop sampling value of the PN junction is collected during the micro-current pulse. An NTC thermistor is connected to a reference resistor to form a voltage divider circuit. The voltage divider circuit outputs the voltage value at the package substrate, and the substrate temperature sampling value is calculated based on the voltage divider value.

[0024] Specifically, within a very short time window after the LED main drive current is turned off, the internal carrier storage effect of the LED chip gradually disappears and stabilizes around 100μs. At this time, the forward voltage drop of the PN junction is determined only by its instantaneous temperature. Therefore, injecting a micro-current pulse within this window can obtain a pure voltage signal unaffected by the main drive current. The constant current source module is configured to output a constant pulse current with an amplitude of 1mA and a pulse width of 5ms. The pulse current is sufficient to excite the PN junction to generate a stable forward voltage drop without causing considerable self-heating of the chip, thus minimizing thermal interference during junction temperature measurement. As the pulse is applied, a forward voltage drop with an amplitude varying with temperature is formed across the PN junction. The ADC channel inside the microcontroller samples the forward voltage drop at high speed with a 3.3V reference voltage and a resolution of 0.8mV, and stores the sampled value in a circular buffer. To obtain the substrate temperature after the package structure is coupled with the external environment, an NTC thermistor is installed at a location with sufficient thermal coupling in the aluminum substrate structure of the LED chip. The NTC thermistor has a nominal resistance of 10kΩ (25℃) and a B-value of 3950K, maintaining a stable resistance change within a range of -40℃ to 125℃. A voltage divider circuit is constructed using the NTC thermistor and a 10kΩ reference resistor, generating a temperature-dependent voltage signal under a 3.3V supply. The divided voltage is electrically led out to the microcontroller's second ADC channel, ensuring synchronized sampling with the PN junction voltage drop sampling, allowing the junction temperature and substrate temperature to be captured simultaneously on the same time base. After reading the divided voltage value, the microcontroller calculates the real-time resistance of the NTC according to the voltage division ratio formula and converts the resistance value into a substrate temperature sample value using a temperature lookup table stored in Flash memory. The lookup table covers the range of -40℃ to 125℃, achieving a temperature resolution of 0.5℃, and linear interpolation is used to improve calculation accuracy.

[0025] In one specific embodiment, the process of performing step S2 may specifically include the following steps: Substitute the positive voltage drop sample value into the linear temperature relationship to perform junction temperature conversion calculation and obtain the junction temperature value; The junction temperature difference is calculated by comparing the junction temperature value with the sampled substrate temperature value. Read the base temperature sample value at time i and time in, which are within a preset time interval n. Calculate the difference between the base temperature sample value at time i and time in and divide it by the preset time interval n to obtain the base temperature rise rate value.

[0026] Specifically, the microcontroller converts the quantized voltage value output by the ADC into the actual forward voltage drop with a voltage resolution of 0.8mV, and substitutes this forward voltage drop into the linear temperature relationship of the LED chip. This linear temperature relationship is based on the typical voltage drop of 2.85V for the LED chip at 25℃ and a temperature coefficient of 0.0023V / ℃ obtained through constant temperature chamber calibration. The microcontroller calculates the voltage drop difference and performs proportional conversion according to the temperature coefficient, making the forward voltage drop numerically correspond to the PN junction temperature, thus obtaining the true junction temperature value, reflecting the thermal state of the current-carrying region inside the LED chip. The junction temperature value is then compared with the substrate temperature sampled in the same period. By subtracting the substrate temperature sampled value from the junction temperature value, the junction-to-shell temperature difference is obtained, thus quantitatively characterizing the temperature difference from the PN junction through the solder joints, the encapsulation resin layer, and finally to the aluminum substrate. Since the junction-to-shell temperature difference is normally stable between 35℃ and 45℃, it increases rapidly when LED power consumption or heat dissipation path abnormalities occur. To identify thermal disturbances caused by the external environment, the substrate temperature rise rate is calculated. The microcontroller maintains over 50 sets of historical substrate temperature data in a circular buffer, enabling the system to simultaneously acquire substrate temperature samples at time i and time in any sampling period. Time i represents the current sampling period, while time in corresponds to a historical temperature point n sampling periods ago, with n corresponding to a 5-second time window. The temperature increment is obtained by subtracting the substrate temperature at time in from the temperature at time i, and then dividing the temperature increment by the corresponding time length n to obtain the substrate temperature rise rate in °C / s. The substrate temperature rise rate is used to determine whether the packaged substrate has experienced a non-internal heat accumulation-type temperature jump due to rapid heating of the external environment. For example, when the heating rate exceeds 1.5 °C / s and the junction-to-case temperature difference remains low, it can be determined that the ambient temperature is rising rapidly and thermal runaway detection can be disabled, thus avoiding false triggering of warnings or alarms.

[0027] In one specific embodiment, the process of performing step S3 may specifically include the following steps: When the temperature difference between the crust and the junction exceeds the warning threshold, the current timestamp is recorded and the warning timer is started. Within the preset monitoring time, it is continuously judged whether the temperature difference between the crust and the junction exceeds the warning threshold and whether the temperature increment exceeds the preset increment threshold. When the conditions are met, the warning status indicator is set. Determine whether the junction temperature difference exceeds the alarm threshold or whether the junction temperature exceeds the absolute temperature limit. If either condition is met, immediately set the alarm status indicator. When the substrate temperature rise rate exceeds the environmental thermal shock threshold and the junction temperature difference is less than the environmental exclusion threshold, an environmental interference flag is set and thermal runaway detection is blocked. When the substrate temperature rise rate drops below the recovery threshold and the preset confirmation time is maintained, the environmental interference flag is cleared.

[0028] Specifically, when the junction-to-shell temperature difference first exceeds the warning threshold (e.g., 48℃), the system timestamp of the current sampling period is written to the warning time register, and a warning timer is started to record the cumulative time of subsequent continuous monitoring periods. This enters the warning observation phase, where the junction-to-shell temperature difference is checked every 100ms sampling period to determine if it remains above the warning threshold. Simultaneously, using the recorded start time as the reference time point, the difference between the current junction temperature and the initial junction temperature is calculated to obtain the current junction temperature increment, which is then compared with a preset increment threshold (e.g., 3℃). If the junction-to-shell temperature difference never falls below the warning threshold during the entire preset monitoring duration (e.g., 2 seconds) and the junction temperature increment exceeds the increment threshold at the end of the observation window, it is considered that the internal heat accumulation of the LED chip has a clear and continuous trend. Therefore, a warning status flag is set and the normal status flag is cleared, causing the adjustment module to execute a current reduction strategy according to the warning status. If the junction-to-shell temperature difference at any sampling point falls below the warning threshold or the junction temperature increment is insufficient within the observation window, it is determined to be a short-term disturbance rather than actual heat accumulation. The warning timer is then stopped, and normal operation is maintained, thus avoiding false triggering. Alarm condition detection is performed in each sampling cycle, determining whether the current junction-to-case temperature difference has reached the alarm threshold (e.g., 55℃) or whether the junction temperature exceeds the absolute temperature limit (e.g., 100℃). Since such temperature conditions represent a high-risk state where the chip is about to run away, the system does not require continuous time verification. Instead, it directly sets an alarm status flag within the same sampling cycle where the condition is met and immediately clears the warning and normal flags, allowing the LED driver current limiting mechanism to execute with the highest priority. This rapidly reduces the PN junction thermal load and prevents irreversible thermal damage. To avoid misjudging the system as thermal runaway in the event of a sudden temperature rise in the external environment, environmental thermal shock exclusion logic is introduced. When the substrate temperature rise rate exceeds the environmental thermal shock threshold (e.g., 1.5℃ / s), it checks whether the junction-to-case temperature difference remains in a low range (e.g., less than the environmental exclusion threshold of 50℃). If both conditions are met, the temperature change is considered to originate from the external environment rather than internal chip heating. Therefore, an environmental interference flag is set, and all warning and alarm logic is paused, temporarily shielding thermal runaway detection and preventing false triggering of active power reduction or alarm mechanisms due to environmental temperature fluctuations. During the period when the environmental interference flag is set, the change in the substrate temperature rise rate is continuously monitored. Only when the substrate temperature rise rate drops below the recovery threshold (e.g., 1.0℃ / s) and remains stable for the preset confirmation time (e.g., 3 seconds) is the environmental interference flag cleared and the normal thermal runaway detection process restored.

[0029] In one specific embodiment, the process of setting an environmental interference flag and shielding thermal runaway detection when the substrate temperature rise rate exceeds the environmental thermal shock threshold and the junction-shell temperature difference is less than the environmental exclusion threshold, and clearing the environmental interference flag after the substrate temperature rise rate drops below the recovery threshold and continues for a preset confirmation period, can specifically include the following steps: Determine whether the substrate temperature rise rate exceeds the environmental thermal shock threshold and whether the shell temperature difference is less than the environmental exclusion threshold. If both conditions are met, set an environmental interference flag. During the effective period of the environmental interference indicator, the setting logic of the warning status indicator and the alarm status indicator is blocked to keep the current working status unchanged; The system continuously monitors the base temperature rise rate and determines whether it has decreased below the recovery threshold. Once the preset confirmation time is met, the environmental interference flag is cleared and the thermal runaway detection logic is restored.

[0030] Specifically, the substrate temperature rise rate is calculated and updated every 100ms sampling period. In the thermal characteristic processing module, this rate is compared with the environmental thermal shock threshold. When the substrate temperature rise rate exceeds 1.5℃ / s, the temperature change of the packaged substrate is considered to be in a rapid rise state. However, this is not immediately considered thermal runaway. Instead, the junction-to-shell temperature difference is read to determine if it remains below the environmental exclusion threshold, such as less than 50℃. Only when both rapid temperature rise and low temperature difference conditions are met simultaneously can the conclusion be drawn that the temperature change originates from the external environment rather than the chip's internal power consumption accumulation. Subsequently, an environmental interference flag is immediately set and written to the status register, officially putting the system into the environmental interference protection phase. During the validity period of the environmental interference flag, all warning and alarm status flag setting logic is disabled to prevent transient thermal disturbances caused by external temperature changes from being misjudged as internal heat dissipation problems. During this phase, the current operating state remains unchanged. The warning logic based on the junction-shell temperature difference exceeding the warning threshold and lasting for a preset duration is no longer executed, nor is the alarm logic based on a junction-shell temperature difference exceeding 55°C or a junction temperature exceeding 100°C. Instead, the entire thermal runaway detection process is paused through a priority overlay mechanism of the environmental interference flag, thereby avoiding erroneous drops in LED drive current, sudden changes in luminous flux, or unnecessary temperature control actions. The substrate temperature rise rate is continuously monitored to determine whether the external temperature disturbance has been alleviated. When the monitoring results show that the substrate temperature rise rate has decreased below the recovery threshold, for example, below 1.0°C / s, and remains stable for multiple consecutive sampling cycles, after meeting the preset confirmation time (e.g., 3 seconds), the external thermal disturbance is considered to have been eliminated. At this time, the microcontroller clears the environmental interference flag, exits the environmental shielding mode from the status register, and simultaneously restores the normal logic for warning and alarm detection, making the thermal runaway detection function effective again.

[0031] In one specific embodiment, the process of performing step S4 may specifically include the following steps: When the normal state is indicated, the ambient temperature compensation coefficient is calculated based on the difference between the sampled base temperature and the reference temperature. The ambient temperature compensation coefficient is then multiplied by the rated current value to obtain the first compensation current value. When the warning status is indicated, the junction temperature compensation coefficient is calculated based on the difference between the junction temperature difference and the warning threshold. The second compensation current value is obtained by multiplying the first compensation current value by the junction temperature compensation coefficient. When the alarm status is indicated, the second compensation current value is multiplied by the preset reduction ratio to obtain the alarm current limit value.

[0032] Specifically, when the system is in a normal state, it indicates that the temperature difference between the junction temperature inside the LED chip and the substrate temperature is maintained within the normal heat transfer range, and the heat dissipation channel is not blocked or saturated. At this time, the main goal of the compensation strategy is to offset the impact of the external ambient temperature on the LED luminous flux, thereby maintaining stable light output. The currently collected substrate temperature sampling value is read, and the difference between the substrate temperature value and the reference temperature of 25°C is calculated. Based on the luminous efficacy characteristic that the luminous flux of the LED decreases by 0.5% for every 1°C increase in ambient temperature, the ambient temperature compensation coefficient is derived. The ambient temperature compensation coefficient decreases linearly with the increase of substrate temperature. Then, the microcontroller multiplies the ambient temperature compensation coefficient by the rated drive current of 350mA to obtain the first compensation current value, and makes the first compensation current change smoothly in different ambient temperature ranges. For example, when the substrate temperature rises to 45°C, the first compensation current value can naturally decrease from 350mA to 315mA, thereby effectively compensating for luminous efficacy loss. When the system is in a warning state, it indicates that the junction-to-case temperature difference has exceeded 48°C and is showing a continuous upward trend. This suggests that the internal heat accumulation of the chip is approaching the limit of the heat dissipation structure. Therefore, the drive current is reduced based on the ambient temperature compensation to actively suppress the thermal load. The microcontroller reads the latest junction-to-case temperature difference value and calculates the difference between it and the warning threshold. This difference is used as input to construct a junction temperature compensation coefficient, which decreases linearly as the junction-to-case temperature difference rises from 45°C to 55°C. For example, it decreases from 1 to 0.6 within this range, resulting in a current reduction of up to 40%. The junction temperature compensation coefficient is multiplied by the first compensation current value to obtain a second compensation current value. This allows the drive current to further decrease from the ambient compensation level in the warning state. For example, when the substrate temperature is 40°C and the junction-to-case temperature difference is 50°C, the second compensation current value is approximately 259mA, thereby reducing the rate of increase in PN junction temperature. When the system enters an alarm state, it indicates that the junction-to-case temperature difference has increased dramatically or the junction temperature itself has approached the absolute temperature limit of 100°C. At this time, the LED chip is in a high-risk zone for thermal runaway, and forced current limiting must be implemented immediately to prevent irreversible damage to the device. A preset reduction ratio is directly applied to the second compensation current value, for example, a hard reduction of 50%, causing the LED drive current to drop instantly to a lower level, such as only about 153mA in some typical scenarios. This quickly suppresses PN junction heating and forcibly reduces the thermal load, preventing the system from entering an uncontrollable region.

[0033] Before setting the warning status indicator, the process includes a step of predicting thermal runaway based on the junction temperature change trend: reading a preset number of historical junction temperature values ​​in the circular buffer, calculating the difference between junction temperature values ​​at adjacent times to obtain multiple junction temperature change rate data points, and arranging these data points in a time series; performing linear fitting on the multiple junction temperature change rate data points to obtain the junction temperature change acceleration value, and determining whether the junction temperature change acceleration value is greater than a preset acceleration threshold; if it is greater, it indicates that the junction temperature is in an accelerating upward state; performing trend extrapolation calculation based on the current junction temperature value, the current junction temperature change rate, and the junction temperature change acceleration value to predict the predicted junction temperature value after a preset prediction time, and determining whether the predicted junction temperature value exceeds the warning threshold; when the predicted junction temperature value exceeds the warning threshold and the junction temperature change acceleration value is greater than the preset acceleration threshold, setting a prediction warning indicator; during the effective period of the prediction warning indicator, reducing the ambient temperature compensation coefficient corresponding to the base temperature sampling value in advance, so that the drive current enters the pre-drop mode in advance to suppress the junction temperature from continuing to accelerate upward.

[0034] The warning threshold and alarm threshold are determined using a dynamic adaptive adjustment method, including the following steps: Within each working cycle of the LED bead, the junction temperature difference and junction temperature are collected and stored in a historical database according to a preset statistical cycle; the distribution characteristics of the junction temperature difference within a preset time window are statistically analyzed, and the mean and standard deviation of the junction temperature difference are calculated; a temperature difference distribution interval is constructed based on the mean and standard deviation of the junction temperature difference, and this interval is divided into a normal working interval, a transition interval, and a danger interval; the corresponding temperature difference boundary values ​​for each interval are calculated; dynamic warning thresholds and dynamic alarm thresholds are calculated based on the temperature difference boundary values ​​and a preset safety margin coefficient. The dynamic warning threshold is the product of the upper boundary value of the normal working interval and the preset safety margin coefficient, and the dynamic alarm threshold is the product of the upper boundary value of the transition interval and the preset safety margin coefficient; the temperature difference distribution characteristics in the historical database are re-statistically analyzed and the dynamic warning thresholds and dynamic alarm thresholds are updated every preset update cycle; when the LED working environment changes, the dynamic warning threshold and dynamic alarm threshold are adaptively adjusted to the optimal values ​​under the new working conditions.

[0035] Before calculating the compensation current value, the process includes a step of identifying the heat source type based on temperature fluctuation spectrum analysis: Reading a continuous preset number of base temperature sampling value sequences and junction temperature value sequences from a circular buffer; performing mean-reduction processing on the base temperature sampling value sequences and junction temperature value sequences to obtain base temperature fluctuation sequences and junction temperature fluctuation sequences, respectively; performing a fast Fourier transform on the base temperature fluctuation sequences to obtain base temperature spectrum data; calculating the energy proportion of the base temperature spectrum data in the low-frequency and high-frequency bands; when the energy proportion in the high-frequency band exceeds a preset high-frequency threshold, it is determined to be a rapid thermal shock characteristic of the environment; and analyzing the junction temperature fluctuation... The sequence is subjected to Fast Fourier Transform to obtain junction temperature spectrum data. The energy proportion of the junction temperature spectrum data in the low-frequency band is calculated. When the energy proportion in the low-frequency band exceeds the preset low-frequency threshold and the junction-shell temperature difference continues to increase, it is determined to be a chip self-heating accumulation feature. A differentiated compensation strategy is selected according to the heat source type identification result. When it is identified as an environmental rapid thermal shock feature, only environmental temperature compensation is performed and junction temperature compensation is shielded. When it is identified as a chip self-heating accumulation feature, both environmental temperature compensation and junction temperature compensation are performed. When it is identified as a mixed heat source feature, the calculation ratio of compensation current is allocated according to the weighting coefficients of the low-frequency energy proportion and the high-frequency energy proportion.

[0036] In one specific embodiment, the active heat dissipation method for LED beads further includes the following steps: Divide the alarm current limit value by the rated current value to obtain the target duty cycle, and determine whether the difference between the target duty cycle and the current duty cycle exceeds the duty cycle change threshold. When the difference exceeds the duty cycle change threshold, the current duty cycle is adjusted to the target duty cycle in multiple sampling periods according to the preset adjustment step size; Based on the adjusted target duty cycle and preset PWM frequency, the timer is configured to generate a pulse width modulation signal, and the pulse width modulation signal is output to the dimming port of the LED chip to output the drive current.

[0037] Specifically, the alarm current limit value is proportionally converted to the rated current value of 350mA, and the target duty cycle is obtained through division. This ensures that the PWM output current corresponds linearly to the alarm current limit value and that the duty cycle value falls within the effective range that the driver chip can resolve. The difference between the target duty cycle and the currently output duty cycle is checked to see if it exceeds the duty cycle change threshold (e.g., 5%). If the difference is small, the duty cycle can be directly adjusted to the target value to quickly respond to thermal protection requirements. However, if the difference exceeds the change threshold, to avoid sudden changes in LED light output, a phased, gradual adjustment is performed according to a preset adjustment step size. During the gradual adjustment process, the target duty cycle is gradually approached within each 100ms sampling period using a fixed step size (e.g., 5% change per cycle). This ensures that the duty cycle change has a smooth transition characteristic of gradual rise and fall, avoiding current spikes or current steps in the driver stage when the duty cycle changes significantly, and reducing secondary thermal disturbances inside the chip caused by a sudden drop in luminous flux. During the adjustment process, the difference between the current duty cycle and the target duty cycle is continuously monitored. Duty cycle alignment is completed when the difference gradually decreases to below a threshold, allowing the duty cycle to naturally transition to the target level within a limited number of sampling cycles. For example, when the duty cycle drops from 80% to 44%, it is adjusted sequentially in 5% increments over multiple sampling cycles to 75%, 70%, 65%, 60%, 55%, 50%, and 45% until the final target is reached, thus achieving smooth current limiting within approximately 400ms. After the duty cycle adjustment is complete, the microcontroller reconfigures the internal timer based on the adjusted final duty cycle and the preset PWM frequency (e.g., 1kHz). By calculating the CCR value in the comparison register, the high-level duration of the PWM waveform is made completely consistent with the target duty cycle. Subsequently, the PWM pulse width modulation signal is output to the dimming port of the LED driver chip through the timer output channel. The driver chip controls the actual output current of the internal constant current loop by linearly analyzing the PWM duty cycle, ensuring a linear physical correspondence between the PWM duty cycle and the LED drive current.

[0038] In one specific embodiment, the process of adjusting the current duty cycle to the target duty cycle in multiple sampling periods according to a preset adjustment step size when the difference exceeds the duty cycle change threshold can specifically include the following steps: Calculate the absolute value of the difference between the target duty cycle and the current duty cycle, and divide it by the preset adjustment step size to obtain the number of cycles that need to be adjusted; Within each sampling period, the adjustment direction is determined based on whether the target duty cycle is greater than or less than the current duty cycle, and the current duty cycle is incremented or decremented according to the preset adjustment step size; Determine whether the adjusted current duty cycle has reached the target duty cycle. If not, continue the adjustment operation in the next sampling period until the current duty cycle equals the target duty cycle.

[0039] Specifically, the absolute value of the difference between the target duty cycle and the current duty cycle is calculated to obtain the duty cycle difference that needs to be adjusted. This difference is then divided by a preset adjustment step size (e.g., 5%) to calculate the required number of adjustment cycles. This clarifies the total number of sampling cycles that the duty cycle adjustment should span, ensuring the entire duty cycle adjustment process executes at a fixed rhythm. The system enters a gradual duty cycle adjustment mode, and in each 100ms sampling cycle, the adjustment direction is determined based on the relationship between the target and current duty cycles. When the target duty cycle is greater than the current duty cycle, an increment operation is performed to increase the drive current; conversely, when the target duty cycle is less than the current duty cycle, a decrement operation is performed to limit the drive current. After determining the correct direction, the microcontroller directly applies the preset adjustment step size to the current duty cycle, causing it to increase or decrease proportionally, thus making the PWM duty cycle exhibit a linear and smooth dynamic change trend. With each sampling period completing a duty cycle update, the new duty cycle value is used to determine whether it has reached or exceeded the target duty cycle threshold. If the difference between the two falls within the single-step adjustment range, the current duty cycle is directly locked as the target duty cycle, thus avoiding duty cycle fluctuations caused by overshooting of the last adjustment step. If the current duty cycle has not yet reached the target value in a certain period, the same adjustment process continues in the next sampling period, gradually approaching the target duty cycle in the correct direction until the two are completely consistent. This ensures that the duty cycle adjustment process is completed in a precise and linear manner, and the final state is stable and reliable.

[0040] In one specific embodiment, the active heat dissipation method for LED beads further includes the following steps: Determine whether the junction temperature is less than the junction temperature recovery threshold and whether the junction-shell temperature difference is less than the temperature difference recovery threshold. If both conditions are met, start the recovery confirmation timer. Verify whether the conditions are continuously met cycle by cycle within the recovery confirmation time. If any parameter exceeds the recovery threshold, reset the recovery confirmation timer. When the recovery confirmation timer reaches the recovery confirmation duration, the operating state segment to be entered is determined based on the current junction temperature value and the junction-shell temperature difference value, and the target operating segment current value of the corresponding operating state segment is calculated. The alarm current limit value is incremented by a fixed increment in each sampling period according to the preset current recovery rate. The rising rate of the junction temperature and the incremental change of the junction-shell temperature difference are monitored simultaneously. When the rising rate of the junction temperature exceeds the temperature rise rate threshold or the increment of the junction-shell temperature difference exceeds the temperature difference increment threshold, the increment is paused and the alarm current limit value is maintained.

[0041] Specifically, after entering the alarm state, the system continuously monitors whether the junction temperature is lower than the set junction temperature recovery threshold (e.g., 90℃) and whether the junction-to-shell temperature difference is lower than the temperature difference recovery threshold (e.g., 42℃). A recovery confirmation timer is started within the sampling period when both conditions are met simultaneously, allowing the recovery determination process to enter the time consistency verification phase. The system repeatedly checks whether the above two conditions remain true in each 100ms sampling period. If the threshold requirements are met in all sampling periods within the recovery confirmation duration (e.g., 5 seconds), the LED chip temperature is considered to have recovered to a safe range. If the junction temperature or junction-to-shell temperature difference exceeds the recovery threshold in any sampling period, the recovery confirmation timer is immediately reset, causing the system to re-enter the observation period, thereby avoiding erroneous recovery caused by a brief temperature drop. Once the recovery confirmation timer reaches the set confirmation duration, the thermal state recovery is deemed complete. Based on the position of the current junction temperature and junction-to-shell temperature difference in the numerical distribution, the appropriate operating state segment is determined. For example, if the junction temperature is below 85°C and the junction-to-shell temperature difference is below 45°C, the system returns to the normal operating segment. Conversely, if the junction temperature has decreased but remains between 85°C and 95°C, or the junction-to-shell temperature difference remains between 45°C and 50°C, the system returns to the warning operating segment to ensure the safety of the recovery process. After determining the target operating segment, the target operating segment current value is recalculated based on the temperature compensation logic of the target operating segment. After determining the target operating segment current value, a fixed increment is generated periodically according to a preset current recovery rate (e.g., increasing by 5% of the rated current per second). In each sampling cycle, the alarm current limit value is increased by a fixed increment, allowing the LED drive current to recover in a controlled and gradual manner. Meanwhile, to prevent the risk of secondary temperature rise caused by excessively rapid current increase during the recovery process, the real-time rise rate of the junction temperature and the incremental change of the junction-to-shell temperature difference are monitored simultaneously. When the rise rate of the junction temperature exceeds the temperature rise rate threshold (e.g., >2℃ / s) or the increment of the junction-to-shell temperature difference exceeds the temperature difference increment threshold (e.g., >3℃), the current increase action is immediately paused and the current value is kept unchanged, so that the chip thermal state can be stabilized again before the recovery process continues.

[0042] The alarm current limit value is incremented by a fixed increment in each sampling period according to a preset current recovery rate. This is achieved through adaptive adjustment of the recovery rate, including the following steps: initializing the current recovery rate to a baseline recovery rate value, initializing the historical temperature gradient accumulation variable and the recovery rate adjustment accumulation variable to preset initial values, and setting the recovery process counter to zero; calculating the difference between the current junction temperature value and the junction temperature value of the previous period in each sampling period to obtain the junction temperature change, dividing the junction temperature change by the sampling period duration to obtain the current junction temperature gradient value, multiplying the square of the current junction temperature gradient value by the gradient decay coefficient, and accumulating it to the historical temperature gradient accumulation variable; calculating the square root of the historical temperature gradient accumulation variable to obtain the root mean square value of the temperature gradient, and determining whether the root mean square value of the temperature gradient is... If the temperature is less than the steady gradient threshold, it indicates that the temperature is in a steady rising state. The product of the calculation rate increase coefficient and the baseline recovery rate value is used to obtain the accelerated recovery rate value. If the temperature is greater than the preset fluctuation gradient threshold, it indicates that the temperature is fluctuating significantly. The product of the calculation rate decrease coefficient and the baseline recovery rate value is used to obtain the decelerated recovery rate value. The current increment for this cycle is calculated based on the currently used recovery rate value. The current increment is accumulated to the current alarm current limit value to obtain the updated compensation current value. At the same time, the square of the current increment is accumulated to the recovery rate adjustment cumulative variable. The historical trajectory of current recovery is tracked through the recovery rate adjustment cumulative variable. When the root mean square value of the temperature gradient for several consecutive cycles is less than the steady gradient threshold, the recovery rate is gradually increased until the upper limit of the recovery rate is reached.

[0043] The active heat dissipation method for LED beads in the embodiments of the present invention has been described above. The active heat dissipation system for LED beads in the embodiments of the present invention will be described below. Please refer to [link / reference]. Figure 2 One embodiment of the active heat dissipation system for LED beads in this invention includes: The acquisition module 201 is used to inject micro-current pulses into the PN junction of the LED chip through a constant current source, acquire the forward voltage drop sampling value, and acquire the substrate temperature sampling value through an NTC thermistor. The first calculation module 202 is used to calculate the junction temperature value based on the forward pressure drop sampling value, and to calculate the junction-shell temperature difference value and the substrate temperature rise rate value based on the junction temperature value and the substrate temperature sampling value. Setting module 203 is used to set an alarm status indicator when the temperature difference between the junction and the shell exceeds the warning threshold and the duration meets the preset duration, set an alarm status indicator when the temperature difference between the junction and the shell exceeds the alarm threshold, and shield thermal runaway detection when the base temperature rise rate exceeds the environmental thermal shock threshold and the temperature difference between the junction and the shell is less than the environmental exclusion threshold. The second calculation module 204 is used to calculate the first compensation current value when the status is normal, calculate the second compensation current value when the status is warning, and calculate the alarm current limit value when the status is alarm.

[0044] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0045] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0046] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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. Such 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 active heat dissipation of LED beads, characterized in that, include: A micro-current pulse is injected into the PN junction of the LED chip by a constant current source, the forward voltage drop is sampled, and the substrate temperature is sampled by an NTC thermistor. The junction temperature is calculated based on the positive pressure drop sampling value, and the junction-shell temperature difference and the substrate temperature rise rate are calculated based on the junction temperature and the substrate temperature sampling value. When the temperature difference between the junction and the shell exceeds the warning threshold and the duration meets the preset duration, a warning status indicator is set; when the temperature difference between the junction and the shell exceeds the alarm threshold, an alarm status indicator is set; when the base temperature rise rate exceeds the environmental thermal shock threshold and the temperature difference between the junction and the shell is less than the environmental exclusion threshold, thermal runaway detection is shielded. When the status is normal, calculate the first compensation current value; when the status is warning, calculate the second compensation current value; and when the status is alarm, calculate the alarm current limit value.

2. The active heat dissipation method for LED beads according to claim 1, characterized in that, The process of injecting micro-current pulses into the PN junction of the LED chip using a constant current source, acquiring forward voltage drop samples, and acquiring substrate temperature samples using an NTC thermistor includes: After the main drive current of the LED is turned off, a micro-current pulse is injected into the PN junction of the LED chip, and the forward voltage drop sampling value of the PN junction is collected during the micro-current pulse. An NTC thermistor is connected to a reference resistor to form a voltage divider circuit. The voltage divider circuit outputs the voltage value at the package substrate, and the substrate temperature sampling value is calculated based on the voltage divider value.

3. The active heat dissipation method for LED beads according to claim 1, characterized in that, The step of calculating the junction temperature based on the positive voltage drop sampling value, and calculating the junction-shell temperature difference and the substrate temperature rise rate based on the junction temperature and the substrate temperature sampling value, includes: The positive voltage drop sampling value is substituted into the linear temperature relationship to perform junction temperature conversion calculation, and the junction temperature value is obtained; The difference between the junction temperature value and the sampled substrate temperature value is calculated to obtain the junction-shell temperature difference value. Read the base temperature sample value at time i and time in, which are within a preset time interval n. Calculate the difference between the base temperature sample value at time i and time in and divide it by the preset time interval n to obtain the base temperature rise rate value.

4. The active heat dissipation method for LED beads according to claim 1, characterized in that, The method of setting a warning status indicator when the junction temperature difference exceeds a warning threshold and the duration meets a preset duration, setting an alarm status indicator when the junction temperature difference exceeds an alarm threshold, and shielding thermal runaway detection when the substrate temperature rise rate exceeds an environmental thermal shock threshold and the junction temperature difference is less than an environmental exclusion threshold includes: When the temperature difference between the crust and the junction exceeds the warning threshold, the current timestamp is recorded and the warning timer is started. Within the preset monitoring time, it is continuously judged whether the temperature difference between the crust and the junction exceeds the warning threshold and whether the temperature increment exceeds the preset increment threshold. When the conditions are met, the warning status indicator is set. Determine whether the junction temperature difference exceeds the alarm threshold or whether the junction temperature exceeds the absolute temperature limit. If either condition is met, immediately set an alarm status indicator. When the substrate temperature rise rate exceeds the environmental thermal shock threshold and the junction temperature difference is less than the environmental exclusion threshold, an environmental interference flag is set and thermal runaway detection is blocked. When the substrate temperature rise rate drops below the recovery threshold and is continuously confirmed for a preset duration, the environmental interference flag is cleared.

5. The active heat dissipation method for LED beads according to claim 4, characterized in that, The step of setting an environmental interference flag and shielding thermal runaway detection when the substrate temperature rise rate exceeds the environmental thermal shock threshold and the junction-shell temperature difference is less than the environmental exclusion threshold, and clearing the environmental interference flag after the substrate temperature rise rate drops below the recovery threshold and continues for a preset confirmation period, includes: Determine whether the substrate temperature rise rate exceeds the environmental thermal shock threshold and whether the junction temperature difference is less than the environmental exclusion threshold. If both conditions are met, set an environmental interference flag. During the effective period of the environmental interference indicator, the setting logic of the early warning status indicator and the alarm status indicator is blocked, and the current working state remains unchanged; The system continuously monitors the substrate temperature rise rate and determines whether it has decreased below the recovery threshold. Once the preset confirmation time is met, the environmental interference flag is cleared and the thermal runaway detection logic is restored.

6. The active heat dissipation method for LED beads according to claim 5, characterized in that, When the status is normal, the first compensation current value is calculated. When the status is a warning, calculate the second compensation current value; when the status is an alarm, calculate the alarm current limit value, including: When the normal state is indicated, the ambient temperature compensation coefficient is calculated based on the difference between the sampled base temperature and the reference temperature, and the ambient temperature compensation coefficient is multiplied by the rated current value to obtain the first compensation current value. When the warning status is indicated, the junction temperature compensation coefficient is calculated based on the difference between the junction temperature difference value and the warning threshold. The first compensation current value is multiplied by the junction temperature compensation coefficient to obtain the second compensation current value. When the alarm status is indicated, the second compensation current value is multiplied by the preset reduction ratio to obtain the alarm current limit value.

7. The active heat dissipation method for LED beads according to claim 6, characterized in that, The active heat dissipation method for LED beads also includes: Divide the alarm current limit value by the rated current value to obtain the target duty cycle, and determine whether the difference between the target duty cycle and the current duty cycle exceeds the duty cycle change threshold. When the difference exceeds the duty cycle change threshold, the current duty cycle is adjusted to the target duty cycle in multiple sampling periods according to a preset adjustment step size; Based on the adjusted target duty cycle and preset PWM frequency, the timer is configured to generate a pulse width modulation signal, and the pulse width modulation signal is output to the dimming port of the LED chip to output the drive current.

8. The active heat dissipation method for LED beads according to claim 7, characterized in that, When the difference exceeds the duty cycle change threshold, adjusting the current duty cycle to the target duty cycle in multiple sampling periods according to a preset adjustment step size includes: Calculate the absolute value of the difference between the target duty cycle and the current duty cycle, and divide it by the preset adjustment step size to obtain the number of cycles that need to be adjusted; Within each sampling period, the adjustment direction is determined based on whether the target duty cycle is greater than or less than the current duty cycle, and the current duty cycle is incremented or decremented according to the preset adjustment step size; Determine whether the adjusted current duty cycle has reached the target duty cycle. If not, continue the adjustment operation in the next sampling period until the current duty cycle equals the target duty cycle.

9. The active heat dissipation method for LED beads according to claim 7, characterized in that, The active heat dissipation method for LED beads also includes: Determine whether the junction temperature value is less than the junction temperature recovery threshold and whether the junction-shell temperature difference value is less than the temperature difference recovery threshold. If both conditions are met, start the recovery confirmation timer. Verify whether the condition is continuously met cycle by cycle within the recovery confirmation time. If any parameter exceeds the recovery threshold, reset the recovery confirmation timer. When the recovery confirmation timer reaches the recovery confirmation duration, the operating state segment to be entered is determined based on the current range of the junction temperature value and the junction-shell temperature difference value, and the target operating segment current value of the corresponding operating state segment is calculated. The alarm current limit value is incremented by a fixed increment in each sampling period according to a preset current recovery rate. The rate of increase of the junction temperature value and the incremental change of the junction-shell temperature difference value are monitored simultaneously. When the rate of increase of the junction temperature value exceeds the temperature rise rate threshold or the increment of the junction-shell temperature difference value exceeds the temperature difference increment threshold, the increment is paused and the alarm current limit value is maintained.

10. An active heat dissipation system for LED beads, characterized in that, The method for performing active heat dissipation of LED beads as described in any one of claims 1-9 includes: The acquisition module is used to inject micro-current pulses into the PN junction of the LED chip through a constant current source, acquire the forward voltage drop sampling value, and acquire the substrate temperature sampling value through an NTC thermistor. The first calculation module is used to calculate the junction temperature value based on the positive pressure drop sampling value, and to calculate the junction-shell temperature difference value and the substrate temperature rise rate value based on the junction temperature value and the substrate temperature sampling value. The setting module is used to set an early warning status indicator when the temperature difference between the junction and the shell exceeds the early warning threshold and the duration meets the preset duration, set an alarm status indicator when the temperature difference between the junction and the shell exceeds the alarm threshold, and shield thermal runaway detection when the base temperature rise rate exceeds the environmental thermal shock threshold and the temperature difference between the junction and the shell is less than the environmental exclusion threshold. The second calculation module is used to calculate the first compensation current value when the status is normal, to calculate the second compensation current value when the status is warning, and to calculate the alarm current limit value when the status is alarm.

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