Energy-saving light-emitting regulation and control method for LED light source

Abstract

The invention relates to the technical field of dimming, in particular to an LED light source energy-saving light-emitting regulation and control method which comprises the following steps that a target illumination value is obtained, a reference square wave pulse sequence is generated according to the target illumination value, and the pulse width of the reference square wave pulse sequence corresponds to a basic light-emitting time period; the resonance excitation pulse is used for exciting the driving loop to generate energy back vibration, so that the loop current continuously keeps vibration after the turn-off moment and flows through the LED chip for the second time; and enabling the average additional luminous flux generated by the energy back vibration and the luminous flux of the basic light-emitting time period to be superposed to reach the target illumination value, recording a direct current power value input at the moment, and taking the direct current power value as an energy-saving reference of the next regulation and control period. According to the invention, a closed-loop regulation mechanism directly carries out quantitative modeling and feedback control on the LC oscillation physical process, so that the coupling efficiency of resonance back vibration energy is always maintained in an optimal interval.

Description

Technical Field

[0001] This invention relates to the field of dimming technology, and in particular to an energy-saving luminous control method for LED light sources. Background Technology

[0002] With the widespread application of LED light sources in indoor lighting, industrial lighting, and intelligent lighting systems, pulse width modulation (PWM)-based dimming has become the mainstream control method. Existing technologies typically adjust the average on-time of the LED by changing the duty cycle of the PWM signal, thereby controlling the light output intensity. In this control method, the LED is on and emits light during high-level periods and off and does not emit light during low-level periods; brightness adjustment is achieved by changing the on-time ratio. However, traditional PWM dimming primarily focuses on controlling the on-time, neglecting the electromagnetic transient energy characteristics inherent in the drive circuit at the off-time. In actual circuits, the LED drive circuit inevitably contains parasitic inductance, device pin inductance, and the equivalent junction capacitance of the LED chip. When the PWM signal switches from high to low, the current in the circuit does not instantly become zero, but a brief natural oscillation or energy return process occurs between the parasitic inductance and the equivalent junction capacitance. This transient energy usually disappears in the form of heat loss or damping dissipation and is not effectively utilized.

[0003] Most existing dimming technologies treat the off-state phase as an ineffective period, lacking active control and energy reuse mechanisms for the transient oscillation process during off-state. This results in decreased energy utilization efficiency and limited overall system luminous efficacy in low duty cycle or frequent dimming scenarios. Furthermore, traditional dimming systems typically perform open-loop or simple closed-loop control based solely on target illuminance or preset brightness values, lacking real-time monitoring and adaptive adjustment capabilities for oscillation attenuation characteristics. When ambient temperature changes, device parameters drift, or LEDs age, dimming accuracy and energy efficiency stability are difficult to guarantee.

[0004] In summary, existing LED dimming technologies have the following shortcomings: The transient oscillation energy during the turn-off phase of the drive circuit was not actively utilized, and the turn-off energy was dissipated without contributing to effective light emission. The lack of a quantitative feedback control mechanism based on oscillation decay characteristics makes it impossible to achieve adaptive optimization of resonant energy coupling. Summary of the Invention

[0005] This invention provides an energy-saving luminous emission control method for LED light sources. Under the premise of ensuring that the illuminance meets the comfort requirements, the method actively utilizes the driving circuit to shut off transient energy and achieves continuous energy-saving optimization through closed-loop feedback and energy efficiency memory mechanism, thereby improving the overall energy utilization efficiency and system stability.

[0006] An energy-saving luminous emission control method for LED light sources includes the following steps: S1, Obtain the target illuminance value, and generate a reference square wave pulse sequence based on the target illuminance value, wherein the pulse width of the reference square wave pulse sequence corresponds to the basic luminous period; S2, detect the inherent resonant frequency of the LED driving circuit, and generate a resonant excitation pulse that matches the inherent resonant frequency after each turn-off moment of the reference square wave pulse sequence according to the inherent resonant frequency. The resonant excitation pulse is used to excite the driving circuit to generate energy reverberation, so that the circuit current continues to oscillate after the turn-off moment and flows through the LED chip again. S3, monitor the decay rate of the energy reverberation, adjust the pulse parameters of the resonant excitation pulse in the next cycle according to the decay rate, so that the average additional luminous flux generated by the energy reverberation is superimposed with the luminous flux of the basic luminous period to reach the target illuminance value, and record the DC power value input at this time, and use the DC power value as the energy saving benchmark for the next control cycle.

[0007] Optionally, obtaining the target illuminance value includes: collecting the basic illuminance value of the current environment and the location information of the personnel activity area; comparing the basic illuminance value with a preset comfortable illuminance range; when the basic illuminance value is lower than the lower limit of the comfortable illuminance range, calculating the required supplementary illuminance difference, and using the illuminance difference as the target illuminance value.

[0008] Optionally, the theoretical duty cycle of the reference square wave pulse sequence is determined based on the ratio of the target illuminance value to the rated full illuminance; the theoretical duty cycle is input to a pulse width modulation generator to output the reference square wave pulse sequence with a constant frequency and a pulse width corresponding to the theoretical duty cycle, wherein the high-level period of the reference square wave pulse sequence is the basic luminous period, and the length of the basic luminous period is positively correlated with the theoretical duty cycle.

[0009] Optionally, when the LED light source is in a non-light-emitting intermittent period, a low-voltage detection signal with linear frequency scanning is injected into the driving circuit, and the voltage response amplitude at both ends of the driving circuit is collected in real time. The frequency of the detection signal corresponding to the peak value of the voltage response amplitude is determined as the current inherent resonant frequency f0 of the driving circuit.

[0010] Optionally, based on the current inherent resonant frequency f0, the pulse width tw of the resonant excitation pulse is calculated, such that the pulse width tw satisfies the relationship tw = 1 / (4f0), so that the excitation energy of the resonant excitation pulse is maximized and coupled to the LC resonant cavity of the driving circuit.

[0011] Optionally, at each turn-off moment of the reference square wave pulse sequence, the falling edge zero-crossing point of the current in the drive circuit is monitored, and a single pulse generator is triggered when the falling edge zero-crossing point is reached. The single pulse generator outputs a resonant excitation pulse with the pulse width tw and a voltage amplitude lower than the forward conduction voltage drop of the LED light source.

[0012] Optionally, the resonant excitation pulse is applied to the control terminal of the switch in the drive circuit, causing the switch to briefly turn on again after the turn-off time, thereby exciting the energy reverberation between the parasitic inductance and equivalent junction capacitance of the drive circuit. The alternating current generated by the energy reverberation causes the charge in the circuit to continue to flow back and forth through the LED chip after the turn-off time and excite secondary light emission.

[0013] Optionally, during the energy reverberation period after the resonant excitation pulse injection, the oscillation current waveform flowing through the LED chip is acquired at a sampling rate higher than the inherent resonant frequency. The peak current of two adjacent oscillation cycles in the oscillation current waveform is extracted, and the energy reverberation decay rate of the current control cycle is calculated based on the peak current of the two adjacent oscillation cycles. .

[0014] Optionally, the pulse parameters include phase and amplitude, and adjusting the pulse parameters includes adjusting the attenuation rate. With the preset target decay rate Comparison: when When the resonant excitation pulse is generated in the next control cycle, its phase is shifted forward by a preset phase compensation amount, and its amplitude is increased by a preset amplitude compensation amount. when When the resonant excitation pulse is generated in the next control cycle, its phase is shifted backward by the phase compensation amount, and its amplitude is reduced by the amplitude compensation amount.

[0015] Optionally, the basic luminous flux during the basic emission period is calculated based on the pulse width of the reference square wave pulse sequence, and the additional luminous flux contributed by energy reverberation is calculated based on the effective value integration of the oscillating current waveform. The basic luminous flux and the additional luminous flux are superimposed to obtain the total luminous flux, and it is determined whether the deviation between the total luminous flux and the target luminous flux corresponding to the target illuminance value is within the preset tolerance range. If the deviation exceeds the tolerance range, the pulse parameter adjustment is repeated for iterative optimization. Energy-saving benchmark recording sub-step: When the total luminous flux reaches the target luminous flux within the preset tolerance range, the input DC power of the drive circuit at this time is collected synchronously, and the input DC power is stored as the energy-saving benchmark power under the current lighting scenario. In step S1 of the next control cycle, the energy-saving benchmark power is used as a constraint condition to participate in the correction calculation of the target illuminance value.

[0016] The beneficial effects of this invention are: This invention achieves differential compensation dimming control by real-time detection of ambient ambient illuminance and using only the illuminance difference as the target illuminance output for the LED. This allows the LED to function solely as supplementary lighting, avoiding the excessive luminescence and energy waste caused by traditional fixed target illuminance output. Furthermore, this invention does not rely solely on adjusting the duty cycle of a reference square wave pulse sequence. Instead, it actively excites the LC resonant cavity formed by parasitic inductance and equivalent junction capacitance by injecting a resonant excitation pulse matching the inherent resonant frequency of the drive circuit after the turn-off moment. This converts the energy dissipated during turn-off into a controllable oscillating current that flows through the LED chip, generating additional light emission. This breaks through the traditional PWM dimming approach of controlling average light output solely through conduction time, transforming the energy during the turn-off phase into usable light emission contribution, forming a dual-source superposition model of basic luminous flux plus reverberating additional luminous flux. This not only reduces the DC input power required during the basic light emission period but also improves the light output efficiency per unit energy.

[0017] This invention extracts the peak current between two adjacent oscillation cycles by high-frequency sampling of the oscillating current waveform and calculates the energy return decay rate. This decay rate is used as a physical quantity characterizing the energy loss of the circuit and is introduced into the control system as a feedback indicator. By comparing the current decay rate with a preset target decay rate and coordinating the phase and amplitude of the resonant excitation pulse in two dimensions, the excitation timing and energy injection amount are always kept in an optimal matching state. This closed-loop adjustment mechanism based on damping characteristics differs from traditional dimming systems that simply adjust based on current or brightness errors. Instead, it directly performs quantitative modeling and feedback control of the LC oscillation physical process, ensuring that the coupling efficiency of the resonant return energy is always maintained within the optimal range. This mechanism possesses adaptive, self-convergent, and disturbance-resistant capabilities, automatically compensating for parameter shifts caused by temperature drift, device aging, or environmental changes, thereby improving the long-term stability and energy efficiency of the system.

[0018] This invention verifies the deviation between the total luminous flux and the target luminous flux after superimposing the base luminous flux and the target luminous flux. When the deviation reaches a tolerance range, the corresponding input DC power is recorded as the energy-saving baseline power for the current scenario. This energy-saving baseline power is not a theoretical set value, but rather the minimum effective power obtained through closed-loop optimization during actual system operation, thus possessing real-world scenario adaptability. In subsequent adjustment cycles, this energy-saving baseline power participates in the correction calculation of the target illuminance value, enabling the system to prioritize maintaining or approaching the historical optimal energy consumption level while meeting visual comfort requirements. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the control method flow according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the closed-loop control of energy reverberation in an embodiment of the present invention. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. For some well-known technologies, those skilled in the art may also use other alternative methods to implement the invention. Moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0022] like Figures 1-2 As shown, an energy-saving luminous emission control method for LED light sources includes the following steps: S1, Obtain the target illuminance value, and generate a reference square wave pulse sequence based on the target illuminance value, wherein the pulse width of the reference square wave pulse sequence corresponds to the basic luminous period; Essentially, it's based on the principle of time modulation. It doesn't dim by changing the voltage, but by changing how long the LED is on. When an LED is on, it emits a fixed intensity of light. By shortening or lengthening the on-time, the average light output per unit time is changed; in other words, brightness control is equal to time-proportional control. Within one cycle, if the LED is on continuously (100% duty cycle), the average power is maximum. If it's on for only half the time (50% duty cycle), the average power is approximately halved; if it's on for only 10% of the time, the average power is even lower. Therefore, the duty cycle directly determines the average input power and average light output. The LED's illumination time is determined by controlling the duration of the PWM high-level signal. The longer the high-level duration, the longer the illumination time, and the higher the average brightness. Adjusting the average light output using time proportions is a time-modulation dimming mechanism.

[0023] S11, Collect the current ambient illuminance value. and location information of personnel activity areas This ensures that dimming is targeted at areas with people in the room, rather than blindly adding light to the entire space, thereby adjusting the base illuminance value of the current environment. With the preset comfortable illumination range Perform a comparison; when Calculate the required supplemental illuminance difference: ; and the difference in illuminance As the target illuminance value for LEDs ,Right now: . These are the lower and upper limits of the comfortable illumination range, respectively.

[0024] S12, Calculate the theoretical duty cycle: based on the target illuminance value... With rated full luminous intensity The ratio of the two values ​​is used to determine the theoretical duty cycle of the reference square wave pulse sequence. : ;in, The rated full-luminous illumination is the maximum illuminance that can be provided when the PWM duty cycle is 100% and the LED is always on.

[0025] S13, the theoretical duty cycle The input is fed to a pulse width modulation (PWM) generator with soft-start capability. The PWM generator features a fixed cycle length, a high-level signal lasting for a period within each cycle, and a low-level signal for the remaining time, repeating continuously to form a periodic square wave signal. In each cycle, when the signal is high, the LED is on and illuminated; when the signal is low, the LED is off. Therefore, the actual duration of the LED's illumination depends on the duration of the high-level signal within each cycle, which is determined by the theoretical duty cycle. The output is a constant-frequency reference square wave pulse sequence, represented as: ; Indicates at time At that time, the instantaneous output voltage value of the PWM control signal, when When the LED driver switch is turned on, the LED lights up; when... When the LED driver switch is off, the LED does not emit light. The voltage is a time-varying square wave function used to control the LED's on / off state, defining a rule for the voltage change of a periodic square wave signal within one cycle. This formula indicates that within each PWM cycle, the output voltage has only two states: high and low, and these states occur in segments over time. Specifically, starting from the beginning of a complete cycle, the output remains at a high level for the period from 0 to the duty cycle multiplied by the cycle length. After this high-level duration, the output becomes low until the end of the cycle, and then the process repeats from 0 in the next cycle. For PWM period, High-level voltage, Low-level voltage, This indicates the period during which the LED remains on (high level) within one PWM cycle, and the PWM operating frequency. This is the PWM operating frequency (constant).

[0026] The S13 part converts the required light into how long the LED is lit in each cycle. By fixing the frequency and changing the conduction time ratio, a reference square wave pulse sequence is formed.

[0027] S14 defines the basic emission period, the pulse width of the reference square wave pulse sequence, i.e., the high-level period: The basic light-emitting period refers to the duration of the high-level PWM signal, which is the actual time the LED emits light. Therefore, within one PWM cycle, the actual light-emitting time of the LED only occurs during the high-level period. Compared with theoretical duty cycle There is a positive correlation: When the theoretical duty cycle increases, the basic luminescence period is correspondingly prolonged.

[0028] S2, detect the inherent resonant frequency of the LED driving circuit, and generate a resonant excitation pulse that matches the inherent resonant frequency after each turn-off moment of the reference square wave pulse sequence according to the inherent resonant frequency. The resonant excitation pulse is used to excite the driving circuit to generate energy reverberation, so that the circuit current continues to oscillate after the turn-off moment and flows through the LED chip again. S21, Frequency Detection: The purpose is to find the true inherent resonant frequency of the driving circuit at this moment. This is because S2 requires a precisely matched excitation pulse to inject energy into the LC resonant cavity to form the maximum amplitude energy return. If the frequency is inaccurate, the energy coupling efficiency will decrease. Therefore, during the non-emitting intermittent period of the LED light source, a low-voltage detection signal with a linear frequency scan is injected into the driving circuit. The instantaneous frequency of the probe signal satisfies linear frequency sweep: ;in, The scan start frequency, For frequency scanning rate, This is the scan time variable.

[0029] During the scanning process, the voltage response amplitude across the drive circuit is acquired in real time. When the voltage response amplitude reaches its peak: Then the corresponding detection signal frequency The current inherent resonant frequency of the driving circuit is determined. In an LC circuit, when the external excitation frequency equals the inherent resonant frequency of the circuit, the inductive reactance and capacitive reactance are equal and cancel each other out, the circuit impedance is at its minimum (or maximum, depending on the topology), and energy is efficiently exchanged between the inductor and capacitor. As a result, the voltage or current response amplitude reaches its maximum, which is the resonance peak. Therefore, if a sudden increase in voltage response is found at a certain frequency during the scanning process, it means that this frequency is closest to the natural oscillation frequency of the circuit. Thus, the frequency corresponding to the peak value of the voltage response is the current inherent resonant frequency.

[0030] in, This is a low-voltage detection signal. To detect the instantaneous frequency of the signal, For the drive circuit at frequency Voltage response amplitude under the condition, The current inherent resonant frequency is defined as the low-level period of the reference square wave pulse sequence during the non-light-emitting interval. At the high level, the LED is conducting, a large current exists in the circuit, and the inductor, capacitor, and charge are all in a controlled operating state, resulting in very strong voltage and current signals. If frequency detection is performed at this time, the strong signal will drown out the weak detection signal. Simultaneously, the operating current will change the instantaneous equivalent parameters of the circuit. Therefore, during the low-level period, the LED is off, the main current in the circuit is essentially zero, and the circuit is in a free decay or static state. Detecting the resonant frequency at this time is the cleanest and most accurate.

[0031] The overall frequency detection logic of S21 can be summarized as follows: when the LED is not emitting light, a low-voltage, continuously increasing detection signal is injected into the circuit, the circuit voltage response is observed, the frequency with the largest response is found, and it is determined as the current inherent resonant frequency.

[0032] S22, Calculate pulse parameters: S21 yields the current natural resonant frequency of the driving circuit, which is the frequency of the circuit's natural oscillation. It's also necessary to determine the optimal pulse length for injection. The key is to ensure the injected energy matches the circuit's natural oscillation rhythm, thereby generating the maximum oscillation amplitude. Therefore, based on the current natural resonant frequency... Calculate the pulse width of the resonant excitation pulse. Given that the resonant period of the circuit is 1 / f0, a complete period contains 360°, and a quarter period corresponds to 90°, when a pulse with a duration equal to a quarter period is applied, it is equivalent to providing a 90° phase energy boost at the very beginning of the oscillation, at which point the energy transfer efficiency is highest. Therefore, the pulse width... satisfy: ;in, Let be the pulse width of the resonant excitation pulse. This formula makes the width of the resonant excitation pulse equal to the resonant period. One-quarter of which: ;Right now: The pulse width corresponds to the 90° phase excitation duration of the LC resonant cavity, so as to maximize the excitation energy of the resonant excitation pulse coupled to the LC resonant cavity of the driving circuit.

[0033] S23, Pulse Generation and Injection: At the correct moment, pulse injection is performed into the drive circuit, converting the energy that would otherwise disappear after shutdown into controllable oscillation, generating secondary light emission. Specifically, at each shutdown moment of the reference square wave pulse sequence, the current in the drive circuit is monitored in real time. The falling edge crosses zero. When the switch is closed, the current starts to decrease from its original positive value. Since the inductor cannot make the current disappear instantaneously, the current will gradually decay and eventually decrease to zero. The moment when the current changes from a positive value to zero is the falling edge crossing zero, which satisfies: ;in, This is the moment when the falling edge of the current crosses zero. When the falling edge reaches its zero-crossing point, the single-pulse generator is triggered, outputting a resonant excitation pulse. It satisfies: the pulse width is equal to and ;in, The peak voltage of the resonant excitation pulse. This represents the forward voltage drop of the LED light source. The turn-off moment refers to the instant when the reference square wave pulse sequence changes from a high level to a low level, that is, when the PWM high level ends, the switching transistor turns off, and the LED's dominant current begins to decrease. This instant is the turn-off moment.

[0034] The single-pulse generator has a fixed-width pulse trigger module, and its working process is as follows: Received zero-crossing trigger signal; Immediately output a control pulse of fixed width; The pulse duration is equal to the previously calculated tw; The pulse amplitude is limited to below the LED forward voltage; This pulse does not directly power the LED, but rather acts on the control terminal of the switching transistor, causing the switching transistor to briefly turn on again after being turned off.

[0035] A resonant excitation pulse is applied to the control terminal of the switch in the drive circuit, causing the switch to briefly turn on again after the turn-off moment. In actual circuits, there are inductances in wires, device pins, and PCB traces, collectively referred to as parasitic inductances. Additionally, the LED chip itself has a PN junction capacitance, which is the equivalent junction capacitance. When the switch briefly turns on again, the inductor Lp and capacitor Cj form a natural oscillating system. Therefore, during the period when the switch turns on again, the parasitic inductance in the drive circuit... With equivalent junction capacitance The inherent resonant frequency of an LC resonant cavity satisfies: ;in, For the parasitic inductance of the drive circuit, The equivalent junction capacitance of the LED is defined as follows: A resonant excitation pulse injects energy into the LC resonant cavity, creating energy reverberation between the parasitic inductance and the equivalent junction capacitance. The alternating current generated by this energy reverberation... The charge in the circuit continues to flow through the LED chip after the turn-off time, thereby exciting secondary light emission.

[0036] S3, monitor the decay rate of the energy reverberation, adjust the pulse parameters of the resonant excitation pulse in the next cycle according to the decay rate, so that the average additional luminous flux generated by the energy reverberation is superimposed with the luminous flux of the basic luminous period to reach the target illuminance value, and record the DC power value input at this time, and use the DC power value as the energy saving benchmark for the next control cycle. S31, Attenuation rate monitoring: The LC resonant structure has been successfully excited in S2, causing the circuit to generate energy reverberation and form an oscillating current. Due to the resistance loss of the circuit, the energy consumption of the LED chip to emit light, and the heat loss of the device, the peak value of the oscillating current will be smaller than the previous one in each oscillation cycle, so that the oscillation will not continue indefinitely and will gradually decay.

[0037] During the energy return period following the injection of the resonant excitation pulse, at a frequency higher than the current inherent resonant frequency. sampling rate Collect the waveform of the oscillating current flowing through the LED chip ,in: ; Indicates the oversampling factor, and , The current sampling frequency, This is the current inherent resonant frequency.

[0038] Extract the peak current between two adjacent oscillation cycles from the oscillating current waveform: First peak current ; Second peak current ; The energy reverberation decay rate of the current control cycle is calculated using the following formula. : ;in, This represents the waveform of the oscillating current during the energy reverberation period. This is the peak current of the first oscillation period. This is the peak current of the second oscillation cycle. The energy reverberation decay rate of the current control cycle. Sampling frequency, This is the current inherent resonant frequency.

[0039] The decay rate essentially reflects how much energy is lost in each cycle. If the decay is too fast, it indicates insufficient energy injection, phase mismatch, or excessive circuit loss. If the decay is slow, it indicates good energy maintenance, reasonable excitation matching, and high energy utilization efficiency. Therefore, the decay rate is the core indicator for evaluating the resonant excitation effect.

[0040] S32, Pulse Parameter Adjustment: Oscillation control has two key dimensions: injection timing (phase) and injection energy magnitude (amplitude). Adjusting only the amplitude may provide sufficient energy, but inaccurate phase will reduce coupling efficiency; adjusting only the phase may provide accurate timing, but insufficient energy. Therefore, the phase determines when to inject, and the amplitude determines how much energy to inject; this is a synergistic optimization structure. Under different pulse parameter conditions in the experimental environment, the luminous flux contribution and input power are measured, and then the unit power light output efficiency is calculated. The decay rate corresponding to the highest luminous efficiency and system stability is found, and this decay rate is set as the target decay rate. The decay rate Compared with the preset target decay rate Compare them.

[0041] Scenario 1: When This indicates that the resonant energy dissipates too quickly. When the resonant excitation pulse is generated in the next control cycle, its phase is shifted forward by a preset phase compensation amount. Set the resonant period to 5°~10°, and increase its amplitude by a preset amplitude compensation amount. Each time, increase or decrease by 2% to 5%.

[0042] Scenario 2: When This indicates that the resonant energy is maintained well. When the resonant excitation pulse is generated in the next control cycle, its phase is shifted backward by the phase compensation amount. and reduce its amplitude by the amplitude compensation amount. .

[0043] in, For the target decay rate, This is the phase compensation amount. This is the amplitude compensation amount. The phase offset is measured in degrees with the current resonance period as the reference unit.

[0044] S33, Luminous flux superposition and verification: S331, Basic Luminous Flux Calculation: This analyzes how much light the LED produces during the basic emission period of the PWM (Pulse Width Modulation). During the high-level period, the LED is on and emits light; during the low-level period, the LED does not emit light. Therefore, the actual time for the LED to produce basic luminous flux is limited to the basic emission period. Thus, based on the pulse width of the reference square wave pulse sequence... Calculate the basic luminous flux during the basic emission period: ;in, The LED photoelectric conversion efficiency coefficient. This represents the average driving current during the basic light-emitting period. The basic luminescence period.

[0045] Within its normal operating range, the luminous intensity of an LED is approximately proportional to its driving current; that is, the higher the current, the stronger the light emission. Within a basic emission period, the current is approximately stable, and the luminous efficiency remains essentially constant. Therefore, the average driving current multiplied by the emission time represents the light energy generated during that period. Multiplying this by an efficiency coefficient yields the luminous flux, essentially an energy mapping relationship. The basic emission portion represents the controllable main emission contribution, contrasting with the subsequent energy reverberation contribution. The average driving current within the basic emission period refers to the average current actually flowing through the LED during the PWM high-level period. This is obtained through real-time sampling. A sampling resistor is connected in series in the driving circuit, and the current waveform is sampled in real-time by an ADC. The sampled values ​​are averaged over the basic emission period to obtain the average driving current. Average current is used here instead of instantaneous current because there may be slight ripples in the current during PWM conduction. However, the relationship between luminous flux and current is integral, so using time-averaged current is more consistent with the physical luminous quantity.

[0046] The photoelectric conversion efficiency coefficient represents the amount of luminous flux generated per unit current per unit time. It is obtained through experimental calibration, as detailed below: 1) Install the LED light source to be calibrated in a standard test space, ensuring that the light output during the test comes only from this LED light source, and shield or keep the ambient light constant as much as possible. Arrange an illuminance meter / luminous flux acquisition device on the measurement plane corresponding to the personnel activity area; if an integrating sphere is available, use the integrating sphere to measure the luminous flux first; if not, use an illuminance meter to convert it into equivalent luminous flux under fixed geometric conditions, start the drive circuit, and put it into a controllable constant current output mode or a mode that can precisely control the PWM conduction current to ensure that the current setting during calibration is repeatable and stable.

[0047] 2) Select several current setting points covering the working range as a calibration point set. Take points evenly from low brightness to high brightness, including points close to the minimum stable current, near the rated working current, and multiple current points in the middle. Each current point should ensure that it will not trigger thermal protection or overcurrent limit and is within the normal working range of the LED.

[0048] 3) Perform steady-state data acquisition for each calibrated current point, including sequentially performing the following steps for each current setpoint: Set the drive circuit to this current point and enable soft start to allow the LED to smoothly enter the current point from low to high, avoiding transient fluctuations from affecting the measurement.

[0049] Wait for a preset stabilization time to allow the LED junction temperature and light output to stabilize. The stabilization criterion is that the change in illuminance / luminous flux from multiple consecutive samples is less than the upper limit.

[0050] During the stable phase, the average driving current and the corresponding light output measurement value during the basic emission period are collected simultaneously.

[0051] The average drive current-light output value at this current point is recorded as a calibration sample.

[0052] 4) Perform a consistency check on the collected samples. If the light output at a certain current point deviates significantly from the trend, for example, due to transient interference, sensor obstruction, or external light disturbance, then recollect the data at that current point or mark it as an anomaly and remove it. If the subsequent operating temperature range is wide, sampling can be repeated under different junction / ambient temperature conditions to form temperature-grouped samples, reserving a data foundation for temperature compensation.

[0053] 5) Establishing a current-light output mapping and obtaining the efficiency coefficient: Sort all valid samples by current magnitude, establish a mapping relationship between current and light output. Within the working range, if the samples show approximately linearity, use linear fitting to obtain the proportional relationship; this proportional coefficient can then be used as... Or as The baseline value. If the sample shows significant nonlinearity in the low current or high current region, piecewise linear fitting or low-order polynomial fitting is used to obtain a corrected model from current to light output; at this time, Defined as a baseline scaling factor plus a nonlinear correction term, it is used for basic luminous flux calculation.

[0054] 6) The obtained The parameter is written to the controller's non-volatile memory as a calibration parameter for the photoelectric conversion efficiency of the LED light source in the driving loop. During operation, when calculating the basic luminous flux, the controller reads this calibration parameter and combines it with the average driving current obtained from real-time sampling during the basic emission period to output an estimated value of the basic luminous flux. This value is then used for subsequent superposition with the energy reverberation additional luminous flux and closed-loop verification.

[0055] S332, Additional Luminous Flux Calculation: In S2, the resonant excitation pulse causes the drive circuit to generate energy reverberation. This reverberation is essentially an oscillating current that gradually decays over time. Although this oscillating current has a very short duration, it does flow through the LED chip. As long as current flows through the LED chip, light will be emitted. Therefore, this oscillating current also contributes a portion of the light output, which is the additional luminous flux. The luminous intensity of an LED within its normal operating range is approximately proportional to the current. Therefore, the luminous intensity at a given moment is approximately equal to the current flowing through the LED at that moment. Since the oscillating current changes over time, summing up the current over this period gives the total amount of light generated during that time. The physical meaning of integration is to accumulate the tiny light output generated at each instant and multiply it by the LED's photoelectric conversion efficiency coefficient to obtain the additional luminous flux. Therefore, the additional luminous flux calculated by integrating the effective value of the oscillating current waveform is expressed as: ;in, The end time of the resonant excitation pulse. To allow the oscillation to decay to a preset threshold time, This represents the waveform of the oscillating current. The oscillation will not continue indefinitely; it will gradually decay. When the amplitude of the oscillating current becomes small enough, further integration is not meaningful. Therefore, we set... When the peak value drops to 5% or 10% of the initial peak value, the oscillation is considered to have been largely exhausted.

[0056] S333, Total Luminous Flux Addition: Total luminous flux Target luminous flux corresponding to the target illuminance value Comparison: ;like Then repeat the pulse parameter adjustment sub-step for iterative optimization.

[0057] Theoretically, it is desirable for the total luminous flux to perfectly equal the target luminous flux. However, in practical engineering systems, there are unavoidable sources of error, including LED luminous efficacy fluctuations with temperature, quantization errors in current sampling, and noise in ADC sampling. Therefore, a certain parameter is set... ,in, Based on luminous flux, To increase luminous flux, Total luminous flux For target luminous flux, To preset the luminous flux tolerance range, it is usually set to 3% to 5% of the target luminous flux.

[0058] S34, Energy Saving Benchmark Record: When: When the current parameter combination is valid and stable, the input DC power of the drive circuit is synchronously collected. ;in, Indicates the input DC voltage. This indicates the input DC current.

[0059] Store the input DC power as the energy-saving baseline power for the current lighting scenario: ; and in S1 of the next control cycle, the energy-saving reference power will be... This constraint is used as a condition in the calculation of the target illuminance value correction. Specifically, when calculating the target illuminance value in the next control cycle, a constraint principle is added: While meeting the lower limit of comfortable illumination, priority should be given to selecting illuminance levels not exceeding [a certain value]. The power level, specifically the logic is as follows: Calculate the theoretical target illuminance value based on ambient illuminance; Predict the theoretical power required to achieve the target illuminance; If the predicted power is greater than Then the target illuminance value is fine-tuned so that the required power does not exceed Pref. If the predicted power is less than or equal to If so, the original target illuminance will be maintained.

[0060] Make This becomes an upper limit constraint on energy consumption.

[0061] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for energy-saving luminous emission control of an LED light source, characterized in that, Includes the following steps: S1, Obtain the target illuminance value, and generate a reference square wave pulse sequence based on the target illuminance value, wherein the pulse width of the reference square wave pulse sequence corresponds to the basic luminous period; S2, detect the inherent resonant frequency of the LED driving circuit, and generate a resonant excitation pulse that matches the inherent resonant frequency after each turn-off moment of the reference square wave pulse sequence according to the inherent resonant frequency. The resonant excitation pulse is used to excite the driving circuit to generate energy reverberation, so that the circuit current continues to oscillate after the turn-off moment and flows through the LED chip again. S3, monitor the decay rate of the energy reverberation, adjust the pulse parameters of the resonant excitation pulse in the next cycle according to the decay rate, so that the average additional luminous flux generated by the energy reverberation is superimposed with the luminous flux of the basic luminous period to reach the target illuminance value, and record the DC power value input at this time, and use the DC power value as the energy saving benchmark for the next control cycle.

2. The LED light source energy-saving luminous emission control method according to claim 1, characterized in that, The acquisition of the target illuminance value includes: collecting the basic illuminance value of the current environment and the location information of the personnel activity area; comparing the basic illuminance value with the preset comfortable illuminance range; when the basic illuminance value is lower than the lower limit of the comfortable illuminance range, calculating the required supplementary illuminance difference, and using the illuminance difference as the target illuminance value.

3. The LED light source energy-saving luminous emission control method according to claim 2, characterized in that, The theoretical duty cycle of the reference square wave pulse sequence is determined based on the ratio of the target illuminance value to the rated full illuminance. The theoretical duty cycle is input to a pulse width modulation generator, which outputs a reference square wave pulse sequence with a constant frequency and a pulse width corresponding to the theoretical duty cycle. The high-level period of the reference square wave pulse sequence is the basic light-emitting period, and the length of the basic light-emitting period is positively correlated with the theoretical duty cycle.

4. The LED light source energy-saving luminous emission control method according to claim 3, characterized in that, When the LED light source is in a non-light-emitting intermittent period, a low-voltage detection signal with linear frequency scanning is injected into the driving circuit, and the voltage response amplitude at both ends of the driving circuit is collected in real time. The frequency of the detection signal corresponding to the peak value of the voltage response amplitude is determined as the current inherent resonant frequency f0 of the driving circuit.

5. The LED light source energy-saving luminous emission control method according to claim 4, characterized in that, Based on the current inherent resonant frequency f0, calculate the pulse width tw of the resonant excitation pulse, and make the pulse width tw satisfy the relationship tw = 1 / (4f0) so that the excitation energy of the resonant excitation pulse is maximized and coupled to the LC resonant cavity of the driving circuit.

6. The LED light source energy-saving luminous emission control method according to claim 5, characterized in that, At each turn-off moment of the reference square wave pulse sequence, the falling edge zero-crossing point of the current in the drive circuit is monitored. When the falling edge zero-crossing point is reached, a single pulse generator is triggered. The single pulse generator outputs a resonant excitation pulse with the pulse width tw and a voltage amplitude lower than the forward conduction voltage drop of the LED light source.

7. The LED light source energy-saving luminous emission control method according to claim 6, characterized in that, The resonant excitation pulse is applied to the control terminal of the switch in the drive circuit, causing the switch to briefly turn on again after the turn-off time. This excites the energy reverberation between the parasitic inductance and equivalent junction capacitance of the drive circuit. The alternating current generated by this energy reverberation causes the charge in the circuit to continue to flow back and forth through the LED chip after the turn-off time, thus exciting secondary light emission.

8. The LED light source energy-saving luminous emission control method according to claim 1, characterized in that, During the energy reverberation period after the resonant excitation pulse injection, the oscillation current waveform flowing through the LED chip is acquired at a sampling rate higher than the inherent resonant frequency. The peak current of two adjacent oscillation cycles in the oscillation current waveform is extracted, and the energy reverberation decay rate of the current control cycle is calculated based on the peak current of the two adjacent oscillation cycles. .

9. The LED light source energy-saving luminous emission control method according to claim 8, characterized in that, The pulse parameters include phase and amplitude, and adjusting the pulse parameters includes adjusting the attenuation rate. With the preset target decay rate Comparison: when When the resonant excitation pulse is generated in the next control cycle, its phase is shifted forward by a preset phase compensation amount, and its amplitude is increased by a preset amplitude compensation amount. when When the resonant excitation pulse is generated in the next control cycle, its phase is shifted backward by the phase compensation amount, and its amplitude is reduced by the amplitude compensation amount.

10. The LED light source energy-saving luminous emission control method according to claim 9, characterized in that, The basic luminous flux during the basic emission period is calculated based on the pulse width of the reference square wave pulse sequence. The additional luminous flux contributed by energy reverberation is calculated based on the effective value integration of the oscillating current waveform. The basic luminous flux and the additional luminous flux are superimposed to obtain the total luminous flux. It is then determined whether the deviation between the total luminous flux and the target luminous flux corresponding to the target illuminance value is within the preset tolerance range. If the deviation exceeds the tolerance range, the pulse parameter adjustment is repeated for iterative optimization. Energy-saving benchmark recording sub-step: When the total luminous flux reaches the target luminous flux within the preset tolerance range, the input DC power of the drive circuit at this time is collected synchronously, and the input DC power is stored as the energy-saving benchmark power under the current lighting scenario. In step S1 of the next control cycle, the energy-saving benchmark power is used as a constraint condition to participate in the correction calculation of the target illuminance value.

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