An LED energy-saving street light system with adaptive ambient light effect and its illuminance adjustment method

Abstract

This invention discloses an adaptive ambient light effect LED energy-saving street light system and its illuminance adjustment method, belonging to the field of novel lighting control and green energy-saving technology. The system includes a light environment sensing module, a traffic flow monitoring module, an LED driver power supply, and an electroluminescent lighting module composed of several light-emitting diodes. The main control module is configured to execute active light effect decoupling logic. Specifically, while the electroluminescent lighting module maintains steady-state illumination, the driver power supply injects a micro-perturbation modulation signal imperceptible to the human eye into the output current, and simultaneously collects illuminance response data from the light environment sensing module. By calculating the ratio of the change in response data to the modulation signal, the road surface reflectivity coupling coefficient is obtained in real time. This allows for the precise removal of the reflected light component excited by the street light itself from the total illuminance value, decoupling the pure ambient background illuminance. This solves the problems of malfunction and energy waste caused by self-emission interference in traditional light-controlled street lights.

Description

Technical Field

[0001] This invention relates to the field of novel lighting control and green energy-saving technology, and in particular to an LED energy-saving street light system with adaptive ambient light effect and its illuminance adjustment method. Background Technology

[0002] With the rapid development of urban infrastructure construction, energy conservation and consumption reduction of urban road lighting systems have become a key issue in the field of green technology. Replacing traditional high-pressure sodium lamps with light-emitting diodes (LEDs) with high luminous efficiency has become an industry consensus.

[0003] However, in existing LED street light energy-saving control technologies, to achieve on-demand lighting, the system typically relies on photosensitive sensors installed on the lamps to detect ambient brightness and automatically adjust power. This passive detection suffers from a significant "self-excited interference" defect at the physical level: the light signal received by the sensor during operation is actually a superposition of ambient light and light emitted by the street light itself after reflection from the road surface. This mixed signal leads to "deadlock" and oscillation in the control logic: when the environment darkens and the street light is turned on, the sensor reading instantly increases due to the superposition of reflected light from the road surface, causing the system to misjudge that the environment has brightened and incorrectly reduce the output power, resulting in insufficient road illumination; conversely, when the system reduces the power, the sensor reading drops sharply, and the system again misjudges that the environment has darkened and suddenly increases the power.

[0004] This nonlinear light environment feedback mechanism not only causes repeated oscillations and flickering of lighting brightness, but also forces the system to set a large redundancy brightness margin in order to maintain stability, resulting in a large amount of ineffective power consumption.

[0005] Furthermore, existing control schemes struggle to cope with complex and ever-changing weather and road conditions. For instance, when rain or snow causes the road surface to form a water film or ice, the road surface reflectivity changes drastically. Traditional technologies cannot distinguish whether fluctuations in sensor values ​​originate from changes in ambient light or alterations in road surface reflectivity. This often leads to lights being mistakenly switched off during severe weather when illumination is most needed, or excessive output when high brightness is not required. This fails to meet the stringent requirements of modern green lighting for extreme energy efficiency and precise control. The industry urgently needs a technology that can utilize the high-frequency response characteristics of electroluminescent devices to decouple ambient light and self-emission in real time, thereby overcoming the energy-saving problems of existing LED streetlights. Summary of the Invention

[0006] The purpose of this invention is to provide an LED energy-saving street light system with adaptive ambient light effect and its illuminance adjustment method to solve the problems mentioned in the background art.

[0007] In a first aspect, an embodiment of the present invention provides an adaptive ambient light effect LED energy-saving street light system, comprising a light pole, a light environment sensing module, a traffic flow monitoring module, an LED driver power supply, an electroluminescent lighting module, and a main control module; the light environment sensing module, the traffic flow monitoring module, and the LED driver power supply are respectively communicatively connected to the main control module; the LED driver power supply is electrically connected to the electroluminescent lighting module; the electroluminescent lighting module includes a plurality of light-emitting diodes;

[0008] The main control module is configured to execute active light effect decoupling logic: when the electroluminescent lighting module maintains steady-state illumination, the LED driver power supply is controlled to inject a micro-perturbation modulation signal into the electroluminescent lighting module, causing the luminous flux output by the electroluminescent lighting module to fluctuate in a way that is imperceptible to the human eye;

[0009] The main control module synchronously collects the illuminance response data of the light environment sensing module during the fluctuation period, and uses digital signal processing algorithms to extract the AC component in the illuminance response data that is in the same frequency and phase as the micro-perturbation modulation signal.

[0010] The main control module calculates the road surface reflectivity coupling coefficient based on the ratio of the change of the AC component to the micro-perturbation modulation signal, and removes the reflected light component excited by the electroluminescent lighting module from the total illuminance value collected by the light environment sensing module based on the road surface reflectivity coupling coefficient to obtain pure ambient background illuminance, and generates a dimming command in combination with the data from the traffic flow monitoring module.

[0011] Optionally, the light environment sensing module is installed on the side of the lamp post facing the road surface and on the lower surface of the lamp. Its photosensitive field of view covers the lighting area formed by the electroluminescent lighting module on the road surface, and is used to collect the total illuminance value including natural light, vehicle headlight interference light and road surface reflected light.

[0012] The spectral response characteristics of the light environment sensing module are matched with those of the light-emitting diode, and it is equipped with an infrared cut-off filter to filter out environmental thermal radiation noise.

[0013] Optionally, the traffic flow monitoring module includes a microwave radar sensor or a thermal imaging sensor for collecting data on road vehicle speed and vehicle density without relying on visible light illumination.

[0014] Optionally, the LED driver power supply integrates a high-bandwidth constant current control circuit and a signal demodulation circuit.

[0015] The signal demodulation circuit is used to parse the dimming command and the micro-disturbance modulation signal sent by the main control module, and generate a reference voltage superimposed with an AC waveform.

[0016] The loop bandwidth of the constant current control circuit is higher than the frequency of the micro-perturbation modulation signal, and is used to adjust the current amplitude output to the electroluminescent lighting module according to the reference voltage, so that its light output waveform follows the command change without distortion.

[0017] Optionally, the micro-perturbation modulation signal is configured as a sinusoidal wave sequence with a frequency higher than the critical flicker fusion frequency of the human eye, and the amplitude of the luminous flux change caused by the micro-perturbation modulation signal is limited to the range of 0.5% to 3% of the current basic luminous flux to ensure visual comfort of the lighting.

[0018] Optionally, the main control module internally stores road surface condition determination thresholds;

[0019] The main control module is configured to compare the calculated road surface reflectivity coupling coefficient with the road surface condition determination threshold. When the road surface reflectivity coupling coefficient is lower than the road surface condition determination threshold, the module determines that the road surface is in a specular reflection state of water accumulation or ice formation, and controls the LED driver power supply to reduce the output power to suppress glare.

[0020] Optionally, the main control module establishes a historical trend database regarding the road surface reflectivity coupling coefficient;

[0021] When the road surface reflectivity coupling coefficient is detected to exhibit a monotonically decreasing trend within a preset long period, the main control module determines that there is dust accumulation on the surface of the light environment sensing module or that there is light decay in the electroluminescent lighting module, and generates a compensation gain that is superimposed on the dimming command.

[0022] Optionally, the system is configured with a neighborhood time-division multiplexing detection mechanism;

[0023] Before executing the active light effect decoupling logic, the main control module detects whether the adjacent street light system is in a detection state through the wireless communication link; if the adjacent street light system is in a detection state, the main control module executes a random backoff delay to stagger the transmission time of the micro-perturbation modulation signal.

[0024] Optionally, the main control module is further configured to perform spectral analysis or variance analysis on the illuminance response data; if the analysis results show that the energy density of its fluctuation exceeds a preset clear sky baseline, the main control module is further configured to analyze the scattering characteristics of the illuminance response data.

[0025] If the illuminance response data exhibits high-frequency disordered fluctuations during non-micro-disturbance periods, and the environment is determined to be rainy, snowy, or foggy, then the main control module switches to the penetrating illumination mode and adjusts the color temperature or brightness of the light-emitting diode.

[0026] Secondly, the illuminance adjustment method of the LED energy-saving street light system with adaptive ambient light efficiency as described in any one of the first aspects, provided by embodiments of the present invention, includes the following steps:

[0027] The total illuminance value is collected through the light environment sensing module, and traffic flow data is collected through the traffic flow monitoring module.

[0028] The main control module controls the LED driver power supply to inject micro-perturbation modulation signals into the electroluminescent lighting module, so that the electroluminescent lighting module produces weak luminous flux fluctuations.

[0029] The main control module synchronously collects the illuminance response data of the light environment sensing module and uses digital signal processing algorithms to extract the AC response amplitude corresponding to the micro-perturbation modulation signal.

[0030] The road surface reflectivity coupling coefficient is calculated based on the ratio of the AC response amplitude to the injected micro-disturbance amplitude.

[0031] The main control module uses the road surface reflectivity coupling coefficient and the current LED output luminous flux to subtract the reflected light component excited by the electroluminescent lighting module from the total illuminance value, thereby separating the ambient background illuminance.

[0032] The main control module calculates the target power and controls the output of the electroluminescent lighting module based on the ambient background illuminance, the road surface reflectivity coupling coefficient, and the traffic flow data.

[0033] The present invention has achieved the following beneficial effects:

[0034] This invention improves the energy efficiency and control precision of lighting systems by superimposing a high-frequency micro-perturbation modulation signal onto the DC output of the LED driver power supply and constructing an active luminous efficacy decoupling mechanism using digital phase-locked loop technology. This mechanism fully utilizes the nanosecond-level electroluminescence response characteristics of LEDs, enabling the system to accurately isolate the reflected light component of the streetlights from the mixed light field without turning off the streetlights or affecting visual comfort. It then calculates the real-time road surface reflectivity coupling coefficient, thereby obtaining pure natural background illuminance. This avoids the "self-excited interference" blind spot of traditional light control systems, allowing streetlights to smoothly and linearly adjust power according to the actual light changes during the transition from dawn to dusk. It eliminates the energy consumption buffer zone reserved in traditional solutions to prevent misjudgment, achieving on-demand lighting and reducing overall operating energy consumption.

[0035] Meanwhile, this system constructs a robust all-weather control closed loop, enhancing traffic safety under adverse weather conditions. By monitoring the abrupt changes in the road surface reflectivity coupling coefficient in real time, the system can intelligently identify whether the road surface is in a highly reflective state (spectral reflection) due to water accumulation or icing, and automatically adjust the output power to enter an anti-glare energy-saving mode, effectively suppressing the "light curtain" effect caused by wet road surfaces from interfering with the driver's vision. In addition, combined with non-visual sensing technologies such as microwave radar, the system can still accurately capture traffic dynamics in low-visibility weather conditions such as rain, fog, and blowing sand, achieving dynamic energy saving of "lights on when cars approach, lights off when cars leave." The system also has a self-diagnostic function based on luminous efficacy trend analysis, which can distinguish between aging lamps and environmental dust accumulation, and automatically compensate by adjusting the drive current, maintaining the consistency of luminous efficacy throughout the entire life cycle of the lighting facilities, extending the service life of the equipment, and reflecting the core values ​​of resource-efficient utilization and environmental friendliness in green technology.

[0036] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0037] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0038] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0039] Figure 1 This is a schematic diagram of an LED energy-saving street light system with adaptive ambient light effect according to an embodiment of the present invention;

[0040] Figure 2 This is a flowchart of an illuminance adjustment method for an adaptive ambient light effect LED energy-saving street light system according to an embodiment of the present invention. Detailed Implementation

[0041] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0042] Example 1:

[0043] like Figure 1As shown, this invention provides an LED energy-saving street light system with adaptive ambient light efficiency. This system aims to solve a long-standing physical and control problem in the field of smart urban lighting: how to accurately, in real-time, and without interference detect the pure natural ambient light illuminance while the street light itself is on and providing high-intensity illumination. In traditional street lights, when the light control probe is installed on the luminaire, the total illuminance it receives inevitably includes the component of light reflected from the road surface. This superposition effect leads to inflated sensor readings in rainy, snowy, or high-reflectivity road conditions, causing the system to misjudge sufficient ambient light and incorrectly reduce output power, resulting in insufficient road illuminance and seriously affecting driving safety. Conversely, when the system reduces power, the sensor reading drops sharply, causing the system to misjudge insufficient ambient light and suddenly increase power, resulting in fluctuations and flickering in lighting brightness.

[0044] like Figure 1 As shown, the components of the adaptive ambient light effect LED energy-saving street light system provided in this embodiment include a light pole as a physical support carrier, a light environment sensing module and a traffic flow monitoring module as sensing front-ends, an LED driver power supply and an electroluminescent lighting module as energy execution ends, and a main control module as the core computing and decision-making center. These components work together through electrical connections and an industrial-grade communication bus to jointly complete the analysis and response to complex light environments.

[0045] Considering the harshness of the outdoor environment, light poles are typically made of high-strength low-alloy structural steel (such as Q345), with a surface undergoing double anti-corrosion treatment of hot-dip galvanizing and electrostatic powder coating to resist long-term corrosion from acid rain, salt spray, and ultraviolet radiation. The light pole has independent high-voltage and low-voltage compartments, electromagnetically shielded by metal partitions to prevent interference from the power frequency electromagnetic fields generated by AC mains cables on the data transmission of low-voltage signal cables. An adjustable cantilever is located at the top of the light pole for mounting the main lamp body, ensuring that the light can cover the target lane at the optimal projection angle.

[0046] The electroluminescent lighting module is the actuator that enables the system to emit light. To meet the stringent requirements of CJJ 45-2015 "Urban Road Lighting Design Standard" regarding average illuminance, brightness uniformity, and glare limits, this module uses several high-efficiency, high-power light-emitting diodes (LEDs) as the light source. These LED chips are manufactured on a gallium nitride (GaN) substrate, exhibiting high photoelectric conversion efficiency and extremely fast response speed. Their nanosecond-level response time is the physical basis for the system's active micro-disturbance detection function. Each LED is covered with an asymmetric freeform lens, injection molded from optical-grade PMMA or PC material. Its curved surface design shapes the Lambertian light spot emitted by the LED into a rectangular light spot extending longitudinally along the road, thereby ensuring effective road illumination while minimizing light pollution to the surrounding environment. The lighting module is tightly bonded to the die-cast aluminum heat sink of the lamp housing via a high thermal conductivity metal-based printed circuit board (MCPCB), ensuring that the LED junction temperature remains within a safe range during long-term operation and preventing a decrease in luminous efficiency due to thermal decay.

[0047] The LED driver power supply connects the power grid and the lighting module, and also performs active luminous efficacy decoupling for this system. In this embodiment, the driver power supply's internal circuit topology employs a high-efficiency PFC (Power Factor Correction) cascaded LLC resonant converter, providing stable DC output and extremely high dynamic response bandwidth. The power supply integrates a constant current control circuit and a signal demodulation circuit. The feedback loop of the constant current control circuit has a bandwidth of several kilohertz to ensure that the output current can follow the high-frequency modulation commands issued by the main control module without distortion. The signal demodulation circuit is responsible for receiving and parsing the digital commands from the main control module, converting them into a reference signal for controlling the duty cycle of the power switching transistors.

[0048] To capture road surface reflection characteristics in real time for active decoupling logic, the module is configured to be installed on the side of the light pole facing the road surface or on the lower surface of the light fixture, with its photosensitive field of view directly covering the illumination area formed by the electroluminescent lighting module on the road surface. Although conventional technology suggests that downward mounting is susceptible to interference from vehicle lights, this system utilizes the micro-perturbation phase-locked demodulation technology described later to effectively shield against non-co-frequency interference from vehicle lights in the frequency domain, thereby accurately acquiring illuminance data containing road surface reflection information.

[0049] Although it faces away from the road surface, due to Rayleigh scattering from the atmosphere and diffuse reflection from the ground, this position can still linearly perceive changes in the average brightness of the road surface, while shielding most direct glare interference. More importantly, the module integrates a high-precision photoelectric conversion device whose spectral response characteristics are designed with filtering to highly match the emission spectrum of the light-emitting diode, thereby filtering out environmental thermal radiation noise such as infrared rays and improving the signal-to-noise ratio.

[0050] The traffic flow monitoring module is used to sense the road's usage status. Considering the limitations of visible light cameras at night in low light or in rainy / foggy weather, this system selects either a microwave radar sensor or a thermal imaging sensor. Microwave radar utilizes the Doppler effect and FMCW technology to accurately measure vehicle speed, distance, and traffic flow in dark environments; thermal imaging sensors effectively identify pedestrians and animals by detecting the thermal radiation contours of objects. The application of these two non-visual sensors ensures the system's robustness in all weather conditions.

[0051] The main control module integrates a high-performance 32-bit microcontroller (MCU) or digital signal processor (DSP) embedded motherboard. This module establishes bidirectional communication connections with the aforementioned modules via onboard RS-485, CAN, or carrier communication interfaces. Internally, the main control module runs a real-time operating system and algorithm engine, configured to execute active light effect decoupling logic.

[0052] Specifically, when the electroluminescent lighting module is in the steady-state lighting stage, the main control module controls the LED driver power supply to inject a micro-perturbation modulation signal into the lighting module. Let the instantaneous drive current output by the LED driver power supply be... for:

[0053] ;

[0054] in, For steady-state drive current, The amplitude of the micro-perturbation current (the precise value is known to the system). This is the modulation angular frequency.

[0055] At this time, the total illuminance signal collected by the light environment sensing module It can be represented as:

[0056] ;

[0057] in, For ambient background light, The overall transmission gain of the system includes LED luminous efficacy, optical path transmission efficiency, and road surface reflectivity. For phase delay, It is noise.

[0058] The main control module utilizes internally generated quadrature reference signals ( and The acquired signal is digitally quadrature demodulated, and the square root of the sum of the squares of the in-phase and quadrature components is calculated to eliminate phase delay. The influence of the driving current is used to accurately extract the AC response amplitude that is in the same frequency as the driving current. .

[0059] Subsequently, the main control module calculates the system transmission gain (i.e., the representation of the road surface reflectivity coupling coefficient in the current domain):

[0060] ;

[0061] get Then, the main control module can use this real-time gain to obtain the DC average of the total illuminance. After removing the DC component of reflected light excited by the streetlight itself, the decoupling calculation formula is as follows:

[0062] ;

[0063] This model has significant advantages: due to It is based on real-time measurements and naturally includes the LED's aging and light decay factor at the current moment. That is, when the LED's luminous efficiency decreases due to aging, the measured... It will decrease, leading to As the I-Phi curve decreases, the calculated self-emission component also decreases accordingly, thus enabling accurate ambient light data to be obtained without relying on pre-stored I-Phi curves.

[0064] Example 2:

[0065] In this embodiment, the ambient light sensing module is the data source for the active light effect decoupling logic, and its signal quality directly determines the control accuracy of the entire system. In traditional street light control systems, commonly used photoresistors or ordinary photodiodes often have a wide spectral response range, typically covering the visible to near-infrared band (300nm-1100nm). However, this wide spectral characteristic becomes a major pathway for noise introduction in the application scenario of this system. This is because there are numerous non-lighting heat radiation sources in the urban road environment, such as the heat radiation from vehicle engines, infrared security lights from roadside buildings, and even the heat radiation released by asphalt pavement in summer. These infrared radiations are received by the wide spectral sensor and superimposed on the illuminance signal. Since these radiations are not controlled by the street light's micro-perturbation signal, they constitute uncorrelated additive noise, which interferes with the extraction of weak reflection signals.

[0066] To address this issue, this embodiment limits the spectral response characteristics of the ambient light sensing module to match the spectral characteristics of the light-emitting diode (LED). Currently, most LED light sources for road lighting employ a "blue chip + yellow phosphor" technology, with their spectral energy primarily concentrated in the visible light range of 400nm-700nm. They exhibit a sharp blue peak at 450nm and a broad yellow peak at 550nm-600nm, while emitting almost no energy in the infrared band above 750nm. Based on these physical characteristics, the ambient light sensing module in this embodiment integrates a specially designed infrared cut-off filter (IR-Cut Filter) or bandpass filter in front of the photosensitive element. The transmission curve of this filter is designed to allow only visible light to pass through, exhibiting an extremely high attenuation rate (OD4 level or higher) for infrared radiation. This spectral matching design ensures that the sensor is sensitive only to the effective light component emitted by the LED, avoiding thermal radiation noise from the environment. This improves the signal-to-noise ratio of the micro-disturbance signal and ensures that the calculated road surface reflectivity coupling coefficient K truly reflects the reflection characteristics of visible light, rather than the thermal radiation characteristics.

[0067] In terms of the installation layout of the light environment sensing module, it is configured to be installed on the lower surface of the lamp or on the side of the lamp post facing the road surface, and its photosensitive field of view directly covers the lighting spot area formed by the electroluminescent lighting module on the road surface.

[0068] This type of undermount installation is generally considered off-limits in traditional technologies because the headlights of vehicles on the road would directly illuminate the sensor, leading to misjudgments. However, this system overcomes this drawback in principle thanks to its active light effect decoupling logic. Since the micro-perturbation modulation signal injected into this system has a specific carrier frequency (e.g., 300Hz), while the headlights of vehicles on the road are typically DC or low-frequency varying signals (<50Hz), the two are completely separated in the frequency domain. The main control module, through its internal digital phase-locked loop amplification algorithm, essentially constructs an extremely narrow-band bandpass filter at the detection end, effectively filtering out high-intensity headlight interference as out-of-band noise, and precisely extracting only the road surface reflection signal that is in the same frequency and phase as the micro-perturbation signal.

[0069] Therefore, this embodiment adopts an installation method facing the road surface, which not only eliminates external interference, but more importantly, it can directly receive the first-level reflected light from the road surface, improve the signal-to-noise ratio, and enable the system to accurately calculate the road surface reflectivity coupling coefficient K, thereby truly reflecting the dry and wet state of the road surface.

[0070] Example 3:

[0071] In existing intelligent transportation technologies, video surveillance is the mainstream method for traffic flow collection. However, directly applying it to street light control presents problems: video analysis algorithms rely on good visible light illumination. If streetlights are dimmed or turned off to save energy, the camera's image quality deteriorates, making it unable to detect vehicles. This leads to the system being unable to determine whether a vehicle is approaching and thus unable to turn on the streetlights, creating a "deadlock." Furthermore, video surveillance has poor penetration in severe weather conditions such as dense fog and heavy rain, and it also raises sensitive issues related to public privacy.

[0072] Therefore, in this embodiment, the traffic flow monitoring module employs a microwave radar sensor or a thermal imaging sensor. Both types of sensors do not rely on external visible light illumination and have the capability to actively or passively detect infrared / microwave bands.

[0073] Microwave radar sensors typically employ 24GHz ISM band or 77GHz millimeter wave band FMCW (Frequency Modulated Continuous Wave) radar. This radar is installed in the middle of a light pole or at the base of a cantilever, with its antenna beam covering the roadway below. It transmits continuous linearly modulated electromagnetic waves and receives the echoes reflected from vehicles. According to the Doppler effect, the frequency of the reflected waves from moving vehicles shifts, with the shift proportional to the vehicle speed. The distance to the vehicle can be calculated based on the time difference or frequency difference between the round trip. Microwave radar is environmentally adaptable; its long wavelength allows it to penetrate rain, fog, and dust, and is unaffected by lighting conditions. The main control module analyzes the radar data to obtain real-time traffic flow (vehicles / minute), average vehicle speed (km / h), and lane occupancy rate (%). For example, when the system detects a high vehicle speed, it will increase the brightness of the streetlights ahead in advance to ensure that the driver has sufficient visibility. When the system detects extremely heavy traffic but slow speed (congestion), it can appropriately reduce the road surface illumination, because at this time the vehicle mainly relies on its own headlights and the taillights of the vehicle in front, and the braking distance is short. Reducing the illumination saves energy and reduces light pollution.

[0074] Thermal imaging sensors, based on uncooled microbolometer arrays, detect 8-14μm long-wave infrared radiation emitted by objects within their field of view. In nature, the temperature of vehicle engines, tires, exhaust pipes, and pedestrians' bodies is typically significantly higher than the background environment such as road surfaces and green belts. Thermal imaging sensors convert this temperature distribution into grayscale images, and through built-in image processing algorithms, can identify the outlines of vehicles and pedestrians. Compared to radar, the advantage of thermal imaging technology lies in its ability to identify stationary targets and non-metallic targets (such as pedestrians and animals). On sparsely populated side streets or rural roads at night, thermal imaging sensors can detect pedestrians wearing dark clothing or animals crossing the road, thereby triggering streetlights to enter safety alert mode and improving road safety.

[0075] Example 4:

[0076] Traditional LED street light power supplies are typically designed as constant voltage sources or simple constant current sources, with the core objective of outputting DC power with minimal ripple to ensure stable LED illumination. However, in this embodiment, the system requires the power supply to not only output DC but also to superimpose high-frequency AC disturbance signals.

[0077] The LED driver power supply in this embodiment integrates two functional modules: a constant current control circuit and a signal demodulation circuit. In terms of power stage topology, to meet the requirements of high efficiency and high power factor, a two-stage architecture is typically adopted. The front stage is an active power factor correction (Active PFC) circuit, usually employing a boost topology, which rectifies and boosts the AC mains voltage to a stable DC bus voltage of approximately 400V, ensuring a grid-side power factor greater than 0.95 and harmonic content meeting the IEC 61000-3-2 standard. The rear stage is a DC / DC constant current converter circuit, preferably using an LLC resonant half-bridge topology or a high-frequency Buck buck topology.

[0078] Traditional LED power supplies typically use large-capacity electrolytic capacitors in parallel at the output to filter out power frequency ripple, and the bandwidth of the voltage / current feedback loop is designed to be very low (usually only tens of hertz). The constant current control circuit in this embodiment adopts a high-bandwidth feedback design, with its loop cutoff frequency pushed up to over 1kHz. At the same time, the parameters of the output filter network are precisely calculated, allowing micro-disturbance signal frequencies (hundreds of hertz) to pass through without attenuation while filtering out switching frequency ripple (usually tens of kHz).

[0079] The main control module sends a composite signal containing dimming commands (e.g., brightness 50%) and micro-perturbation commands (e.g., perturbation amplitude 2%, frequency 300Hz) via a PWM interface, DALI interface, or 0-10V analog interface. The microcontroller (MCU) or dedicated decoding chip inside the signal demodulation circuit parses these commands and generates a composite reference voltage signal via an internal high-speed digital-to-analog converter (DAC). This signal It is a DC level with sinusoidal ripple, which is fed into the reference terminal of the error amplifier in the constant current control circuit, forcing the output current to strictly follow its waveform changes. In addition, the circuit also has protection functions such as over-temperature, over-voltage, and short-circuit protection, and feeds back the real-time status of the power supply (such as output voltage, current, and temperature) to the main control module to achieve full-link digital management.

[0080] Example 5:

[0081] If the signal frequency is too low or the amplitude is too large, the human eye will perceive the flickering of the streetlights, causing visual discomfort; if the signal is too weak or the frequency is too high, the light environment sensing module will have difficulty detecting it, and the signal-to-noise ratio will deteriorate.

[0082] Therefore, when selecting the frequency, it is configured as a sine wave or pulse wave sequence with a frequency higher than the critical flicker fusion frequency (CFF) of the human eye. The human eye's perception of changes in light intensity exhibits a time integral effect. When the flicker frequency exceeds a certain threshold, the photoreceptor cells on the retina do not have enough time to generate independent nerve impulses, and the brain fuses the discontinuous light signals into a continuous brightness perception. Generally, the CFF under photopic vision conditions is approximately 50Hz-60Hz. To allow sufficient safety margin and considering the greater sensitivity of peripheral vision to flicker, this embodiment sets the frequency of the micro-perturbation signal between 200Hz and 500Hz. This frequency band is not only far above the upper limit of human eye perception but also avoids the frame rates commonly used by cameras (25fps / 30fps / 60fps) and their low-order harmonics, preventing scrolling stripe interference (water ripple effect) in the monitoring image.

[0083] Secondly, regarding the amplitude, the resulting change in luminous flux is limited to a preset safe proportion range of the current base luminous flux. According to the Weber-Fechner Law, the human eye's ability to distinguish changes in brightness is proportional to the background brightness, with a minimum noticeable difference (JND) of approximately 1%-2%. To ensure imperceptibility, this embodiment controls the amplitude of the disturbance signal between 0.5% and 3% of the base luminous flux. For example, when a streetlight outputs 10,000 lumens, the peak-to-peak value of the disturbance is only about 100 lumens. This change is below the human eye's perception threshold, but for a light environment perception module with a high bit-depth ADC (e.g., 16-bit) and lock-in amplification algorithm, it has a sufficiently high signal-to-noise ratio. Preferably, to accommodate sensitive individuals in extremely quiet and dark environments, the amplitude can be further limited to between 0.5% and 1% to ensure absolute visual imperceptibility.

[0084] In waveform selection, a sine wave is preferred. This is because a sine wave is a single-frequency signal, with its spectral energy highly concentrated at the fundamental frequency and lacking higher harmonic components. This allows for the use of extremely narrowband filters during spectrum analysis or phase-locked amplification at the receiving end, maximizing the removal of ambient white noise and interference from other frequencies, thus improving detection sensitivity. In contrast, while square waves or pulse waves are simple to generate, their energy is dispersed across the fundamental frequency and various odd harmonics, and high-frequency harmonics are easily distorted by line inductance and capacitance, hindering accurate measurement.

[0085] Example 6:

[0086] The physical meaning of the road surface reflectivity coupling coefficient K is: what proportion of the luminous flux emitted by the luminaire is reflected back to the sensor. This coefficient depends not only on the geometric parameters of the luminaire, but also on the bidirectional reflectance distribution function (BRDF) of the road surface. Dry asphalt or cement roads are rough surfaces, mainly exhibiting diffuse reflection, with the reflected light being relatively uniformly distributed in space and having low intensity. However, when there is standing water, ice, or oil on the road surface, the water film fills in the micro-texture of the road surface, causing its optical properties to change towards specular reflection.

[0087] When the road surface is in a specular reflective state, the reflection of light is directional. If the sensor is located within the reflective light cone, the received light intensity will increase dramatically; if it is located outside the light cone, the light intensity may decrease dramatically. In the specific sensor installation position of this embodiment (facing away from the road surface or top-mounted), ambient diffuse light is typically received. When the road surface experiences severe specular reflection (such as water accumulation), a large amount of light energy is reflected forward to a distant location, causing a characteristic change in the diffuse reflection component fed back to the sensor above the luminaire (usually a significant decrease, or possibly a significant increase if there is a secondary reflection at a specific angle).

[0088] The main control module internally stores a road surface condition judgment threshold table. This table establishes a mapping relationship between K-value ranges and road surface conditions through extensive pre-measured calibration. During system operation, the main control module compares the real-time calculated road surface reflectivity coupling coefficient with this threshold table.

[0089] When the road surface reflectivity coupling coefficient K is detected to have significantly decreased and fallen below a preset wet / slippery threshold, the road surface is determined to be in a highly reflective state (spectral reflection) due to water accumulation or icing. The physical mechanism is as follows: dry road surfaces exhibit diffuse reflection characteristics, with a uniform spatial distribution of reflected light, and the K value remains within a baseline range; however, when the road surface is wet or icy, its optical characteristics tend towards specular reflection, with most light rays following the law of reflection and escaping forward and away from the sensor below the luminaire, resulting in a sharp reduction in the diffuse luminous flux fed back to the sensor. Based on this characteristic, the system identifies the wet / slippery road surface state and controls the LED driver to enter anti-glare mode, reducing the output power (e.g., limiting it to below 70%). Although the total illuminance of the road surface is reduced, due to the high specular reflection efficiency, sufficient light still enters the human eye, and glare is effectively suppressed, thus achieving safe lighting in adverse weather conditions.

[0090] Example 7:

[0091] All outdoor optical systems face the problems of aging and contamination. The light-transmitting cover of the ambient light sensing module, exposed to air for extended periods, gradually accumulates dust and oil, leading to a decrease in light transmittance. Similarly, the luminous efficacy of the LED light source in the electroluminescent lighting module naturally decays over time (light decay). Both of these factors result in a weaker reflected signal received by the sensor under the same driving current, meaning a smaller calculated coupling coefficient K value for the road surface reflectivity.

[0092] However, the changes in K-values ​​caused by aging or dust accumulation differ in time scale from those caused by weather changes (such as road surface dryness / wetness). Weather changes are typically sudden and short-lived (minutes or hours), while aging and dust accumulation are slow and gradual (months or years). Based on this, the main control module establishes a historical trend database of the road surface reflectivity coupling coefficient. Each detected K-value is timestamped and stored in the database.

[0093] The system periodically (e.g., every morning) performs trend analysis on the K values ​​in the database. When it detects that the road surface reflectivity coupling coefficient exhibits a monotonically decreasing trend over a preset long period (e.g., 90 days), and this decrease conforms to an exponential decay model or a linear cumulative model, the main control module determines that there is dust accumulation on the surface of the light environment sensing module or light decay in the electroluminescent lighting module. At this point, the system not only records the data but also proactively takes compensatory measures.

[0094] The main control module calculates the current attenuation ratio and generates a compensation gain that is added to the dimming command. For example, if the analysis shows that the K value has decreased by 10%, it means that the optical circuit efficiency of the system has decreased by 10%. To ensure that the road surface illumination remains at or above the design standard, the system will automatically increase the LED drive current by a corresponding percentage (within the power supply's rated power range) to offset the effects of light decay or dust accumulation. This constant luminous flux output strategy ensures that the streetlights provide consistent lighting effects throughout their entire lifespan, while also providing management with precise maintenance recommendations (such as "cleaning recommended" or "replacement recommended"), reducing operation and maintenance costs.

[0095] Example 8:

[0096] In urban road lighting scenarios, streetlights are arranged in a continuous and dense manner, and the light spots of adjacent streetlights often overlap on the road surface.

[0097] If two adjacent streetlights (lamp A and lamp B) simultaneously emit micro-perturbation signals with the same frequency and random phase, the reflected light from their signals in the overlapping area will physically superimpose. For the sensor of lamp A, it will receive not only its own reflected perturbation light but also the reflected perturbation light emitted by lamp B. Because it cannot distinguish between the two, the calculated K value will be severely deviated, leading to decoupling failure.

[0098] To address this issue, in this embodiment, the system is configured with a neighborhood time-division multiplexing detection mechanism. The main control module has a built-in wireless communication unit (such as ZigBee Mesh or LoRa). Before executing the active light effect decoupling logic, the main control module performs carrier sensing operations through the wireless communication link to detect whether adjacent street light systems (especially several adjacent lights in front and behind) are in a detection state.

[0099] If a neighboring streetlight system is detected to be in a probing state (i.e., transmitting a micro-perturbation signal), the main control module will not forcibly initiate probing. Instead, it will execute a random backoff delay strategy. It will generate a random waiting time (e.g., a random value between 200ms and 2000ms) to temporarily suspend the probing task. After the delay ends, the channel status will be checked again, and the micro-perturbation modulation signal will only be officially transmitted once it is confirmed that the surrounding neighborhood is silent. This mechanism ensures that at any given time, only one light source is actively probing within the local spatial range. This guarantees that the perturbation signal received by the sensor originates uniquely from itself, thus ensuring the absolute accuracy of the K-value calculation.

[0100] Example 9:

[0101] The propagation of light through a medium is affected by scattering effects. In a clear night sky, the air is clean, and light transmission is mainly affected by geometric divergence, resulting in a relatively stable signal. However, in rainy, snowy, or foggy weather, the air contains a large number of water droplets or aerosol particles. Micro-perturbations will undergo strong Mie scattering or Rayleigh scattering when passing through these media.

[0102] This scattering effect not only attenuates light intensity but also alters the statistical characteristics of the signal. The random falling of raindrops or snowflakes cuts the light path, causing transient high-frequency impulse noise in the illuminance response data; the Brownian motion of haze particles introduces broadband background noise, leading to a rise in the signal floor. Therefore, in this embodiment, the main control module is configured to analyze the scattering characteristics of the illuminance response data. Specifically, the main control module performs spectral analysis or variance analysis on the residual signal during non-perturbation periods (or after filtering out the main frequency perturbation).

[0103] If significant high-frequency disordered fluctuations are detected in the illuminance response data, and the energy density of these fluctuations exceeds the clear weather baseline, the main control module determines that the environment is experiencing rain, snow, or fog / haze. For such low-visibility weather, the system automatically switches to penetrating lighting mode. In this mode, the main control module adjusts the color temperature of the LEDs. If the luminaire is equipped with a dual-color-temperature LED module (e.g., 3000K warm white + 5000K cool white), the system will reduce the proportion of 5000K cool white light and increase the proportion of 3000K warm white light. This is because longer wavelength light (warm light) has a smaller scattering coefficient in the medium and stronger penetrating power. This color temperature adjustment strategy reduces the "light curtain" effect, providing drivers with clearer road guidance and improving driving safety in adverse weather conditions.

[0104] Example 10:

[0105] This invention provides a method for adjusting the illuminance of an adaptive ambient light effect LED energy-saving street light system, such as... Figure 2 As shown, the method includes the following steps:

[0106] Step 1: Full-Dimensional Data Acquisition. After the system is powered on, the main control module activates the ambient light perception module to continuously monitor the changing trend of the total ambient illuminance value at a low sampling rate. Simultaneously, the traffic flow monitoring module (radar / thermal imaging) continuously scans the road, outputting real-time data on traffic volume, average vehicle speed, and lane occupancy.

[0107] Step Two: Active Micro-Perturbation Injection. When the system decides to perform a precise ambient light calibration (this decision can be based on a timing strategy or triggered by a sudden change in total illuminance), the main control module first performs neighborhood interference detection. After confirming channel safety, it controls the LED driver power supply to superimpose a sinusoidal micro-perturbation signal with a frequency of 300Hz (example) and an amplitude of 2% onto the current DC drive current. The electroluminescent lighting module then generates a weak luminous flux fluctuation invisible to the human eye.

[0108] Step 3: Synchronous Acquisition and Coefficient Calculation. Simultaneously with the injected disturbance, the main control module controls the ambient light sensing module to perform high-speed synchronous sampling. Using a digital lock-in amplification algorithm, the acquired illuminance data is multiplied and integrated with an internally generated reference sine wave to extract the amplitude of the response component with the same frequency as the disturbance from the strong background noise. This response amplitude is divided by the injected disturbance amplitude to calculate the current road surface reflectivity coupling coefficient K.

[0109] Step 4: Ambient light decoupling. Using the formula... .in, The DC average of the total illuminance measured by the sensor. This is the DC output current of the current LED driver power supply. This represents the system transmission gain calculated in step three. Through this calculation, the main control module precisely removes the reflected light component excited by the streetlights themselves from the total illuminance value, thereby obtaining a pure ambient background illuminance. .

[0110] Step 5: Multi-parameter fusion decision-making and execution. The main control module will integrate the decoupled parameters... Real-time traffic flow data, road condition assessment results (based on K-value anomaly analysis), meteorological assessment results (based on scattering characteristic analysis), and historical light decay compensation coefficients are input into the internal intelligent decision engine. The engine calculates the final target power and color temperature based on preset control strategies (e.g., dark environment + heavy traffic = full power; dark environment + light traffic = energy-saving power; bright environment = lights off; fog / haze = warm light mode; slippery road = anti-glare mode). Finally, the main control module converts these parameters into control commands and sends them to the LED driver power supply to adjust the output of the electroluminescent lighting module, completing one closed-loop adjustment.

[0111] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An adaptive ambient light efficiency LED energy-saving street light system, comprising a light pole, a light environment sensing module, a traffic flow monitoring module, an LED driver, an electroluminescent lighting module, and a main control module; wherein the light environment sensing module, the traffic flow monitoring module, and the LED driver are respectively communicatively connected to the main control module; the LED driver is electrically connected to the electroluminescent lighting module; and the electroluminescent lighting module comprises a plurality of light-emitting diodes; Its features are, The main control module is configured to execute active light effect decoupling logic: when the electroluminescent lighting module maintains steady-state illumination, the LED driver power supply is controlled to inject a micro-perturbation modulation signal into the electroluminescent lighting module, causing the luminous flux output by the electroluminescent lighting module to fluctuate in a way that is imperceptible to the human eye; The main control module synchronously collects the illuminance response data of the light environment sensing module during the fluctuation period, and uses digital signal processing algorithms to extract the AC component in the illuminance response data that is in the same frequency and phase as the micro-perturbation modulation signal. The main control module calculates the road surface reflectivity coupling coefficient based on the ratio of the change of the AC component to the micro-perturbation modulation signal, and removes the reflected light component excited by the electroluminescent lighting module from the total illuminance value collected by the light environment sensing module based on the road surface reflectivity coupling coefficient to obtain pure ambient background illuminance, and generates a dimming command in combination with the data from the traffic flow monitoring module.

2. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The light environment sensing module is installed on the side of the lamp post facing the road surface and on the lower surface of the lamp. Its photosensitive field of view covers the lighting area formed by the electroluminescent lighting module on the road surface and is used to collect the total illuminance value including natural light, vehicle headlight interference light and road surface reflected light. The spectral response characteristics of the light environment sensing module are matched with those of the light-emitting diode, and it is equipped with an infrared cut-off filter to filter out environmental thermal radiation noise.

3. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The traffic flow monitoring module includes a microwave radar sensor or a thermal imaging sensor, used to collect data on road vehicle speed and vehicle density without relying on visible light illumination.

4. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The LED driver power supply integrates a high-bandwidth constant current control circuit and a signal demodulation circuit. The signal demodulation circuit is used to parse the dimming command and the micro-disturbance modulation signal sent by the main control module, and generate a reference voltage superimposed with an AC waveform. The loop bandwidth of the constant current control circuit is higher than the frequency of the micro-perturbation modulation signal, and is used to adjust the current amplitude output to the electroluminescent lighting module according to the reference voltage, so that its light output waveform follows the command change without distortion.

5. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The micro-perturbation modulation signal is configured as a sinusoidal wave sequence with a frequency higher than the critical flicker fusion frequency of the human eye, and the amplitude of the change in luminous flux caused by the micro-perturbation modulation signal is limited to the range of 0.5% to 3% of the current basic luminous flux to ensure visual comfort of the lighting.

6. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The main control module stores road surface condition determination thresholds internally. The main control module is configured to compare the calculated road surface reflectivity coupling coefficient with the road surface condition determination threshold. When the road surface reflectivity coupling coefficient is lower than the road surface condition determination threshold, the module determines that the road surface is in a specular reflection state of water accumulation or ice formation, and controls the LED driver power supply to reduce the output power to suppress glare.

7. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The main control module establishes a historical trend database regarding the road surface reflectivity coupling coefficient; When the road surface reflectivity coupling coefficient is detected to exhibit a monotonically decreasing trend within a preset long period, the main control module determines that there is dust accumulation on the surface of the light environment sensing module or that there is light decay in the electroluminescent lighting module, and generates a compensation gain that is superimposed on the dimming command.

8. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The system is equipped with a neighborhood time-division multiplexing detection mechanism; Before executing the active light effect decoupling logic, the main control module detects whether the adjacent street light system is in a detection state through the wireless communication link; if the adjacent street light system is in a detection state, the main control module executes a random backoff delay to stagger the transmission time of the micro-perturbation modulation signal.

9. The LED energy-saving street light system with adaptive ambient light effect according to claim 1, characterized in that, The main control module is also configured to perform spectrum analysis or variance analysis on the illuminance response data; if the analysis results show that the energy density of the fluctuation exceeds the preset clear sky baseline, it is determined that there is rain, snow or fog in the environment, and the main control module switches to the penetrating lighting mode to adjust the color temperature or brightness of the light-emitting diode.

10. A method for adjusting the illuminance of an LED energy-saving street light system with adaptive ambient light efficiency as described in any one of claims 1 to 9, characterized in that, Includes the following steps: The total illuminance value is collected through the light environment sensing module, and traffic flow data is collected through the traffic flow monitoring module. The main control module controls the LED driver power supply to inject micro-perturbation modulation signals into the electroluminescent lighting module, so that the electroluminescent lighting module produces weak luminous flux fluctuations. The main control module synchronously collects the illuminance response data of the light environment sensing module and uses digital signal processing algorithms to extract the AC response amplitude corresponding to the micro-perturbation modulation signal. The road surface reflectivity coupling coefficient is calculated based on the ratio of the AC response amplitude to the injected micro-disturbance amplitude. The main control module uses the road surface reflectivity coupling coefficient and the current LED output luminous flux to subtract the reflected light component excited by the electroluminescent lighting module from the total illuminance value, thereby separating the ambient background illuminance. The main control module calculates the target power and controls the output of the electroluminescent lighting module based on the ambient background illuminance, the road surface reflectivity coupling coefficient, and the traffic flow data.

Images