A single lamp monitoring system and method

Abstract

The application relates to a single lamp monitoring system and method. The single lamp monitoring system comprises a voltage sampling circuit connected between the secondary side output terminals of an isolation transformer; a short circuit bypass circuit comprising a magnetic latching relay connected across the secondary side output terminals of the isolation transformer; a control unit electrically connected with the voltage sampling circuit and the short circuit bypass circuit respectively; the control unit is configured to receive the voltage sampling signal, determine that an LED lamp fails when the voltage value indicated by the voltage sampling signal is lower than a preset fault threshold value and the duration exceeds a preset delay time, and output a set driving signal to drive a set coil of the magnetic latching relay to make the normally open contact closed, so as to realize secondary side short circuit of the isolation transformer; and a communication module electrically connected with the control unit. The application simplifies the LED lamp circuit and eliminates the adverse effects of the failed lamp on the power quality of the constant current source loop.

Description

Technical Field

[0001] This application relates to the field of navigation lights, and in particular to a single-lamp monitoring system and method. Background Technology

[0002] In airport navigation lighting systems, runway lights, taxiway lights, and other navigation lights are powered by a constant current source series circuit. In this circuit, each light draws power from the series circuit through an isolation transformer, and the lights are electrically isolated from each other. Traditional navigation lights use halogen bulbs; when the filament of a halogen bulb burns out, the circuit becomes open. Existing single-lamp monitoring systems are based on this characteristic, detecting open circuits to confirm bulb damage and issuing alarms to maintenance personnel.

[0003] With the advancement of energy conservation and emission reduction, many airports have begun replacing halogen lamps with LED lamps. However, the failure modes of LED lamps are quite different from those of halogen bulbs: when an LED chip or driver circuit fails, the circuit state is uncertain, potentially exhibiting a short circuit or abnormal impedance, rather than a deterministic open circuit. To ensure compatibility with existing single-lamp monitoring systems, current LED lamp technologies have to incorporate additional open-circuit simulation circuits to actively disconnect the circuit upon detecting a fault, thus simulating an open-circuit state.

[0004] The above technical solution has the following drawbacks: First, an additional open-circuit simulation circuit needs to be set up inside the LED lamp, increasing the complexity, cost, and potential failure points of the lamp. Second, and most critically, when the lamp indicates a fault through simulated open circuit, the secondary side of the corresponding isolation transformer is in an open-circuit state. At this time, the isolation transformer is equivalent to an unloaded inductor, introducing a significant inductive reactive load into the constant current source series circuit. When multiple lamps in the circuit fail simultaneously, the accumulated inductive load will seriously affect the power quality of the constant current source circuit, leading to a decrease in the circuit power factor, voltage waveform distortion, and may even affect the normal operation of the constant current regulator and the power supply stability of other normal lamps.

[0005] Based on the above, the technical problem to be solved in this field is how to avoid the isolation transformer from becoming an open-circuit inductive load when an LED lamp fails, while simplifying the internal circuit of the LED lamp and reliably realizing fault detection and alarm. Summary of the Invention

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, this application provides a single-lamp monitoring system and method. By setting a short-circuit bypass circuit connected across the secondary output terminal of the isolation transformer in the single-lamp monitoring system, the secondary side of the isolation transformer is short-circuited when an LED lamp fault is detected, making the transformer present as a low-impedance load rather than a high-inductive open-circuit load. Fault judgment is achieved by monitoring the voltage drop, thereby simplifying the LED lamp circuit and eliminating the adverse effects of faulty lamps on the power quality of the constant current source circuit.

[0007] The embodiments of this application adopt the following technical solutions: In a first aspect, this application provides a single-lamp monitoring system for use in a constant current source series circuit, wherein each lamp position in the constant current source series circuit is powered through an isolation transformer, and the single-lamp monitoring system includes: A voltage sampling circuit is connected between the secondary output terminals of the isolation transformer to collect the output voltage of the secondary side of the isolation transformer and output a voltage sampling signal. The short-circuit bypass circuit includes a magnetic latching relay connected across the secondary output terminals of the isolation transformer. The normally open contacts of the magnetic latching relay are connected between the secondary output terminals. The magnetic latching relay has a set coil and a reset coil. When the set coil is energized, the normally open contacts close to short-circuit the secondary output terminals. When the reset coil is energized, the normally open contacts open. The control unit is electrically connected to the voltage sampling circuit and the short-circuit bypass circuit respectively; the control unit is configured to: receive the voltage sampling signal, and when the voltage value indicated by the voltage sampling signal is lower than a preset fault threshold and the duration exceeds a preset delay time, determine that the LED lamp is faulty, and output a set drive signal to drive the set coil of the magnetic latching relay to close the normally open contact, thereby realizing a short circuit on the secondary side of the isolation transformer; The communication module is electrically connected to the control unit and is used to send fault alarm information to the upper-level monitoring system when the control unit determines that the LED lamp is faulty.

[0008] Through the above technical solution, when an LED lamp malfunctions, the single-lamp monitoring system short-circuits the secondary side of the isolation transformer via a magnetic latching relay, causing the transformer to present a low-impedance load instead of a high-inductive load in an open-circuit state. This avoids the introduction of inductive reactive load into the constant current source series circuit by the faulty lamp, thus improving the power quality of the circuit. At the same time, the LED lamp does not require an additional open-circuit simulation circuit, simplifying the internal structure of the lamp and reducing system complexity and cost. Through voltage sampling detection combined with a delay confirmation mechanism, the reliability of fault diagnosis is ensured, avoiding misjudgments caused by transient interference.

[0009] In some embodiments, the short-circuit bypass circuit further includes: The first driving sub-circuit includes a first transistor and a first freewheeling diode; the control terminal of the first transistor is connected to the first driving output terminal of the control unit through a first current-limiting resistor, the first terminal of the first transistor is connected to one end of the set coil, and the second terminal of the first transistor is grounded; the first freewheeling diode is connected in anti-parallel to both ends of the set coil. The second driving sub-circuit includes a second transistor and a second freewheeling diode; the control terminal of the second transistor is connected to the second driving output terminal of the control unit through a second current-limiting resistor, the first terminal of the second transistor is connected to one end of the reset coil, and the second terminal of the second transistor is grounded; the second freewheeling diode is connected in anti-parallel to both ends of the reset coil. The control terminals of the first and second transistors are respectively connected to ground via pull-down resistors to keep the transistors off when the control unit does not output a drive signal.

[0010] The above technical solution employs a circuit structure with transistor drive and freewheeling diode. When the magnetic latching relay coil is de-energized, the freewheeling diode provides a discharge path for the coil current, preventing the back electromotive force from damaging the control unit and drive circuit. At the same time, the pull-down resistor ensures that the drive transistor remains in the off state during the power-on process of the control unit or during abnormal reset, preventing the magnetic latching relay from malfunctioning and causing the lamp to be incorrectly short-circuited or bypassed.

[0011] In some embodiments, the control unit is further configured to: Obtain the current operating level information of the constant current source series circuit; Based on the current operating gear information, the corresponding fault threshold and degradation threshold are queried from the preset gear-threshold correspondence table; wherein, the degradation threshold is higher than the fault threshold; When the voltage value indicated by the voltage sampling signal is lower than the degradation threshold but higher than the fault threshold, the LED lamp performance is determined to be degraded, and a degradation warning message is sent through the communication module, but the short-circuit bypass circuit is not triggered.

[0012] The above technical solution dynamically adjusts the detection threshold according to the actual operating level of the constant current source circuit, avoiding false alarms caused by switching the dimming level of the circuit. At the same time, it sets two levels of judgment: degradation threshold and fault threshold. It can identify the performance degradation state and provide early warning before the lamps completely fail, providing maintenance personnel with a time window for preventive maintenance and improving the operational reliability of the airport navigation lighting system.

[0013] In some implementations, the control unit is also configured to perform a self-recovery detection: After the normally open contact of the magnetic latching relay is closed, a reset drive signal is output at a preset self-recovery detection period to drive the reset coil to open the normally open contact. Within a preset sampling window period after the normally open contact is opened, the voltage sampling signal is re-acquired; If the voltage value indicated by the voltage sampling signal is higher than the fault threshold, it is determined that the LED lamp has resumed normal operation, the normally open contact remains open, and fault recovery information is sent through the communication module. If the voltage value indicated by the voltage sampling signal is still lower than the fault threshold, a set drive signal is output again to close the normally open contact and maintain the short-circuit bypass state.

[0014] By utilizing the above technical solution and the characteristic of magnetic latching relays that can be repeatedly set / reset, the system periodically attempts to restore the system after fault bypass. This allows for the automatic identification of temporary shutdowns of LED lights caused by reasons such as instantaneous over-temperature protection. Once the lights return to normal, the system automatically releases the short-circuit bypass and cancels the alarm, thus avoiding the problem of permanent bypassing of lights due to a one-time misjudgment. This improves the intelligence level of the system and the availability of the lights.

[0015] In some embodiments, a fault signal output circuit disposed inside the LED lamp is also included; the fault signal output circuit includes: A current detection unit is used to detect the output current of the LED driver circuit of the LED lamp. The comparator has its non-inverting input connected to a preset reference voltage and its inverting input connected to the output of the current detection unit. An optocoupler is provided, wherein the input terminal of the optocoupler is connected to the output of the comparator, and the output terminal of the optocoupler is connected to the power supply voltage of the control unit through a pull-up resistor, and is also connected to the fault signal input terminal of the control unit. When the output current of the LED driver circuit is lower than the preset current threshold, the comparator output turns on the optocoupler isolator, the fault signal input terminal is pulled low, and the control unit obtains an auxiliary judgment signal for lamp fault based on this.

[0016] Through the above technical solution, an independent fault signal output circuit is set inside the LED lamp, and electrical isolation and signal transmission between the lamp and the monitoring unit are achieved through optocoupler isolation; the control unit can perform dual verification and judgment by combining the voltage sampling signal and the fault signal actively output by the lamp, which improves the accuracy and reliability of fault detection and reduces the probability of missed and false alarms.

[0017] In some implementations, the control unit is configured to: When only the voltage sampling signal indicates that the voltage is lower than the fault threshold, but the fault signal input terminal is not pulled low, the delay time is extended to a first extension time before the fault is confirmed. When only the fault signal input terminal is pulled low, and the voltage sampling signal indicates that the voltage is not lower than the fault threshold, the delay time is extended to a second extension time before the fault is confirmed. When the voltage sampling signal indicates that the voltage is lower than the fault threshold and the fault signal input terminal is simultaneously pulled low, the fault is confirmed with the original preset delay time.

[0018] The above technical solution employs a dual-signal cross-verification mechanism. When two independent detection channels simultaneously indicate a fault, the fault is quickly confirmed. When only a single channel indicates a fault, the confirmation time is extended for careful judgment. This mechanism effectively balances the speed and accuracy of fault detection, reduces the probability of misjudgment caused by interference from a single detection channel, and ensures that real faults can be detected and handled in a timely manner.

[0019] In some implementations, the control unit obtains the current operating level information of the constant current source series circuit in the following ways: The control unit collects the amplitude of the voltage sampling signal within a preset calibration time window after the system is powered on and stabilized through the voltage sampling circuit, compares the amplitude with the pre-stored standard voltage range for each gear, and determines the current operating gear. And / or, the control unit receives a gear switching command issued by the upper-level monitoring system through the communication module, thereby knowing the current operating gear.

[0020] The above technical solution provides two ways to obtain the operating status of the circuit: autonomous detection and notification from the upper-level system, which serve as backups for each other. The autonomous detection method enables the single-lamp monitoring system to automatically adapt the threshold according to the actual voltage even when communication is interrupted, ensuring the independent operation capability of the system. The upper-level system notification method provides faster and more accurate information updates when the status is switched, improving the system's response speed.

[0021] Secondly, this application provides a single-lamp monitoring method, applied to the single-lamp monitoring system described in the first aspect, comprising the following steps: S1: The output voltage value of the secondary side of the isolation transformer is periodically collected through a voltage sampling circuit connected between the output terminals of the secondary side of the isolation transformer; S2: Compare the collected output voltage value with the preset fault threshold; S3: When the output voltage value is lower than the fault threshold and the duration exceeds the preset delay time, the LED lamp at the corresponding lamp position is determined to be faulty; S4: After determining that the LED lamp is faulty, drive the set coil of the magnetic latching relay connected across the secondary output terminal of the isolation transformer to close the normally open contact of the magnetic latching relay and short-circuit the secondary output terminal of the isolation transformer. S5: Send fault alarm information to the upper-level monitoring system.

[0022] The above technical solution employs voltage detection combined with short-circuit bypass to short-circuit the secondary side of the isolation transformer instead of opening it when the LED lamp fails, making the transformer present a low-impedance load and eliminating the inductive reactive load problem caused by the open circuit of the faulty lamp in the traditional solution; the delay confirmation mechanism avoids misjudgment caused by instantaneous interference; the whole method has clear logic, is simple to implement, and has high reliability.

[0023] In some implementations, a self-recovery detection step is also included: S6: Drive the reset coil of the magnetic latching relay to open the normally open contact at a preset self-recovery detection cycle interval; S7: Within a preset sampling window time after the normally open contact is opened, the output voltage value of the secondary side of the isolation transformer is re-acquired; S8: If the output voltage value is higher than the fault threshold, the LED lamp is determined to be back to normal, the normally open contact is kept open, and fault recovery information is sent; if the output voltage value is still lower than the fault threshold, the set coil is re-driven to close the normally open contact and maintain the short-circuit bypass state.

[0024] Through the above technical solution, periodic recovery detection under fault bypass state can automatically detect when the lamp recovers from a temporary fault and automatically remove the bypass, avoiding unnecessary lamp shutdowns caused by permanent bypass, and improving lamp utilization and system availability.

[0025] In some embodiments, the method further includes the following step before step S2: Obtain the current operating level of the constant current source series circuit; Based on the current operating gear, determine the corresponding fault threshold and degradation threshold; In step S2, the output voltage value is further compared with the degradation threshold. When the output voltage value is lower than the degradation threshold but higher than the fault threshold, the LED lamp performance is determined to be degraded, a degradation warning message is sent but the short-circuit bypass operation in step S4 is not executed.

[0026] The above technical solution dynamically sets thresholds based on the circuit's operating level, avoiding false alarms caused by dimming. At the same time, by distinguishing between degradation warnings and fault short-circuit responses, it achieves refined monitoring of the luminaire's status, providing maintenance personnel with richer decision-making information and supporting the implementation of preventive maintenance strategies.

[0027] In summary, this application includes at least the following beneficial technical effects: 1. When an LED lamp malfunctions, the single-lamp monitoring system short-circuits the secondary side of the isolation transformer via a magnetic latching relay, causing the transformer to present a low-impedance load instead of a high-inductive load in an open-circuit state. This avoids introducing an inductive reactive load into the constant current source series circuit of the faulty lamp, improving the power quality of the circuit. At the same time, the LED lamp does not require an additional open-circuit simulation circuit, simplifying the internal structure of the lamp and reducing system complexity and cost. Through voltage sampling detection combined with a delay confirmation mechanism, the reliability of fault diagnosis is ensured, avoiding misjudgments caused by transient interference. 2. The detection threshold is dynamically adjusted according to the actual operating level of the constant current source circuit, avoiding false alarms caused by switching the dimming level of the circuit; at the same time, two levels of judgment are set, namely degradation threshold and fault threshold, so that the performance degradation state can be identified and early warning can be given before the lamp completely fails, providing maintenance personnel with a time window for preventive maintenance and improving the operational reliability of the airport navigation lighting system. 3. An independent fault signal output circuit is set up inside the LED lamp, and electrical isolation and signal transmission between the lamp and the monitoring unit are achieved through optocoupler isolation. The control unit can perform dual verification judgment by combining the voltage sampling signal and the fault signal actively output by the lamp, which improves the accuracy and reliability of fault detection and reduces the probability of missed and false alarms. Furthermore, a dual-signal cross-verification mechanism is adopted. When two independent detection channels indicate a fault at the same time, the fault is quickly confirmed. When only a single channel indicates a fault, the confirmation time is extended for careful judgment. This mechanism effectively balances the speed and accuracy of fault detection, reduces the probability of false judgment caused by interference of a single detection channel, and ensures that real faults can be detected and handled in a timely manner. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This application provides a schematic diagram of the overall architecture of a single-lamp monitoring system. Figure 2This is a block diagram of the internal structure of a single-lamp system provided in an embodiment of this application; Figure 3 The schematic diagram of the short-circuit bypass circuit and voltage sampling circuit provided in the embodiments of this application; Figure 4 This is a flowchart of the MCU detection and control logic provided in the embodiments of this application; Figure 5 A schematic diagram of the LED driver fault signal output interface circuit provided in the embodiments of this application; Figure 6 A comparison diagram of the operating states of the system provided in the embodiments of this application in the constant current source circuit. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other.

[0031] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Example 1

[0032] It should be noted that in the constant current source series circuit of airport navigation lights, after LED lights replace halogen lights, the original single-lamp monitoring system requires the lights to be in an open-circuit state to detect faults. However, simulating an open-circuit state with LED lights requires additional circuitry, and the open-circuit state causes the isolation transformer to become an inductive load, degrading the power quality of the circuit. A new fault detection and indication method is needed that can reliably detect LED light faults while avoiding the introduction of inductive loads into the circuit.

[0033] Based on the above problems, this embodiment 1 provides a single-lamp monitoring system, deployed at each lamp position in the constant current source series circuit of airport navigation lights. (Reference) Figure 1 As shown, multiple isolation transformers T1, T2, ..., Tn are connected in series in the constant current source series circuit. The secondary side of each isolation transformer is connected to a single-lamp system. The single-lamp system includes a single-lamp monitoring unit and an LED lamp, which are connected as a whole to the output terminal of the secondary side of the isolation transformer.

[0034] refer to Figure 2 and Figure 3 As shown, the single-lamp monitoring unit includes a voltage sampling circuit, a short-circuit bypass circuit, a control unit, and a communication module.

[0035] Voltage sampling circuit: Connected between the output terminals L and N of the secondary side of the isolation transformer. The voltage sampling circuit includes a sampling resistor R1 and a voltage divider resistor R2 connected in series. The connection node of R1 and R2 outputs a voltage sampling signal V_sense to the ADC (analog-to-digital converter) input terminal of the control unit. In this embodiment, the effective value of the output voltage of the secondary side of the isolation transformer at brightness level 5 (highest level) is approximately 6.6V. Through the voltage divider network of R1=10kΩ and R2=2kΩ, V_sense is approximately 1.1V at its maximum, which is compatible with the 3.3V ADC input range of the MCU. The voltage sampling circuit may also include a filter capacitor C1 connected in parallel across R2 to filter out high-frequency interference.

[0036] Short-circuit bypass circuit: The core component is a magnetic latching relay K1, whose normally open contacts are connected between the secondary output terminals L and N of the isolation transformer. A magnetic latching relay is chosen because it only requires pulse current excitation during state switching, and maintaining the state does not consume electrical energy, making it suitable for low-power continuous operation scenarios. In this embodiment, a double-coil magnetic latching relay with a rated contact current of not less than 5A and a coil excitation voltage of 5V is selected.

[0037] Among them, the relay drive circuit reference Figure 3 As shown: First driving sub-circuit: The output terminal of GPIO1 of the control unit is connected to the base of the first NPN transistor Q1 through the first current-limiting resistor R3 (1kΩ). The base of Q1 is grounded through the pull-down resistor R4 (10kΩ). The collector of Q1 is connected to one end of the set coil SET, and the other end of the set coil is connected to VCC (5V). The emitter of Q1 is grounded. The first freewheeling diode D1 is connected in anti-parallel across the set coil (cathode connected to the VCC side).

[0038] The second driving sub-circuit: The output terminal of the control unit GPIO2 is connected to the base of the second NPN transistor Q2 through the second current-limiting resistor R5 (1kΩ). The base of Q2 is grounded through the pull-down resistor R6 (10kΩ). The collector of Q2 is connected to one end of the reset coil RESET, and the other end of the reset coil is connected to VCC. The emitter of Q2 is grounded. The second freewheeling diode D2 is connected in anti-parallel across the reset coil.

[0039] When the control unit GPIO1 outputs a high level, Q1 is turned on, the set coil is energized for about 20ms, and the magnetic latching relay contacts close (short circuit bypass established); when the control unit GPIO2 outputs a high level, Q2 is turned on, the reset coil is energized for about 20ms, and the magnetic latching relay contacts open (short circuit bypass released).

[0040] The function of pull-down resistors R4 and R6 is to ensure that the base of Q1 and Q2 remains low and cut off during the MCU power-on initialization phase when the GPIO is in a high-impedance state, thus preventing the relay from malfunctioning.

[0041] Control Unit: Employs a low-power MCU (such as the STM32L series), including an ADC module for acquiring the V_sense signal, a GPIO module for outputting relay drive signals, and a UART / RS485 interface for connection to the communication module. The control unit internally runs a fault detection algorithm; for specific logic, please refer to [reference needed]. Figure 4 As shown.

[0042] Communication module: It adopts an RS485 bus interface or a wireless communication module (such as LoRa) to communicate with the upper monitoring system, report the status information of the lamps and receive control commands.

[0043] Working principle: See Figure 4 and Figure 6 .

[0044] Normal working status ( Figure 6 State A): The normally open contact of the magnetic latching relay K1 is open, the secondary voltage of the isolation transformer is normally applied to the LED driver, and the LED lamp illuminates normally. The voltage sampling circuit collects V_sense, which is the normal operating voltage (approximately 1.1V for level 5 brightness), and the control unit determines that the lamp is working normally.

[0045] Fault Detection and Bypass Process: When an LED lamp malfunctions (e.g., an open circuit in the LED bead or a damaged driver), the LED driver no longer consumes normal power, and the voltage on the secondary side of the isolation transformer changes. The control unit periodically (e.g., every 100ms) collects the V_sense value. When V_sense is detected to be lower than the preset fault threshold V_th2 (e.g., 0.3V corresponding to level 5 brightness), and this state persists for more than the delay time T_delay (e.g., 2 seconds), the control unit confirms the lamp malfunction. Subsequently, the control unit outputs a 20ms high-level pulse through GPIO1, driving Q1 to conduct, energizing the set coil, and closing the magnetic latching relay contacts. At this time, the secondary side of the isolation transformer is short-circuited ( Figure 6 (State B) The transformer presents a low-impedance load. Simultaneously, the control unit sends a fault alarm to the upper-level system via the communication module.

[0046] The effect of the loop under short-circuit conditions ( Figure 6 Comparison of State B and State C: When the relay closes and short-circuits the secondary side of the transformer, the primary side of the transformer is equivalent to a low impedance (approximately the equivalent impedance of the short-circuited turns). Only a small voltage drop is generated in the constant current source circuit, exhibiting resistive / weak capacitive characteristics, and no additional inductive reactive load is introduced. In contrast, in the traditional scheme, when the secondary side of the transformer is open-circuited ( Figure 6In state C), the primary side is equivalent to a no-load inductor (inductive high impedance), which introduces significant inductive reactive power into the constant current source loop.

[0047] In summary, under the above solution, the LED lamp does not need to be provided with an additional open circuit simulation circuit, which simplifies the internal structure of the lamp; when the lamp fails, the isolation transformer presents low impedance instead of high inductive reactance, which reduces the inductive reactive load in the loop and improves the power quality of the loop; the latching relay does not consume electric energy in the holding state, and the system power consumption is low; the false judgment caused by transient interference such as lightning strike is avoided through the delay confirmation mechanism. Embodiment 2

[0048] It should be noted that the constant current source loop of airport aid navigation lights usually has a multi-level brightness adjustment function (such as 5 levels of brightness), different brightness levels correspond to different loop currents, and the output voltage on the secondary side of the isolation transformer also changes accordingly. If the fault detection threshold is fixed, when operating at the low brightness gear, the normal operating voltage itself is relatively low, which may be lower than the fault threshold set for the high brightness gear, resulting in a false alarm. Therefore, it is necessary to adaptively adjust the detection threshold according to the loop operating gear.

[0049] Based on the above situation, in the second embodiment, on the basis of the first embodiment, a gear-threshold correspondence table is pre-stored in the control unit. The establishment method of the correspondence table is as follows: the brightness gear, the loop current, the nominal voltage on the secondary side of the transformer, the degradation threshold V_th1, and the fault threshold V_th2 are set in one-to-one correspondence.

[0050] For example: First gear determination method, autonomous detection: after the system is powered on, the control unit enters the calibration mode. After the lamp is normally lit and operates stably (for example, 5 seconds after power-on), the amplitude of V_sense is collected, which is matched with the nominal voltage range of each gear in the pre-stored table to determine the current operating gear.

[0051] Second gear determination method, upper system notification: when the upper monitoring system switches the brightness gear of the loop, it issues a gear switching instruction to each single-lamp monitoring unit through the communication module. After receiving the instruction, the control unit updates the current gear information and the corresponding threshold.

[0052] The two methods are mutually backup: when the communication is normal, the upper system notification is the main method (with faster response), and when the communication is interrupted, the autonomous detection is taken as the standard.

[0053] Multi-level fault judgment logic: When V_sense < V_th1 but V_sense ≥ V_th2, it is determined as a performance degradation state, the control unit reports degradation warning information through the communication module, but does not trigger the short-circuit bypass action, and the lamp continues to work. This state usually corresponds to the situation where the driving power decreases due to partial failure of the LED lamp beads (for example, one string of multiple strings of LEDs is open-circuited).

[0054] When V_sense < V_th2 and the duration exceeds T_delay, a complete fault is determined, a short-circuit bypass is triggered, and a fault alarm is reported.

[0055] Through the above solution, the detection threshold is dynamically adjusted according to the actual operating gear of the loop, which eliminates the false alarm problem caused by dimming gear shifting; two states of performance degradation and complete fault are distinguished, so as to realize refined monitoring of the lamp state; in the performance degradation state, the lamp continues to work but gives an early warning, providing a planned replacement time window for maintenance personnel, avoiding unnecessary early offline of the lamp; the dual-path gear acquisition mechanism ensures that the system can still work correctly in the case of communication interruption. Embodiment 3

[0056] It should be noted that LED lamps may experience a temporary shutdown due to over-temperature protection, temporary abnormality of the driver and other reasons, and can resume working by themselves after the temperature drops or the abnormality is eliminated. If the single-lamp monitoring system permanently performs short-circuit bypass immediately after the first fault is detected, the lamp will not be able to work again even if it has returned to normal, resulting in unnecessary lamp shutdown. A mechanism is needed to automatically detect whether the lamp has recovered from a temporary fault.

[0057] Based on the above situation, in this Embodiment 3, on the basis of Embodiment 1, a self-recovery detection logic is added to the control unit. The specific implementation is as follows: Self-recovery detection period setting: after the contacts of the latching relay are closed (the short-circuit bypass is established), the control unit starts a self-recovery detection timer. The period T_recovery of the timer is set to 30 minutes (remotely configurable through the upper system). The basis for selecting 30 minutes is: after the LED lamp shuts down due to over-temperature protection, it usually takes 15-25 minutes to cool down to the restartable temperature under natural heat dissipation conditions.

[0058] Self-recovery detection process: When the self-recovery detection timer expires, the control unit outputs a 20ms high-level pulse through GPIO2, drives Q2 to conduct to energize the reset coil, disconnects the contacts of the latching relay, and releases the short-circuit bypass.

[0059] Wait for a sampling window time T_window (set to 3 seconds) to allow the LED driver sufficient time to complete power-on startup.

[0060] During the T_window period, the control unit collects the V_sense value at a high frequency (for example, every 50ms).

[0061] Judgment: If V_sense steadily rises above V_th1 (normal operating voltage range) during the T_window period, the lighting fixture is determined to have returned to normal. The control unit keeps the relay contacts open, reports the fault recovery information through the communication module, and the system returns to normal monitoring status.

[0062] If V_sense remains below V_th2 (fault threshold) during the T_window period, the luminaire is determined to still be in a fault state. The control unit immediately re-drives the set coil closed contact via GPIO1 to restore the short-circuit bypass state and continues timing to wait for the next self-recovery detection cycle.

[0063] Self-recovery test limit: To avoid frequent reset / set operations causing premature wear on the relay's mechanical life, a maximum number of self-recovery tests, N_max, is set (e.g., 48 times, corresponding to 24 hours). Light fixtures that fail to recover after N_max tests will be marked as having a confirmed permanent fault and will no longer undergo self-recovery testing until manually reset by maintenance personnel or remotely reset via a host system command.

[0064] The above solution can automatically identify temporary faults and automatically de-circuit after the lights are restored, improving the utilization rate of the lights; setting a reasonable detection cycle and sampling window ensures that the recovery detection process does not affect the normal operation of the circuit (short-term short circuit disconnection will not have a significant impact on the constant current source circuit); limiting the mechanical life of the protection relay by the maximum number of detections balances the relationship between intelligent recovery and equipment life; maintenance personnel can remotely adjust the self-recovery detection parameters through the upper system to adapt to the actual needs of different seasons and different installation environments.

[0065] refer to Figure 4 Based on the above embodiments 1-3, the MCU detection and control logic may include: After the system is powered on, the initial steps are as follows: Relay RESET (disconnect); read / detect the circuit operating position; set the thresholds V_th1 (degradation threshold) / V_th2 (fault threshold) according to the circuit position; periodically sample V_sense (every 100ms); determine if V_sense > V_th1; if yes, it is in normal condition, and periodic sampling continues; otherwise, further determine if V_th2 < V_sense ≤ V_th1; if yes, issue a performance degradation warning (report / do not bypass), and continue periodic sampling; otherwise, further determine if... If V_sense ≤ V_th2 and the duration is greater than the preset delay time T_delay, then periodic sampling continues; if so, the lamp is confirmed to be faulty, and the relay SET is triggered to bypass the short circuit; then, the fault alarm information is reported; wait for the self-recovery detection cycle T_recovery; the relay RESET (disconnects) → resampling, and V_sense is detected in the sampling window T_window; if V_sense > V_th1, the lamp returns to normal and the alarm is canceled; otherwise, SET is re-established to maintain the short circuit and returns to waiting for the self-recovery detection cycle. Example 4

[0066] It should be noted that relying solely on voltage sampling to detect luminaire faults has the following limitations: In certain LED driver fault modes (such as output short-circuit faults), the driver still draws power from the isolation transformer but the LED does not light up. In this case, the voltage on the secondary side of the transformer may still be at a certain level (the driver is still consuming power but the lamp is not lit), and voltage sampling may not be able to detect this type of dimming fault in time. Therefore, it is necessary to add an active fault signal from the luminaire side to achieve dual verification.

[0067] Based on the above, see Figure 5 In this embodiment 4, a fault signal output circuit is added to the driver circuit of the LED lamp, specifically including: Current detection unit: A low-resistance precision sampling resistor Rs (e.g., 0.1Ω) is connected in series at the output terminal of the LED driver (in the current path driving the LED string). The voltage across Rs is proportional to the LED operating current.

[0068] Comparator Circuit: A single-supply operational amplifier is configured in comparator mode. The inverting input is connected to the voltage signal on Rs (appropriately amplified), and the non-inverting input is connected to a reference voltage Vref generated by a resistor divider network. The current threshold I_th corresponding to Vref is set to 30% of the LED's rated current (i.e., a fault is determined when the LED current is lower than 30% of the rated value). When the LED output current is normal, the voltage on Rs is higher than Vref, and the comparator outputs a low level; when the LED output current is lower than I_th, the voltage on Rs is lower than Vref, and the comparator outputs a high level.

[0069] Optocoupler isolated output: The output of the comparator drives the input-side LED of the optocoupler isolator through a current-limiting resistor. The output side of the optocoupler is of open-collector / open-drain configuration, the output terminal is connected to VCC (3.3V) of the monitoring unit via a pull-up resistor R_pull (10kΩ), and is also connected to a GPIO interrupt input terminal of the control unit MCU, which is also the fault signal input terminal, for outputting the auxiliary judgment signal FAULT_OUT for lamp faults. When the fault signal input terminal is pulled low, that is, when FAULT_OUT is at a low level, it is determined that the lamp signal indicates a fault.

[0070] In normal state: The optocoupler is not conductive, and the GPIO terminal is at a high level (pulled up to VCC).

[0071] In fault state: The optocoupler is conductive, the GPIO terminal is pulled low to a level close to zero, triggering a falling edge interrupt of the MCU.

[0072] Dual verification logic: The control unit makes a judgment by integrating the voltage sampling signal and the lamp fault signal: Both signals indicate a fault at the same time (V_sense < V_th2 and FAULT_OUT is at low level): The fault is confirmed with the shortest delay time T_delay (2 seconds), and the short-circuit bypass is triggered quickly.

[0073] Only the voltage sampling signal indicates a fault (V_sense < V_th2 but FAULT_OUT is at high level): The delay is extended to T_delay1 (5 seconds) to prevent misjudgment caused by transient interference. If the voltage sampling value is still lower than the threshold V_th2 after the 5-second delay, the fault is confirmed; if the voltage returns to the normal range, it is determined as transient interference, and no fault protection is triggered.

[0074] Only the lamp signal indicates a fault (FAULT_OUT is at low level but V_sense ≥ V_th2): This may be a dark lamp fault situation. The waiting time is extended to T_delay2 (10 seconds) for continuous observation and confirmation. If V_sense gradually drops below V_th2 within T_delay2, the fault is confirmed; if V_sense remains in the normal range, it may be optocoupler signal interference, the bypass is not triggered, but a suspicious state is reported for judgment by maintenance personnel.

[0075] The above solution, through dual verification of the fault signal actively output by the lamp side and voltage sampling, can detect the hidden fault mode where the voltage is normal but the lamp does not light up; optocoupler isolation ensures electrical safety isolation between the internal lamp circuit and the monitoring unit; the differentiated delay confirmation strategy dynamically adjusts the response speed according to the signal credibility, achieving an optimal balance between fast response and misjudgment prevention; even if the optocoupler signal line is broken (permanently at high level), the system can still work independently solely by voltage sampling, with good degraded operation capability. Embodiment 5

[0076] It should be noted that in actual airport navigation lighting systems, a single constant current source series circuit typically connects dozens to hundreds of lights. When multiple lights fail simultaneously, the traditional open-circuit method will cause multiple transformers to experience inductive loads simultaneously, resulting in a more severe cumulative impact on the circuit. Therefore, it is necessary to verify the superiority of this solution in scenarios involving simultaneous multi-light failures at the system level.

[0077] refer to Figure 1 and Figure 6 As shown, taking a constant current source circuit with 60 lamps connected in series as an example, the single lamp monitoring system of this application is deployed at each lamp position.

[0078] System topology: Constant current source (constant current regulator CCR) → series loop cable → isolation transformers T1...T60 → the secondary side of each transformer is connected to the single-lamp system of this application (including monitoring unit and LED lamp). All single-lamp monitoring units are connected to the communication aggregation unit in the loop centralized control box via RS485 bus, and the communication aggregation unit is connected to the upper-level monitoring system via Ethernet or fiber optic cable.

[0079] During normal operation: all relays of the 60 individual lamp systems are in the open state, and each LED lamp illuminates normally. The constant current source outputs a constant current (e.g., 6.6A for level 5), and the total load of the circuit is the equivalent impedance of the 60 lamps connected in series.

[0080] Single-lamp fault scenario: When the LED lamp at position 15 fails, the single-lamp monitoring unit at position 15 detects a voltage drop and triggers the relay to close after confirming the fault. The secondary side of T15 is short-circuited, and the primary side of T15 is equivalent to a low impedance (approximately 0.1-0.3Ω). It consumes only a small amount of power (approximately 0.5-2W) in the constant current source circuit and exhibits resistive characteristics, which does not affect the normal power supply of the other 59 lamps.

[0081] Comparison of multiple light failure scenarios: This solution assumes that 10 lamps fail simultaneously, causing a short circuit on the secondary side of each of the 10 transformers, resulting in a resistive load of approximately 0.2Ω on the primary side. The total impact on the circuit is an increase of approximately 2Ω resistive load. The constant current source only needs to slightly increase its output voltage (approximately 13V) to maintain constant current, with no adverse effects on the circuit's power factor or waveform quality.

[0082] Traditional solution: The secondary sides of 10 transformers are open-circuited, and the primary side of each transformer exhibits inductive impedance (approximately J5Ω @ 400Hz). An inductive load of approximately J50Ω is added to the circuit. The constant current source needs to significantly increase the output voltage, and there is a significant phase difference between the output current and voltage. The power factor drops significantly, and it may even cause the constant current regulator to activate its overvoltage protection.

[0083] At the upper-level system level: The upper-level monitoring system aggregates the status information of all individual lamp systems and uses different colors to indicate the lamp status on the monitoring interface: green - normal, yellow - performance degradation, red - fault bypassed, gray - confirmed permanent fault awaiting maintenance. Maintenance personnel arrange inspection and maintenance plans based on alarm information.

[0084] In summary, in scenarios where multiple lamps fail simultaneously, this solution uses short-circuit bypass to present each faulty lamp's transformer as a low-impedance resistive load, ensuring that the cumulative impact is controllable and does not deteriorate the circuit's power quality. The constant current source can maintain constant current output within its normal adjustment range, guaranteeing stable power supply to the remaining normal lamps. The system has a complete status monitoring link from a single lamp to the entire circuit, ensuring real-time and reliable information transmission. The overall solution is fully compatible with existing constant current source series circuit architectures, allowing for gradual upgrades at the lamp level without requiring a complete replacement of the circuit equipment. Example 6

[0085] Based on the single-lamp monitoring system provided in Embodiments 1-5, Embodiment 6 of this application provides a single-lamp monitoring method. In this embodiment, the method includes the following steps: S1: The output voltage value of the secondary side of the isolation transformer is periodically collected through a voltage sampling circuit connected between the output terminals of the secondary side of the isolation transformer; S2: Compare the collected output voltage value with the preset fault threshold; S3: When the output voltage value is lower than the fault threshold and the duration exceeds the preset delay time, the LED lamp at the corresponding lamp position is determined to be faulty; S4: After determining that the LED lamp is faulty, drive the set coil of the magnetic latching relay connected across the secondary output terminal of the isolation transformer to close the normally open contact of the magnetic latching relay and short-circuit the secondary output terminal of the isolation transformer. S5: Send fault alarm information to the upper-level monitoring system.

[0086] Furthermore, after determining that the LED lighting fixture is faulty, a self-recovery test step is also included: S6: Drive the reset coil of the magnetic latching relay to open the normally open contact at a preset self-recovery detection cycle interval; S7: Within a preset sampling window time after the normally open contact is opened, the output voltage value of the secondary side of the isolation transformer is re-acquired; S8: If the output voltage value is higher than the fault threshold, the LED lamp is determined to be back to normal, the normally open contact is kept open, and fault recovery information is sent; if the output voltage value is still lower than the fault threshold, the set coil is re-driven to close the normally open contact and maintain the short-circuit bypass state.

[0087] Furthermore, prior to step S2, the following is also included: Obtain the current operating level of the constant current source series circuit; Based on the current operating gear, determine the corresponding fault threshold and degradation threshold; In step S2, the output voltage value is further compared with the degradation threshold. When the output voltage value is lower than the degradation threshold but higher than the fault threshold, the LED lamp performance is determined to be degraded, a degradation warning message is sent but the short-circuit bypass operation in step S4 is not executed.

[0088] The principles and extension schemes of the above methods and steps have been described in detail in the foregoing embodiments, and will not be repeated here.

[0089] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A single-lamp monitoring system for use in a constant current source series circuit, wherein each lamp position in the constant current source series circuit is powered through an isolation transformer, characterized in that, The single-lamp monitoring system includes: A voltage sampling circuit is connected between the secondary output terminals of the isolation transformer to collect the output voltage of the secondary side of the isolation transformer and output a voltage sampling signal. The short-circuit bypass circuit includes a magnetic latching relay connected across the secondary output terminals of the isolation transformer. The normally open contacts of the magnetic latching relay are connected between the secondary output terminals. The magnetic latching relay has a set coil and a reset coil. When the set coil is energized, the normally open contacts close to short-circuit the secondary output terminals. When the reset coil is energized, the normally open contacts open. The control unit is electrically connected to the voltage sampling circuit and the short-circuit bypass circuit respectively; the control unit is configured to: receive the voltage sampling signal, and when the voltage value indicated by the voltage sampling signal is lower than a preset fault threshold and the duration exceeds a preset delay time, determine that the LED lamp is faulty, and output a set drive signal to drive the set coil of the magnetic latching relay to close the normally open contact, thereby realizing a short circuit on the secondary side of the isolation transformer; The communication module is electrically connected to the control unit and is used to send fault alarm information to the upper-level monitoring system when the control unit determines that the LED lamp is faulty.

2. The single-lamp monitoring system according to claim 1, characterized in that, The short-circuit bypass circuit also includes: The first driving sub-circuit includes a first transistor and a first freewheeling diode; the control terminal of the first transistor is connected to the first driving output terminal of the control unit through a first current-limiting resistor, the first terminal of the first transistor is connected to one end of the set coil, and the second terminal of the first transistor is grounded; the first freewheeling diode is connected in anti-parallel to both ends of the set coil. The second driving sub-circuit includes a second transistor and a second freewheeling diode; the control terminal of the second transistor is connected to the second driving output terminal of the control unit through a second current-limiting resistor, the first terminal of the second transistor is connected to one end of the reset coil, and the second terminal of the second transistor is grounded; the second freewheeling diode is connected in anti-parallel to both ends of the reset coil. The control terminals of the first and second transistors are respectively connected to ground via pull-down resistors to keep the transistors off when the control unit does not output a drive signal.

3. The single-lamp monitoring system according to claim 1, characterized in that, The control unit is also configured to: Obtain the current operating level information of the constant current source series circuit; Based on the current operating gear information, the corresponding fault threshold and degradation threshold are queried from the preset gear-threshold correspondence table; wherein, the degradation threshold is higher than the fault threshold; When the voltage value indicated by the voltage sampling signal is lower than the degradation threshold but higher than the fault threshold, the LED lamp performance is determined to be degraded, and a degradation warning message is sent through the communication module, but the short-circuit bypass circuit is not triggered.

4. The single-lamp monitoring system according to claim 1, characterized in that, The control unit is also configured to perform self-recovery detection: After the normally open contact of the magnetic latching relay is closed, a reset drive signal is output at a preset self-recovery detection period to drive the reset coil to open the normally open contact. Within a preset sampling window period after the normally open contact is opened, the voltage sampling signal is re-acquired; If the voltage value indicated by the voltage sampling signal is higher than the fault threshold, it is determined that the LED lamp has resumed normal operation, the normally open contact remains open, and fault recovery information is sent through the communication module. If the voltage value indicated by the voltage sampling signal is still lower than the fault threshold, a set drive signal is output again to close the normally open contact and maintain the short-circuit bypass state.

5. The single-lamp monitoring system according to claim 1, characterized in that, It also includes a fault signal output circuit disposed inside the LED lamp; The fault signal output circuit includes: A current detection unit is used to detect the output current of the LED driver circuit of the LED lamp. The comparator has its non-inverting input connected to a preset reference voltage and its inverting input connected to the output of the current detection unit. An optocoupler is provided, wherein the input terminal of the optocoupler is connected to the output of the comparator, and the output terminal of the optocoupler is connected to the power supply voltage of the control unit through a pull-up resistor, and is also connected to the fault signal input terminal of the control unit. When the output current of the LED driver circuit is lower than the preset current threshold, the comparator output turns on the optocoupler isolator, the fault signal input terminal is pulled low, and the control unit obtains an auxiliary judgment signal for lamp fault based on this.

6. The single-lamp monitoring system according to claim 5, characterized in that, The control unit is configured to: When only the voltage sampling signal indicates that the voltage is lower than the fault threshold, but the fault signal input terminal is not pulled low, the delay time is extended to a first extension time before the fault is confirmed. When only the fault signal input terminal is pulled low, and the voltage sampling signal indicates that the voltage is not lower than the fault threshold, the delay time is extended to a second extension time before the fault is confirmed. When the voltage sampling signal indicates that the voltage is lower than the fault threshold and the fault signal input terminal is simultaneously pulled low, the fault is confirmed with the original preset delay time.

7. The single-lamp monitoring system according to claim 3, characterized in that, The control unit obtains the current operating level information of the constant current source series circuit in the following ways: The control unit collects the amplitude of the voltage sampling signal within a preset calibration time window after the system is powered on and stabilized through the voltage sampling circuit, compares the amplitude with the pre-stored standard voltage range for each gear, and determines the current operating gear. And / or, the control unit receives a gear switching command issued by the upper-level monitoring system through the communication module, thereby knowing the current operating gear.

8. A single-lamp monitoring method, applied to the single-lamp monitoring system according to any one of claims 1-7, characterized in that, Includes the following steps: S1: The output voltage value of the secondary side of the isolation transformer is periodically collected through a voltage sampling circuit connected between the output terminals of the secondary side of the isolation transformer; S2: Compare the collected output voltage value with the preset fault threshold; S3: When the output voltage value is lower than the fault threshold and the duration exceeds the preset delay time, the LED lamp at the corresponding lamp position is determined to be faulty; S4: After determining that the LED lamp is faulty, drive the set coil of the magnetic latching relay connected across the secondary output terminal of the isolation transformer to close the normally open contact of the magnetic latching relay and short-circuit the secondary output terminal of the isolation transformer. S5: Send fault alarm information to the upper-level monitoring system.

9. The single-lamp monitoring method according to claim 8, characterized in that, It also includes a self-recovery detection step: S6: Drive the reset coil of the magnetic latching relay to open the normally open contact at a preset self-recovery detection cycle interval; S7: Within a preset sampling window time after the normally open contact is opened, the output voltage value of the secondary side of the isolation transformer is re-acquired; S8: If the output voltage value is higher than the fault threshold, the LED lamp is determined to be back to normal, the normally open contact is kept open, and fault recovery information is sent; if the output voltage value is still lower than the fault threshold, the set coil is re-driven to close the normally open contact and maintain the short-circuit bypass state.

10. The single-lamp monitoring method according to claim 8, characterized in that, The procedure before step S2 also includes: Obtain the current operating level of the constant current source series circuit; Based on the current operating gear, determine the corresponding fault threshold and degradation threshold; In step S2, the output voltage value is further compared with the degradation threshold. When the output voltage value is lower than the degradation threshold but higher than the fault threshold, the LED lamp performance is determined to be degraded, a degradation warning message is sent but the short-circuit bypass operation in step S4 is not executed.

Images