A method and apparatus for multi-channel LED constant current dimming based on PD protocol EPR AVS mode

Abstract

The application discloses a multi-channel LED constant-current dimming method and device based on a PD protocol EPR AVS mode, which comprises the following steps: receiving external brightness control information and analyzing the target brightness data corresponding to a plurality of LED drive branches; collecting the working voltage and working current of each LED drive branch, and determining a reference branch according to the working voltage of each LED drive branch; controlling a PD power receiving module to adjust the bus output voltage according to the working state of the reference branch, and adjust the PWM duty cycle of the reference branch; determining the compensation PWM duty cycle of each non-reference branch according to the current bus output voltage, the working voltage of each non-reference branch and the PWM duty cycle of the reference branch; and performing closed-loop correction on the compensation PWM duty cycle according to the actual working current of each non-reference branch. The device comprises a PD power receiving module, an input module, a collection module, a control module and a driving module. The application can realize the collaborative control of bus power supply and multi-branch driving, reduce the voltage difference loss and improve the multi-channel LED dimming consistency.

Description

Technical Field

[0001] This application relates to the field of LED dimming control technology, and in particular to a multi-channel LED constant current dimming method and device based on the PD protocol EPR AVS mode. Background Technology

[0002] With the development of multi-channel LED lighting, ambient lighting, automotive lighting, and modular lighting equipment, it has become common practice to set up multiple LED driver branches within the same device and adjust their brightness separately. Meanwhile, power supply based on the USB PD protocol, due to its advantages of strong power supply capability and high interface versatility, is also gradually being applied to related lighting equipment. In particular, the EPR AVS mode in the PD protocol can dynamically negotiate output over a wide voltage range, providing an adjustable bus voltage for multi-channel LED systems. Therefore, combining the dynamic power supply capability of PD with constant current dimming control of multi-channel LEDs has become an important direction in this technology.

[0003] In existing multi-channel LED dimming solutions, one type typically uses a fixed bus voltage, with brightness control achieved through PWM dimming or constant current driving of each branch. This type of solution has a relatively simple structure, but because the LED groups connected to different LED driver branches often differ in terms of the number of LEDs in series, forward voltage drop, line loss, and temperature rise, the actual bus voltage requirements of each branch are not consistent. A fixed bus voltage cannot simultaneously meet the driving needs of all branches, easily leading to situations where the overall bus voltage setting is too high, resulting in redundant voltage drop losses and heat generation, or the bus voltage setting is too low, causing some branches to fail to reach the target current, thus causing inconsistencies in current and brightness between multiple branches. Another type of solution attempts to improve adaptability by independently adjusting the power supply of each branch or adding complex power stages, but often suffers from problems such as complex circuits, a large number of components, long control links, and high cost and size, making it unsuitable for implementation in multi-channel compact lighting equipment.

[0004] Furthermore, even when adjustable power supplies are introduced in existing technologies, power supply regulation and branch dimming are often handled separately, lacking a mechanism for coordinated control based on the actual load status of multiple branches. For example, when branch loads change, brightness demands change abruptly, or an anomaly occurs in a branch, existing solutions often struggle to promptly rematch the bus voltage with the driving relationships of each branch, leading to lag in regulation, unstable control, or inaccurate references. Therefore, there is an urgent need for a multi-channel LED constant current dimming solution based on the PD protocol EPR AVS mode. This solution should be able to dynamically determine the voltage regulation basis according to the actual operating status of multiple branches under shared bus power supply conditions, coordinate bus output voltage regulation with compensation control of each branch, and rebuild the corresponding control relationships when branch status changes, thus balancing energy efficiency, consistency, and dynamic adaptability in the multi-channel LED dimming process. Summary of the Invention

[0005] The purpose of this application is to solve the aforementioned problems (summarized in a dozen or so words).

[0006] According to one aspect of this application, a multi-channel LED constant current dimming method based on the PD protocol EPR AVS mode is provided, comprising: S10. Receive external brightness control information and parse it to obtain the target brightness data corresponding to multiple LED driver branches; S20. Collect the operating voltage and operating current of each LED driver branch, and determine the reference branch based on the operating voltage of each LED driver branch. S30. Control the PD power receiving module to work in PD protocol EPR AVS mode, adjust the bus output voltage according to the working state of the reference branch, and adjust the PWM duty cycle of the reference branch so that the working current of the reference branch reaches the preset constant current threshold. S40. Based on the current bus output voltage, the operating voltage of each non-reference branch, and the PWM duty cycle of the reference branch, determine the compensation PWM duty cycle of each non-reference branch, and output the corresponding PWM control signal. S50. Collect the actual operating current of each non-reference branch, and perform closed-loop correction on the compensation PWM duty cycle of each non-reference branch based on the deviation of the actual operating current of each non-reference branch from the preset constant current threshold. After the reference branch is re-determined, readjust the bus output voltage based on the re-determined reference branch, and re-determine the compensation PWM duty cycle of each non-reference branch.

[0007] Preferably, step S40 includes: S41. Based on the correspondence between the working voltage of each non-reference branch and the current bus output voltage, and in conjunction with the PWM duty cycle of the reference branch, determine the initial compensation amount of each non-reference branch. S42. Generate the compensation PWM duty cycle of each non-reference branch based on the initial compensation amount of each non-reference branch, so that the working current of each non-reference branch is adjusted towards the preset constant current threshold.

[0008] Preferably, step S50 includes: S51. Collect the actual operating current of each non-reference branch at a preset sampling period, and determine the corresponding current deviation rate based on the deviation between the actual operating current and the preset constant current threshold. S52. Select the corresponding dynamic correction coefficient according to the deviation range where the current deviation rate is located, and correct the compensation PWM duty cycle of each non-reference branch. S53. After each correction, the actual operating current is collected again after a preset stabilization waiting period, and the current deviation rate is re-determined. S54. When the corrected current deviation rate is within the allowable range, the closed-loop correction is completed. S55. When the corrected current deviation rate still exceeds the allowable range, repeat steps S51 to S53 until the accuracy requirement is met or the preset maximum number of iterations is reached. S56. When the current deviation rate still exceeds the allowable range after the preset maximum number of iterations is reached, a fault warning signal is output.

[0009] Preferably, step S50 further includes: S57. When the actual operating current of the reference branch deviates from the preset constant current threshold by more than the preset reference deviation threshold, the PWM duty cycle of the reference branch is adjusted first to make the operating current of the reference branch adjust toward the preset constant current threshold. S58. Based on the adjusted PWM duty cycle of the reference branch and the current bus output voltage, redetermine the compensation PWM duty cycle of each non-reference branch. S59. Perform closed-loop correction on the compensated PWM duty cycle of each non-reference branch after redetermining.

[0010] Preferably, in step S50, the re-determination of the reference branch includes: S501: Cyclicly collect and compare the operating voltage of each LED driver branch according to a preset collection cycle; S502. When the operating voltage of any LED driver branch is higher than the operating voltage of the current reference branch for multiple consecutive sampling cycles, and the difference between the two is greater than or equal to a preset voltage difference threshold, the LED driver branch is updated to a new reference branch. S503. After the new reference branch is determined, the bus output voltage is readjusted based on the new reference branch, and the compensation PWM duty cycle of each non-reference branch is re-determined based on the readjusted bus output voltage and the PWM duty cycle of the new reference branch. The compensation PWM duty cycle of each non-reference branch is then corrected in a closed loop.

[0011] Preferably, in step S50, the re-determination of the reference branch further includes: S504. When an open circuit, short circuit or overcurrent fault occurs in the current reference branch, the faulty branch is shielded, and the LED driver branch with the largest working voltage is selected from the remaining normal branches as the new reference branch. At the same time, a fault signal is output. S505. When the change in brightness requirement corresponding to the external brightness control information is greater than or equal to the preset brightness change threshold, a reference branch re-identification is performed after the brightness adjustment is completed. S506. The reference branch is re-determined according to the priority of fault-triggered reselection over brightness change-triggered reselection, and brightness change-triggered reselection over regular cycle reselection, and the original bus output voltage is kept temporarily stable during the reselection process.

[0012] Preferably, step S30 includes: S31. When the voltage difference between the working voltage of the reference branch and the initial bus output voltage is greater than or equal to a preset voltage difference threshold, the deviation of the working current of the reference branch relative to the preset constant current threshold is greater than or equal to a preset deviation threshold, or the change in the external brightness control information is greater than or equal to a preset brightness change threshold, the PD power receiving module is triggered to perform bus output voltage adjustment. S32. During the process of regulating the bus output voltage, set the dead zone for bus output voltage regulation, the delay confirmation period after the voltage regulation command is issued, and the minimum time interval for continuous voltage regulation to suppress bus output voltage oscillation.

[0013] Preferably, step S30 further includes: S33. Limit the voltage regulation range of the PD power receiving module to a preset voltage range; S34. Limit the single voltage adjustment step to within the preset step limit; S35. When the target voltage regulation value exceeds the preset voltage range or the single voltage regulation step exceeds the preset step upper limit, the target voltage regulation value or the single voltage regulation step is corrected to the corresponding critical value and then the bus output voltage is regulated.

[0014] Preferably, step S10 includes: S11. Receive external independent frequency PWM signal, brightness data in serial port format, or brightness data in I2C format as the external brightness control information, and the external brightness control information is independent of the local LED current control PWM signal and has no synchronization constraint. S12. Read the control signal configuration and determine the target channel corresponding to the external brightness control information; S13. According to the preset channel mapping relationship, map the target channel as at least one target LED driving branch; S14. Determine the corresponding target brightness data and load requirements based on the mapped target LED driving branch, and adjust the bus output voltage and output the corresponding PWM control signal based on the target brightness data and load requirements.

[0015] This application also provides a multi-channel LED constant current dimming device based on the PD protocol EPR AVS mode, wherein the device operates by applying the multi-channel LED constant current dimming method based on the PD protocol EPR AVS mode as described above, and the device includes: The PD power receiving module is used to connect to an external PD power supply and output bus voltage; The input module is used to receive external control signals; The acquisition module is used to acquire the status signals of each LED driver branch; The control module is connected to the PD power receiving module, the input module, and the acquisition module respectively, and is used to output control signals according to the external control signals and the status signals; A driving module, connected to the PD power receiving module and the control module, is used to drive multiple LED driving branches according to the control signal; The output terminals of both the input module and the acquisition module are connected to the control module. The output terminal of the control module is connected to both the PD power receiving module and the drive module. The output terminal of the PD power receiving module is connected to the drive module.

[0016] This application offers the following advantages: By receiving and parsing external brightness control information, it identifies the reference branch with the highest current demand for bus output voltage. It then dynamically adjusts the bus output voltage using the PD protocol EPR AVS mode, generates compensating PWM duty cycles for each non-reference branch based on the PWM duty cycle of the reference branch, performs closed-loop correction in conjunction with the actual operating current, and synchronously reconstructs the bus adjustment relationship and branch compensation relationship when the reference branch changes. This solves the problems in existing multi-channel LED dimming, such as the difficulty of using a fixed bus output voltage to meet the voltage demands of different branches, the generation of redundant voltage drop losses, poor consistency of current and brightness between different lamp groups, and adjustment lag after load changes. It achieves coordinated control of bus power supply and multi-branch drive, reduces power consumption and heat generation, and improves the consistency, dynamic adaptability, and operational stability of multi-channel LED dimming. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a multi-channel LED constant current dimming method based on the PD protocol EPR AVS mode, as described in one embodiment of this application. Detailed Implementation

[0019] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Please refer to Figure 1 One embodiment of this application provides a multi-channel LED constant current dimming method based on the PD protocol EPR AVS mode, including: S10. Receive external brightness control information and parse it to obtain the target brightness data corresponding to multiple LED driver branches.

[0022] In this step, it should be noted that the external brightness control information is used to characterize the brightness adjustment requirements of multiple LEDs by the external control terminal. This information can be an external independent frequency PWM signal, or brightness data in serial or I2C format. The target brightness data is used to characterize the target brightness level, target drive intensity, or target current reference for each LED driver branch at the current moment. The technical feature of this step is that it first uniformly converts external control inputs from different sources and in different formats into target brightness data that can be directly called by the subsequent control chain, so that subsequent branch identification, bus voltage regulation, and compensation control are established on a unified target reference. The "receiving" in this step includes not only the acquisition of external signals but also the identification of signal frequency, amplitude, data bit width, channel identifier, and update timing. The "parsing" not only includes converting the signal into brightness values ​​but also mapping the brightness adjustment requirements to multiple LED driver branches to form target information that can be called by subsequent bus output voltage linkage and PWM regulation. Preferably, the external brightness control information and the local LED current control PWM signal are independent of each other and have no synchronization constraints, so that the external control side and the local execution side belong to different control domains, avoiding the direct interference of changes in the external control protocol with the local constant current control rhythm.

[0023] S20. Collect the operating voltage and current of each LED driver branch, and determine the reference branch based on the operating voltage of each LED driver branch.

[0024] In this step, it should be noted that the operating voltage is used to characterize the actual demand of the corresponding LED driver branch on the bus output voltage under the current target brightness, and the operating current is used to characterize the current driving state and actual light output execution state of the corresponding LED driver branch. Since the LED groups connected to different LED driver branches may have differences in the number of LEDs in series, forward voltage drop, wiring loss, and thermal drift, the demand for bus output voltage for each LED driver branch under the same brightness target is not consistent. The technical feature of this step is that by simultaneously acquiring the operating voltage and operating current, the actual load state of multiple branches is sensed online, and the branch with the highest operating voltage is selected as the reference branch. The "reference branch" in this step refers to the LED driver branch with the highest demand for bus output voltage among all branches, and serves as the reference object for adjusting the bus output voltage. Using it as the adjustment anchor point can avoid setting the bus output voltage too low, causing high-voltage demand branches to fail to reach the target current, and also avoid setting the overall bus output voltage too high, causing other branches to suffer unnecessary voltage difference losses. Preferably, the operating voltage can be the voltage across the LED lamp group, the voltage at the drive output terminal, or an equivalent voltage signal that can reflect the load requirements of the branch. The operating current can be obtained by a sampling resistor, a current detection chip, or a drive feedback path.

[0025] S30: Control the PD power receiving module to work in PD protocol EPR AVS mode, adjust the bus output voltage according to the working status of the reference branch, and adjust the PWM duty cycle of the reference branch so that the working current of the reference branch reaches the preset constant current threshold.

[0026] In this step, it should be noted that the PD protocol EPR AVS mode refers to the PD receiving end being able to dynamically negotiate with the external PD power supply within an extended power range and request output voltage in small steps; the bus output voltage is the power supply voltage shared by multiple LED driver branches; the preset constant current threshold refers to a pre-set target operating current, such as 300mA or other target values ​​set according to the lamp group specifications. The technical feature of this step is that instead of using a fixed bus output voltage to uniformly power all branches, the bus output voltage is dynamically adjusted according to the operating state of the reference branch, and at the same time, the operating current of the reference branch is made to reach the preset constant current threshold by adjusting the PWM duty cycle of the reference branch, thereby forming a joint control structure of "protocol layer voltage regulation + branch-side current control". The "operating state" in this step includes at least the operating voltage and operating current of the reference branch and their deviation relationship with the preset constant current threshold; "adjusting the bus output voltage" means outputting a voltage regulation request to the PD receiving module according to the current voltage margin required by the reference branch, so that the bus output voltage changes in a direction that is more suitable for the load state of the reference branch. Preferably, the bus output voltage is adjusted in small steps, such as with an adjustment granularity of 0.1V, and can be combined with a voltage regulation dead zone, a delay confirmation period, and a minimum voltage regulation interval to reduce the fluctuation of the bus output voltage around the target. When the target voltage regulation value is close to the boundary or exceeds the allowable range, the voltage regulation result can be limited to a preset voltage range, such as 5V to 48V.

[0027] S40. Based on the current bus output voltage, the operating voltage of each non-reference branch and the PWM duty cycle of the reference branch, determine the compensation PWM duty cycle of each non-reference branch and output the corresponding PWM control signal.

[0028] In this step, it should be noted that the non-reference branches refer to the LED driving branches other than the reference branch; the compensation PWM duty cycle is a PWM control quantity generated for each non-reference branch based on the current bus output voltage conditions and the driving state of the reference branch. The technical feature of this step is that, after the reference branch has completed bus output voltage anchoring, instead of further increasing the bus output voltage to satisfy all branches, the compensation PWM duty cycle of each non-reference branch is determined by utilizing the coordination relationship between the operating voltage of each non-reference branch, the current bus output voltage, and the PWM duty cycle of the reference branch. This allows each non-reference branch to still obtain driving capability adapted to its own load state under the condition of sharing the bus output voltage. The "correspondence relationship" in this step can be a proportional relationship, a difference relationship, a segmented relationship, or a preset mapping relationship. Essentially, it generates the initial compensation control quantity for each non-reference branch based on the voltage margin state of each non-reference branch relative to the current bus output voltage, combined with the driving level corresponding to the current PWM duty cycle of the reference branch. Therefore, the reference branch is responsible for determining the bus output voltage, while the non-reference branch relies on the compensated PWM duty cycle to complete fine adjustment, thus forming a collaborative dimming method with a clear division of responsibilities among the branches.

[0029] S50. Collect the actual operating current of each non-reference branch, and perform closed-loop correction on the compensation PWM duty cycle of each non-reference branch based on the deviation of the actual operating current of each non-reference branch from the preset constant current threshold. After the reference branch is re-determined, readjust the bus output voltage based on the re-determined reference branch, and re-determine the compensation PWM duty cycle of each non-reference branch.

[0030] In this step, it should be noted that the compensated PWM duty cycle obtained in step S40 is preferably used as the initial open-loop value. Step S50 further utilizes the actual operating current of each non-reference branch to construct a feedback closed loop to correct the compensated PWM duty cycle online. The "closed-loop correction" in this step refers to dynamically increasing or decreasing the compensated PWM duty cycle based on the deviation between the actual operating current and the preset constant current threshold, so that the operating current of each non-reference branch gradually converges to near the preset constant current threshold. "Re-determination of the reference branch" means that when a branch exhibits a higher operating voltage requirement in subsequent operation, or when the original reference branch malfunctions or the brightness requirement changes significantly, a new LED driver branch is determined as the reference branch. The technical feature of this step is that the non-reference branch not only obtains the initial compensated PWM duty cycle based on open-loop calculation, but also continuously corrects it through feedback from the actual operating current. Once the reference branch changes, not only is the reference branch re-identified, but the control chain of "bus output voltage—reference branch PWM duty cycle—non-reference branch compensated PWM duty cycle" is also simultaneously rebuilt, rather than simply replacing the branch name. Preferably, the closed-loop correction can adopt a preset sampling period and a stabilization waiting period, such as a sampling period of 5ms and a stabilization waiting period of 3ms, and be combined with the allowable error range and the maximum number of iterations, so that the correction process takes into account both convergence speed and stability.

[0031] The technical solution implemented in this embodiment can first unify various forms of external control requirements into target brightness data corresponding to each LED driving branch. Then, it identifies the reference branch with the highest current demand for bus output voltage through the branch operating voltage, and uses the PD protocol EPR AVS mode to dynamically match the bus output voltage, so that the bus output voltage is no longer fixed at a single high voltage level, but is adaptively adjusted around the current load demand. At the same time, using the PWM duty cycle of the reference branch as a reference, a compensating PWM duty cycle is generated for each non-reference branch, so that different branches can still obtain drive control that matches their own load state under the condition of sharing the bus output voltage. Furthermore, the actual operating current feedback is used to perform closed-loop correction of the compensating PWM duty cycle. When the reference branch changes, the bus output voltage regulation relationship and the non-reference branch compensation relationship can be reconstructed synchronously. Therefore, this embodiment can reduce redundant voltage difference losses caused by fixed high bus output voltage in scenarios where multiple LEDs work together, reduce current inconsistency and brightness inconsistency caused by differences in parameters of different lamp groups, and improve the system's dynamic adaptability and operational stability to load changes, brightness step changes, branch faults and multi-protocol input scenarios.

[0032] In one specific embodiment, step S40 includes: S41. Based on the correspondence between the working voltage of each non-reference branch and the current bus output voltage, and in conjunction with the PWM duty cycle of the reference branch, determine the initial compensation amount of each non-reference branch.

[0033] In this step, it should be noted that the non-reference branches refer to the LED driving branches other than the reference branch; the operating voltage is used to characterize the actual driving voltage requirement of the corresponding non-reference branch under the current target brightness; the current bus output voltage is the power supply voltage shared by all LED driving branches after being regulated by the PD power receiving module; the PWM duty cycle of the reference branch is used to characterize the driving intensity corresponding to the reference branch reaching the preset constant current threshold under the current bus output voltage. The technical feature of this step is that it does not directly apply a uniform duty cycle control to each non-reference branch, but first determines the voltage margin, compensation requirement, and adjustment direction of each non-reference branch under the current bus output voltage condition based on the correspondence between the operating voltage of each non-reference branch and the current bus output voltage, and then combines the PWM duty cycle of the reference branch to form the initial compensation amount corresponding to each non-reference branch. The correspondence can be expressed as a proportional relationship, a difference relationship, a segmented relationship, or a preset mapping relationship. Essentially, it utilizes the load matching degree of each non-reference branch relative to the bus output voltage to establish a compensation reference relationship between each non-reference branch and the reference branch. Preferably, when the operating voltage of a non-reference branch is closer to the current bus output voltage, its corresponding initial compensation amount can be set closer to the drive level of the reference branch; when the operating voltage of a non-reference branch is significantly lower than the current bus output voltage, its corresponding initial compensation amount can be reduced accordingly to avoid applying excessively high drive intensity under a large voltage margin, resulting in excessively high current. By first determining the initial compensation amount, the branch voltage difference, bus power supply status, and reference branch drive status can be uniformly incorporated into the same compensation calculation link, providing an intermediate reference amount for subsequently generating the compensation PWM duty cycle.

[0034] S42. Generate the compensation PWM duty cycle of each non-reference branch based on the initial compensation amount of each non-reference branch, so that the working current of each non-reference branch is adjusted to compensate towards the preset constant current threshold.

[0035] In this step, it should be noted that the compensated PWM duty cycle is a control quantity applied to the corresponding non-reference branch drive circuit, used to adjust the conduction level and average drive energy of the corresponding non-reference branch; the preset constant current threshold is the target operating current expected to be achieved by each LED drive branch. The technical feature of this step is that the initial compensation quantity obtained in step S41 is further converted into a compensated PWM duty cycle that can be directly executed by each non-reference branch, enabling each non-reference branch to obtain differentiated drive control based on its own load state while sharing the current bus output voltage. The generation process may include normalization of the initial compensation quantity, upper and lower limit constraint processing, duty cycle resolution matching processing, and outlier correction processing to ensure that the generated compensated PWM duty cycle meets the output requirements and control stability requirements of the drive circuit. Preferably, when the generated result exceeds the preset duty cycle range, it can be limited to the corresponding boundary value; when the duty cycle change between two adjacent control cycles is too large, the duty cycle change amplitude can also be limited to reduce sudden changes in branch current. By generating a compensation PWM duty cycle based on the initial compensation amount, each non-reference branch can pre-compensate the actual operating current with its corresponding PWM control signal without changing the current bus output voltage. This allows the operating current of each non-reference branch to converge from the initial state toward the preset constant current threshold, and provides an initial control amount closer to the target value for subsequent closed-loop correction.

[0036] The technical solution implemented in this embodiment can first establish a compensation reference relationship between branches by utilizing the operating voltage of each non-reference branch, the current bus output voltage, and the PWM duty cycle of the reference branch. Then, this compensation reference relationship is converted into a compensation PWM duty cycle that can be executed by each non-reference branch. This allows the non-reference branches to obtain targeted drive compensation according to their respective load states, even when the bus output voltage has been anchored by the reference branch. This not only avoids the current imbalance problem caused by applying the same PWM control signal to all branches, but also reduces the redundant voltage drop loss and heat generation caused by raising the overall bus output voltage to take into account all branches. Thus, in scenarios where multiple LEDs work together, it can balance dimming consistency, drive efficiency, and control stability.

[0037] In one specific embodiment, step S50 includes: S51. Collect the actual operating current of each non-reference branch at a preset sampling period, and determine the corresponding current deviation rate based on the deviation between the actual operating current and the preset constant current threshold.

[0038] In this step, it should be noted that the actual operating current is used to characterize the true output state of each non-reference branch under the current compensated PWM duty cycle; the preset sampling period is used to limit the update time interval of current feedback sampling to balance control response speed and sampling stability. Preferably, the preset sampling period can be set to 5ms or other periods adapted to the drive frequency and sampling accuracy; the current deviation rate is used to characterize the degree of deviation of the current non-reference branch from the target drive state. The technical feature of this step is that it does not rely solely on the theoretical calculation results of the compensated PWM duty cycle for static control, but further establishes a feedback relationship between the control quantity and the true output result by real-time acquisition of the actual operating current of each non-reference branch. The determination of the current deviation rate based on the deviation between the actual operating current and the preset constant current threshold can be achieved by using difference normalization, proportional conversion, or preset deviation mapping. The essence of all these methods is to uniformly convert the deviations of different branches under different absolute current values ​​into comparable and graded deviation quantities. This step ensures that the selection of subsequent dynamic correction coefficients and the correction of the PWM duty cycle are based on actual output feedback, thereby avoiding the cumulative error between branches caused by relying solely on open-loop estimation.

[0039] S52. Select the corresponding dynamic correction coefficient according to the deviation range where the current deviation rate is located, and correct the compensation PWM duty cycle of each non-reference branch.

[0040] In this step, it should be noted that the dynamic correction coefficient is used to characterize the correction intensity of the PWM duty cycle compensation under the current deviation state. It can be obtained by segmenting according to a preset deviation range, or by looking up a table or a preset algorithm. The technical feature of this step is that it transforms the current deviation rate from a simple detection result into a control basis for actual correction actions, i.e., different correction intensities are applied for different degrees of deviation. When the current deviation rate is small, a smaller dynamic correction coefficient can be used for fine-tuning to reduce duty cycle jitter; when the current deviation rate is large, a larger dynamic correction coefficient can be used for rapid pull-back to shorten the convergence time. Preferably, the deviation range can be divided into at least an allowable error range, a small deviation correction range, and a large deviation correction range, wherein no correction or only a very small correction may be performed within the allowable error range. By selecting the dynamic correction coefficient according to the deviation range, the compensation PWM duty cycle correction process of each non-reference branch can maintain sufficient adjustment sensitivity while avoiding over-response to small disturbances.

[0041] S53. After each correction, the actual operating current is collected again after a preset stabilization waiting period, and the current deviation rate is re-determined.

[0042] In this step, it should be noted that the preset stabilization waiting period is used to provide stabilization time for the LED drive branch, current sampling link, and bus-side state after the PWM duty cycle update, avoiding the introduction of transient errors due to immediate resampling before the control quantity change has completed its transmission and convergence. Preferably, the preset stabilization waiting period can be set to 3ms or other time lengths adapted to the drive response speed and sampling characteristics. The technical feature of this step is that a clear dynamic buffer stage is set between two adjacent corrections, so that each current feedback reflects the stable state under the current correction result as much as possible, rather than reflecting the transitional state during the control quantity switching process. Through this step, the effectiveness and reliability of subsequent current deviation rate recalculation can be improved.

[0043] S54. When the corrected current deviation rate is within the allowable range, the closed-loop correction is completed.

[0044] In this step, it should be noted that the allowable range is used to define the conditions under which each non-reference branch has reached an acceptable current accuracy within the current control cycle. This range can be set according to the system's consistency requirements, for example, ±2% or other allowable error ranges. The technical feature of this step is that it sets a clear termination criterion for the closed-loop correction process, avoiding unnecessary correction actions when the control accuracy requirements are already met. Through this step, each non-reference branch can exit the current correction process promptly after reaching the target current current accuracy, thereby reducing control resource consumption and duty cycle disturbance frequency.

[0045] S55. If the corrected current deviation rate still exceeds the allowable range, repeat steps S51 to S53 until the accuracy requirement is met or the preset maximum number of iterations is reached.

[0046] In this step, it should be noted that the preset maximum number of iterations is used to limit the maximum number of repetitions of closed-loop correction within a single control cycle, in order to avoid prolonged ineffective iterations. Preferably, the preset maximum number of iterations can be set to 5 times or other upper limits that are compatible with the response requirements. The technical feature of this step is that it allows the closed-loop correction to be repeated multiple times within a certain range, enabling each non-reference branch to gradually absorb the control errors caused by device discreteness, line losses, temperature rise changes, and LED forward voltage drop fluctuations; at the same time, it constrains the correction process by limiting the maximum number of iterations, preventing the continuous occupation of control resources under abnormal conditions. Through this step, the closed-loop correction is no longer a single correction action, but becomes a convergence process with multi-round adaptive adjustment capabilities.

[0047] S56. When the current deviation rate still exceeds the allowable range after reaching the preset maximum number of iterations, output a fault warning signal.

[0048] In this step, it should be noted that the fault warning signal is used to characterize the inability of the current non-reference branch to converge to the target current state within the predetermined control range. This may correspond to situations such as abnormal branch load, abnormal drive, abnormal sampling, abnormal line contact, or control failure. The technical feature of this step is that when the closed-loop correction cannot converge within a preset number of iterations, it no longer blindly continues iterating, but instead reports the state as an anomaly so that external control equipment, the host computer, or protection logic can intervene. The fault warning signal can be used to trigger prompt display, operation recording, branch isolation, power limiting operation, or subsequent protection actions. Through this step, the closed-loop control chain, in addition to normal adjustment capabilities, also possesses the ability to identify and report anomalies.

[0049] The technical solution implemented in this embodiment can continuously acquire the actual operating current of each non-reference branch through a preset sampling period after the initial control result is formed by the compensated PWM duty cycle. The deviation between the actual operating current and the preset constant current threshold is converted into a current deviation rate. Then, the corresponding dynamic correction coefficient is selected according to the deviation range of the current deviation rate to perform graded correction on the compensated PWM duty cycle. At the same time, by setting a preset stable waiting period after each correction and establishing a complete closed-loop judgment chain between the allowable range, the maximum number of iterations, and the fault warning signal, the control process of each non-reference branch can gradually converge to near the preset constant current threshold, and can output abnormal information in a timely manner when convergence fails. Therefore, this embodiment can not only improve the current control accuracy of each non-reference branch and the brightness consistency between multiple branches, but also avoid frequent over-adjustment and long-term ineffective correction, thereby improving the stability, reliability, and anomaly controllability of the entire multi-channel LED constant current dimming process.

[0050] In one specific embodiment, step S50 further includes: S57. When the actual operating current of the reference branch deviates from the preset constant current threshold by more than the preset reference deviation threshold, the PWM duty cycle of the reference branch is adjusted first to make the operating current of the reference branch adjust toward the preset constant current threshold.

[0051] In this step, it should be noted that the reference branch serves as both the adjustment reference branch for the current bus output voltage and the reference branch for compensating the PWM duty cycle of each non-reference branch. Its control state directly affects the accuracy of the subsequent compensation results of each non-reference branch. The preset reference deviation threshold is used to characterize the judgment boundary of whether the reference branch deviates from the reference state. It can be set according to the system's requirements for current consistency, for example, it can be set to a threshold higher than the allowable error range to avoid frequent triggering of linkage adjustment by the reference branch when there are small fluctuations. The technical feature of this step is that when it is detected that the deviation of the actual operating current of the reference branch from the preset constant current threshold has reached the preset reference deviation threshold, instead of directly continuing to independently correct the non-reference branches, the PWM duty cycle of the reference branch itself is adjusted first, so that the reference branch is restored to a reference state closer to the preset constant current threshold. The "priority adjustment" means that within the same control cycle, the correction action of the reference branch is performed before the compensation correction action of the non-reference branches, so that the reference quantity is corrected first, and then the referenced quantity is corrected. Preferably, the adjustment of the PWM duty cycle of the reference branch can be done in small increments or decrements to reduce disturbances to the current bus output voltage and the driving states of other branches. This step avoids distortion of the overall dimming relationship caused by non-reference branches continuing to compensate using inaccurate reference values ​​when the reference branch has deviated from the target state.

[0052] S58. Based on the adjusted PWM duty cycle of the reference branch and the current bus output voltage, redetermine the compensation PWM duty cycle of each non-reference branch.

[0053] In this step, it should be noted that the adjusted reference branch PWM duty cycle represents the updated drive reference state of the reference branch under the current bus output voltage condition; the current bus output voltage represents the power supply conditions shared by all branches. The technical feature of this step is that when the reference branch PWM duty cycle changes, the updated reference branch PWM duty cycle and the current bus output voltage are used together as a new compensation reference basis to re-determine the compensation PWM duty cycle of each non-reference branch. That is, the compensation relationship of the non-reference branches is not fixed, but is synchronously reconstructed as the reference state of the reference branch changes. The "re-determination" may include recalculating the initial compensation amount, regenerating the compensation PWM duty cycle, and applying upper and lower limit constraints and variation amplitude constraints to the compensation PWM duty cycle. Preferably, the re-determination process is still based on the correspondence between the operating voltage of each non-reference branch and the current bus output voltage, combined with the updated reference branch PWM duty cycle, to form a new compensation control quantity. This step ensures that the compensation results of each non-reference branch are always consistent with the latest driving state of the reference branch, thereby avoiding new current deviations caused by the other branches continuing to use the old compensation amount after the reference branch is updated.

[0054] S59. Perform closed-loop correction on the compensated PWM duty cycle of each non-reference branch after the redetermined condition.

[0055] In this step, it should be noted that although the redefined compensated PWM duty cycle has been reconstructed based on the updated reference state, it is still a control result obtained based on the branch voltage relationship and the reference branch state. It may still be affected by factors such as the dispersion of LED lamp parameters, line voltage drop, temperature rise changes, sampling errors, and drive response deviations. Therefore, it is necessary to continue closed-loop correction by combining the actual operating current of each non-reference branch. The technical feature of this step is that control does not end directly after redefining the compensated PWM duty cycle. Instead, it continues to collect the actual operating current of each non-reference branch, determine its deviation from the preset constant current threshold, and further correct the compensated PWM duty cycle based on the deviation, so that the updated compensated control result gradually converges to within the allowable error range. The closed-loop correction preferably still follows the aforementioned correction method based on current deviation rate, dynamic correction coefficient, stabilization waiting period, and iterative judgment, thereby ensuring that the updated compensated control chain continues the original stable correction mechanism under the new reference conditions. This step allows the updated control relationship of the reference branch to go beyond simply recalculating and enter the feedback convergence stage, enabling each non-reference branch to reach a stable state that matches the preset constant current threshold on the basis of the new compensation.

[0056] The technical solution implemented in this embodiment can, when the actual operating current of the reference branch deviates from the preset constant current threshold, firstly correct the reference branch itself to restore it to a more accurate reference state. Then, based on the adjusted PWM duty cycle of the reference branch and the current bus output voltage, re-establish the compensation PWM duty cycle of each non-reference branch, and continue to gradually converge the re-established compensation relationship through closed-loop correction. Therefore, this embodiment can avoid the situation where other branches continue to adjust using the old reference relationship when the reference branch is inaccurate, reduce the linkage error caused by reference drift between multiple branches, and ensure that the control relationship between the reference branch and non-reference branches is updated consistently, thereby improving the overall consistency, dynamic stability, and reliability of reference control in the multi-channel LED constant current dimming process.

[0057] In one specific embodiment, step S50, re-determining the reference branch, includes: S501: Collect and compare the operating voltage of each LED driver branch in a preset collection cycle.

[0058] In this step, it should be noted that the preset acquisition period is used to limit the detection frequency of the operating voltage of each LED driver branch during the reference branch reselection process. It can be the same as the sampling period of the closed-loop correction, or it can be independently set to a period more suitable for branch status determination, such as 20ms or other preset durations. The cyclic acquisition and comparison refers to continuously and periodically acquiring the operating voltage of multiple LED driver branches and comparing the operating voltage of each branch horizontally within the same determination period to identify the current changes in the demand for bus output voltage from each branch. The technical feature of this step is that it does not determine the reference branch only once during initialization, but continuously tracks the changing trend of the operating voltage of each branch during system operation, allowing the reference branch to be dynamically updated according to changes in branch load status, brightness requirements, device temperature rise, and line voltage drop. In this step, the operating voltage not only reflects the current voltage demand of the branch but also serves as the core basis for determining whether a particular branch should replace the current reference branch. Through cyclic comparison under the preset acquisition period, it is possible to avoid the long-term use of an outdated reference branch due to the failure to promptly identify changes in branch status.

[0059] S502. When the operating voltage of any LED driving branch is higher than the operating voltage of the current reference branch for multiple consecutive sampling cycles, and the difference between the two is greater than or equal to a preset voltage difference threshold, the LED driving branch is updated to a new reference branch.

[0060] In this step, it should be noted that the multiple consecutive acquisition cycles are used to constrain the time-dimensional stability of the reference branch reselection conditions, so as to avoid frequent switching of the reference branch due to instantaneous disturbances, sampling glitches, or short-term fluctuations; the preset voltage difference threshold is used to constrain the amplitude-dimensional effectiveness of the reselection conditions, so as to ensure that switching is only performed when the voltage demand difference between the candidate branch and the current reference branch reaches a preset level. Preferably, the multiple consecutive acquisition cycles can be two, three, or more consecutive acquisition cycles, and the preset voltage difference threshold can be set to 0.2V or other suitable values. The technical feature of this step is that it introduces both "duration criteria" and "difference amplitude criteria" to double-limit the reference branch update conditions, so that the new reference branch is only formally determined when it stably shows a higher voltage demand. The new reference branch refers to the LED driver branch that has a higher demand for bus output voltage in the current operation stage and should be used as the reference object for subsequent bus voltage regulation. Through this step, the repeated switching of the reference branch near the critical state can be effectively suppressed, and the basis for bus output voltage regulation can be avoided from changing frequently in a short period of time.

[0061] S503. After the new reference branch is determined, the bus output voltage is readjusted based on the new reference branch, and the compensation PWM duty cycle of each non-reference branch is re-determined based on the readjusted bus output voltage and the PWM duty cycle of the new reference branch. The compensation PWM duty cycle of each non-reference branch is then corrected in a closed loop.

[0062] In this step, it should be noted that once the new reference branch is determined, the adjustment basis of the original bus output voltage, the reference role of the original reference branch PWM duty cycle, and the compensation basis of each non-reference branch all change accordingly. Therefore, it is not enough to simply replace the reference branch identifier; the entire control chain needs to be rebuilt simultaneously. The step of readjusting the bus output voltage based on the new reference branch means using the new reference branch as the bus voltage adjustment anchor point, re-evaluating whether the current bus output voltage meets the requirements of the new reference branch, and then re-outputting the bus output voltage adapted to the new reference branch through the PD power receiving module. The step of re-determining the compensation PWM duty cycle of each non-reference branch based on the readjusted bus output voltage and the new reference branch PWM duty cycle means re-establishing the compensation relationship between each non-reference branch and the reference branch under the new reference branch and new power supply conditions. The closed-loop correction is used to further integrate the re-established compensation PWM duty cycle with the actual operating current feedback to achieve convergence. The key technical feature of this step is that the reselection of the reference branch, the readjustment of the bus output voltage, the reconstruction of the compensated PWM duty cycle, and the closed-loop correction are reconnected into a continuous action chain. This ensures that the entire multi-branch dimming system synchronously migrates to the new reference state after the reference branch is updated, rather than undergoing local adjustments. Preferably, after the new reference branch is determined, the bus output voltage can be temporarily stabilized for a short period before initiating a new bus output voltage adjustment based on the new reference branch state, thereby reducing voltage disturbances during switching.

[0063] The technical solution implemented in this embodiment can identify the LED driver branch with the highest current demand for bus output voltage in real time through continuous monitoring and comparison of working voltages between branches under a preset acquisition cycle. It also uses multiple consecutive acquisition cycles and a preset voltage difference threshold to constrain the stability and effectiveness of the reference branch reselection conditions, thereby avoiding frequent switching of the reference branch due to instantaneous fluctuations. Simultaneously, after a new reference branch is determined, it can synchronously complete the rematching of the bus output voltage, the re-establishment of the PWM duty cycle for non-reference branch compensation, and subsequent closed-loop correction. This ensures that the switching of the reference branch is not merely a replacement of the reference object, but rather a complete reconstruction of the bus voltage regulation chain and the branch compensation chain. Therefore, this embodiment can continuously maintain the bus output voltage matching the current core load demand and maintain the effectiveness of the compensation control relationship of each non-reference branch in scenarios where the load status of multiple LEDs changes dynamically, the lamp parameters differ significantly, or the voltage demand is reordered during operation. This improves the dynamic adaptability, operational stability, and dimming consistency of the entire multi-channel LED constant current dimming system.

[0064] In one specific embodiment, step S50, the re-determination of the reference branch, further includes: S504. When an open circuit, short circuit, or overcurrent fault occurs in the current reference branch, the faulty branch is shielded, and the LED driver branch with the highest operating voltage is selected from the remaining normal branches as the new reference branch. At the same time, a fault signal is output.

[0065] In this step, it should be noted that the open-circuit fault is used to characterize an abnormal state such as an open circuit, disconnection, or load interruption in the current reference branch; the short-circuit fault is used to characterize an abnormal state such as abnormal low-resistance conduction or device breakdown in the current reference branch; and the overcurrent fault is used to characterize that the actual operating current of the current reference branch exceeds a preset safety range, such as reaching 1.2 times or other preset multiples of the preset constant current threshold. The technical feature of this step is that when the current reference branch experiences the above-mentioned faults, it is no longer allowed to continue as the basis for adjusting the bus output voltage. Instead, the faulty branch is first shielded from the set of branches participating in comparison and adjustment, and then only the LED driver branch with the largest operating voltage is selected as the new reference branch from the remaining normal branches. "Shielding the faulty branch" means at least stopping the inclusion of this branch in the reference branch determination process and stopping the use of the branch's state as the adjustment reference for the bus output voltage. If necessary, the output of drive control signals to this branch can also be stopped. The "fault signal" indicates that the current system has identified an abnormal state in the reference branch. It can be sent to external control equipment, a host computer, a fault display unit, or a protection logic unit to trigger alarm display, fault recording, derating operation, or protection action. This step prevents the faulty branch from continuing to participate in the bus voltage regulation reference, which would cause distortion of the bus output voltage regulation basis. It also ensures that a new control reference can be recovered from the remaining normal branches in a fault scenario.

[0066] S505. When the change in brightness requirement corresponding to the external brightness control information is greater than or equal to the preset brightness change threshold, a reference branch re-identification is performed after the brightness adjustment is completed.

[0067] In this step, it should be noted that the brightness demand change is used to characterize the magnitude of change in external brightness control information relative to the previous moment or control cycle. This change can be determined based on changes in brightness level, target duty cycle, target current, or other equivalent brightness control quantities. The preset brightness change threshold is used to characterize the brightness change judgment boundary for triggering the re-identification of the reference branch. Preferably, it can be set to 10%, 20%, or other suitable thresholds. The technical feature of this step is that when the external brightness demand undergoes a large step change, the reference branch before the change is not directly used. Instead, after brightness adjustment, the operating voltage of each LED driving branch is re-identified and compared to determine whether the original reference branch still maintains the highest voltage requirement under the new brightness demand. In other words, the brightness demand change not only affects the target brightness data of each branch but may also change the order of operating voltages between branches. Therefore, the brightness change needs to be used as an independent trigger source for re-determining the reference branch. The phrase "brightness adjustment completed" indicates that the re-identification of the reference branch should be established after the new brightness demand has actually been applied to each branch, so that the re-identification basis reflects the updated real load state, rather than the transient state during the brightness switching process. This step prevents the continued use of the reference branch before the change after a significant change in brightness demand, which would cause the bus output voltage matching relationship to lag behind the current control requirements.

[0068] S506. The reference branch is re-determined according to the priority of fault-triggered reselection over brightness change-triggered reselection, and brightness change-triggered reselection over regular cycle reselection, and the original bus output voltage is kept temporarily stable during the reselection process.

[0069] In this step, it should be noted that: the fault-triggered reselection refers to the reference branch update triggered by anomalies such as open circuit, short circuit, or overcurrent in the current reference branch; the brightness change-triggered reselection refers to the reference branch update triggered by a change in external brightness control information reaching a preset brightness change threshold; and the regular periodic reselection refers to the regular update triggered by cyclically comparing the operating voltage of each LED driver branch according to a preset acquisition cycle. The technical feature of this step is that it sets clear execution priorities for reselection requests from different sources, enabling the system to prioritize situations with a greater impact on the control chain when multiple triggering conditions occur simultaneously. Specifically, fault-triggered reselection directly relates to the validity of the current reference branch and has the highest priority; brightness change-triggered reselection relates to the accuracy of the reference branch after the brightness update and has the next highest priority; and regular periodic reselection is mainly used for continuous tracking during operation and has a relatively low priority. The phrase "maintaining the original bus output voltage temporarily stable" means that when the new reference branch has not been determined or the priority determination of each reselection condition has not been completed, the current bus output voltage is not immediately changed. Instead, the bus output voltage is maintained in its current state until the new reference branch is determined before entering a new bus adjustment process. This approach avoids frequent fluctuations in the bus output voltage during the reselection process caused by trigger source switching, changes in branch determination, or the inability to determine the reference object. Preferably, the temporary stabilization can be implemented in combination with a short-term holding strategy, a confirmation waiting strategy, or a strategy that allows the next reselection to begin only after the previous one is completed, to further improve the continuity and stability of the reselection process.

[0070] The technical solution implemented in this embodiment can promptly remove faulty branches from the reference determination and bus adjustment reference system when an open circuit, short circuit, or overcurrent fault occurs in the current reference branch, and restore new reference branches from the remaining normal branches, avoiding the continued participation of faulty branches in control and causing distortion in bus output voltage regulation. Simultaneously, when external brightness control information causes significant changes in brightness demand, the reference branch can be re-identified after brightness adjustment, ensuring that the reference branch determination always matches the updated load demand. Furthermore, by setting clear priorities for fault-triggered reselection, brightness change-triggered reselection, and regular periodic reselection, and maintaining temporary stability of the original bus output voltage during the reselection process, the reference branch update process can remain orderly, stable, and controllable in abnormal scenarios, dynamic dimming scenarios, and normal operating scenarios. Therefore, this embodiment can improve the effectiveness of reference branch determination, the reliability of the bus output voltage adjustment reference, and the continuous operation capability and stability of the entire multi-channel LED constant current dimming system under abnormal and dynamic operating conditions.

[0071] In one specific embodiment, step S30 includes: S31. When the voltage difference between the working voltage of the reference branch and the initial bus output voltage is greater than or equal to the preset voltage difference threshold, the deviation of the working current of the reference branch from the preset constant current threshold is greater than or equal to the preset deviation threshold, or the change in external brightness control information is greater than or equal to the preset brightness change threshold, the PD power receiving module is triggered to perform bus output voltage regulation.

[0072] In this step, it should be noted that the initial bus output voltage refers to the bus supply voltage output by the PD power receiving module to each LED driver branch before the current voltage regulation action begins; the preset differential voltage threshold is used to characterize the level at which the deviation of the reference branch's demand for the bus output voltage should trigger a new voltage regulation process; the preset deviation threshold is used to characterize the level at which the actual operating current of the reference branch deviates from the preset constant current threshold to trigger bus linkage regulation; and the preset brightness change threshold is used to characterize the magnitude at which changes in external brightness control information should be considered as a significant change in load demand. The technical feature of this step is that it does not continuously and unconditionally adjust the bus output voltage frequently, but rather selectively triggers the PD power receiving module to perform bus output voltage regulation based on three conditions that directly reflect the necessity of control: "voltage demand mismatch," "current target mismatch," and "significant change in external brightness demand." The voltage difference between the operating voltage of the reference branch and the initial bus output voltage is used to characterize whether the current bus output voltage can no longer effectively cover the voltage requirements of the reference branch; the deviation of the operating current of the reference branch from the preset constant current threshold is used to characterize whether the current reference branch has deviated from the target driving state; the change in the external brightness control information is used to characterize whether the external control requirements have changed significantly, which may lead to a change in the load distribution of each branch and the requirements of the reference branch. Preferably, the preset voltage difference threshold can be set to 0.3V or other suitable values, the preset deviation threshold can be set to ±5% of the actual operating current of the reference branch relative to the preset constant current threshold or other suitable ranges, and the preset brightness change threshold can be set to 10% or other thresholds that can reflect obvious brightness step changes. By establishing the bus output voltage adjustment on the basis of the above multi-source triggering conditions, the voltage regulation action of the PD power receiving module can be kept in correspondence with the current branch demand changes, avoiding frequent negotiations caused by slight fluctuations.

[0073] S32. During the process of regulating the bus output voltage, set the dead zone for bus output voltage regulation, the delay confirmation period after the voltage regulation command is issued, and the minimum time interval for continuous voltage regulation to suppress bus output voltage oscillation.

[0074] In this step, it should be noted that the dead zone for bus output voltage regulation refers to the adjustment-free interval set around the target bus output voltage or around the voltage regulation judgment boundary. Within this interval, even if there are slight fluctuations in the sampled value, a new voltage regulation action will not be triggered immediately. The delay confirmation period refers to the waiting time reserved for bus output voltage stabilization, branch current response, and sampled signal convergence after issuing a voltage regulation command to the PD receiving module. The minimum time interval for continuous voltage regulation refers to the shortest allowable time interval between two adjacent bus output voltage regulation actions. The technical feature of this step is that by setting the above three types of constraint mechanisms during the voltage regulation process, the bus output voltage regulation not only has triggering conditions but also stabilization conditions and rhythm control conditions, thereby suppressing the oscillation phenomenon of mutual chasing and back-and-forth correction between PD-side voltage regulation and branch-side response. Preferably, the dead zone can be set to ±0.1V or other suitable range to prevent frequent readjustment of the bus output voltage due to minor disturbances when it approaches the target value; the delay confirmation period can be set to 8ms or other durations that can cover the PD voltage regulation response and branch stabilization process; the minimum time interval for continuous voltage regulation can be set to 50ms or other suitable time to limit the repeated initiation of new voltage regulation requests within a short period of time. The "suppression of bus output voltage oscillation" includes not only suppressing the back-and-forth fluctuations of the bus output voltage itself near the target, but also suppressing the repeated adjustments of the reference branch PWM duty cycle, frequent recalculation of the non-reference branch compensated PWM duty cycle, and instability of the entire multi-branch dimming control link caused by frequent changes in the bus output voltage. By simultaneously setting the dead zone, confirmation period, and minimum interval during the voltage regulation process, the bus output voltage regulation of the PD power receiving module can be made more convergent and controlled.

[0075] The technical solution implemented in this embodiment can trigger the PD power receiving module to adjust the bus output voltage only when there is a significant mismatch between the demand for the bus output voltage of the reference branch, a significant deviation of the actual operating current of the reference branch from the preset constant current threshold, or a significant change in the external brightness control requirements. This establishes a clear correspondence between the voltage adjustment action and the actual demand changes of the branch, avoiding indiscriminate and continuous repeated voltage adjustments. Simultaneously, by setting a dead zone for bus output voltage adjustment, a delay confirmation period, and a minimum time interval for continuous voltage adjustment, the voltage adjustment rhythm and boundaries can be constrained during the voltage adjustment process. This prevents the bus output voltage from frequently jumping due to minor disturbances when approaching the target value and provides necessary stabilization buffer time between adjacent voltage adjustment actions. Therefore, this embodiment can maintain the dynamic matching capability of the bus output voltage while reducing jitter and repeated corrections during the PD negotiated voltage adjustment process, improving the stability of bus power supply control, the consistency of branch drive control, and the operational stability of the entire multi-channel LED constant current dimming process.

[0076] In one specific embodiment, step S30 further includes: S33. Limit the voltage regulation range of the PD power receiving module to a preset voltage range.

[0077] In this step, it should be noted that the preset voltage range is used to define the allowable output boundary of the PD power receiving module during the bus output voltage regulation process. Its lower and upper limits correspond to the minimum and maximum bus output voltages that allow the system to operate stably, respectively. The setting of the preset voltage range needs to comprehensively consider the negotiable output range of the external PD power supply, the voltage conversion capability of the PD power receiving module, the withstand voltage capability of the LED driver branch, the forward voltage drop range of the lamp group, and the overall safe operating requirements. For example, in one example, the preset voltage range can be set to 5V to 48V to adapt to the dynamic voltage regulation capability in EPRAS mode; in other embodiments, it can also be limited to a narrower operating range depending on the specific lamp group configuration. The technical feature of this step is that it does not allow the PD power receiving module to arbitrarily adjust the voltage within the entire range supported by the protocol, but rather, combined with the multi-channel LED driving characteristics of this solution, it establishes an effective voltage regulation boundary for the bus output voltage that matches the hardware conditions of this system. By pre-limiting the voltage regulation range, it is possible to avoid the bus output voltage being too low, which would prevent the reference branch from failing to reach the preset constant current threshold. It is also possible to avoid the bus output voltage being too high, which would cause excessive differential voltage loss, temperature rise, and device stress in the non-reference branch.

[0078] S34. Limit the single voltage adjustment step to within the preset step upper limit.

[0079] In this step, it should be noted that the single voltage regulation step is used to characterize the voltage change amplitude between two adjacent bus output voltage adjustments, and the preset step upper limit is used to limit the maximum voltage value allowed to change in a single voltage regulation action. The technical feature of this step is that the voltage regulation action of the PD receiving module not only sets an overall range constraint but also further sets a single change amplitude constraint, so that the change process of the bus output voltage presents a gradual adjustment rather than a sudden jump. Preferably, the single voltage regulation step can be controlled at a small granularity, for example, with 0.1V as the conventional adjustment granularity, and the single voltage regulation step upper limit is limited to within 0.5V; in other embodiments, other step upper limits can also be set according to the system response speed and stability requirements. By limiting the single voltage regulation step, the impact of rapid changes in the bus output voltage on the reference branch PWM duty cycle control, the calculation of the non-reference branch compensated PWM duty cycle, and the stability of the actual operating current feedback can be reduced, avoiding excessive changes on the bus side before the branch-side control is stable, thereby improving the synergy between bus voltage regulation and branch dimming.

[0080] S35. When the target voltage regulation value exceeds the preset voltage range or the single voltage regulation step exceeds the preset step upper limit, the target voltage regulation value or the single voltage regulation step is corrected to the corresponding critical value and then the bus output voltage is regulated.

[0081] In this step, it should be noted that the target voltage regulation value refers to the expected bus output voltage calculated or determined based on the current operating state of the reference branch; the corresponding critical value refers to the limit value corresponding to the preset voltage range boundary or preset step upper limit. The technical feature of this step is that a boundary correction mechanism is set before the actual voltage regulation is executed. That is, when the target voltage regulation value exceeds the preset voltage range, it is not executed directly according to the over-limit result, but rather it is truncated or mapped to the boundary value within the preset voltage range; when a single voltage regulation step exceeds the preset step upper limit, it is not directly jumped to the target value, but rather the voltage regulation amplitude is first compressed to the allowable step upper limit before execution. In other words, this step does not simply determine "whether regulation is possible," but rather, when the voltage regulation request exceeds the limit, it converts the over-limit request into a controlled, executable boundary voltage regulation action. Preferably, when the target voltage regulation value is higher than the upper limit of the preset voltage range, it is corrected to the upper limit value; when the target voltage regulation value is lower than the lower limit of the preset voltage range, it is corrected to the lower limit value; when a single voltage regulation step exceeds the upper limit of the preset step, it approaches the target voltage regulation value in stages according to the upper limit of the preset step. Through this step, the PD power receiving module can still complete the bus output voltage regulation in a constrained manner when faced with abnormal calculation results, large changes in external brightness, or sudden changes in branch status, avoiding out-of-range output or large jumps in output.

[0082] The technical solution implemented in this embodiment can set voltage boundary constraints on the voltage regulation range of the PD power receiving module and amplitude constraints on the single voltage regulation step. When the target voltage regulation value or voltage regulation step exceeds the limit, it automatically corrects to the corresponding critical value before resuming voltage regulation. This allows the bus output voltage regulation to not only dynamically change with the needs of the reference branch, but also has clear range and step limitations. Therefore, the bus output voltage will not enter an incompatible high or low voltage range due to an excessively wide regulation range, nor will it cause significant impact on the branch drive state due to an excessively large single voltage regulation amplitude. This ensures the flexibility of dynamic voltage regulation while improving the safety, smoothness, and overall operational stability of the bus power supply control.

[0083] In one specific embodiment, step S10 includes: S11. Receive external independent frequency PWM signals, serial port format brightness data, or I2C format brightness data as external brightness control information, and the external brightness control information is independent of the local LED current control PWM signal and has no synchronization constraints.

[0084] In this step, it should be noted that the external independent frequency PWM signal refers to an external PWM control signal whose frequency is not limited by the local LED current control PWM signal and can change independently; the serial port format brightness data and I2C format brightness data refer to brightness control commands transmitted via serial communication; the local LED current control PWM signal refers to the execution signal output by the local control terminal and directly used to adjust the conduction level of each LED drive branch. The technical feature of this step is that the external brightness control information and the local LED current control PWM signal are set as two independent control levels. The external brightness control information serves as the brightness intention input, while the local LED current control PWM signal serves as the specific drive execution function. They do not need to be frequency-, phase-, or synchronously updated. In other words, the external control terminal can send brightness control requests according to its own protocol and rhythm, while the local control terminal can generate the current control PWM signal according to its own sampling period, bus adjustment rhythm, and branch closed-loop correction rhythm, thereby avoiding the external control protocol directly constraining the local constant current control process. Preferably, the frequency of the external independent frequency PWM signal can be any adapted frequency different from the local current control PWM frequency, and the brightness data in serial or I2C format can include brightness values, channel commands, grouping commands, or other control fields. Through this step, the system can maintain the independence and stability of the local bus regulation and branch compensation closed loop when connected to different types of external control sources.

[0085] S12. Read the control signal configuration and determine the target channel corresponding to the external brightness control information.

[0086] In this step, it should be noted that the control signal configuration is used to characterize the correspondence rules between external control information and internal control objects. This configuration may include input port identifiers, logical channel numbers, group control rules, broadcast control rules, or other preset channel management information. The target channel refers to the internal control object number pointed to by the current external brightness control information. The technical feature of this step is that after receiving external brightness control information, it is not directly applied to all LED driver branches. Instead, the target channel corresponding to the external brightness control information is first determined by reading the control signal configuration, thereby clarifying the target of this control request. "Reading" may include calling pre-stored configuration tables, register parameters, communication fields, or logical mapping tables. "Determining the target channel" involves converting the control object identifier carried in the external control information into a channel identifier that can be recognized internally by the system. Through this step, external brightness control information from different control interfaces, different protocol formats, and different control granularities can first complete object attribution determination before entering the subsequent driver branch mapping and control processing, thereby preventing external control requests from losing their object targeting in the internal control chain.

[0087] S13. According to the preset channel mapping relationship, map the target channel to at least one target LED driving branch.

[0088] In this step, it should be noted that the preset channel mapping relationship is used to characterize the correspondence between internal logic channels and actual LED driver branches. This can be one channel corresponding to one branch, one channel corresponding to multiple branches, a group of channels corresponding to a group of branches, or other preset mapping methods. The target LED driver branch refers to one or more branches actually selected based on the target channel that need to execute the current control request. The technical feature of this step is that it further converts the target channel determined in the previous step into an actual target LED driver branch, allowing the external control intent to continue to be transmitted from the logic control layer to the actual driving object layer. In other words, the target channel is more used to characterize the logical affiliation of the external control object, while the target LED driver branch is the execution object for subsequent bus adjustment, PWM duty cycle compensation generation, and closed-loop correction. Preferably, the preset channel mapping relationship can support fixed mapping, lookup table mapping, group mapping, or configurable mapping to adapt to different lighting fixture topologies, different branch grouping methods, and different lighting layout requirements. Through this step, external control information can be accurately mapped to one or more specific branches, rather than remaining at the abstract channel level.

[0089] S14. Determine the corresponding target brightness data and load requirements based on the mapped target LED driver branch, and adjust the bus output voltage and output the corresponding PWM control signal based on the target brightness data and load requirements.

[0090] In this step, it should be noted that the target brightness data is used to characterize the brightness target that the mapped target LED driving branch should achieve under the current control cycle; the load requirement is used to characterize the comprehensive requirements of the mapped target LED driving branch on the bus output voltage and branch driving capability under the current target brightness, which can be determined by a combination of target brightness data, branch operating voltage, lamp configuration, number of branches, historical driving status, or other branch status parameters. The technical feature of this step is that it not only generates corresponding target brightness data based on the mapped target LED driving branch, but also further introduces the target brightness data and load requirement into the subsequent bus output voltage adjustment and PWM control signal output process, so that the channel mapping result directly participates in the actual power supply control and branch driving control. The "adjusting the bus output voltage based on the target brightness data and load requirement" refers to triggering or influencing the voltage regulation decision of the PD power receiving module according to the degree of demand of the target branch on the bus output voltage under the current brightness requirement; the "outputting the corresponding PWM control signal" refers to generating a branch driving control quantity that is adapted to its load status according to the control requirements of the target branch. Preferably, the target brightness data can first be converted into the target drive intensity of each target branch, and then combined with the number of mapped branches, branch voltage requirements, and the current bus status to form a comprehensive load requirement. Through this step, external brightness control information no longer only affects channel selection, but directly participates in forming the basis for bus voltage regulation and branch drive, making the input processing chain closely connected with the subsequent dimming execution chain.

[0091] The technical solution implemented in this embodiment first receives external independent frequency PWM signals, serial port format brightness data, or I2C format brightness data as external brightness control information. Through a control structure that is independent of and without synchronization constraints from the local LED current control PWM signal, the external control intent is decoupled from the local constant current execution process. Then, the target channel is determined by reading the control signal configuration, and the target channel is mapped to at least one target LED driver branch according to a preset channel mapping relationship, ensuring that external control requests are accurately assigned to the actual branch object. Furthermore, the corresponding target brightness data and load requirements are determined based on the mapped target LED driver branch, and these data directly participate in the bus output voltage regulation and PWM control signal output. This allows the external control input to not only complete object allocation but also directly influence subsequent power supply control and branch drive control. Therefore, this embodiment improves the system's compatibility with different external control protocols, different branch grouping relationships, and different luminaire topologies, and enables the multi-channel LED constant current dimming process to respond more accurately to external brightness control requirements while maintaining local control stability.

[0092] In one specific embodiment, another embodiment of this application provides a multi-channel LED constant current dimming device based on the PD protocol EPR AVS mode. The device operates using the aforementioned multi-channel LED constant current dimming method based on the PD protocol EPR AVS mode. The device includes: a PD power receiving module for connecting to an external PD power supply and outputting a bus voltage; an input module for receiving external control signals; a data acquisition module for acquiring the status signals of each LED driver branch; a control module connected to the PD power receiving module, input module, and data acquisition module, respectively, for outputting control signals based on the external control signals and status signals; and a driver module connected to the PD power receiving module and control module, for driving multiple LED driver branches according to the control signals. The output terminals of both the input module and the data acquisition module are connected to the control module, the output terminal of the control module is connected to both the PD power receiving module and the driver module, and the output terminal of the PD power receiving module is connected to the driver module.

[0093] In this embodiment, it should be noted that the PD power receiving module is used to complete power receiving negotiation with the external PD power supply and bus power output, and its output bus voltage serves as the power supply basis shared by multiple LED driving branches; the input module is used to receive external control requests, and the information received can be brightness adjustment signals, channel control signals, or other external control signals; the acquisition module is used to acquire status signals that can characterize the operating status of each LED driving branch, and the status signals can include operating voltage signals, operating current signals, fault status signals, or other detection signals that can reflect the branch load status; the control module is used to comprehensively process the external control signals provided by the input module and the status signals provided by the acquisition module, and form control signals for the PD power receiving module and the driving module; the driving module is used to drive multiple LED driving branches to work according to the control signals output by the control module under the bus voltage supply. The technical feature of this embodiment is that the control module serves as the signal convergence and control decision center, organizing external control input, branch status acquisition, PD-side bus power supply adjustment, and branch-side drive control into a closed-loop signal chain, rather than setting each function separately. In other words, the input module is responsible for introducing external control requirements into the system, the acquisition module is responsible for feeding back the actual operating status of the branches to the system, the control module generates control decisions based on the above two types of information, the PD power receiving module is responsible for performing power supply regulation on the bus side, and the drive module is responsible for performing drive control on the branch side, thus forming an ordered signal flow of "input—acquisition—decision—power supply—drive". Furthermore, the control signal output from the control module to the PD power receiving module is used to regulate the bus voltage, and the control signal output to the drive module is used to regulate the drive state of each LED drive branch, enabling the dynamic power supply regulation on the bus side and the PWM compensation control on the branch side to be executed collaboratively under the same control core. Preferably, the control module can be implemented using a microcontroller, programmable logic device, or other control circuits; the drive module can be implemented using an independent drive circuit or partially integrated with the control module to reduce control delay caused by signal chain length and module dispersion; the acquisition module can be set independently or integrated into the drive module or control module, as long as it can provide the control module with detection signals reflecting the branch status. With the above module settings, the device is not overly limited in structure by specific data formats, specific driver chips or specific signal types, but can fully reflect the synergistic relationship between dynamic adjustment of bus voltage, branch status feedback and multi-branch drive control.

[0094] The technical solution implemented in this embodiment can form a complete control link from external control input, branch status acquisition, control decision output to bus power supply regulation and branch drive execution through the coordinated cooperation between the PD power receiving module, input module, acquisition module, control module and drive module. This enables the dynamic power supply control on the bus side and the fine drive control on the branch side to achieve orderly linkage in the same device. At the same time, since the responsibilities of each module are clearly defined, the signal flow is clear, and the modules themselves are not excessively limited by specific data types and specific device forms, it can not only ensure the complete support of the device for multi-channel LED constant current dimming function, but also improve the device's integration adaptability, deployment flexibility and engineering implementation stability in different types of lighting equipment.

[0095] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A multi-channel LED constant current dimming method based on PD protocol EPR AVS mode, characterized in that, include: S10. Receive external brightness control information and parse it to obtain the target brightness data corresponding to multiple LED driver branches; S20. Collect the operating voltage and operating current of each LED driver branch, and determine the reference branch based on the operating voltage of each LED driver branch. S30. Control the PD power receiving module to work in PD protocol EPR AVS mode, adjust the bus output voltage according to the working state of the reference branch, and adjust the PWM duty cycle of the reference branch so that the working current of the reference branch reaches the preset constant current threshold. S40. Based on the current bus output voltage, the operating voltage of each non-reference branch, and the PWM duty cycle of the reference branch, determine the compensation PWM duty cycle of each non-reference branch, and output the corresponding PWM control signal. S50. Collect the actual operating current of each non-reference branch, and perform closed-loop correction on the compensation PWM duty cycle of each non-reference branch based on the deviation of the actual operating current of each non-reference branch from the preset constant current threshold. After the reference branch is re-determined, readjust the bus output voltage based on the re-determined reference branch, and re-determine the compensation PWM duty cycle of each non-reference branch.

2. The multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 1, characterized in that, Step S40 includes: S41. Based on the correspondence between the working voltage of each non-reference branch and the current bus output voltage, and in conjunction with the PWM duty cycle of the reference branch, determine the initial compensation amount of each non-reference branch. S42. Generate the compensation PWM duty cycle of each non-reference branch based on the initial compensation amount of each non-reference branch, so that the working current of each non-reference branch is adjusted towards the preset constant current threshold.

3. The multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 2, characterized in that, Step S50 includes: S51. Collect the actual operating current of each non-reference branch at a preset sampling period, and determine the corresponding current deviation rate based on the deviation between the actual operating current and the preset constant current threshold. S52. Select the corresponding dynamic correction coefficient according to the deviation range where the current deviation rate is located, and correct the compensation PWM duty cycle of each non-reference branch. S53. After each correction, the actual operating current is collected again after a preset stabilization waiting period, and the current deviation rate is re-determined. S54. When the corrected current deviation rate is within the allowable range, the closed-loop correction is completed. S55. When the corrected current deviation rate still exceeds the allowable range, repeat steps S51 to S53 until the accuracy requirement is met or the preset maximum number of iterations is reached. S56. When the current deviation rate still exceeds the allowable range after the preset maximum number of iterations is reached, a fault warning signal is output.

4. The multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 3, characterized in that, Step S50 also includes: S57. When the actual operating current of the reference branch deviates from the preset constant current threshold by more than the preset reference deviation threshold, the PWM duty cycle of the reference branch is adjusted first to make the operating current of the reference branch adjust toward the preset constant current threshold. S58. Based on the adjusted PWM duty cycle of the reference branch and the current bus output voltage, redetermine the compensation PWM duty cycle of each non-reference branch. S59. Perform closed-loop correction on the compensated PWM duty cycle of each non-reference branch after redetermining.

5. A multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 4, characterized in that, In step S50, the re-determination of the reference branch includes: S501: Cyclicly collect and compare the operating voltage of each LED driver branch according to a preset collection cycle; S502. When the operating voltage of any LED driver branch is higher than the operating voltage of the current reference branch for multiple consecutive sampling cycles, and the difference between the two is greater than or equal to a preset voltage difference threshold, the LED driver branch is updated to a new reference branch. S503. After the new reference branch is determined, the bus output voltage is readjusted based on the new reference branch, and the compensation PWM duty cycle of each non-reference branch is re-determined based on the readjusted bus output voltage and the PWM duty cycle of the new reference branch. The compensation PWM duty cycle of each non-reference branch is then corrected in a closed loop.

6. The multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 5, characterized in that, In step S50, the re-determination of the reference branch further includes: S504. When an open circuit, short circuit or overcurrent fault occurs in the current reference branch, the faulty branch is shielded, and the LED driver branch with the largest working voltage is selected from the remaining normal branches as the new reference branch. At the same time, a fault signal is output. S505. When the change in brightness requirement corresponding to the external brightness control information is greater than or equal to the preset brightness change threshold, a reference branch re-identification is performed after the brightness adjustment is completed. S506. The reference branch is re-determined according to the priority of fault-triggered reselection over brightness change-triggered reselection, and brightness change-triggered reselection over regular cycle reselection, and the original bus output voltage is kept temporarily stable during the reselection process.

7. A multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 1, characterized in that, Step S30 includes: S31. When the voltage difference between the working voltage of the reference branch and the initial bus output voltage is greater than or equal to a preset voltage difference threshold, the deviation of the working current of the reference branch relative to the preset constant current threshold is greater than or equal to a preset deviation threshold, or the change in the external brightness control information is greater than or equal to a preset brightness change threshold, the PD power receiving module is triggered to perform bus output voltage adjustment. S32. During the process of regulating the bus output voltage, set the dead zone for bus output voltage regulation, the delay confirmation period after the voltage regulation command is issued, and the minimum time interval for continuous voltage regulation to suppress bus output voltage oscillation.

8. A multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 7, characterized in that, Step S30 also includes: S33. Limit the voltage regulation range of the PD power receiving module to a preset voltage range; S34. Limit the single voltage adjustment step to within the preset step limit; S35. When the target voltage regulation value exceeds the preset voltage range or the single voltage regulation step exceeds the preset step upper limit, the target voltage regulation value or the single voltage regulation step is corrected to the corresponding critical value and then the bus output voltage is regulated.

9. A multi-channel LED constant current dimming method based on PD protocol EPR AVS mode according to claim 1, characterized in that, Step S10 includes: S11. Receive external independent frequency PWM signal, brightness data in serial port format, or brightness data in I2C format as the external brightness control information, and the external brightness control information is independent of the local LED current control PWM signal and has no synchronization constraint. S12. Read the control signal configuration and determine the target channel corresponding to the external brightness control information; S13. According to the preset channel mapping relationship, map the target channel as at least one target LED driving branch; S14. Determine the corresponding target brightness data and load requirements based on the mapped target LED driving branch, and adjust the bus output voltage and output the corresponding PWM control signal based on the target brightness data and load requirements.

10. A multi-channel LED constant current dimming device based on PD protocol EPR AVS mode, characterized in that, The device operates by employing the multi-channel LED constant current dimming method based on the PD protocol EPR AVS mode as described in any one of claims 1-9, and the device comprises: The PD power receiving module is used to connect to an external PD power supply and output bus voltage; The input module is used to receive external control signals; The acquisition module is used to acquire the status signals of each LED driver branch; The control module is connected to the PD power receiving module, the input module, and the acquisition module respectively, and is used to output control signals according to the external control signals and the status signals; A driving module, connected to the PD power receiving module and the control module, is used to drive multiple LED driving branches according to the control signal; The output terminals of the input module and the acquisition module are both connected to the control module. The output terminal of the control module is connected to the PD power receiving module and the drive module, respectively. The output terminal of the PD power receiving module is connected to the drive module.

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