Pulse-driven uv led current source for charge management and optical power automatic control method

Abstract

The application discloses a pulse driving ultraviolet LED current source and a light power automatic control method for charge management, and belongs to the technical field of ultraviolet LED current source control. In order to solve the problem of accurate output of ultraviolet light power controlled by the ultraviolet LED current source, the pulse waveform generating unit of the application comprises an FPGA and a digital-to-analog conversion unit; the current source unit comprises an enhanced HOWLAND current source and an ultraviolet LED lamp; the signal acquisition unit comprises a current detection circuit, a voltage detection circuit, an ultraviolet light power detection circuit, two temperature detection circuits and an analog-to-digital conversion unit; the upper computer is connected with the FPGA, the FPGA is connected with the digital-to-analog conversion unit and the analog-to-digital conversion unit respectively, and the digital-to-analog conversion unit is connected with the enhanced HOWLAND current source; and the enhanced HOWLAND current source is connected with the current detection circuit, the voltage detection circuit, the temperature detection circuit and the ultraviolet LED lamp respectively. The application realizes dynamic self-adaptive regulation and control of light power.

Description

Technical Field

[0001] This invention belongs to the field of ultraviolet LED current source control technology, specifically relating to a pulse-driven ultraviolet LED current source for charge management and an automatic control method for optical power. Background Technology

[0002] High-precision space inertial sensors are core components of space gravitational wave detection, measuring the attitude and relative position of spacecraft. A crucial component is the isolated conductor suspended inside the sensor—the test mass (TM). However, interference from high-energy solar particles and galactic cosmic rays in space causes the test mass to accumulate charge, introducing additional acceleration noise. This results in the space inertial sensor's performance failing to meet the total noise requirements in the millihertz frequency band for gravitational wave detection. The required magnitude. To successfully perform scientific measurements, the charge level of the test mass must be managed.

[0003] The non-contact charge control method used in space exploration missions is a photoelectric effect-based charge control method for testing quality. Early missions selected mercury lamps as the ultraviolet light source. However, due to the slow response speed and unstable output power of mercury lamps, the control effect of the charge management system was unstable. Furthermore, the long warm-up time of mercury lamps extended the on-orbit measurement cycle. With the development of semiconductor technology, ultraviolet LED lamps have advantages in energy consumption, packaging, stability, lifespan, and high-frequency modulation performance, gradually gaining the ability to replace mercury lamps and becoming the next-generation light source for charge management systems.

[0004] Currently, current source technologies used to drive ultraviolet LED lamps mainly face the following problems: First, traditional current sources are bulky and expensive, and their shortcomings in high response speed and precise control, especially in rapid start-up and precise adjustment, make it difficult to meet the needs of space applications; second, the bias current, stray capacitance, and the limitations of the current source itself severely affect the stability and accuracy of the current source, resulting in a reduction in output current and output impedance; third, small current sources are difficult to meet the stringent requirements of special environments such as space when integrating additional functions such as PWM control and equipment monitoring. Therefore, developing a compact, high-speed, and high-precision current source with the additional functions required by the charge management system and the ability to effectively overcome the limitations of traditional current sources has become an important requirement in current technology. In the article "Wang Y, Lv B, Yu T, et al. Design of High-Precision Driving Control System for Charge Management [J]. Sensors, 2024, 24(9):2883", the researchers designed an ultraviolet LED driving control system to address the problem of charge interference affecting the quality of inspection in space inertial sensors. This system employs an improved HOWLAND current source, using analog PWM signal modulation to control the ultraviolet light power and achieve precise output of the ultraviolet LED drive current. However, the system's pulse frequency is only 1kHz, which is insufficient to meet the requirements of 100kHz high-frequency ultraviolet LED pulse drive in space missions. Under high-frequency operating conditions, the system is prone to problems such as a decrease in output current amplitude and a reduction in output impedance, affecting the stability of the ultraviolet light source and the accuracy of discharge control, thus limiting its further application in high-bandwidth, high-speed response scenarios. Summary of the Invention

[0005] This invention aims to solve the problem of accurately controlling the ultraviolet light power output of an ultraviolet LED current source, and proposes a pulse-driven ultraviolet LED current source and an automatic control method for light power for charge management.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A pulse-driven ultraviolet LED current source for charge management includes a pulse waveform generation unit, a current source unit, and a signal acquisition unit;

[0008] The pulse waveform generation unit includes an FPGA and a digital-to-analog converter; the current source unit includes an enhanced HOWLAND current source and an ultraviolet LED lamp; the signal acquisition unit includes a current detection circuit, a voltage detection circuit, an ultraviolet light power detection circuit, a temperature detection circuit 1, a temperature detection circuit 2, and an analog-to-digital converter.

[0009] The host computer is connected to an FPGA. The FPGA is connected to a digital-to-analog converter (DAC) and an analog-to-digital converter (ADC). The DAC is connected to an enhanced HOWLAND current source. The enhanced HOWLAND current source is connected to a current detection circuit, a voltage detection circuit, a temperature detection circuit 1, and an ultraviolet LED lamp. The ultraviolet LED lamp is connected to an ultraviolet light power detection circuit and a temperature detection circuit 2. The ADC is connected to a current detection circuit, a voltage detection circuit, an ultraviolet light power detection circuit, a temperature detection circuit 1, and a temperature detection circuit 2.

[0010] The digital-to-analog conversion unit includes a digital-to-analog conversion circuit and a filtering unit;

[0011] The enhanced HOWLAND current source includes operational amplifiers U1, U2, U3, a precision resistor network U4, an operational amplifier U5, an ultraviolet LED lamp L1, and a current sensing resistor R6 and a capacitor C1; wherein, the precision resistor network U4 is composed of resistors R1, R2, R3, and R4 connected in parallel;

[0012] The inverting input of operational amplifier U1 is connected to resistor R1 and capacitor C1 of precision resistor network U4; the other end of resistor R1 in precision resistor network U4 is grounded; one end of resistor R2 in precision resistor network U4 is connected to resistor R1 in precision resistor network U4 and the inverting input of operational amplifier U1, and the other end is connected to the output and inverting input of voltage follower U2; the non-inverting input of operational amplifier U1 is connected to the pulse waveform output unit through resistor R4 in precision resistor network U4; one end of resistor R3 in precision resistor network U4 is connected to resistor R4 in precision resistor network U4. The positive input terminal of operational amplifier U1 is connected to the negative input terminal of the voltage follower U3, and the other end is connected to the output terminal and the inverting input terminal of the voltage follower U2. The output terminal of operational amplifier U1 is connected to one end of resistor R5, the other end of capacitor C1, and the positive input terminal of voltage follower U2. The positive output terminal of voltage follower U3 is connected to the other end of resistor R5, the anode of ultraviolet LED lamp L1, and the inverting input terminal of operational amplifier U5. The cathode of ultraviolet LED lamp L1 is connected to current sensing resistor R6. The other end of current sensing resistor R6 is connected to the output terminal of operational amplifier U5. The positive input terminal of operational amplifier U5 is grounded.

[0013] Furthermore, the PWM pulse waveform is synthesized by the FPGA using direct digital frequency synthesis technology.

[0014] Furthermore, the logic design of the voltage waveform generation circuit is implemented using the hardware description language Verilog HDL, and the amplitude, frequency, duty cycle and phase of the output current are changed by buttons on the FPGA.

[0015] Furthermore, the signal input terminal of the digital-to-analog converter unit is connected to the FPGA via a 40-pin expansion interface; the digital-to-analog converter circuit includes a digital-to-analog converter chip and a two-stage amplifier circuit; the digital-to-analog converter circuit performs digital-to-analog conversion on the waveform signal generated by the FPGA and outputs the converted analog voltage signal to the filtering unit; the filtering unit filters the received analog voltage signal and outputs the filtered analog voltage signal to the input terminal of the current source circuit.

[0016] Furthermore, the current detection circuit in the signal acquisition unit includes a current sensing resistor R6 and a current sensing amplifier;

[0017] The voltage detection circuit includes resistors R13 and R14 and operational amplifier U10;

[0018] The ultraviolet light power detection circuit includes a silicon photodiode D1, an ultra-low bias current operational amplifier U6, a multiplexer U7, feedback resistors R7, R8, R9, and R10, and a feedback capacitor C2.

[0019] Temperature detection circuit 1 and temperature detection circuit 2 respectively include temperature sensor U11, temperature sensor U12, resistor R15, resistor R16, capacitor C6 and capacitor C7.

[0020] An automatic control method for the optical power of a pulse-driven ultraviolet LED current source for charge management includes the following steps:

[0021] Step 1: Using silicon photodiode D1 in zero-bias photovoltaic mode, the received ultraviolet light is converted into a photocurrent signal proportional to the incident light power, thereby obtaining the ultraviolet light power value.

[0022] Step 2: Real-time selection of feedback resistor and feedback capacitor for ultra-low bias current op-amp U6; output voltage of ultra-low bias current op-amp U6. From transconductance coefficient The transconductance coefficient is dynamically adjusted using an n-level selection mechanism based on the characteristics of the input signal; the n-level selection mechanism dynamically selects a suitable transconductance coefficient based on the input signal of the enhanced HOWLAND current source, thereby achieving automatic switching of the optical power range. Its expression is:

[0023]

[0024] Where S is the photosensitive function of the photodiode. Here, represents the photoelectric conversion coefficient of the ultraviolet LED lamp, and K represents the conversion coefficient of the enhancement-mode HOWLAND circuit. Voltage for FPGA to synthesize PWM pulse waveforms;

[0025] Step 3: Connect a high-precision current sensing resistor R6 in series at the cathode of the UV LED lamp L1, and perform voltage conversion through a low-noise current sensing operational amplifier U5 to indirectly obtain the working current flowing through the UV LED lamp L1. The converted voltage signal is then sent to the FPGA for processing via an analog-to-digital converter module.

[0026] Step 4: By sampling the potential difference between the anode and cathode of the UV LED lamp L1, and combining the resistor voltage divider and voltage follower buffer structure, a stable operating voltage for the UV LED lamp is obtained. This voltage is then input into the analog-to-digital converter module and sent to the FPGA for processing.

[0027] Step 5: The high-precision temperature sensors mounted next to the enhanced HOWLAND current source and the UV LED L1 are used to collect their respective operating temperatures. After high-frequency interference is filtered out by a low-pass filter, the data are sent to the analog-to-digital conversion module for subsequent temperature compensation and deviation correction.

[0028] Step 6: Input the collected ultraviolet light power, working current, working voltage, working temperature of ultraviolet LED L1, and multi-dimensional signals of working voltage and working temperature of ultraviolet LED into the FPGA control unit. Through the embedded MS-FNCC algorithm, the ultraviolet light power is automatically controlled in real time.

[0029] Furthermore, the 𝑛-level selection mechanism used in step two is implemented in the following way:

[0030] Parameters related to system operation include PWM voltage signals Real-time measurement of current source conversion coefficient K and photodiode photosensitivity S calculate;

[0031] Based on multiple preset thresholds and rules, the transconductance coefficient It will automatically select from multiple levels; whenever the characteristics of the input signal reach the range switching threshold, the system will automatically adjust the transconductance coefficient and send a signal to the logic control input terminal A1-m of the multiplexer U7. The value of m is determined according to the specific level of n, ensuring that the output voltage is always within the effective input range of the analog-to-digital conversion unit, thereby converting the ultraviolet light power into the corresponding voltage.

[0032] Furthermore, the specific implementation method of the MS-FNCC algorithm in step six includes the following steps:

[0033] Step 61: Set the input signals in the control algorithm as follows: ultraviolet light power P(t), ultraviolet light power change rate ΔP(t), driving current I(t), ultraviolet LED lamp operating voltage V(t), and enhanced HOWALAND current source operating temperature T. c (t) and the operating temperature T of the ultraviolet LED lamp L (t);

[0034] Step 62: In the first layer of the adaptive neural network, the system performs fuzzification processing on each input signal through a predefined membership function, converting each input variable into a membership value of multiple fuzzy sets, reflecting its degree of belonging in different fuzzy semantics. This process is controlled by the forward parameters to shape and distribute the membership function.

[0035] Step 63: In the second layer, the network performs a multiplication operation on the membership degree of each input variable output from the first layer to obtain the trigger strength of each fuzzy rule, which is used to represent the activation strength of each fuzzy rule.

[0036] Step 64: In the third layer, the system normalizes the trigger strength of all rules obtained in the second layer, that is, divides the trigger strength of each rule by the sum of the trigger strengths of all rules, and obtains its relative contribution to the system output during the reasoning process, which is used as a weighting factor for the rule output.

[0037] Step 65: In the fourth layer, the system constructs a linear backward function for each rule. Under the premise that the forward parameters are fixed, the least squares method is used to optimize the backward parameters, so that the model output is closer to the training samples and the inference accuracy is improved.

[0038] Step 66: In the fifth layer, the system performs a weighted average of all rule output values ​​according to the weights obtained from the normalization in the third layer, and completes the defuzzification process, finally outputting three precise control quantities: ΔK p ΔK i ΔK d It is used to dynamically adjust the proportional coefficient Kp, integral coefficient Ki and derivative coefficient Kd of the PID controller, thereby achieving high-precision closed-loop control of the ultraviolet LED light power;

[0039] Steps six and seven: The control signal output by the PID controller is processed by the digital-to-analog converter module and driven by the enhanced HOWLAND current source through the filtering module, thereby precisely adjusting the drive current of the UV LED lamp and realizing closed-loop automatic control of the UV light power. The automatic control system has a fast response capability, supports multi-dimensional adjustment of PWM frequency, amplitude, duty cycle and phase, and can dynamically adapt to changes in the system to ensure the stability of the UV LED lamp's light power under different temperatures, loads or long-term use conditions. It also adaptively corrects for temperature drift or device aging to ensure efficient operation of the system in changing environments.

[0040] The beneficial effects of this invention are:

[0041] The present invention describes a pulse-driven ultraviolet LED current source for charge management, which uses an FPGA to directly synthesize pulse voltage waveforms. Under the action of an enhanced HOWLAND circuit, the influence of stray capacitance is effectively isolated, forming a high-speed, high-output current pulse to drive the ultraviolet LED lamp and acquire current, voltage and temperature signals.

[0042] This invention discloses an automatic power control method for a pulse-driven ultraviolet LED current source for charge management. Based on multi-source signal acquisition, adaptive transconductance adjustment technology, and a multi-source perceptual fuzzy neural collaborative control mechanism, it achieves precise adjustment and stable control of the ultraviolet LED driving current. Specifically, the ultraviolet light power acquisition employs automatic selection of the transconductance coefficient. To make the output voltage of the ultra-low bias current op-amp The technical solution, in which the transconductance coefficient is based on the characteristics of the input signal (such as PWM voltage signal) The parameters (such as the current source conversion coefficient K, the photosensitivity S of the photodiode, etc.) are dynamically adjusted, and the output voltage is optimized through an n-level selection mechanism to ensure that it stably falls within the linear operating range of the analog-to-digital conversion module. Simultaneously, a multi-source sensing fuzzy neural collaborative control method (MS-FNCC) is proposed, which achieves online adaptive tuning of controller parameters through multi-dimensional input fusion and fuzzy rule self-learning mechanism. This algorithm uses ultraviolet light power P(t), light power change rate ΔP(t), driving current I(t), ultraviolet LED lamp operating voltage V(t), and enhanced HOWALAND current source operating temperature T as parameters. c (t) and the operating temperature T of the ultraviolet LED lamp L (t) is the input, and the dynamic tuning of the PID parameters is achieved through a fuzzy neural network structure. The MS-FNCC algorithm fuzzifies the multi-dimensional input features, and then performs weighted calculations through fuzzy rule base inference and linear output layer to output the proportional, integral, and derivative coefficient adjustments (ΔKp, ΔKi, ΔKd) of the PID controller, achieving adaptive adjustment of the control strategy. This fusion strategy can fully utilize various physical feedback information to dynamically optimize control accuracy and system response speed under complex environmental conditions, improving the system's adaptability to operating conditions such as temperature drift, load changes, and device aging.

[0043] The present invention discloses an automatic control method for the optical power of a pulse-driven ultraviolet LED current source for charge management. It adopts an automatic range ultraviolet optical power detection circuit to collect ultraviolet optical power, which effectively improves the accuracy of optical power measurement. The output optical power is compensated by a multi-source sensing fuzzy neural co-controller (MS-FNCC), which reduces the inherent error of the output optical power of analog devices. At the same time, the current source adopts aerospace-grade devices to meet the needs of long-term space operation. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of a pulse-driven ultraviolet LED current source for charge management according to the present invention;

[0045] Figure 2 This is a schematic diagram of the current source circuit described in this invention;

[0046] Figure 3 This is a schematic diagram of the signal detection circuit described in this invention;

[0047] Figure 4 This is a block diagram illustrating the optical power control principle of an automatic optical power control method for a pulse-driven ultraviolet LED current source used for charge management, as described in this invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0049] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0050] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 -Appendix Figure 4 Detailed explanation is as follows:

[0051] Example 1:

[0052] A pulse-driven ultraviolet LED current source for charge management includes a pulse waveform generation unit, a current source unit, and a signal acquisition unit;

[0053] The pulse waveform generation unit includes an FPGA and a digital-to-analog converter; the current source unit includes an enhanced HOWLAND current source and an ultraviolet LED lamp; the signal acquisition unit includes a current detection circuit, a voltage detection circuit, an ultraviolet light power detection circuit, a temperature detection circuit 1, a temperature detection circuit 2, and an analog-to-digital converter.

[0054] Temperature detection circuit 1 is used for current source temperature detection; temperature detection circuit 2 is used for UV LED lamp temperature detection.

[0055] Furthermore, the FPGA chip used is the XC7K325TFFG900. The PWM pulse waveform is synthesized by the FPGA using Direct Digital Frequency Synthesis (DDFS) technology. The logic design of the voltage waveform generation circuit is implemented using the hardware description language Verilog HDL. The amplitude, frequency, duty cycle, and phase of the output current are changed via buttons on the FPGA. The digital-to-analog converter (DAC) unit includes a DAC circuit and a filtering unit. The signal input terminal of the DAC unit is connected to the FPGA via a 40-pin expansion interface. The DAC circuit includes a DAC chip and a two-stage amplifier circuit. The DAC chip is a 14-bit AD9767 DAC chip. The DAC circuit performs digital-to-analog conversion on the waveform signal generated by the FPGA and outputs the converted analog voltage signal to the filtering unit. The filtering unit filters the received analog voltage signal and outputs the filtered analog voltage signal to the input terminal of the current source circuit. The output PWM waveform amplitude has a 14-bit resolution, and the number of pulses generated by the 100kHz PWM waveform within a 1Hz period is 0 to 10. 5 Each pulse, the duty cycle of the PWM waveform is adjustable at 1%, therefore, from 2 14 ×10 5 ×100≈1.64×10 11 A high output dynamic range of ultraviolet light power was achieved.

[0056] The host computer is connected to an FPGA. The FPGA is connected to a digital-to-analog converter (DAC) and an analog-to-digital converter (ADC). The DAC is connected to an enhanced HOWLAND current source. The enhanced HOWLAND current source is connected to a current detection circuit, a voltage detection circuit, a temperature detection circuit 1, and an ultraviolet LED lamp. The ultraviolet LED lamp is connected to an ultraviolet light power detection circuit and a temperature detection circuit 2. The ADC is connected to a current detection circuit, a voltage detection circuit, an ultraviolet light power detection circuit, a temperature detection circuit 1, and a temperature detection circuit 2.

[0057] The digital-to-analog conversion unit includes a digital-to-analog conversion circuit and a filtering unit;

[0058] The enhanced HOWLAND current source includes operational amplifiers U1, U2, U3, a precision resistor network U4, an operational amplifier U5, an ultraviolet LED lamp L1, and a current sensing resistor R6 and a capacitor C1; wherein, the precision resistor network U4 is composed of resistors R1, R2, R3, and R4 connected in parallel;

[0059] The inverting input of operational amplifier U1 is connected to resistor R1 and capacitor C1 of precision resistor network U4; the other end of resistor R1 in precision resistor network U4 is grounded; one end of resistor R2 in precision resistor network U4 is connected to resistor R1 in precision resistor network U4 and the inverting input of operational amplifier U1, and the other end is connected to the output and inverting input of voltage follower U2; the non-inverting input of operational amplifier U1 is connected to the pulse waveform output unit through resistor R4 in precision resistor network U4; one end of resistor R3 in precision resistor network U4 is connected to resistor R4 in precision resistor network U4. The positive input terminal of operational amplifier U1 is connected to the negative input terminal of the voltage follower U3, and the other end is connected to the output terminal and the inverting input terminal of the voltage follower U2. The output terminal of operational amplifier U1 is connected to one end of resistor R5, the other end of capacitor C1, and the positive input terminal of voltage follower U2. The positive output terminal of voltage follower U3 is connected to the other end of resistor R5, the anode of ultraviolet LED lamp L1, and the inverting input terminal of operational amplifier U5. The cathode of ultraviolet LED lamp L1 is connected to current sensing resistor R6. The other end of current sensing resistor R6 is connected to the output terminal of operational amplifier U5. The positive input terminal of operational amplifier U5 is grounded.

[0060] Furthermore, the current source unit includes an enhanced HOWLAND current source and a UV LED lamp; the enhanced HOWLAND current source includes an operational amplifier U1, a voltage follower U2, a voltage follower U3, a precision resistor network U4, and a UV LED lamp L1; the precision resistor network uses an LT5400 chip; the precision resistor network U4 includes resistors R1, R2, R3, R4, R5, and capacitor C1; the operational amplifier and voltage follower use an LM7171 chip. The inverting input of the operational amplifier U1 is connected to resistor R1 and capacitor C1 of the precision resistor network U4; the other end of resistor R1 in the precision resistor network U4 is grounded; one end of resistor R2 in the precision resistor network U4 is connected to resistor R1 in the precision resistor network U4 and the inverting input of the operational amplifier U1, and the other end is connected to the output and inverting input of the voltage follower U2; the non-inverting input of the operational amplifier U1 is connected to the precision resistor network U4. Resistor R4 is connected to the analog PWM pulse voltage signal output by the filter unit. One end of resistor R3 in the precision resistor network U4 is connected to resistor R4 in the precision resistor network U4 and the positive input terminal of operational amplifier U1, and the other end is connected to the output terminal and the inverting input terminal of voltage follower U3. The output terminal of operational amplifier U1 is connected to resistor R5, capacitor C1, and the positive input terminal of voltage follower U2. Capacitor C1 is connected across the inverting input terminal and the output terminal of operational amplifier to eliminate high-frequency self-oscillation of the current source. The ultraviolet LED lamp is model OPTAN-250J-BL. The operational amplifier is model AD8067. The positive output terminal of voltage follower U3 is connected to resistor R5, the anode of ultraviolet LED lamp L1, and the inverting input terminal of operational amplifier U5. The cathode of ultraviolet LED lamp L1 is connected to current sensing resistor R6. The other end of current sensing resistor R6 is connected to the output terminal of operational amplifier U5. The positive input terminal of operational amplifier U5 is grounded. Voltage follower U2 improves the speed of the current source, achieving a fast settling time and enhancing the accuracy of the output current; voltage follower U3 improves the circuitry to reduce output DC offset and noise levels; voltage follower U2 and voltage follower U3 together increase the output impedance of the current source, preventing current distortion; the precision resistor network U4 uses the LT5400 model, with resistors R1, R2, R3, and R4 having a matching accuracy of 0.01%, improving the output impedance of the current source; operational amplifier U5 ensures that all current flows through the UV LED, preventing current from flowing into the output parasitic capacitance, thus minimizing the impact of the output capacitance.

[0061] Furthermore, the PWM pulse waveform is synthesized by the FPGA using direct digital frequency synthesis technology.

[0062] Furthermore, the logic design of the voltage waveform generation circuit is implemented using the hardware description language Verilog HDL, and the amplitude, frequency, duty cycle and phase of the output current are changed by buttons on the FPGA.

[0063] Furthermore, the signal input terminal of the digital-to-analog converter unit is connected to the FPGA via a 40-pin expansion interface; the digital-to-analog converter circuit includes a digital-to-analog converter chip and a two-stage amplifier circuit; the digital-to-analog converter circuit performs digital-to-analog conversion on the waveform signal generated by the FPGA and outputs the converted analog voltage signal to the filtering unit; the filtering unit filters the received analog voltage signal and outputs the filtered analog voltage signal to the input terminal of the current source circuit.

[0064] Furthermore, the current detection circuit in the signal acquisition unit includes a current sensing resistor R6 and a current sensing amplifier; the high-voltage end of the current sensing resistor R6 is connected to the positive input pin of the current sensing amplifier, and the low-voltage end is connected to the negative input pin of the current sensing amplifier and ground; the analog-to-digital conversion unit includes an analog-to-digital conversion chip and a reference voltage source; the output of the current sensing amplifier is connected to the analog-to-digital conversion unit through an SMA interface;

[0065] Furthermore, the current sensing resistor is a metal film type low-temperature drift resistor with an accuracy of 0.1%; the current sensing amplifier uses an INA241 chip.

[0066] The voltage detection circuit includes resistors R13 and R14 and operational amplifier U10;

[0067] Furthermore, one end of resistor R13 is connected to the anode of the UV LED and the output terminal of the current source, and the other end is connected to resistor R14 and the positive input terminal of operational amplifier U11; one end of resistor R14 is connected to resistor R13 and the positive input terminal of operational amplifier U11, and the other end is connected to ground; the inverting input terminal and output terminal of operational amplifier U11 are connected; the output terminal of operational amplifier U11 is connected to the analog-to-digital converter unit through an SMA interface; the operational amplifier used is model ADA4897.

[0068] The ultraviolet light power detection circuit includes a silicon photodiode D1, an ultra-low bias current operational amplifier U6, a multiplexer U7, feedback resistors R7, R8, R9, and R10, and a feedback capacitor C2.

[0069] Furthermore, feedback capacitors C3, C4, and C5, voltage follower U8, and non-inverting proportional operational circuit; the cathode of silicon photodiode D1 is connected to the inverting input of ultra-low bias current operational amplifier U6 and the input of multiplexer U8; the anode of silicon photodiode D1 is connected to ground; the inverting input of ultra-low bias current operational amplifier U6 is connected to ground; the multiplexer includes input D, outputs S1-4, logic control inputs A1-2, and a high-level enable signal input EN; logic control inputs A1-2 and high-level enable signal input EN are connected to the FPGA via ribbon cables; feedback resistor R7 and feedback capacitor C2 are connected in parallel, with their ends connected to the output of ultra-low bias current operational amplifier U6 and the output S1 of the multiplexer, respectively; feedback resistor R8 and feedback capacitor C... 3 are connected in parallel, with their two ends connected to the output of the ultra-low bias current operational amplifier U6 and the output of the multiplexer S2, respectively; feedback resistor R9 and feedback capacitor C4 are connected in parallel, with their two ends connected to the output of the ultra-low bias current operational amplifier U6 and the output of the multiplexer S3, respectively; feedback resistor R10 and feedback capacitor C5 are connected in parallel, with their two ends connected to the output of the ultra-low bias current operational amplifier U6 and the output of the multiplexer S4, respectively; the output of the ultra-low bias current operational amplifier U6 is connected to the positive input of the voltage follower U8; the non-inverting proportional operational circuit includes operational amplifier U9 and resistors R11 and R12; the output of the voltage follower U8 is connected to the input of the non-inverting proportional operational circuit; the output of the non-inverting proportional operational circuit is connected to the input of the analog-to-digital converter unit via an SMA interface;

[0070] Furthermore, the silicon photodiode is model S1337-66BQ; the ultra-low bias current operational amplifier is model LTC6269-10; the multiplexer is model ADG5204; the operational amplifier is model ADA4897; the FPGA calculates the range of the ultraviolet light power detection circuit through the output voltage signal, and sends the corresponding logic level signal to the logic control input terminal of the multiplexer through the ribbon cable.

[0071] Temperature detection circuit 1 and temperature detection circuit 2 each include a temperature sensor U11, a temperature sensor U12, resistors R15 and R16, and capacitors C6 and C7. Temperature detection circuit 1 and temperature detection circuit 2 are two circuits with identical structures. Temperature sensor U11 is located next to the current source to measure the temperature of the current source circuit. The output terminal of temperature sensor U11 is connected to resistor R15. Resistor R15 is connected to capacitor C6 and then to the analog-to-digital converter unit via an SMA interface. Temperature sensor U12 is located next to the ultraviolet LED lamp to measure the temperature of the ultraviolet LED lamp. The output terminal of temperature sensor U12 is connected to resistor R16. Resistor R16 is connected to capacitor C7 and then to the analog-to-digital converter unit via an SMA interface. The temperature sensors are model LMT70A, with an accuracy of ±0.1℃, and are positioned very close to the current source and the ultraviolet LED lamp. If any problems occur during operation of the current source or the ultraviolet LED lamp, the temperature sensors can be used to confirm whether it is an electronic fault.

[0072] Furthermore, the analog-to-digital conversion unit includes an analog-to-digital conversion chip, an SMA interface, and a 40-pin expansion interface; the analog-to-digital conversion chip is model AD7606; the outputs of the current detection circuit, the ultraviolet light power detection circuit, the voltage detection circuit, and the two temperature detection circuits are connected to the analog-to-digital conversion unit through the SMA interface, the analog-to-digital conversion unit communicates with the FPGA through the 40-pin expansion interface, and the FPGA and the host computer communicate through UART to display the detection data on the host computer.

[0073] Example 2:

[0074] An automatic power control method for a pulse-driven ultraviolet LED current source for charge management, as described in Embodiment 1, includes the following steps:

[0075] Step 1: Using silicon photodiode D1 in zero-bias photovoltaic mode, the received ultraviolet light is converted into a photocurrent signal proportional to the incident light power, thereby obtaining the ultraviolet light power value.

[0076] Step 2: Real-time selection of feedback resistor and feedback capacitor for ultra-low bias current op-amp U6; output voltage of ultra-low bias current op-amp U6. From transconductance coefficient The transconductance coefficient is dynamically adjusted using an n-level selection mechanism based on the characteristics of the input signal; the n-level selection mechanism dynamically selects a suitable transconductance coefficient based on the input signal of the enhanced HOWLAND current source, thereby achieving automatic switching of the optical power range. Its expression is:

[0077]

[0078] Where S is the photosensitive function of the photodiode. Here, represents the photoelectric conversion coefficient of the ultraviolet LED lamp, and K represents the conversion coefficient of the enhancement-mode HOWLAND circuit. Voltage for FPGA to synthesize PWM pulse waveforms;

[0079] Furthermore, the 𝑛-level selection mechanism used in step two is implemented in the following way:

[0080] Parameters related to system operation include PWM voltage signals Real-time measurement of current source conversion coefficient K and photodiode photosensitivity S calculate;

[0081] Based on multiple preset thresholds and rules, the transconductance coefficient It will automatically select from multiple levels; whenever the characteristics of the input signal reach the range switching threshold, the system will automatically adjust the transconductance coefficient and send a signal to the logic control input terminal A1-m of the multiplexer U7. The value of m is determined according to the specific level of n, ensuring that the output voltage is always within the effective input range of the analog-to-digital conversion unit, thereby converting the ultraviolet light power into the corresponding voltage.

[0082] Step 3: Connect a high-precision current sensing resistor R6 in series at the cathode of the UV LED lamp L1, and perform voltage conversion through a low-noise current sensing operational amplifier U5 to indirectly obtain the working current flowing through the UV LED lamp L1. The converted voltage signal is then sent to the FPGA for processing via an analog-to-digital converter module.

[0083] Step 4: By sampling the potential difference between the anode and cathode of the UV LED lamp L1, and combining the resistor voltage divider and voltage follower buffer structure, a stable operating voltage for the UV LED lamp is obtained. This voltage is then input into the analog-to-digital converter module and sent to the FPGA for processing.

[0084] Step 5: The high-precision temperature sensors mounted next to the enhanced HOWLAND current source and the UV LED L1 are used to collect their respective operating temperatures. After high-frequency interference is filtered out by a low-pass filter, the data are sent to the analog-to-digital conversion module for subsequent temperature compensation and deviation correction.

[0085] Step 6: Input the collected ultraviolet light power, working current, working voltage, working temperature of ultraviolet LED L1, and multi-dimensional signals of working voltage and working temperature of ultraviolet LED into the FPGA control unit. Through the embedded MS-FNCC algorithm, the ultraviolet light power is automatically controlled in real time.

[0086] Furthermore, the specific implementation method of the MS-FNCC algorithm in step six includes the following steps:

[0087] Step 61: Set the input signals in the control algorithm as follows: ultraviolet light power P(t), ultraviolet light power change rate ΔP(t), driving current I(t), ultraviolet LED lamp operating voltage V(t), and enhanced HOWALAND current source operating temperature T. c (t) and the operating temperature T of the ultraviolet LED lamp L (t);

[0088] Step 62: In the first layer of the adaptive neural network, the system performs fuzzification processing on each input signal through a predefined membership function, converting each input variable into a membership value of multiple fuzzy sets, reflecting its degree of belonging in different fuzzy semantics. This process is controlled by the forward parameters to shape and distribute the membership function.

[0089] Step 63: In the second layer, the network performs a multiplication operation on the membership degree of each input variable output from the first layer to obtain the trigger strength of each fuzzy rule, which is used to represent the activation strength of each fuzzy rule.

[0090] Step 64: In the third layer, the system normalizes the trigger strength of all rules obtained in the second layer, that is, divides the trigger strength of each rule by the sum of the trigger strengths of all rules, and obtains its relative contribution to the system output during the reasoning process, which is used as a weighting factor for the rule output.

[0091] Step 65: In the fourth layer, the system constructs a linear backward function for each rule. Under the premise that the forward parameters are fixed, the least squares method is used to optimize the backward parameters, so that the model output is closer to the training samples and the inference accuracy is improved.

[0092] Step 66: In the fifth layer, the system performs a weighted average of all rule output values ​​according to the weights obtained from the normalization in the third layer, and completes the defuzzification process, finally outputting three precise control quantities: ΔK p ΔK i ΔK d It is used to dynamically adjust the proportional coefficient Kp, integral coefficient Ki and derivative coefficient Kd of the PID controller, thereby achieving high-precision closed-loop control of the ultraviolet LED light power;

[0093] Steps six and seven: The control signal output by the PID controller is processed by the digital-to-analog converter module and driven by the enhanced HOWLAND current source through the filtering module, thereby precisely adjusting the drive current of the UV LED lamp and realizing closed-loop automatic control of the UV light power. The automatic control system has a fast response capability, supports multi-dimensional adjustment of PWM frequency, amplitude, duty cycle and phase, and can dynamically adapt to changes in the system to ensure the stability of the UV LED lamp's light power under different temperatures, loads or long-term use conditions. It also adaptively corrects for temperature drift or device aging to ensure efficient operation of the system in changing environments.

[0094] This embodiment uses an FPGA to directly synthesize pulse voltage waveforms. Under the action of the enhanced HOWLAND circuit, the influence of stray capacitance is effectively isolated, forming a high-speed, high-output current pulse to drive the ultraviolet LED lamp. Current, voltage, and temperature signals are acquired. Furthermore, this method uses an automatic range ultraviolet light power detection circuit to acquire ultraviolet light power, which effectively improves the accuracy of light power measurement. The output light power is compensated by a multi-source sensing fuzzy neural co-controller (MS-FNCC), which reduces the inherent error of the output light power of analog devices. At the same time, the current source uses aerospace-grade devices, and the precision resistor network can operate in a temperature range of -55℃ to 150℃ to meet the needs of long-term space operation.

[0095] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0096] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A pulse-driven ultraviolet LED current source for charge management, characterized in that, It includes a pulse waveform generation unit, a current source unit, and a signal acquisition unit; The pulse waveform generation unit includes an FPGA and a digital-to-analog converter; the current source unit includes an enhanced HOWLAND current source and an ultraviolet LED lamp; the signal acquisition unit includes a current detection circuit, a voltage detection circuit, an ultraviolet light power detection circuit, a temperature detection circuit 1, a temperature detection circuit 2, and an analog-to-digital converter. The host computer is connected to the FPGA. The FPGA is connected to the digital-to-analog converter and the analog-to-digital converter. The digital-to-analog converter is connected to the enhanced HOWLAND current source. The enhanced HOWLAND current source is connected to the current detection circuit, the voltage detection circuit, the temperature detection circuit 1, and the ultraviolet LED lamp. The ultraviolet LED lamp is connected to the ultraviolet light power detection circuit and the temperature detection circuit 2. The analog-to-digital conversion unit is connected to the current detection circuit, voltage detection circuit, ultraviolet light power detection circuit, temperature detection circuit 1, and temperature detection circuit 2, respectively. The digital-to-analog conversion unit includes a digital-to-analog conversion circuit and a filtering unit; The enhanced HOWLAND current source includes operational amplifiers U1, U2, U3, a precision resistor network U4, an operational amplifier U5, an ultraviolet LED lamp L1, and a current sensing resistor R6 and a capacitor C1; wherein, the precision resistor network U4 is composed of resistors R1, R2, R3, and R4 connected in parallel; The inverting input of operational amplifier U1 is connected to resistor R1 and capacitor C1 of precision resistor network U4; the other end of resistor R1 in precision resistor network U4 is grounded; one end of resistor R2 in precision resistor network U4 is connected to resistor R1 in precision resistor network U4 and the inverting input of operational amplifier U1, and the other end is connected to the output and inverting input of voltage follower U2; the non-inverting input of operational amplifier U1 is connected to the pulse waveform output unit through resistor R4 in precision resistor network U4; one end of resistor R3 in precision resistor network U4 is connected to resistor R4 in precision resistor network U4. The positive input terminal of operational amplifier U1 is connected to the negative input terminal of the voltage follower U3, and the other end is connected to the output terminal and the inverting input terminal of the voltage follower U2. The output terminal of operational amplifier U1 is connected to one end of resistor R5, the other end of capacitor C1, and the positive input terminal of voltage follower U2. The positive output terminal of voltage follower U3 is connected to the other end of resistor R5, the anode of ultraviolet LED lamp L1, and the inverting input terminal of operational amplifier U5. The cathode of ultraviolet LED lamp L1 is connected to current sensing resistor R6. The other end of current sensing resistor R6 is connected to the output terminal of operational amplifier U5. The positive input terminal of operational amplifier U5 is grounded.

2. The pulse-driven ultraviolet LED current source for charge management according to claim 1, characterized in that, The PWM pulse waveform is synthesized by the FPGA using direct digital frequency synthesis technology.

3. A pulse-driven ultraviolet LED current source for charge management according to claim 1 or 2, characterized in that, The logic design of the voltage waveform generation circuit is implemented using the hardware description language Verilog HDL. The amplitude, frequency, duty cycle, and phase of the output current are changed by buttons on the FPGA.

4. A pulse-driven ultraviolet LED current source for charge management according to claim 3, characterized in that, The signal input terminal of the digital-to-analog converter unit is connected to the FPGA via a 40-pin expansion interface; the digital-to-analog converter circuit includes a digital-to-analog converter chip and a two-stage amplifier circuit; the digital-to-analog converter circuit performs digital-to-analog conversion on the waveform signal generated by the FPGA and outputs the converted analog voltage signal to the filtering unit; The filtering unit filters the received analog voltage signal and outputs the filtered analog voltage signal to the input terminal of the current source circuit.

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