High-precision, low-interference laser temperature control system and method

Abstract

This invention relates to a high-precision, low-interference laser temperature control system and method, belonging to the field of laser temperature control technology. It includes: a temperature acquisition module containing n linearly arranged temperature sensors, positioned at preset intervals around the laser; a signal conditioning circuit connected to the temperature acquisition module, comprising a linearization unit, an amplification unit, and a subtraction unit, wherein the temperature sensor outputs sequentially pass through a voltage divider in the linearization unit, gain adjustment in the amplification unit, and bias elimination in the subtraction unit to form a conditioning signal matching the full-scale input range of an ADC; and a temperature estimation unit, which constructs a polynomial curve based on the temperature sensor position coordinates and calculates the coefficients using the least squares method to estimate the laser chip temperature. This invention provides a stable and reliable temperature control solution for high-precision laser applications through spatially distributed precise temperature estimation, active spectrum broadening to enhance electromagnetic interference suppression, highly reliable execution drive, and intelligent algorithm optimization.

Description

Technical Field

[0001] This invention relates to a high-precision, low-interference laser temperature control system and method, belonging to the field of laser temperature control technology. Background Technology

[0002] As precision optical devices, lasers are extremely sensitive to temperature changes in their output wavelength, power, and long-term stability. For example, the wavelength temperature coefficient of a distributed feedback (DFB) semiconductor laser can reach 0.1 nm / ℃, and even small temperature fluctuations can lead to systematic errors in high-precision applications such as lidar and spectral analysis. Although existing temperature control technologies have achieved basic temperature regulation, they still have significant limitations in terms of measurement accuracy, anti-interference capability, and operational reliability, specifically:

[0003] 1. Limitations of traditional single-point temperature measurement and static models

[0004] Existing technologies mostly rely on single-point temperature sensors (such as NTC thermistors or thermocouples) to directly obtain the surface temperature of the laser, ignoring the temperature gradient between the chip and the casing. Single-point sensors can only reflect local temperatures and cannot capture the true temperature distribution in the core area of ​​the chip, leading to large estimation errors. For example, the temperature control device and method for a laser disclosed in existing patent publication number CN118299919A only achieves closed-loop control through single-channel temperature feedback and does not involve a method for estimating temperature using polynomial curve fitting.

[0005] 2. Electromagnetic interference issues of fixed-frequency PWM drive

[0006] Most temperature control systems use fixed-frequency PWM signals to drive semiconductor coolers (TECs). Fixed frequencies can generate concentrated spectral interference, especially in scenarios with stringent electromagnetic compatibility (EMC) requirements, such as laser communication and medical testing. Interference signals may couple to the optical detection link, leading to a decrease in the signal-to-noise ratio.

[0007] 3. The contradiction between the reliability and response speed of the actuator

[0008] Traditional H-bridge driver circuits often suffer from short circuits in the same-side bridge arm due to timing conflicts in the drive signals, or the single voltage configuration cannot simultaneously achieve cooling / heating efficiency. While a laser secondary temperature control device disclosed in patent announcement number CN222896930U improves stability through two-stage temperature control, its TEC response speed is limited by a single voltage drive, resulting in a temperature adjustment time of hundreds of milliseconds, which is insufficient to meet the requirements of ultrafast laser pulse applications.

[0009] 4. Shortcomings in control algorithm and noise suppression

[0010] Existing PID control is mostly implemented using analog circuits. Due to the drift of component parameters, the long-term temperature control accuracy is easily degraded to ±0.1℃. Although digital PID parameters are adjustable, the fixed control cycle is difficult to adapt to nonlinear temperature changes, and it does not combine random frequency carrier technology to suppress system noise.

[0011] In summary, existing technologies have room for improvement in multiple dimensions, and a high-precision, low-interference laser temperature control system and method has become an urgent need. Summary of the Invention

[0012] The purpose of this invention is to propose a high-precision, low-interference laser temperature control system and method. This invention improves the accuracy of temperature measurement and the reliability of execution through innovative designs such as multi-sensor polynomial fitting, random frequency carrier PWM, H-bridge mutual exclusion drive and cascaded voltage configuration, and solves the problems existing in the prior art.

[0013] The high-precision, low-interference laser temperature control system of the present invention includes:

[0014] The temperature acquisition module includes n linearly arranged temperature sensors, which are arranged around the laser at a preset interval.

[0015] The signal conditioning circuit, connected to the temperature acquisition module, includes a linearization unit, an amplification unit, and a subtraction unit. The output of the temperature sensor is sequentially divided by the linearization unit, adjusted by the gain of the amplification unit, and eliminated by the bias of the subtraction unit to form a conditioning signal that matches the full-scale input range of the ADC.

[0016] The temperature estimation unit constructs a polynomial curve based on the location coordinates of the temperature sensor and solves for the coefficients using the least squares method to estimate the temperature of the laser chip.

[0017] The PID control unit receives the temperature value output by the temperature estimation unit and generates an adjustment amount through closed-loop control.

[0018] The random frequency carrier PWM module generates a PWM signal whose carrier frequency varies randomly within a preset range according to the adjustment amount;

[0019] The temperature control actuator is composed of an H-bridge circuit consisting of transistor modules, wherein the drive signals of the transistor modules are mutually exclusive and are configured with cascaded voltages.

[0020] Preferably, the equivalent resistance of the temperature sensor It is connected in series with a fixed-value resistor R to form a voltage divider circuit; this voltage divider circuit is connected to a high-precision voltage source. The voltage divider terminals of the fixed resistor R are directly connected to the input terminals of the amplification unit. The amplification unit consists of a first-stage operational amplifier U1, whose input terminal receives the output signal from the linearization unit. Resistors R1 and R2 are connected in series in the feedback loop of the first-stage operational amplifier U1, and its output terminal is directly connected to the non-inverting input terminal of the subtraction unit. The subtraction unit consists of a second-stage operational amplifier U2, whose non-inverting input terminal receives the output signal V from the amplification unit. out1 The inverting input terminal is connected to a bias voltage V. _offset Bias voltage V _offset After being generated by a DAC or resistor divider network, the voltage is isolated and buffered by a voltage follower U3, and then connected to the inverting input of the second-stage operational amplifier U2; the subtraction unit is equipped with four equivalent resistors: R3, R4, R5, and R6, and the output is directly connected to the ADC interface.

[0021] Preferably, the polynomial curve in the temperature estimation unit is an nth-degree polynomial, where n is the number of sensors, and the polynomial coefficients are solved by minimizing the sum of squared errors between the measured temperature and the fitted temperature.

[0022] Preferably, the transistor module includes a left transistor and a right transistor; the left transistor is an NPN transistor or an N-type MOSFET, and the right transistor is a PNP transistor or a P-type MOSFET; the collector / drain of the left transistor is connected to voltage 1, and the emitter / source is connected to the first terminal of the thermoelectric cooler TEC; the emitter / source of the right transistor is connected to voltage 2, and the collector / drain, together with the emitter / source of the left transistor, is connected to the first terminal of the thermoelectric cooler TEC; the second terminal of the thermoelectric cooler TEC is connected to voltage 3 separately; voltages 1, 2, and 3 satisfy the following condition: voltage 1 > voltage 3 > voltage 2.

[0023] Preferably, voltage 3 is the reference ground voltage or the system reference voltage.

[0024] Preferably, the carrier frequency of the random frequency carrier PWM module is dynamically adjusted by a circuit noise signal, which is then scaled and biased to generate a frequency control word.

[0025] The high-precision, low-interference laser temperature control method of the present invention includes the following steps:

[0026] S1: Acquire temperature signals around the laser using multiple linearly arranged temperature sensors;

[0027] S2: Perform linearization transformation, amplification and bias elimination processing on the sensor signal in sequence to make the conditioned signal match the ADC input range;

[0028] S3: Construct a polynomial curve based on sensor coordinates, fit the coefficients using the least squares method, and calculate the laser chip temperature;

[0029] S4: The PID algorithm is used to perform closed-loop control on the estimated temperature and the target temperature, and the PWM duty cycle adjustment is generated.

[0030] S5: Dynamically adjust the PWM carrier frequency based on circuit noise to generate a PWM signal that varies randomly within a preset range;

[0031] S6: Drives the semiconductor cooler TEC through the H-bridge actuator, controlling the N-type and P-type transistors to work alternately to achieve temperature regulation.

[0032] Preferably, step S2 includes the following sub-steps:

[0033] S21: Equivalent resistance of the temperature sensor A voltage divider circuit is formed by connecting it in series with a fixed-value resistor R, and this voltage divider circuit is connected to a high-precision voltage source. The voltage division of a fixed resistor R is used as the sensor output signal. ,Right now The output of the linearization unit is directly connected to the input of the amplification unit;

[0034] S22: The input of the first-stage operational amplifier U1 receives the output of the linearization unit. The signal, the series resistors R1 and R2 in the feedback loop of the first-stage operational amplifier U1, are configured... , To adjust the signal gain by increasing the amplification factor, the amplified intermediate signal V is output. out1 ;

[0035] S23: The non-inverting input of the second-stage operational amplifier U2 receives the V output from the amplification unit. out1 The inverting input terminal is connected to a bias voltage V. _offset Bias voltage V _offset After being generated by a DAC or resistor divider network, the signal is isolated and buffered by a voltage follower U3, and then connected to the inverting input of the second-stage operational amplifier U2. The external resistors of the second-stage operational amplifier U2 satisfy the following conditions: R3 = R4 = R5 = R6. The final output is the conditioned signal V. out =V out1 -V _offset It is directly fed into the ADC interface; the amplification factor is... , where V inmin V is the output of the temperature sensor at the lowest temperature. inmax This is the output of the temperature sensor at the highest temperature. This is the input range of the ADC.

[0036] Preferably, step S3 includes the following sub-steps:

[0037] S31: Sensor Data Acquisition

[0038] Obtain the position coordinates (x, y) of n sensors in the temperature acquisition module. i , y i ), where x i Let y be the linear distance of the sensor along the central axis of the laser. i This corresponds to the actual measured temperature value of the sensor (i=1,2,...,n).

[0039] S32: Polynomial Model Construction

[0040] Based on the number of temperature sensors n, construct an nth-degree polynomial temperature distribution model:

[0041]

[0042] Where a0, a1, ..., a n Let x be the coefficients of the polynomial to be solved, x be the position variable along the axis, and y be the temperature value.

[0043] S33: Definition of Error Function

[0044] Define the sum of squared errors function to characterize the deviation between the measured temperature from the model-fitted temperature:

[0045]

[0046] in, To fit the temperature to the model, The actual temperature measured by the sensor;

[0047] S34: Solving coefficients using the least squares method

[0048] Taking the partial derivatives of each coefficient of the error function J and setting them to zero, we obtain the system of linear equations:

[0049]

[0050] Represent the system of equations in matrix form: ;

[0051] Where: X is an n×(n+1) order design matrix, elements ; For coefficient vectors; Given the measured temperature vector; solve for the coefficient vector by matrix inversion: ;

[0052] S35: Laser position temperature estimation

[0053] The position coordinates x of the laser chip laser Substitute the obtained polynomial model into the solution and calculate the corresponding temperature value: Tlaser = a n x n laser + a n-1 x n-1 laser + ... + a1x laser + a0; Output T laser As an estimated temperature for laser chips.

[0054] Preferably, step S5 includes the following sub-steps:

[0055] S51: Random noise acquisition: Random noise in the circuit is used as the source of random frequency, and the noise type is Gaussian white noise;

[0056] S52: Voltage signal acquisition: A voltage signal with a fixed amplitude of V is acquired using an ADC acquisition circuit. The actual acquired value is V. adc V adc =V+N, where N is Gaussian white noise.

[0057] S53: Noise component extraction: by calculating N = V adc - V, separating out the noise component N;

[0058] S54: Random frequency calculation: Multiply the noise component N by the coefficient K, and then add the bias F. offset The random frequency F is obtained by rounding down. vary The formula is: F vary =N K+F offset ;

[0059] S55: Frequency Range Constraint: Set the highest frequency F varymax and lowest frequency F varymin Ensure that the random frequency satisfies F varymin ≤F vary ≤F varymax This is to limit the range of carrier frequency fluctuations.

[0060] Compared with existing technologies, the high-precision, low-interference laser temperature control system and method of the present invention exhibit the following beneficial effects in terms of technical performance and practical application:

[0061] 1. Improved temperature measurement accuracy and temperature field modeling capabilities

[0062] By employing a distributed temperature sensor array and a polynomial curve fitting algorithm, the limitations of traditional single-point temperature measurement are overcome, enabling accurate estimation of the laser chip temperature and effectively eliminating measurement deviations caused by temperature gradients.

[0063] The signal conditioning circuit design was optimized, and the sensor signal quality was improved by linearization, amplification and bias elimination processing, thereby reducing the impact of noise interference on temperature acquisition.

[0064] 2. Enhanced electromagnetic interference suppression capability

[0065] By introducing random frequency carrier PWM technology, the concentrated spectrum interference generated by traditional fixed frequency drive is dispersed, the electromagnetic compatibility of the system is improved, and it is suitable for scenarios that are sensitive to electromagnetic environment, such as medical and aviation.

[0066] By reducing noise coupling through circuit isolation design, the signal-to-noise ratio of the optical detection link is improved, ensuring the stability of high-precision laser applications.

[0067] 3. Optimization of actuator reliability and response speed

[0068] The H-bridge circuit uses mutually exclusive drive logic and cascaded voltage configuration to avoid the risk of short circuits in the same bridge arm from the hardware level, thereby improving the reliability of power devices.

[0069] Cascaded voltage design accelerates the switching between cooling and heating modes of a thermoelectric cooler (TEC), shortens the dynamic response time, and meets the requirements for rapid temperature regulation.

[0070] 4. Upgrade the control algorithm and system robustness

[0071] By integrating digital PID control with least squares fitting, adaptive adjustment of temperature deviation is achieved, solving the problem of traditional analog PID being easily affected by temperature drift and improving long-term temperature control stability.

[0072] In summary, this invention comprehensively overcomes existing technical bottlenecks by employing spatially distributed temperature measurement, active spectrum broadening to enhance electromagnetic interference suppression, highly reliable execution drive, and intelligent algorithm optimization, providing a stable and reliable temperature control solution for high-precision laser applications. Attached Figure Description

[0073] Figure 1 This is a diagram showing the arrangement of multiple sensors for data acquisition in this invention;

[0074] Figure 2 This is the overall block diagram of the PID control in this invention;

[0075] Figure 3 This is a circuit diagram of the signal conditioning circuit in this invention;

[0076] Figure 4 This is a circuit diagram of the actuator of the temperature control system in this invention;

[0077] Figure 5 This is a spectrum analysis diagram of the PWM signal with a fixed carrier frequency in this invention;

[0078] Figure 6 This is a spectral analysis diagram of the PWM signal of the random carrier frequency in this invention. Detailed Implementation

[0079] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0080] Example 1:

[0081] This embodiment discloses a high-precision, low-interference laser temperature control system, comprising:

[0082] The temperature acquisition module contains n linearly arranged temperature sensors, which are arranged around the laser at a preset interval.

[0083] The signal conditioning circuit, connected to the temperature acquisition module, includes a linearization unit, an amplification unit, and a subtraction unit. The output of the temperature sensor is sequentially divided by the linearization unit, adjusted by the gain of the amplification unit, and eliminated by the bias of the subtraction unit to form a conditioning signal that matches the full-scale input range of the ADC.

[0084] The temperature estimation unit constructs a polynomial curve based on the location coordinates of the temperature sensor and solves for the coefficients using the least squares method to estimate the temperature of the laser chip.

[0085] like Figure 2 As shown, the PID control unit receives the temperature value output by the temperature estimation unit and generates an adjustment amount through closed-loop control.

[0086] The random frequency carrier PWM module generates a PWM signal whose carrier frequency varies randomly within a preset range according to the adjustment amount;

[0087] The temperature control actuator is composed of an H-bridge circuit consisting of transistor modules, wherein the drive signals of the transistor modules are mutually exclusive and are configured with cascaded voltages.

[0088] like Figure 3 As shown, the equivalent resistance of the temperature sensor It is connected in series with a fixed-value resistor R to form a voltage divider circuit; this voltage divider circuit is connected to a high-precision voltage source. The voltage divider terminals of the fixed resistor R are directly connected to the input terminals of the amplification unit. The amplification unit consists of a first-stage operational amplifier U1, whose input terminal receives the output signal from the linearization unit. Resistors R1 and R2 are connected in series in the feedback loop of the first-stage operational amplifier U1, and its output terminal is directly connected to the non-inverting input terminal of the subtraction unit. The subtraction unit consists of a second-stage operational amplifier U2, whose non-inverting input terminal receives the output signal V from the amplification unit. out1 The inverting input terminal is connected to a bias voltage V._offset Bias voltage V _offset After being generated by a DAC or resistor divider network, the voltage is isolated and buffered by a voltage follower U3, and then connected to the inverting input of the second-stage operational amplifier U2; the subtraction unit is equipped with four equivalent resistors: R3, R4, R5, and R6, and the output is directly connected to the ADC interface.

[0089] First, the nonlinear temperature sensor voltage is approximated as linear by connecting a fixed-value resistor in series, and the voltage drop across this resistor is used as the sensor output. V ref It is a high-precision voltage source, not exceeding the reference voltage of the ADC.

[0090] Assume the sensor output is V at the lowest temperature. inmin At the highest temperature, the sensor output is V. inmax The input range of the ADC is Then the magnification factor is The first-stage operational amplifier U1 amplifies the Vin signal to obtain V. out1 R2 and R1 in the circuit should satisfy... .

[0091] After the signal is amplified, a bias voltage V should be removed. _offset To prevent V out1 The maximum value exceeds the maximum input value of the ADC, V _offset =G V inmin U2 is a subtraction circuit, where R3=R4=R5=R6. _offset It can be generated by a DAC or by a resistor divider. A voltage follower constructed using U3 is connected to the inverting input of U2, and the final output V... out =V out1 -V _offset This circuit converts the sensor's output range into the ADC's input range.

[0092] The polynomial curve in the temperature estimation unit is an nth-degree polynomial, where n is the number of sensors. The polynomial coefficients are solved by minimizing the sum of squared errors between the measured temperature and the fitted temperature.

[0093] like Figure 4As shown, the temperature control actuator consists of two transistors, one on the left and one on the right. The left transistor is an NPN or N-type MOSFET, while the right transistor is a P-type or PNP MOSFET. The diagram uses two MOSFETs as an example. The drain of the left N-type MOSFET or the collector of the NPN transistor is connected to voltage 1, and the source of the N-type MOSFET or the emitter of the NPN transistor is connected to the TEC. The source of the right P-type MOSFET or the emitter of the PNP transistor is connected to voltage 2, and the drain of the P-type MOSFET or the collector of the PNP transistor is connected to the same side of the TEC as the left transistor. The other side of the TEC is connected to voltage 3. The order of voltages 1, 2, and 3 is: voltage 1 > voltage 3 > voltage 2. When drive signal 1 is active on the left, drive signal 2 is inactive to ensure the right transistor remains off; when drive signal 2 is active on the right, drive signal 1 is inactive to ensure the left transistor remains off. Voltage 3 is the reference ground voltage or the system reference voltage.

[0094] The carrier frequency of the random frequency carrier PWM module is dynamically adjusted by the circuit noise signal, which is then scaled and biased to generate a frequency control word.

[0095] As a preferred option, during operation, the temperature acquisition module uses four NTC thermistor chips, arranged at 2mm intervals along the axis of the laser tube, which are connected in series with a 10kΩ fixed resistor to form a voltage divider circuit and connected to a 3.3V high-precision voltage source.

[0096] Signal conditioning circuit: The output of the linearization unit is amplified by op-amp U1 (AD8628) (feedback resistors R1=10kΩ, R2=20kΩ, gain=3), and then the 1.25V bias is eliminated by the subtraction circuit of op-amp U2 (OPA2376). The conditioned signal range is 0-3.3V, which is matched to the 16-bit ADC input of STM32H743VIT6;

[0097] Temperature estimation unit: based on the position coordinates of 4 sensors (x i , y i A cubic polynomial model T(x) = a0 + a1x + a2x² + a3x³ is constructed, and the coefficients are solved by the least squares method to estimate the chip center temperature (at x = 0).

[0098] PID control unit: The PID controller is an STM32H743VIT6 with a sampling period of 1ms, a proportional coefficient KP=5.2, an integral coefficient KI=0.1, and a derivative coefficient KD=0.05, achieving temperature stability of ±0.001℃.

[0099] Random frequency PWM module: dynamically adjusts the carrier frequency (randomly changing from 1kHz to 5kHz) based on circuit noise (Gaussian white noise), with a duty cycle adjustment accuracy of 0.1%;

[0100] Temperature control system actuator: IR2104 drives 4 N-channel MOSFETs (IRF540), configured with +12V / -5V cascade voltage, drive signal dead time 5μs to avoid short circuit of the same side bridge arm.

[0101] Example 2:

[0102] The high-precision, low-interference laser temperature control method of the present invention includes the following steps:

[0103] S1: Acquire temperature signals around the laser using multiple linearly arranged temperature sensors;

[0104] S2: The sensor signal is sequentially linearized, amplified, and bias-canceled to ensure the conditioned signal matches the ADC input range.

[0105] S21: Resistance of the temperature sensor A voltage divider circuit is formed by connecting it in series with a fixed-value resistor R, and this voltage divider circuit is connected to a high-precision voltage source. The voltage division of a fixed resistor R is used as the sensor output signal. ,Right now The output of the linearization unit is directly connected to the input of the amplification unit;

[0106] S22: The input of the first-stage operational amplifier U1 receives the output of the linearization unit. The signal, the series resistors R1 and R2 in the feedback loop of the first-stage operational amplifier U1, are configured... , To adjust the signal gain by increasing the amplification factor, the amplified intermediate signal V is output. out1 ;

[0107] S23: The non-inverting input of the second-stage operational amplifier U2 receives the V output from the amplification unit. out1 The inverting input terminal is connected to a bias voltage V. _offset Bias voltage V _offset After being generated by a DAC or resistor divider network, the signal is isolated and buffered by a voltage follower U3, and then connected to the inverting input of the second-stage operational amplifier U2. The external resistors of the second-stage operational amplifier U2 satisfy the following conditions: R3 = R4 = R5 = R6. The final output is the conditioned signal V. out =V out1 -V _offset It is directly fed into the ADC interface; the amplification factor is... , where V inmin V is the output of the temperature sensor at the lowest temperature. inmax This is the output of the temperature sensor at the highest temperature. This is the input range of the ADC.

[0108] S3: Construct a polynomial curve based on sensor coordinates, fit the coefficients using the least squares method, and calculate the laser chip temperature;

[0109] S31: Sensor Data Acquisition

[0110] Obtain the position coordinates (x, y) of n sensors in the temperature acquisition module. i , y i ), where x i Let y be the linear distance of the sensor along the central axis of the laser. i This corresponds to the actual measured temperature value of the sensor (i=1,2,...,n).

[0111] like Figure 1 As shown, with the position of sensor 1 as the zero point, an x-axis is constructed along the directions of sensor 1, sensor 2, sensor n, and laser LD. The y-axis is constructed with the temperature values ​​of sensor n, sensor 2, and sensor 1 as the zero point. Sensor 1 can be described as (x1, y1), sensor 2 as (x2, y2), and sensor n as (x...). n ,y n Because temperature in space cannot change abruptly and is smooth and continuous, a smooth and continuous temperature curve can be constructed starting from any point. Therefore, there exists a smooth, continuous, and differentiable curve passing through sensor 1, sensor 2...sensor n, and laser LD. Let the positions of sensor 1, sensor 2...sensor n be t1, t2...t... n The position of the laser LD is t n+1 The sensor closest to the laser should be less than 2mm away from the laser, and other sensors should be arranged at equal intervals L.

[0112] S32: Polynomial Model Construction

[0113] Based on the number of temperature sensors n, construct an nth-degree polynomial temperature distribution model:

[0114]

[0115] Where a0, a1, ..., a n Let x be the coefficients of the polynomial to be solved, x be the position variable along the axis, and y be the temperature value.

[0116] S33: Definition of Error Function

[0117] Define the sum of squared errors function to characterize the deviation between the measured temperature from the model-fitted temperature:

[0118]

[0119] in, To fit the temperature to the model, The actual temperature measured by the sensor;

[0120] S34: Solving coefficients using the least squares method

[0121] Taking the partial derivatives of each coefficient of the error function J and setting them to zero, we obtain the system of linear equations:

[0122]

[0123] Represent the system of equations in matrix form: ;

[0124] Where: X is an n×(n+1) order design matrix, elements ; For coefficient vectors; Given the measured temperature vector; solve for the coefficient vector by matrix inversion: ;

[0125] S35: Laser position temperature estimation

[0126] The position coordinates x of the laser chip laser Substitute the obtained polynomial model into the solution and calculate the corresponding temperature value: T laser = a n x n laser + a n-1 x n-1 laser + ... + a1x laser + a0; Output T laser As an estimated temperature for laser chips.

[0127] S4: The PID algorithm is used to perform closed-loop control on the estimated temperature and the target temperature, and the PWM duty cycle adjustment is generated.

[0128] S5: Dynamically adjust the PWM carrier frequency based on circuit noise to generate a PWM signal that varies randomly within a preset range.

[0129] S51: Random noise acquisition: Random noise in the circuit is used as the source of random frequency, and the noise type is Gaussian white noise;

[0130] S52: Voltage signal acquisition: A voltage signal with a fixed amplitude of V is acquired using an ADC acquisition circuit. The actual acquired value is V. adc V adc =V+N, where N is Gaussian white noise.

[0131] S53: Noise component extraction: by calculating N = V adc- V, separating out the noise component N;

[0132] S54: Random frequency calculation: Multiply the noise component N by the coefficient K, and then add the bias F. offset The random frequency F is obtained by rounding down. vary The formula is: F vary =N K+F offset ;

[0133] S55: Frequency Range Constraint: Set the highest frequency F varymax and lowest frequency F varymin Ensure that the random frequency satisfies F varymin ≤F vary ≤F varymax This is to limit the range of carrier frequency fluctuations.

[0134] like Figures 5-6 As shown, the spectral analysis of PWM signals with fixed carrier frequencies and those with random carrier frequencies is as follows: the fixed-frequency carrier PWM uses a 10kHz carrier, while the random-frequency carrier PWM uses carrier frequencies ranging from 1kHz to 100kHz. It can be seen that the PWM signal using a random carrier has a smoother spectrum and a more uniform energy distribution. The PWM signal using a fixed-frequency carrier has obvious harmonic components in its spectrum, with energy concentrated at the PWM frequency and its harmonics. This proves that random-frequency carrier PWM can avoid the influence of fixed-frequency signals and their harmonics.

[0135] S6: Drives the semiconductor cooler TEC through the H-bridge actuator, controlling the N-type and P-type transistors to work alternately to achieve temperature regulation.

[0136] This embodiment estimates the core temperature of a 5mm×5mm DFB laser chip (model: Thorlabs DFB1550S) based on a distributed temperature sensor array and a polynomial fitting algorithm. Four PT100 platinum resistance sensors (accuracy ±0.01℃, package size 1mm×1mm) are arranged at equal intervals along the chip's central axis. A third-order polynomial model is used to reconstruct the temperature field, solving the problem that traditional single-point temperature measurement cannot capture temperature gradients.

[0137] Sensor layout:

[0138] Four sensors are arranged linearly along the central axis (x-axis) of the laser chip, with position coordinates (x... i The values ​​are: x1=0mm (left edge of the chip), x2=2mm, x3=4mm, x4=6mm (right edge of the chip, exceeding the actual length of the chip by 1mm to cover the edge effect).

[0139] Measured temperature value (yi ):

[0140] Under a constant temperature environment of 25℃, the actual measured temperature of the sensor (after signal conditioning) is:

[0141] y1=24.998℃, y2=25.031℃, y3=25.052℃, y4=25.020℃.

[0142] Polynomial model construction:

[0143] Model order: Based on the number of sensors n=4, construct a 3rd-order polynomial model:

[0144] T(x) = a0 + a1x + a2x 2 +a3x 3 )

[0145] Where x is the position variable along the axis (unit: mm), and T(x) is the fitted temperature (unit: ℃).

[0146] Error function definition

[0147] Error sum of squares function:

[0148]

[0149] Solving coefficients using the least squares method

[0150] Design matrices and vectors:

[0151] The system of equations can be expressed in matrix form as Xa=y, where:

[0152]

[0153] Coefficient calculation:

[0154] Finding the inverse of a matrix The calculations yield: a0 = 24.998, a1 = 0.0185, a2 = 0.00225, a3=0.000125.

[0155] Laser position temperature estimation

[0156] Core location of the chip: Midpoint of the central axis of the laser chip (x) laser =3mm, substituting into the polynomial model:

[0157] T laser =24.998+0.0185×3 0.00225×3 2 +0.000125×3 3 =25.025℃

[0158] Estimated error: Compared with the actual measured value of 25.024℃ by the high-precision infrared thermometer (FLIR T650sc, accuracy ±0.001℃), the error is only +0.001℃.

[0159] Test results: At a set temperature of 25℃, the core temperature estimation error of the laser chip is ≤ ±0.002℃ (the error of traditional single-point temperature measurement is ±0.08℃).

[0160] Random frequency PWM drive (compared to fixed frequency PWM)

[0161] The PWM carrier frequency was dynamically adjusted (randomly distributed from 1kHz to 10kHz), and the radiated interference field strength was tested in the 30MHz-1GHz frequency band.

[0162] Test results: The peak field strength decreased from 54 dBμV / m at a fixed frequency (2 kHz) to 32 dBμV / m (limit 40 dBμV / m).

[0163] H-bridge mutual exclusion drive and cascade voltage response

[0164] Apply a step temperature perturbation (25℃→25.5℃) and test the TEC response time.

[0165] Test results: The time from the occurrence of the disturbance to the temperature stabilization (within ±0.005℃) was 45ms, and the power consumption was 1.2W (the traditional single voltage drive response time is 300ms and the power consumption is 1.7W, the response speed is improved by 4 times and the power consumption is reduced by 29%).

[0166] Digital PID and Least Squares Fusion Control

[0167] Method of the present invention:

[0168] Control cycle 1ms, proportional coefficient K P =5.2, Integral coefficient K I =0.1, differential coefficient K D =0.05, dynamically adjust the PID parameters based on the temperature field fitting results.

[0169] Test results: Long-term (1000h) temperature control stability ±0.0058℃, temperature overshoot <1.5% (traditional analog PID overshoot 9.13%, stabilization time shortened from 41s to 30s).

[0170] Table 1. Comparison of performance indicators between the method of the present invention and existing technologies.

[0171]

[0172] This embodiment achieves a temperature measurement accuracy of ±0.002℃, long-term stability of ±0.0058℃, and a dynamic response of 45ms by integrating distributed temperature field modeling, random frequency PWM driving, H-bridge mutual exclusion logic and cascaded voltage configuration, and intelligent PID algorithm. It is comprehensively superior to the problems of large single-point temperature measurement error, strong electromagnetic interference, and slow response speed in the existing technology, and can meet the high-precision application requirements of lidar, quantum communication, etc.

[0173] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-precision low-interference laser temperature control system, characterized in that, The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip.

2. The high-precision low-interference laser temperature control system according to claim 1, characterized in that, The equivalent resistance of the temperature sensor In series with a fixed resistance R, forming a voltage divider circuit; the voltage divider circuit is connected to a high-precision voltage source , the voltage dividing end of the fixed resistance R is directly connected to the input end of the amplification unit; the amplification unit is composed of the first stage operational amplifier U1, and the input end receives the output signal of the linearization unit; the feedback loop of the first stage operational amplifier U1 is in series with resistors R1 and R2, and the output end is directly connected to the non-inverting input end of the subtraction unit, which is composed of the second stage operational amplifier U2, and the non-inverting input end receives the output signal V out1 of the amplification unit, and the inverting input end is connected to the bias voltage V _offset ; the bias voltage V _offset is generated through a DAC or a resistance voltage dividing network, and is isolated and buffered through a voltage follower U3, and then connected to the inverting input end of the second stage operational amplifier U2; the periphery of the subtraction unit is configured with four equivalent resistors: R3, R4, R5, and R6, and the output end is directly connected to the ADC interface.

3. The high-precision low-disturbance laser temperature control system according to claim 1, wherein, The application relates to a temperature control method and device for a laser chip.

4. The high-precision low-interference laser temperature control system according to claim 2, characterized in that, The application relates to a temperature control method and device for a laser chip.

5. The high-precision low-interference laser temperature control system according to claim 4, characterized in that, The application relates to a temperature control method and device for a laser chip.

6. The high-precision low-disturbance laser temperature control system according to claim 1, wherein, The application relates to a temperature control method and device for a laser chip.

7. A high-precision low-interference laser temperature control method based on the high-precision low-interference laser temperature control system of claim 4 or 5, characterized in that, The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip.

8. The high-precision low-interference laser temperature control method according to claim 7, characterized in that, The application relates to a temperature control method and device for a laser chip. S21: equivalent resistance of the temperature sensor In series with a fixed resistance R, forming a voltage divider circuit, which is connected to a high-precision voltage source With the voltage division of the fixed resistance R as the sensor output signal That is The output of the linearization unit is directly connected to the input of the amplification unit S22: the input end of the first-stage operational amplifier U1 receives the output signal of the linearization unit, the feedback loop of the first-stage operational amplifier U1 is connected in series with resistors R1 and R2, and the signal gain is adjusted by configuring the amplification multiple of the feedback loop The output amplified intermediate signal V out1 ;​​ S23: the non-inverting input terminal of the second stage operational amplifier U2 receives the V out1 output from the amplification unit _offset , the inverting input terminal is connected to the bias voltage V _offset After being generated by the DAC or the resistor voltage dividing network, it is isolated and buffered by the voltage follower U3, and then connected to the inverting input terminal of the second stage operational amplifier U2; the peripheral resistance of the second stage operational amplifier U2 satisfies: R3 = R4 = R5 = R6, and finally outputs the conditioned signal V out = V out1 -V _offset , which is directly sent to the ADC interface; the amplification factor is , wherein V inmin is the output of the temperature sensor at the lowest temperature, V inmax is the output of the temperature sensor at the highest temperature, and V is the input range of the ADC.

9. The high-precision low-interference laser temperature control method according to claim 7, characterized in that, The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. Obtaining the position coordinates (x i , y i ) of n sensors in the temperature collection module, wherein x i is the linear distance of the sensor along the central axis of the laser, y i is the measured temperature value of the corresponding sensor (i=1, 2,..., n); The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. wherein a0, a1,..., a n are polynomial coefficients to be solved, x is a position variable along the axis, and y is a temperature value. The application relates to a temperature control method and device for a laser chip. 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The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method and device for a laser chip. The application relates to a temperature control method Define error square sum function to represent the deviation between the measured temperature of the temperature sensor and the model fitting temperature: wherein, Tmodel is the model fitted temperature, Tsensor is the sensor measured temperature; S34: Least square method coefficient solving Take the partial derivative of the error function J with respect to each coefficient and set it to zero to obtain a system of linear equations: The system of equations is represented in matrix form: ; where X is an n x (n + 1) design matrix, elements of which are ; are the coefficient vector; is the measured temperature vector; the coefficient vector is solved by matrix inversion: ; S35: Laser position temperature calculation The position coordinates x of the laser chip laser Substitute the obtained polynomial model into the solution and calculate the corresponding temperature value: T laser =a n x n laser + a n-1 x n-1 laser + ... + a1x laser + a0; Output T laser As an estimated temperature for laser chips.

10. The high-precision low-disturbance laser temperature control method of claim 7, wherein, Step S5 includes the following sub-steps: S51: Random noise acquisition: take the random noise in the circuit as the source of random frequency, and the noise type is Gaussian white noise; S52: Voltage signal acquisition: the voltage signal with a fixed amplitude of V in the ADC acquisition circuit is collected, and the actual collection value V adc , V adc =V+N, wherein N is Gaussian white noise, S53: Noise component extraction: by computing N = V adc - V, the noise component N is isolated; S54: Random frequency calculation: multiply the noise component N by the coefficient K, and superimpose the bias F offset , and take the integer to obtain the random frequency F vary , the formula is: F vary =N K+F offset ; S55: Frequency range constraint: set the highest frequency F varymax and the lowest frequency F varymin , ensuring that the random frequency meets F varymin ≤ F vary ≤ F varymax to limit the range of carrier frequency fluctuations.

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