Excimer lamp power supply intelligent control method and system

Abstract

The invention belongs to the technical field of power supply control, and particularly relates to an excimer lamp power supply intelligent control method and system, and the method comprises the following steps: S1, obtaining the real-time output voltage and output current of an excimer lamp and the DC bus voltage of a phase-shifted full bridge; estimating an equivalent complex impedance amplitude, a phase angle and a phase angle change rate of the excimer lamp in a next switching period according to voltage and current sampling values in a plurality of continuous switching periods by adopting an extended Kalman filtering model; and S2, according to the deviation between the target output power and the real-time power, a basic phase shift angle is calculated through a proportional-integral controller, and the gain of the proportional-integral controller is determined according to the change rate of the phase angle. According to the invention, the accuracy of power control and the inhibition capability on load disturbance and voltage fluctuation are improved, the stability of output power is ensured, the switching loss is reduced, the rapid success of the lighting process is ensured, and the stable switching to closed-loop control is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power supply control, and particularly relates to an intelligent control method and system for a power supply of an excimer lamp. BACKGROUND

[0002] The power supply for powering the excimer lamp usually adopts a high-frequency alternating current form, wherein the phase-shifted full-bridge (PSFB) excimer lamp is a typical gas discharge load, and the equivalent impedance of the excimer lamp will change dramatically before and after lighting and during the working process. In the starting stage, the lamp tube presents a capacitive high-impedance state; after the plasma is formed, it is converted into a resistive low-impedance state.

[0003] The existing control is difficult to adapt to wide-range impedance changes, and problems such as slow dynamic response, large power overshoot, and even system oscillation are likely to occur in the power regulation process, which cannot meet the requirements of rapidity and stability at the same time. Therefore, for the lighting starting process, an open-loop sweep frequency or a high-voltage pulse is usually used to find the resonance point and break down the gas, but the reliability of this method is not high, and there is no judgment on whether the lighting is successful or not, which may lead to lighting failure or impact on components. Most of these methods are based on a simplified load model, and the equivalent complex impedance information of the excimer lamp at different operating points cannot be obtained in real time, resulting in limited compensation accuracy. In addition, when the load impedance changes or is light, the lagging bridge arm of the phase-shifted full-bridge is likely to lose the zero-voltage opening condition, resulting in increased switching loss, which is also a problem to be solved in the prior art. SUMMARY

[0004] The application provides an intelligent control method and system for a power supply of an excimer lamp to solve the technical problems of poor power regulation, unreliable lighting starting, low compensation accuracy, and increased switching loss of the power supply of the excimer lamp due to dramatic changes in the load impedance in the prior art.

[0005] In a first aspect, the application provides an intelligent control method for a power supply of an excimer lamp, comprising the following steps: S1, obtaining real-time output voltage, output current of the excimer lamp, and DC bus voltage of the phase-shifted full-bridge; using an extended Kalman filter model, estimating the equivalent complex impedance amplitude, phase angle, and phase angle change rate of the excimer lamp in the next switching period according to the voltage and current sampling values in the continuous multiple switching periods; S2, calculating the basic phase-shifted angle through a proportional-integral controller according to the deviation of the target output power and the real-time power, wherein the gain of the proportional-integral controller is determined according to the phase angle change rate; superimposing the basic phase-shifted angle, the nonlinear feedforward compensation based on the equivalent complex impedance amplitude and phase angle of the excimer lamp, and the voltage feedforward compensation based on the DC bus voltage to generate a target phase-shifted angle; S3, when the equivalent complex impedance amplitude of the excimer lamp is greater than the light load threshold and the DC bus voltage fluctuation is less than the stability threshold, the duty cycle adjustment amount is determined by the equivalent complex impedance amplitude of the excimer lamp and the DC bus voltage change rate, and the asymmetric driving is used for the lagging bridge arm of the phase-shifted full-bridge by using the duty cycle adjustment amount; S4, in the starting lighting stage, the phase-shifted full-bridge is driven in a sweep frequency mode, and the mutual correlation coefficient of voltage and current and the third harmonic amplitude of voltage are monitored; when the absolute value of the mutual correlation coefficient reaches the peak value and the third harmonic amplitude exceeds the ignition threshold, the current frequency is locked, the maximum phase shift angle is applied to ignite; when the equivalent complex impedance amplitude of the excimer lamp is stable below the plasma formation threshold, the closed-loop power control is switched to, and the phase-shifted full-bridge is driven by using the target phase shift angle.

[0006] Further, an extended Kalman filter model is used to estimate the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp in the next switching period according to the voltage and current sampling values in the continuous multiple switching periods, including: A state space model is constructed with the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp as state variables; The voltage and current fundamental components are extracted by fast Fourier transform to calculate the complex impedance measurement value of the current period; The extended Kalman filter algorithm is used to update and output the state variable estimation value of the next period by combining the state prediction and the complex impedance measurement value of the current period.

[0007] Further, the duty cycle adjustment amount is determined by the equivalent complex impedance amplitude of the excimer lamp and the DC bus voltage change rate, including: High and low sets of proportional integral gain parameters and phase angle change rate stability thresholds are set; When the absolute value of the phase angle change rate is less than the stability threshold, the proportional integral control is performed by using the high gain parameter; When the absolute value of the phase angle change rate is greater than or equal to the stability threshold, the proportional integral control is performed by using the low gain parameter.

[0008] Further, in S2, the target phase shift angle includes a nonlinear feedforward compensation angle and a voltage feedforward compensation angle, and the nonlinear feedforward compensation angle is obtained by querying a two-dimensional lookup table with the equivalent complex impedance amplitude and the phase angle of the excimer lamp as inputs; The voltage feedforward compensation angle is proportional to the deviation of the real-time value and the nominal value of the DC bus voltage.

[0009] Further, the asymmetric driving is used for the lagging bridge arm of the phase-shifted full-bridge by using the duty cycle adjustment amount, including: When the equivalent complex impedance amplitude of the excimer lamp is greater than the light load threshold and the absolute value of the DC bus voltage change rate is less than the stability threshold, the asymmetric driving is enabled; The duty cycle adjustment amount is calculated according to the difference between the equivalent complex impedance amplitude of the excimer lamp and the light load threshold value and the DC bus voltage change rate. The driving duty cycles of the upper and lower switch tubes of the lagging bridge arm are respectively set as 0.5 plus the duty cycle adjustment amount and 0.5 minus the duty cycle adjustment amount.

[0010] Further, when the equivalent complex impedance amplitude of the excimer lamp is stabilized below the plasma formation threshold value, the driving mode is switched to the closed-loop power control, including: After ignition, the equivalent complex impedance amplitude of the excimer lamp is continuously monitored; When the equivalent complex impedance amplitude of the excimer lamp is maintained below the preset plasma formation threshold value for more than the preset stabilization time, the driving mode is switched from the ignition mode to the closed-loop power control mode.

[0011] In a second aspect, the present application provides an intelligent control system for an excimer lamp power supply, including the following modules: An estimation module is configured to obtain the real-time output voltage, output current and DC bus voltage of the excimer lamp; an extended Kalman filter model is adopted to estimate the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp in the next switching period according to the voltage and current sampling values in continuous multiple switching periods; A phase shift angle determination module is configured to calculate a basic phase shift angle through a proportional-integral controller according to the deviation between the target output power and the real-time power, wherein the gain of the proportional-integral controller is determined according to the phase angle change rate; the basic phase shift angle, the nonlinear feedforward compensation based on the equivalent complex impedance amplitude and phase angle of the excimer lamp and the voltage feedforward compensation based on the DC bus voltage are superimposed to generate a target phase shift angle; An adjustment module is configured to determine the duty cycle adjustment amount from the equivalent complex impedance amplitude of the excimer lamp and the DC bus voltage change rate when the equivalent complex impedance amplitude of the excimer lamp is greater than the light load threshold value and the DC bus voltage fluctuation is less than the stabilization threshold value, and to use the duty cycle adjustment amount to adopt asymmetric driving for the lagging bridge arm of the phase-shift full-bridge; A driving module is configured to drive the phase-shift full-bridge in a sweep frequency mode during the starting ignition stage, and to monitor the cross-correlation coefficient of voltage and current and the third harmonic amplitude of voltage; when the absolute value of the cross-correlation coefficient reaches the peak value and the third harmonic amplitude exceeds the ignition threshold value, the current frequency is locked and the maximum phase shift angle is applied for ignition; when the equivalent complex impedance amplitude of the excimer lamp is stabilized below the plasma formation threshold value, the driving mode is switched to the closed-loop power control, and the phase-shift full-bridge is driven by the target phase shift angle.

[0012] Further, an extended Kalman filter model is adopted to estimate the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp in the next switching period according to the voltage and current sampling values in continuous multiple switching periods, including: A state space model is constructed with the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp as state variables; The fundamental component of the voltage and current is extracted by fast Fourier transform, and the complex impedance measurement value of the current cycle is calculated; The extended Kalman filtering algorithm is adopted, the state prediction is combined with the complex impedance measurement value of the current cycle, and the state variable estimation value of the next cycle is updated and output.

[0013] Further, the duty cycle adjustment amount is determined by the equivalent complex impedance amplitude of the excimer lamp and the DC bus voltage change rate, comprising: Set high and low two sets of proportional integral gain parameters and phase angle change rate stability threshold; When the absolute value of the phase angle change rate is less than the stability threshold, high gain parameters are used for proportional integral control; When the absolute value of the phase angle change rate is greater than or equal to the stability threshold, low gain parameters are used for proportional integral control.

[0014] Further, the target phase shift angle includes a nonlinear feedforward compensation angle and a voltage feedforward compensation angle, and the nonlinear feedforward compensation angle is obtained by querying a two-dimensional lookup table with the equivalent complex impedance amplitude and phase angle of the excimer lamp as inputs; The voltage feedforward compensation angle is proportional to the deviation between the real-time value and the nominal value of the DC bus voltage.

[0015] The beneficial effects are: compared with the prior art, by adopting the extended Kalman filtering model, the equivalent complex impedance amplitude, phase angle and change rate of the excimer lamp can be identified, so that the real-time state of the load is obtained. Combined with the nonlinear feedforward based on the complex impedance and the bus voltage feedforward compensation, the accuracy of power control and the suppression ability to load disturbance and voltage fluctuation are improved, and the stability of the output power is ensured. Moreover, the asymmetric driving strategy can effectively expand the zero-voltage opening range of the lagging bridge arm under light load conditions, and reduce the switching loss. During the lamp starting stage, by monitoring the voltage and current cross-correlation coefficient and the voltage third harmonic, the fast success of the lamp starting process is ensured, and the smooth switching to the closed-loop control is realized. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The flowchart of the intelligent control method for the excimer lamp power supply. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0018] The embodiment of the intelligent control method of the excimer lamp power supply provided by the application comprises the following steps: As shown in the figure, the intelligent control method of the excimer lamp power supply comprises the following steps: Figure 1 S1, acquiring real-time output voltage, output current and DC bus voltage of the excimer lamp; using an extended Kalman filter model, estimating the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp in the next switching cycle according to the voltage and current sampling values in continuous multiple switching cycles. The phase-shifted full-bridge is a DC-DC converter composed of four switching tubes, which are divided into two pairs, i.e. two bridge arms. One bridge arm is called the leading bridge arm, and the other is called the lagging bridge arm. By controlling the phase difference between the driving signals of the two bridge arms, i.e. the phase shift angle, the energy transmitted to the output end is adjusted, so as to control the output voltage or power. The excimer lamp needs hundreds or even thousands of watts of power. The application uses the phase-shifted full-bridge to step up the input DC low voltage to the high voltage required by the lamp tube, and simultaneously realizes the electrical isolation between the input and the output. The data acquisition is preferably realized by setting Hall voltage and current sensors at the output end of the excimer lamp, setting a voltage sensor on the DC bus, and using the analog-to-digital conversion module inside the digital signal processor to synchronously sample the analog signals output by the sensors at a sampling rate higher than the switching frequency. The acquired voltage and current data are converted into digital quantities and stored in the memory.

[0019] The state space equation is established with the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp as the state variables, and the real-time collected voltage and current digital quantities are used as the observation values. First, the prediction step is performed to predict the state prior value at the current time based on the state posterior estimate value at the last time and the system model; then, the update step is performed to calculate the Kalman gain by using the deviation between the actual observation value and the predicted observation value of the voltage and current at the current time, correct the prior state estimate, and thus obtain the optimized posterior estimate value of the complex impedance parameters in the next cycle.

[0020] In an optional embodiment, the extended Kalman filter model is used to estimate the amplitude, phase angle and phase angle change rate of the equivalent complex impedance of the excimer lamp in the next switching cycle according to the voltage and current sampling values in continuous multiple switching cycles, which comprises:

[0021] The state space model is constructed with the equivalent complex impedance amplitude, phase angle and phase angle change rate of the excimer lamp as the state variables; The fundamental wave components of the voltage and current are extracted by fast Fourier transform to calculate the complex impedance measurement value in the current cycle; The extended Kalman filter algorithm is used to update and output the state variable estimate value in the next cycle by combining the state prediction and the complex impedance measurement value in the current cycle. ​

[0022] The state vector of the state space model is the amplitude, phase and phase rate of change of the equivalent complex impedance of the excimer lamp. The model is used to predict the values of these three state quantities after one switching cycle. In order to provide real-time measurement data for the model, the output voltage and current are sampled at high speed within each switching cycle, for example 256 points per cycle at a switching frequency of 100 kHz, and then the fundamental amplitudes and phases of the voltage and current are calculated using a fast Fourier transform algorithm, and the amplitude and phase of the equivalent complex impedance of the excimer lamp at the current time are obtained.

[0023] The extended Kalman filter algorithm is an optimal estimation algorithm for non-linear systems, comprising a prediction step and an update step. In the prediction step, the state space model and the optimal estimate value of the last cycle are used to predict the state of the current cycle. In the update step, the predicted value is compared with the actual measurement value of the current cycle obtained by the fast Fourier transform, and the error between the two is calculated. The error is weighted by the Kalman gain to correct the predicted value, and a more accurate optimal estimate value of the state of the current cycle is obtained. For example, if the predicted phase is 25.5 degrees and the measured value is 25.1 degrees, the filter algorithm outputs an estimate value between the two, such as 25.3 degrees, and also outputs a prediction value for the next cycle, so as to realize tracking and noise suppression of the complex impedance parameters.

[0024] The state vector of the extended Kalman filter model is [amplitude, phase, phase rate of change of the equivalent complex impedance of the excimer lamp], and the observation vector of the extended Kalman filter model is composed of the real-time output voltage and current values of the excimer lamp obtained by direct sampling.

[0025] In one embodiment, the state vector contains three core parameters to be estimated, wherein, is the amplitude of the equivalent complex impedance of the excimer lamp (unit: ohm), is the phase (unit: rad), is the phase rate of change (unit: rad / s). The observation vector is obtained by sampling and calculating the output voltage v(t) and current i(t) of the excimer lamp. Specifically, within one or more switching cycles, the fundamental components of the voltage and current are extracted by a fast Fourier transform or other digital signal processing method, so as to calculate the amplitude and phase of the equivalent complex impedance at the current time.

[0026] wherein, , is the phase difference between the voltage and current fundamental waves.

[0027] The extended Kalman filter algorithm consists of two major steps: prediction and update. Let the sampling period be Δt, preferably Δt = 100 μs.

[0028] The prediction process is: State transition equation : predict the state at the next time instant according to the physical model.

[0029]

[0030]

[0031]

[0032] Prediction covariance matrix : where is the Jacobian matrix of the state transition function f, and Q is the process noise covariance matrix.

[0033] The process noise covariance Q reflects the uncertainty of the extended Kalman filter model prediction, and is a diagonal matrix . Preferably: , which means that the standard deviation of the equivalent complex impedance amplitude of the excimer lamp is about 0.1 ohm, the standard deviation of the phase angle is about 0.01 rad, and the standard deviation of the phase angle change rate is about 0.05 rad / s in one Δt period.

[0034] The update process is: Observation equation , which maps the predicted state into the observation space, .

[0035] Compute the Kalman gain : .

[0036] where is the Jacobian matrix of the observation function h, and R is the measurement noise covariance matrix.

[0037] The measurement noise covariance R reflects the measurement error introduced by the sensor and signal processing, and is a diagonal matrix . Preferably , which means that the measurement standard deviation of the equivalent complex impedance amplitude of the excimer lamp is 0.2 ohm, and the measurement standard deviation of the phase angle is 0.02 rad (about 1.15 degrees).

[0038] Update the state estimate .

[0039] Update the covariance matrix .

[0040] S2, according to the deviation of the target output power and the real-time power, calculating the basic phase-shifting angle through the proportional-integral controller, wherein the gain of the proportional-integral controller is determined according to the phase angle change rate; superimposing the basic phase-shifting angle, the nonlinear feedforward compensation based on the equivalent complex impedance amplitude and phase angle of the excimer lamp, and the voltage feedforward compensation based on the DC bus voltage to generate the target phase-shifting angle.

[0041] The real-time output power is obtained by multiplying the real-time collected output voltage and current value and integrating and averaging in a switching cycle, and then subtracting the set target power value to obtain the power deviation; the deviation is input into the proportional-integral controller, and the proportional-integral controller calculates the basic phase-shifting angle according to the proportional term and the integral term of the deviation. The formula of the proportional-integral controller is wherein, is the power deviation, is the proportional gain, is the integral gain.

[0042] The proportional-integral controller consults a preset gain scheduling table to adjust the proportional gain and the integral gain according to the absolute value of the phase angle change rate output by the extended Kalman filtering algorithm. For example, when the phase angle change rate is large, the gain is automatically adjusted to be low to enhance stability, and vice versa.

[0043] In an embodiment, the gain scheduling table is specifically: 1. Transient / Unstable Region |dθ / dt|>10000, the proportional gain is 0.05, and the integral gain is 1; 2. Dynamic Adjustment Region 2000<|dθ / dt|≤10000, the proportional gain is 0.2, and the integral gain is 5; 3. Normal Working Region 500<|dθ / dt|≤2000, the proportional gain is 0.5, and the integral gain is 20; 4. Steady State Region |dθ / dt|≤500, the proportional gain is 0.8, and the integral gain is 35.

[0044] The equivalent complex impedance amplitude and phase angle of the excimer lamp estimated by the extended Kalman filtering algorithm are used as indexes to query a two-dimensional nonlinear feedforward compensation table established in advance through offline simulation or experimental calibration to obtain an impedance feedforward compensation angle. In an embodiment, the two-dimensional nonlinear feedforward compensation table is specifically shown in Table 1: Table 1

[0045] The difference between the real-time collected DC bus voltage and the standard rated voltage is multiplied by a voltage feedforward coefficient to obtain a voltage feedforward compensation angle; the base phase-shifting angle output by the proportional-integral controller, the impedance feedforward compensation angle, and the voltage feedforward compensation angle are algebraically summed to synthesize the target phase-shifting angle.

[0046] S3, when the equivalent complex impedance amplitude of the excimer lamp is greater than the light load threshold value and the DC bus voltage fluctuation is less than the stability threshold value, the duty cycle adjustment amount is determined by the equivalent complex impedance amplitude of the excimer lamp and the DC bus voltage change rate, and the asymmetric driving is used for the lagging bridge arm of the phase-shifting full-bridge.

[0047] The proportional-integral controller continuously compares the equivalent complex impedance amplitude of the excimer lamp with the preset light load threshold value, for example, five times the rated load impedance, and calculates the differential value of the DC bus voltage, that is, the change rate; when the equivalent complex impedance amplitude of the excimer lamp is higher than the light load threshold value and the absolute value of the voltage change rate is lower than the stability threshold value 0.05V / ms, the proportional-integral controller starts the asymmetric driving; according to the current equivalent complex impedance amplitude of the excimer lamp and the bus voltage change rate, an duty cycle adjustment amount, for example, 5%, is determined by consulting another two-dimensional adjustment table, and then the driving pulse width of the upper tube of the lagging bridge arm is reduced by the adjustment amount and the driving pulse width of the lower tube is increased by the adjustment amount to ensure zero voltage turn-on under light load.

[0048] The asymmetric driving is used to improve the power efficiency under light load conditions, and the enabling condition ensures that the asymmetric driving is activated only when the system is stable and indeed in a light load state. For example, the light load threshold value is set to 300 ohms, and the DC bus voltage change rate stability threshold value is 1V / ms. When it is monitored that the equivalent complex impedance amplitude of the excimer lamp of the current lamp tube is 350 ohms and the bus voltage change rate is only 0.4V / ms, both conditions are met, and the proportional-integral controller starts the asymmetric driving mode.

[0049] In an optional embodiment, the duty cycle adjustment amount is determined by the equivalent complex impedance amplitude of the excimer lamp and the DC bus voltage change rate, which includes: The high and low sets of proportional-integral gain parameters and the phase angle change rate stability threshold value are set; When the absolute value of the phase angle change rate is less than the stability threshold value, the high gain parameter is used for proportional-integral control; When the absolute value of the phase angle change rate is greater than or equal to the stability threshold value, the low gain parameter is used for proportional-integral control.

[0050] Two sets of proportional integral parameters are preset, one set is high gain parameter, the proportional gain is 0.9, and the integral gain is 600, which is used to realize the tracking of power setting when the lamp is stable. Another set is low gain parameter, the proportional gain is 0.3, and the integral gain is 150, which is used to ensure the stability of the system and avoid overshoot and oscillation during the transient process of the state of the lamp.

[0051] At the same time, a stable threshold of phase angle change rate is set, for example, 0.2 degrees per switching cycle. During operation, the phase angle change rate estimated by the Kalman filter is monitored in real time. When the absolute value is less than 0.2 degrees per cycle, it indicates that the plasma discharge is stable, and the proportional integral controller automatically selects the high gain parameter. Otherwise, during the transient process such as lamp starting or load mutation, the absolute value of the phase angle change rate will increase sharply and exceed 0.2 degrees per cycle, at which time the proportional integral controller automatically switches to the low gain parameter, sacrificing part of the response speed in exchange for the system to remain stable under large disturbance.

[0052] In an optional embodiment, the lagging leg of the phase-shifted full-bridge is asymmetrically driven using a duty cycle adjustment amount, including: When the equivalent complex impedance amplitude of the excimer lamp is greater than the light load threshold and the absolute value of the DC bus voltage change rate is less than the stable threshold, the asymmetric driving is enabled; The duty cycle adjustment amount is calculated according to the difference between the equivalent complex impedance amplitude of the excimer lamp and the light load threshold and the DC bus voltage change rate; The driving duty cycles of the upper and lower switch tubes of the lagging leg are set to 0.5 plus the duty cycle adjustment amount and 0.5 minus the duty cycle adjustment amount, respectively.

[0053] For example, the light load threshold is set to 300 ohms, and the stable threshold of the DC bus voltage change rate is set to 1V / ms. When it is monitored that the equivalent complex impedance amplitude of the current lamp is 350 ohms, and the bus voltage change rate is only 0.4V / ms, both conditions are met, and the proportional integral controller will start the asymmetric driving mode. After starting, the proportional integral controller will calculate a duty cycle adjustment amount, which is related to the lightness of the load. For example, the adjustment amount can be a proportional coefficient multiplied by the difference between the equivalent complex impedance amplitude of the excimer lamp and the light load threshold. If the proportional coefficient is 0.02, the duty cycle adjustment amount in the above example is 0.01. Subsequently, the proportional integral controller adjusts the driving duty cycle of the upper tube of the lagging leg from the standard 0.5 to 0.51, and adjusts the driving duty cycle of the lower tube from 0.5 to 0.49. The change of the duty cycle changes the voltage waveform of the bridge leg midpoint, which helps to realize zero voltage turn-on of the switch tube under light load.

[0054] S4, in the starting stage, the full-bridge is driven in a sweep mode, and the cross-correlation coefficient of the voltage and the current and the third harmonic amplitude of the voltage are monitored; when the absolute value of the cross-correlation coefficient reaches a peak value and the third harmonic amplitude exceeds an ignition threshold value, the current frequency is locked, the maximum phase shift angle is applied to ignite; when the equivalent complex impedance amplitude of the excimer lamp is stable below the plasma formation threshold value, the closed-loop power control is switched to, and the target phase shift angle is used to drive the full-bridge.

[0055] At the beginning of the starting, the proportional-integral controller drives the full-bridge with a fixed small phase shift angle, and the switching frequency is linearly or stepwise scanned from high to low, for example, from 100 kHz to 60 kHz; in this process, the cross-correlation coefficient is calculated in real time by convolution operation on the voltage and current sampling sequence, and the third harmonic amplitude of the voltage signal is calculated by fast Fourier transform; when the absolute value of the cross-correlation coefficient is monitored to have an inflection point, i.e., reaches a peak value, and the third harmonic amplitude at this time is greater than a preset ignition threshold value, for example, 10% of the rated voltage, the frequency scanning is immediately stopped, the current frequency is taken as the optimal ignition frequency, and the phase shift angle instruction is immediately set to the maximum value, for example, 175 degrees, to break down the lamp tube gas with high energy; after ignition, the proportional-integral controller continues to monitor the equivalent complex impedance amplitude of the excimer lamp through Kalman filtering, and when the value rapidly decreases from kilo-ohms and is stable below the plasma formation threshold value of 100 ohms for more than 20 ms, it is determined that the starting is successful, and the starting mode is automatically switched to the closed-loop power control mode.

[0056] In an optional embodiment, the target phase shift angle includes a nonlinear feedforward compensation angle and a voltage feedforward compensation angle, the nonlinear feedforward compensation angle is obtained by querying a two-dimensional lookup table with the equivalent complex impedance amplitude and phase angle of the excimer lamp as inputs; The voltage feedforward compensation angle is proportional to the deviation of the real-time value and the nominal value of the DC bus voltage.

[0057] The basic phase-shifting angle is calculated by a conventional proportional-integral controller according to the power error, and the non-linear feed-forward compensation angle is used to overcome the inherent non-linearity of the system, which also varies with the state of the load impedance. Through off-line experiments or simulations, a two-dimensional look-up table is established with the equivalent complex impedance amplitude of the excimer lamp as the horizontal axis and the equivalent complex impedance phase angle as the vertical axis, in which the compensation phase-shifting angle required to achieve a unit power output at different impedance points is stored. During operation, the proportional-integral controller obtains a corresponding compensation angle, for example, 3.5 degrees, from the table according to the real-time estimated amplitude and phase angle of the equivalent complex impedance of the lamp, for example, 150 ohms in amplitude and -10 degrees in phase, and adds it to the basic phase-shifting angle. The voltage feed-forward compensation angle is used to actively suppress the disturbance of the DC bus voltage fluctuation on the output power. For example, if the nominal voltage of the bus is set to 400 volts and the feed-forward gain is 0.1 degrees per volt, a 10-volt voltage difference will be generated if the real-time measured bus voltage drops to 390 volts, and the calculated voltage feed-forward compensation angle will be 1 degree. The proportional-integral controller adds the three, i.e., the basic phase-shifting angle output by the proportional-integral controller, the non-linear feed-forward compensation angle obtained by looking up the table, and the calculated voltage feed-forward compensation angle, to obtain the total phase-shifting angle finally applied to the power inverter.

[0058] In an optional embodiment, when the equivalent complex impedance amplitude of the excimer lamp is stabilized below the plasma formation threshold, the closed-loop power control is switched on, including: After ignition, the equivalent complex impedance amplitude of the excimer lamp is continuously monitored; When the equivalent complex impedance amplitude of the excimer lamp is maintained below the preset plasma formation threshold for more than the preset stabilization time, the driving mode is switched from the ignition mode to the closed-loop power control mode.

[0059] After successful ignition, the proportional-integral controller is still in the open-loop maximum power output mode to consolidate the formation of the plasma. During this period, the equivalent complex impedance amplitude of the lamp is continuously calculated by fast Fourier transform. The lamp presents a capacitive load with high impedance when it is not ignited, and the equivalent complex impedance amplitude of the lamp can reach several thousand ohms, while once a stable plasma glow discharge is formed, it will be converted into a low-impedance purely resistive or weakly inductive load.

[0060] To determine whether the plasma has been stabilized, two parameters are set: a plasma formation threshold and a stabilization time. For example, the impedance threshold is set to 200 ohms and the stabilization time is set to 100 ms. The proportional-integral controller continuously compares the real-time calculated equivalent impedance amplitude of the lamp with 200 ohms after ignition. When the measured equivalent impedance amplitude of the lamp first falls below 200 ohms, an internal timer starts. If the equivalent impedance amplitude of the lamp remains below 200 ohms without a large rebound within the next 100 ms, it is determined that the plasma has been completely established and the state is stable. At this time, the proportional-integral controller automatically switches the driving mode from fixed maximum power ignition.

[0061] The application provides an intelligent control system for a quasi-molecular lamp power supply, comprising the following modules: An estimation module is configured to acquire real-time output voltage, output current and DC bus voltage of the quasi-molecular lamp, and estimate equivalent complex impedance amplitude, phase angle and phase angle change rate of the quasi-molecular lamp in the next switching period by using an extended Kalman filter model according to voltage and current sampling values in continuous multiple switching periods. A phase shift angle determination module is configured to calculate a basic phase shift angle by using a proportional-integral controller according to the deviation between the target output power and the real-time power, wherein the gain of the proportional-integral controller is determined according to the phase angle change rate; and superimpose the basic phase shift angle, nonlinear feedforward compensation based on the equivalent complex impedance amplitude and the phase angle of the quasi-molecular lamp, and voltage feedforward compensation based on the DC bus voltage to generate a target phase shift angle. An adjustment module is configured to determine a duty cycle adjustment amount from the equivalent complex impedance amplitude of the quasi-molecular lamp and the DC bus voltage change rate when the equivalent complex impedance amplitude of the quasi-molecular lamp is greater than a light load threshold and the DC bus voltage fluctuation is less than a stable threshold, and use the duty cycle adjustment amount to perform asymmetric driving on the lagging bridge arm of the phase shift full bridge. A driving module is configured to drive the phase shift full bridge in a sweep frequency mode in a start-up lighting stage, and monitor the cross-correlation coefficient of voltage and current and the third harmonic amplitude of voltage; when the absolute value of the cross-correlation coefficient reaches a peak value and the third harmonic amplitude exceeds an ignition threshold, lock the current frequency and apply a maximum phase shift angle to ignite; and when the equivalent complex impedance amplitude of the quasi-molecular lamp is stabilized below a plasma formation threshold, switch to closed-loop power control and use the target phase shift angle to drive the phase shift full bridge.

[0062] The above are preferred embodiments of the application, which do not limit the protection scope of the application, and thus: any equivalent changes made according to the structure, shape and principle of the application should be covered within the protection scope of the application.

Claims

1. A method for intelligent control of excimer lamp power supply, characterized in that, Includes the following steps: S1: Obtain the real-time output voltage and current of the excimer lamp, as well as the DC bus voltage of the phase-shifted full-bridge; Using an extended Kalman filter model, estimate the equivalent complex impedance amplitude, phase angle, and phase angle change rate of the excimer lamp in the next switching cycle based on the voltage and current sampling values ​​in multiple consecutive switching cycles. S2, based on the deviation between the target output power and the real-time power, the base phase shift angle is calculated by a proportional-integral controller, wherein the gain of the proportional-integral controller is determined according to the phase angle change rate; the base phase shift angle, the nonlinear feedforward compensation based on the equivalent complex impedance amplitude and phase angle of the excimer lamp, and the voltage feedforward compensation based on the DC bus voltage are superimposed to generate the target phase shift angle. S3, when the equivalent complex impedance amplitude of the excimer lamp is greater than the light load threshold and the DC bus voltage fluctuation is less than the stable threshold, the duty cycle adjustment amount is determined by the equivalent complex impedance amplitude of the excimer lamp and the DC bus voltage change rate, and the hysteresis arm of the phase-shifted full bridge is asymmetrically driven using the duty cycle adjustment amount. S4, during the lamp-starting phase, drives the phase-shifting full bridge in a frequency sweep manner and monitors the cross-correlation coefficient of voltage and current and the amplitude of the third harmonic of voltage; when the absolute value of the cross-correlation coefficient reaches the peak value and the amplitude of the third harmonic exceeds the ignition threshold, the current frequency is locked and the maximum phase shift angle is applied for ignition; when the amplitude of the excimer lamp equivalent complex impedance stabilizes below the plasma formation threshold, it switches to closed-loop power control and drives the phase-shifting full bridge with the target phase shift angle.

2. The intelligent control method for excimer lamp power supply according to claim 1, characterized in that, Using an extended Kalman filter model, based on voltage and current sampling values ​​over multiple consecutive switching cycles, the equivalent complex impedance amplitude, phase angle, and phase angle change rate of the excimer lamp in the next switching cycle are estimated, including: A state-space model is constructed with the equivalent complex impedance amplitude, phase angle, and phase angle change rate of the excimer lamp as state variables. The fundamental components of voltage and current are extracted by fast Fourier transform, and the complex impedance measurement value of the current cycle is calculated. An extended Kalman filter algorithm is used, which combines state prediction with the complex impedance measurement of the current cycle to update and output the estimated state variables for the next cycle.

3. The intelligent control method for excimer lamp power supply according to claim 1, characterized in that, The duty cycle adjustment is determined by the amplitude of the excimer lamp's equivalent complex impedance and the rate of change of the DC bus voltage, including: Set the proportional-integral gain parameters and the phase angle change rate stability threshold for both high and low sets; When the absolute value of the phase angle change rate is less than the stability threshold, proportional-integral control is performed using a high-gain parameter. When the absolute value of the phase angle change rate is greater than or equal to the stability threshold, proportional-integral control is performed using a low gain parameter.

4. The intelligent control method for excimer lamp power supply according to claim 1, characterized in that, In S2, the target phase shift angle includes the nonlinear feedforward compensation angle and the voltage feedforward compensation angle. The nonlinear feedforward compensation angle is obtained by querying a two-dimensional lookup table with the equivalent complex impedance amplitude and phase angle of the excimer lamp as input. The voltage feedforward compensation angle is proportional to the deviation between the real-time value and the nominal value of the DC bus voltage.

5. The intelligent control method for excimer lamp power supply according to claim 1, characterized in that, The asymmetric drive of the lag arm of the phase-shifting full-bridge is achieved by utilizing duty cycle adjustment, including: When the amplitude of the equivalent complex impedance of the excimer lamp is greater than the light load threshold and the absolute value of the DC bus voltage change rate is less than the stability threshold, asymmetric drive is enabled. The duty cycle adjustment is calculated based on the difference between the equivalent complex impedance amplitude of the excimer lamp and the light load threshold, as well as the DC bus voltage change rate. The drive duty cycles of the upper and lower switching transistors of the lagging bridge arm are set to 0.5 plus the duty cycle adjustment amount and 0.5 minus the duty cycle adjustment amount, respectively.

6. The intelligent control method for excimer lamp power supply according to any one of claims 1-5, characterized in that, When the equivalent complex impedance amplitude of the excimer lamp stabilizes below the plasma formation threshold, the system switches to closed-loop power control, including: After ignition, continuously monitor the amplitude of the excimer lamp's equivalent complex impedance; When the equivalent complex impedance amplitude of the excimer lamp remains below the preset plasma formation threshold for more than a preset stabilization time, the driving mode will be switched from ignition mode to closed-loop power control mode.

7. An intelligent control system for excimer lamp power supply, characterized in that, Includes the following modules: The estimation module is used to obtain the real-time output voltage and current of the excimer lamp and the DC bus voltage of the phase-shifted full bridge; it adopts an extended Kalman filter model to estimate the amplitude of the equivalent complex impedance of the excimer lamp, the phase angle and the rate of change of the phase angle in the next switching cycle based on the voltage and current sampling values ​​in multiple consecutive switching cycles. The phase shift angle determination module is used to calculate the basic phase shift angle based on the deviation between the target output power and the real-time power through a proportional-integral controller. The gain of the proportional-integral controller is determined based on the phase angle change rate. The basic phase shift angle, the nonlinear feedforward compensation based on the amplitude and phase angle of the excimer lamp equivalent complex impedance, and the voltage feedforward compensation based on the DC bus voltage are superimposed to generate the target phase shift angle. The adjustment module is used to determine the duty cycle adjustment amount by the equivalent complex impedance amplitude of the excimer lamp and the rate of change of the DC bus voltage when the amplitude of the equivalent complex impedance of the excimer lamp is greater than the light load threshold and the DC bus voltage fluctuation is less than the stable threshold. The duty cycle adjustment amount is used to apply asymmetric drive to the hysteresis arm of the phase-shifted full bridge. The drive module is used to drive the phase-shifted full bridge in a frequency sweep manner during the lamp start-up phase, and monitor the cross-correlation coefficient of voltage and current and the amplitude of the third harmonic of voltage. When the absolute value of the cross-correlation coefficient reaches the peak value and the amplitude of the third harmonic exceeds the ignition threshold, the current frequency is locked and the maximum phase shift angle is applied for ignition. When the amplitude of the equivalent complex impedance of the excimer lamp stabilizes below the plasma formation threshold, it switches to closed-loop power control and drives the phase-shifted full bridge with the target phase shift angle.

8. The intelligent control system for excimer lamp power supply according to claim 7, characterized in that, Using an extended Kalman filter model, based on voltage and current sampling values ​​over multiple consecutive switching cycles, the equivalent complex impedance amplitude, phase angle, and phase angle change rate of the excimer lamp in the next switching cycle are estimated, including: A state-space model is constructed with the equivalent complex impedance amplitude, phase angle, and phase angle change rate of the excimer lamp as state variables. The fundamental components of voltage and current are extracted by fast Fourier transform, and the complex impedance measurement value of the current cycle is calculated. An extended Kalman filter algorithm is used, which combines state prediction with the complex impedance measurement of the current cycle to update and output the estimated state variables for the next cycle.

9. The intelligent control system for excimer lamp power supply according to claim 7, characterized in that, The duty cycle adjustment is determined by the amplitude of the excimer lamp's equivalent complex impedance and the rate of change of the DC bus voltage, including: Set the proportional-integral gain parameters and the phase angle change rate stability threshold for both high and low sets; When the absolute value of the phase angle change rate is less than the stability threshold, proportional-integral control is performed using a high-gain parameter. When the absolute value of the phase angle change rate is greater than or equal to the stability threshold, proportional-integral control is performed using a low gain parameter.

10. The intelligent control system for excimer lamp power supply according to claim 7, characterized in that, The target phase shift angle includes the nonlinear feedforward compensation angle and the voltage feedforward compensation angle. The nonlinear feedforward compensation angle is obtained by querying a two-dimensional lookup table with the equivalent complex impedance amplitude and phase angle of the excimer lamp as input. The voltage feedforward compensation angle is proportional to the deviation between the real-time value and the nominal value of the DC bus voltage.

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