An adaptive rectifier control system and method supporting multiple input voltage modes

Abstract

The application provides a kind of adaptive rectifier control system and method supporting multiple input voltage mode, it is related to rectification control technical field, according to input voltage control quantity determines the regulating effect order of rectifier in the current control period that can balance midpoint voltage, determines the voltage amplitude level of rectifier's midpoint potential on adaptation interval and the voltage equalization strategy corresponding to current input voltage mode;Equivalent compensation error corresponding load working condition is judged to jump, and the voltage jump vector of rectifier under matching load condition is obtained, the gain switching of voltage equalization strategy to voltage jump vector is carried out, and the critical output criterion of rectifier under different switching operating state is obtained;According to critical output criterion, the negative sequence superposition instruction of rectifier when correcting input voltage is automatically fault-tolerant regulation and control.The application can accurately fault-tolerant regulation and control to rectifier's negative sequence regulation and control under multiple input voltage fluctuation conditions, to improve the adaptive regulation and control stability of rectifier.

Description

Technical Field

[0001] This application relates to the field of rectification control technology, and more specifically, to an adaptive rectifier control system and method that supports multiple input voltage modes. Background Technology

[0002] Rectifier control is a core technology in power electronics for achieving stable operation of multi-input voltage mode rectifiers. It aims to control the amplitude, frequency, phase, and midpoint potential of the input voltage by adjusting the on / off states and timing of power switching devices to convert AC power to DC power and maintain the stability of the rectifier's output voltage and the balance of its midpoint potential. This technology solves the problems of traditional rectifier control, which only adapts to a single input voltage mode, has a lagging response to load jumps and voltage fluctuations, and lacks sufficient accuracy in controlling midpoint potential imbalances. It also ensures that the rectifier's power conversion efficiency and output parameters meet standards under multiple power sources, including the grid and energy storage. Rectifier control is widely used in the regulation of rectifier equipment in industrial power supply, new energy grid connection, and rail transportation, adapting to input voltage modes with different amplitudes and frequencies. It is a crucial support for the adaptive operation of multi-input voltage mode rectifiers.

[0003] However, existing adaptive rectifier control systems supporting multiple input voltage modes lack hierarchical control of the control sequence, have poor adaptability between voltage balancing strategies and input modes, and fail to effectively adjust for equivalent compensation errors under fluctuating operating conditions or perform load jump detection and gain switching. This results in lag in input voltage control, low accuracy in controlling midpoint potential imbalance, low rectifier power conversion efficiency, and weak adaptability to multiple input modes, making it difficult to meet the high-precision operation requirements of rectifiers. Therefore, how to accurately and fault-tolerantly adjust the negative sequence control of rectifiers under fluctuating multi-input voltage conditions to improve the adaptive control stability of rectifiers is a problem facing the industry. Summary of the Invention

[0004] This application provides an adaptive rectifier control system and method that supports multiple input voltage modes. It can perform precise fault-tolerant adjustment of the negative sequence control of the rectifier under multiple input voltage fluctuation conditions, thereby improving the adaptive control stability of the rectifier.

[0005] In a first aspect, this application provides an adaptive rectifier control method supporting multiple input voltage modes, the control method comprising the following steps: The system responds to the changing characteristics of the voltage signal in multiple input voltage modes and monitors the input voltage control quantity of the rectifier in real time based on the changing characteristics. The rectifier's regulation sequence within the current control cycle is determined based on the input voltage control quantity. The regulation sequence is then graded to obtain the voltage amplitude level of the rectifier's midpoint potential in the adaptation range. The voltage amplitude level is then used to determine the voltage balancing strategy corresponding to the current input voltage mode. Adjust the equivalent compensation error of the input voltage under fluctuating conditions, perform jump judgment on the load condition corresponding to the equivalent compensation error, obtain the voltage jump vector of the rectifier under the matching load condition, and then switch the gain of the voltage jump vector by the voltage balancing strategy to obtain the critical output criterion of the rectifier under different switching operating states. The rectifier performs automatic fault-tolerant control on the negative sequence superposition command when correcting the input voltage based on the critical output criterion.

[0006] In this embodiment, the input voltage control quantity refers to the control condition that suppresses the input voltage within a preset reasonable range.

[0007] In this embodiment, determining the order of rectifier regulation actions within the current control cycle that can balance the midpoint voltage based on the input voltage control quantity specifically includes: The voltage vector sector of the rectifier is determined based on the input voltage control quantity, which is within the current control cycle where the midpoint voltage can be balanced. Extract the voltage balance error of the rectifier at the midpoint voltage within the current control cycle; The rectifier's control sequence for the midpoint voltage within the current control cycle is determined based on the voltage vector sector and the voltage balance error.

[0008] In this embodiment, the "balanced current control cycle" refers to the range within a single switching control cycle of the rectifier where the midpoint voltage is corrected to a preset balance range by performing adaptive control actions.

[0009] In this embodiment, determining the voltage equalization strategy corresponding to the current input voltage mode based on the voltage amplitude level specifically includes: The voltage equalization amount containing the zero-sequence voltage component in the current input voltage mode is determined based on the voltage amplitude level. Separate the modulated wave component that dominates the midpoint potential from the voltage equalization quantity; The voltage equalization strategy corresponding to the current input voltage mode is determined based on the modulated wave components.

[0010] In this embodiment, the equivalent compensation error refers to the difference between the theoretical compensation amount of the input voltage under fluctuating operating conditions and the actual compensation amount performed by the rectifier.

[0011] In this embodiment, the voltage jump determination of the load condition corresponding to the equivalent compensation error, to obtain the voltage jump vector of the rectifier under matched load conditions, specifically includes: Real-time monitoring of the rate of change and threshold of the equivalent compensation error is used to determine the timing direction of the load condition jump. Determine the instantaneous voltage increment required to maintain neutral potential balance at the moment of load transition; The voltage transition vector of the rectifier under matched load conditions is determined based on the transition timing direction and the instantaneous voltage increment.

[0012] In this embodiment, the gain switching refers to the process of dynamically adjusting the gain parameters of the control algorithm in the voltage equalization strategy based on the characteristics of the voltage jump vector.

[0013] In this embodiment, the automatic fault-tolerant control of the negative sequence superposition command of the rectifier when correcting the input voltage based on the critical output criterion specifically includes: The critical output criterion is compared with the negative sequence component of the input voltage acquired in real time to generate a negative sequence superposition command to cancel the voltage imbalance. The disturbance intensity of the rectifier midpoint potential is adaptively adjusted according to the negative sequence superposition command to obtain the fault-tolerant control information of the rectifier when correcting the input voltage. The space vector modulation synthesis process of the input voltage is corrected based on the fault-tolerant control information, and an automatic fault-tolerant control switching signal is output. The rectifier is adaptively controlled using the switching signal.

[0014] Secondly, this application provides an adaptive rectifier control system supporting multiple input voltage modes, used to execute an adaptive rectifier control method supporting multiple input voltage modes, the control system comprising: The feature monitoring module is used to respond to the changing characteristics of the voltage signal in the multi-input voltage mode, and to monitor the input voltage control quantity of the rectifier in real time according to the changing characteristics; The hierarchical control module is used to determine the order of regulation of the rectifier's midpoint voltage within the current control cycle based on the input voltage control quantity, perform hierarchical control on the regulation order, obtain the voltage amplitude level of the rectifier's midpoint potential in the adaptation range, and then determine the voltage balancing strategy corresponding to the current input voltage mode based on the voltage amplitude level. The voltage jump determination module is used to adjust the equivalent compensation error of the input voltage under fluctuating conditions, perform voltage jump determination on the load conditions corresponding to the equivalent compensation error, obtain the voltage jump vector of the rectifier under the matching load conditions, and then use the voltage equalization strategy to switch the gain of the voltage jump vector to obtain the critical output criteria of the rectifier under different switching operating states. The fault-tolerant control module is used to automatically perform fault-tolerant control on the negative sequence superposition command of the rectifier when correcting the input voltage, based on the critical output criterion.

[0015] The technical solutions provided by the embodiments disclosed in this application have the following beneficial effects: The system responds to the voltage signal variation characteristics in multiple input voltage modes and monitors the rectifier's input voltage control quantity in real time based on these characteristics. It determines the rectifier's control sequence for the midpoint voltage within the current control cycle based on the input voltage control quantity, performs hierarchical control on this sequence, and obtains the voltage amplitude level of the rectifier's midpoint potential within the adaptation range. Then, it determines the voltage balancing strategy corresponding to the current input voltage mode based on the voltage amplitude level. It adjusts the equivalent compensation error of the input voltage under fluctuating conditions, performs jump judgment on the load condition corresponding to the equivalent compensation error, obtains the voltage jump vector of the rectifier under matched load conditions, and then switches the gain of the voltage jump vector using the voltage balancing strategy to obtain the critical output criterion of the rectifier under different switching operating states. Based on the critical output criterion, it performs automatic fault-tolerant control on the negative sequence superposition command of the rectifier when correcting the input voltage.

[0016] Therefore, this application demonstrates that when existing adaptive rectifier regulation supporting multiple input voltage modes suffers from input voltage control lag, it can adaptively regulate the rectifier. Specifically, by responding to the changing characteristics of the voltage signal in multiple input voltage modes and monitoring the rectifier's input voltage control quantity in real time, it solves the problems of inaccurate response to voltage signal changes, input voltage control lag, and susceptibility to misjudgment in existing technologies. By determining the order of regulation actions and implementing graded control based on the input voltage control quantity—that is, determining the voltage equalization strategy after obtaining the voltage amplitude level—it can reduce device losses and improve the adaptability of multiple input modes. By adjusting the equivalent compensation error under fluctuating operating conditions and judging load condition jumps, it obtains the voltage jump vector and then switches the gain to obtain the critical output criterion, which can improve the output accuracy and risk avoidance reliability under fluctuating operating conditions. By automatically performing fault-tolerant regulation on negative sequence superposition commands based on the critical output criterion, it can compensate for the lack of a perfect fault-tolerant mechanism for negative sequence superposition commands, improving the rectifier's operational reliability in unstable grid scenarios.

[0017] In summary, the technical solution adopted in this application can perform precise fault-tolerant adjustment of the negative sequence control of the rectifier under multiple input voltage fluctuation conditions, thereby improving the adaptive control stability of the rectifier. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this embodiment of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is an exemplary flowchart of an adaptive rectifier control method supporting multiple input voltage modes provided in this application; Figure 2 This is a flowchart illustrating the process for determining voltage amplitude levels provided in this application; Figure 3 This is a flowchart illustrating the determination of critical output criteria provided in this application; Figure 4 This is a module structure diagram of an adaptive rectifier control system supporting multiple input voltage modes provided in this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] This application provides an adaptive rectifier control system and method supporting multiple input voltage modes. Its core is to respond to the changing characteristics of voltage signals in multiple input voltage modes and monitor the rectifier's input voltage control quantity in real time based on these characteristics. The system determines the control sequence of the rectifier's midpoint voltage within the current control cycle based on the input voltage control quantity, performs hierarchical control on the control sequence to obtain the voltage amplitude level of the rectifier's midpoint potential in the adaptation range, and then determines the voltage balancing strategy corresponding to the current input voltage mode based on the voltage amplitude level. The system adjusts the equivalent compensation error of the input voltage under fluctuating conditions, performs jump judgment on the load condition corresponding to the equivalent compensation error, obtains the voltage jump vector of the rectifier under matched load conditions, and then switches the gain of the voltage jump vector using the voltage balancing strategy to obtain the critical output criterion of the rectifier under different switching operating states. Based on the critical output criterion, the system automatically performs fault-tolerant control on the negative sequence superposition command of the rectifier when correcting the input voltage.

[0022] Example 1: To better understand the above technical solution, the following will provide a detailed description of the technical solution in conjunction with the accompanying drawings and specific implementation methods. (Refer to...)Figure 1 As shown in the figure, this is an exemplary flowchart of an adaptive rectifier control method supporting multiple input voltage modes according to this embodiment of the present application. The control method includes the following steps: In step S1, the voltage signal changes in the multi-input voltage mode are responded to, and the input voltage control quantity of the rectifier is monitored in real time based on the changes.

[0023] In practice, Hall voltage sensors are first connected in series at each input port of the rectifier, and voltage divider sampling resistors are connected in parallel to acquire analog voltage signals at a frequency of 10kHz. These signals are then converted into digital signals by a 16-bit analog-to-digital converter and transmitted to the STM32H7 microcontroller unit. Subsequently, noise is removed by moving average filtering (50 sampling point windows) and Kalman filtering. Then, the voltage signal variation characteristics, such as amplitude fluctuation range, frequency change rate, and harmonic content, are extracted by zero detection method and 1024-point fast Fourier transform. Finally, the deviation between the preset voltage and the real-time voltage is used as input, and the proportional-integral controller calculates the input voltage control quantity. The microcontroller unit reads this control quantity every 100μs and compares it with a safety threshold. If the threshold is exceeded, an early warning is triggered, realizing real-time monitoring of the control quantity. This will not be elaborated further here.

[0024] It should be noted that, in this application, the change characteristics of the voltage signal refer to the quantifiable attributes of multiple input voltages in the time dimension; the input voltage control quantity refers to the control condition that suppresses the input voltage within a preset reasonable range.

[0025] In step S2, the order of regulation of the rectifier's midpoint voltage within the current control cycle is determined based on the input voltage control quantity. The order of regulation is then controlled in stages to obtain the voltage amplitude level of the rectifier's midpoint potential in the adaptation range. The voltage amplitude level is then used to determine the voltage balancing strategy corresponding to the current input voltage mode.

[0026] In this embodiment, determining the order of rectifier regulation of the midpoint voltage within the current control cycle based on the input voltage control quantity can be achieved through the following steps: The voltage vector sector of the rectifier is determined based on the input voltage control quantity, which is within the current control cycle where the midpoint voltage can be balanced. Extract the voltage balance error of the rectifier at the midpoint voltage within the current control cycle; The rectifier's control sequence for the midpoint voltage within the current control cycle is determined based on the voltage vector sector and the voltage balance error.

[0027] In practice, firstly, the three-phase voltage components at the DC side midpoint of the rectifier are acquired by a Hall voltage sensor. After being converted into digital signals by a 16-bit analog-to-digital converter, the voltage in the three-phase stationary coordinate system is converted into α and β axis components by the Clark transformation formula, and then converted into d and q axis components by the Park transformation. Based on the sign and amplitude ratio of the d and q axis components, the voltage vector space is divided into 6 sectors. The sector judgment threshold is corrected by combining the input voltage control quantity (e.g., the sector judgment amplitude range is narrowed when the control quantity exceeds 5mH). Finally, the voltage vector sector of the rectifier that can balance the midpoint voltage in the current control cycle is obtained by comparing the component characteristics. Then, based on the total DC-side voltage of the rectifier, the reference midpoint voltage (1 / 2 of the total voltage) is determined. The actual midpoint voltage is collected at a frequency of 10kHz using a voltage divider voltage sensor, and high-frequency noise is removed by moving average filtering (50 sampling points in the window). The absolute difference between the actual value and the reference value is then calculated, and the difference is fitted for 10 consecutive control cycles using the recursive least squares method to eliminate random errors. Combined with the changing trend of the input voltage control quantity, the fitted error value is dynamically weighted and corrected to obtain the voltage balance error of the current control cycle. Finally, a rectifier simulation model was built using MATLAB / Simulink to simulate the influence coefficients of various control actions on the midpoint voltage under different voltage vector sectors and different error values ​​(k=ΔU_mid / ΔA, where ΔU_mid is the change in midpoint voltage and ΔA is the amplitude of the control action). The control actions were preset in descending order of influence coefficients. Then, the voltage balance error was divided into three levels: micro, medium, and large. A voltage vector sector-error level and sorting correction rule was established. The basic sorting was adjusted by substituting the current voltage vector sector and error level. Finally, the control action order of the rectifier in the current control cycle that can balance the midpoint voltage was output.

[0028] It should be noted that, in this application, the "balanceable current control cycle" refers to the range within a single switching control cycle of the rectifier where the midpoint voltage is corrected to a preset balance range by executing adaptive control actions; the midpoint voltage refers to the voltage regulation target within a single switching control cycle of the rectifier where the midpoint potential can be corrected to a preset balance range by control actions; the voltage vector sector refers to the region where the spatial vector of the rectifier midpoint voltage is divided according to its phase and amplitude characteristics; the voltage balance error refers to the quantized value of the difference between the actual midpoint voltage of the rectifier and the reference midpoint voltage; and the control action sequence refers to the order in which control actions are executed according to their priority in influencing the midpoint voltage balance.

[0029] Preferably, in this embodiment, the order of the regulation actions is controlled in stages to obtain the voltage amplitude levels of the rectifier's midpoint potential within the adaptation range, with reference to... Figure 2 As shown in the figure, this is a flowchart illustrating the process of determining the voltage amplitude level in some embodiments of this application. In this embodiment, determining the voltage amplitude level can be achieved using the following steps: In step S21, the candidate switching state sequence of the corresponding rectifier power switching device is determined according to the priority of the control action sequence; In step S22, the candidate switch state sequence is mapped to a voltage modulation strategy to generate a corresponding modulation wave compensation amount; In step S23, the voltage application time of the three-phase bridge arm of the rectifier is determined based on the modulation wave compensation amount; In step S24, the voltage amplitude level of the rectifier's midpoint potential in the adaptation range is determined based on the charging and discharging effect of the midpoint current on the DC-side capacitor and the voltage application time.

[0030] In practical implementation, firstly, all switching states of the rectifier's power switching devices are analyzed, and invalid states that have no effect on the midpoint voltage are eliminated according to the priority of the control action sequence. Then, a rectifier simulation model is built using MATLAB / Simulink to simulate the midpoint voltage regulation effect of the remaining states under the current input voltage condition, retaining valid states whose regulation amount is greater than a preset threshold. The valid states are sorted according to the priority of the control action sequence to generate a candidate switching state sequence containing state type and switching timing. Next, the voltage modulation strategy currently used by the rectifier (e.g., sinusoidal pulse width modulation) is determined, and a mapping table between the candidate switching state sequence and modulation wave parameters (amplitude, phase) is established. The bridge arm conduction logic corresponding to each switching state in the sequence is extracted and substituted into the pulse width modulation duty cycle calculation formula to obtain the basic modulation wave parameters. Then, the difference between the basic parameters and the ideal modulation wave parameters is calculated, and a proportional-integral controller is used to adjust the difference. The adjustment result is converted into modulation wave amplitude compensation and phase compensation, which are then integrated to obtain the modulation wave compensation amount. Then, the modulation compensation amount is substituted into the conduction time calculation formula of the three-phase bridge arm to obtain the basic conduction time of each bridge arm; the input current signal of the rectifier is then collected, and after removing high-frequency noise through low-pass filtering, the influence of current ripple on conduction time is calculated; combined with the changing trend of input voltage control quantity, the basic conduction time is dynamically corrected to obtain the actual conduction time of each bridge arm in a single control cycle; according to the working logic of the three-phase bridge arm, the conduction time is allocated to the positive and negative half cycles to obtain the voltage action time of the three-phase bridge arm of the rectifier. Finally, the midpoint current is collected by the Hall current sensor and substituted into the capacitor charging and discharging formula to calculate the change in midpoint potential within a single voltage action time; combined with the total DC voltage of the rectifier, the center value of the adaptation interval is determined, and the percentage deviation between the actual midpoint potential and the center value is calculated; the percentage deviation is divided into four intervals: micro deviation, small deviation, medium deviation, and large deviation, corresponding to four voltage amplitude levels A, B, C, and D, respectively; finally, based on the interval to which the calculated percentage deviation belongs, the voltage amplitude level of the current midpoint potential is determined and output.

[0031] It should be noted that, in this application, the adaptation range refers to the safe range of the midpoint potential set according to the rated withstand voltage characteristics of the DC-side devices of the rectifier; the candidate switch state sequence refers to the combination of states with midpoint voltage regulation capability selected from the full switching states of the rectifier power switching devices according to the priority of the control action order; the voltage modulation strategy refers to the control method of adjusting the on / off state and timing of the rectifier power switching devices to accurately control the output voltage amplitude, phase and frequency; the modulation wave compensation amount refers to the variable that adjusts the voltage action time of the bridge arm; the voltage action time refers to the duration for which the three-phase bridge arm of the rectifier maintains a specific switching state within a single control cycle; the charge and discharge effect refers to the phenomenon of charge accumulation or release generated when the midpoint current passes through the DC-side capacitor; and the voltage amplitude level refers to the level of the midpoint potential divided according to the degree of deviation from the center value of the adaptation range.

[0032] In this embodiment, determining the voltage equalization strategy corresponding to the current input voltage mode based on the voltage amplitude level can be achieved through the following steps: The voltage equalization amount containing the zero-sequence voltage component in the current input voltage mode is determined based on the voltage amplitude level. Separate the modulated wave component that dominates the midpoint potential from the voltage equalization quantity; The voltage equalization strategy corresponding to the current input voltage mode is determined based on the modulated wave components.

[0033] In practice, firstly, a mapping table between voltage amplitude levels and zero-sequence voltage component amplitudes is established, and the basic value of the zero-sequence voltage component is initially determined based on the current voltage amplitude level; then, parameters of the current input voltage mode (such as three-phase voltage amplitude and frequency) are collected and substituted into the zero-sequence voltage injection formula to calculate the component correction value; the basic value and the correction value are superimposed to obtain the actual value of the zero-sequence voltage component, and combined with the load current parameters in the input voltage mode, the auxiliary adjustment component is calculated through a proportional-integral controller; finally, the zero-sequence voltage component and the auxiliary component are integrated to obtain a voltage balance quantity containing the zero-sequence voltage component. Then, a 1024-point Fast Fourier Transform can be used to perform spectral analysis on the voltage equalization quantity, decomposing it into modulation wave components of different frequencies and phases. Next, a rectifier simulation model is built using MATLAB / Simulink to simulate the change in midpoint potential when each component acts alone, and the contribution of each component to the midpoint potential balance is calculated (contribution = potential change regulated by the component / total potential change). A contribution threshold is set, and components with a contribution higher than the threshold are identified as modulation wave components that play a dominant role in the midpoint potential and extracted, thus obtaining the modulation wave components that play a dominant role in the midpoint potential. Finally, a mapping library of dominant modulation wave component parameters (amplitude, frequency, phase) and voltage equalization strategies is established, including basic strategies such as "zero-sequence voltage injection regulation," "bridge arm duty cycle correction," and "capacitor charging and discharging control." Then, characteristic parameters of the current input voltage mode (such as input voltage type and fluctuation range) are collected, and the basic strategies in the mapping library are adapted (such as increasing the zero-sequence voltage injection ratio under grid input mode). Finally, based on the corrected strategy parameters, a complete voltage equalization strategy including execution timing, adjustment step size, and stopping conditions is formulated and output, thus obtaining the voltage equalization strategy corresponding to the current input voltage mode.

[0034] It should be noted that, in this application, the current input voltage mode refers to the voltage input form corresponding to different power sources that the rectifier can receive; the zero-sequence voltage component refers to the voltage components with the same phase and equal amplitude in the three-phase rectifier; the voltage balancing quantity refers to the voltage regulation parameter for correcting the neutral point potential imbalance; the modulation wave component refers to the voltage parameter of the rectifier modulation wave; and the voltage balancing strategy refers to the specific control scheme for restoring the neutral point potential to the adaptation range.

[0035] In step S3, the equivalent compensation error of the input voltage under fluctuating conditions is adjusted, and the load condition corresponding to the equivalent compensation error is judged to obtain the voltage jump vector of the rectifier under the matching load condition. Then, the voltage equalization strategy is used to switch the gain of the voltage jump vector to obtain the critical output criterion of the rectifier under different switching operating states.

[0036] In practice, adjusting the equivalent compensation error of the input voltage under fluctuating conditions can be achieved in the following way: First, the analog input voltage signal of the rectifier under fluctuating conditions can be acquired by a Hall voltage sensor at a frequency of 10kHz. After being converted into a digital signal by a 16-bit analog-to-digital converter, it is substituted into a preset voltage compensation model to calculate the theoretical equivalent compensation amount (such as the PWM duty cycle adjustment value). Then, the actual compensation amount executed by the rectifier is acquired by a current sensor, and the initial equivalent compensation error between the theoretical value and the actual value is calculated. Subsequently, the error is dynamically fitted using the recursive least squares method. Combined with the input voltage fluctuation frequency and the gain parameters of the proportional-integral controller, the fitted error is used as the controller input, and the compensation amount correction command is output. Finally, the error is recalculated every 200μs and the adjustment is repeated until the error converges to within the preset threshold, thus completing the adjustment of the equivalent compensation error under fluctuating conditions. This will not be elaborated further here.

[0037] It should be noted that, in this application, the equivalent compensation error refers to the difference between the theoretical compensation amount of the input voltage under fluctuating operating conditions and the actual compensation amount performed by the rectifier.

[0038] In this embodiment, the voltage jump vector of the rectifier under matched load conditions can be obtained by determining the jump in the load condition corresponding to the equivalent compensation error through the following steps: Real-time monitoring of the rate of change and threshold of the equivalent compensation error is used to determine the timing direction of the load condition jump. Determine the instantaneous voltage increment required to maintain neutral potential balance at the moment of load transition; The voltage transition vector of the rectifier under matched load conditions is determined based on the transition timing direction and the instantaneous voltage increment.

[0039] In specific implementation, firstly, with a sampling period of 100μs, the real-time value of the equivalent compensation error is collected by the microcontroller unit, and the error change rate (the difference between adjacent sampled values ​​divided by the sampling period) is calculated using the differential method. Preset thresholds for the error change rate and absolute error value are used. When the change rate exceeds the threshold and the error continues to deviate from the threshold for more than 3 sampling periods, a load condition jump is determined. Then, the numerical change of the error before and after the jump is compared. If the error increases, it is determined to be in the direction of load increase; if the error decreases, it is in the direction of load decrease. Simultaneously, the start and end times of the jump are recorded to determine the jump sequence direction. Next, the sudden change value of the midpoint current at the moment of load jump is collected by a Hall current sensor and substituted into the capacitor charging and discharging formula to calculate the theoretical change in the midpoint potential. Then, based on the total DC voltage of the rectifier, the balance range of the midpoint potential is determined, and the voltage correction required to maintain the midpoint potential within the range is calculated. A proportional-integral controller is used to dynamically adjust the correction, and the controller gain is adjusted in conjunction with the characteristic parameters of the input voltage mode (such as voltage amplitude and frequency). The adjusted result is used as the instantaneous voltage increment required to maintain the balance of the midpoint potential at the moment of load jump. Finally, the transition timing direction is converted into the direction parameter of the voltage transition vector. The increase in load corresponds to the positive direction of the vector, and the decrease in load corresponds to the negative direction of the vector. The transition duration is used as the time dimension parameter of the vector. Then, the instantaneous voltage increment is used as the amplitude parameter of the vector. The direction, amplitude, and time parameters are integrated into a three-dimensional voltage transition vector using the vector synthesis method. Finally, the effectiveness of the vector is verified by MATLAB / Simulink simulation. If the midpoint potential deviates from the equilibrium range after the vector is applied, the amplitude parameter is adjusted until the requirements are met. Finally, the voltage transition vector matching the load conditions is determined.

[0040] It should be noted that, in this application, "jump determination" refers to the process of identifying whether a load condition jump has occurred and the characteristics of the jump based on the rate of change and threshold of the equivalent compensation error; "matching load condition" refers to the operating state requirements of the rectifier to adapt to the jump characteristics of the current load condition; "rate of change of equivalent compensation error" refers to the numerical change of the equivalent compensation error per unit time; "threshold of equivalent compensation error" refers to the critical value for determining whether the equivalent compensation error exceeds the acceptable range; "jump timing direction" refers to the time sequence and trend of load condition jumps; "instantaneous voltage increment" refers to the instantaneous voltage adjustment required to maintain the neutral potential balance at the moment of load jump; and "voltage jump vector" refers to the vector parameters of the rectifier's voltage jump characteristics when the load jumps.

[0041] Preferably, in this embodiment, the voltage balancing strategy is used to switch the gain of the voltage transition vector to obtain the critical output criterion of the rectifier under different switching operating states, with reference to... Figure 3 As shown in the figure, this is a flowchart illustrating the process of determining the critical output criterion in some embodiments of this application. In this embodiment, the determination of the critical output criterion can be achieved using the following steps: In step S31, the gain switching coefficient of the voltage equalization strategy is dynamically configured according to the magnitude of the voltage jump vector; In step S32, the gain switching coefficient is coupled with the space voltage vector modulation model of the rectifier to obtain the predicted value of the midpoint current under different switching operating states. In step S33, the superimposed voltage vector of the equilibrium midpoint potential is determined based on the predicted midpoint current value; In step S34, the critical output criteria of the rectifier under different switching operating states are determined based on the superimposed voltage vector.

[0042] In practical implementation, firstly, a basic mapping table between the voltage jump vector amplitude and the gain switching coefficient is established, and the basic coefficient values ​​are initially selected based on the current vector amplitude. Then, a rectifier simulation model is built using MATLAB / Simulink to simulate the adjustment effect of the voltage equalization strategy under different coefficients and calculate the adjustment error. The error is used as the input of the proportional-integral controller, and the output coefficient correction value is superimposed with the basic value to obtain the gain switching coefficient. Next, the core equations of the space voltage vector modulation model (such as the mapping formula between the voltage vector and the switching state) are extracted, and the gain switching coefficient is substituted into the equation as a correction term to obtain the coupled modulation model. Then, the full range of switching states of the rectifier (such as continuous conduction, intermittent conduction, etc.) are analyzed, and the switching logic of each state is substituted into the coupled model. The theoretical value of the midpoint current under each switching state is calculated using Kirchhoff's current law, and the theoretical value is filtered using the moving average method to finally obtain the predicted value of the midpoint current under different switching states. Then, the difference between the predicted midpoint current and the midpoint current under equilibrium conditions is calculated. This difference is substituted into the capacitor charging / discharging formula to obtain the voltage correction required to restore the midpoint potential to equilibrium. The voltage correction is then converted into a space voltage vector to obtain the initial superimposed voltage vector. A particle swarm optimization algorithm is used to optimize the amplitude and phase of the initial vector, making the predicted midpoint current after vector injection approach the equilibrium value. Finally, simulations verify the optimized vector effect, yielding the superimposed voltage vector of the equilibrium midpoint potential. Next, all switching operating states of the rectifier, including continuous conduction, intermittent conduction, full conduction, and full turn-off, are analyzed. The superimposed voltage vector is substituted into the output parameter calculation formula for each state to obtain the basic output threshold. Then, combined with the rated parameters of the rectifier devices (such as IGBT withstand voltage and capacitor current withstand), a safety margin correction (e.g., multiplying by a margin factor of 0.9) is applied to the basic threshold. Finally, categorized by switching state, the corrected voltage, current, and power thresholds are integrated to form a critical output criterion that includes parameter type, threshold range, and trigger action, thus obtaining the critical output criterion for the rectifier under different switching operating states.

[0043] It should be noted that, in this application, gain switching refers to the process of dynamically adjusting the gain parameters of the control algorithm in the voltage equalization strategy based on the characteristics of the voltage jump vector; gain switching coefficient refers to the proportional parameter for correcting the control gain of the voltage equalization strategy; space voltage vector modulation model refers to the mathematical model of the relationship between the rectifier switching state and the output voltage vector; midpoint current prediction value refers to the estimated value of the current flowing through the midpoint of the rectifier under different switching states; superimposed voltage vector refers to the voltage vector injected into the modulation model to balance the midpoint potential; critical output criterion refers to the output parameter threshold set according to different switching operating states of the rectifier.

[0044] In step S4, the rectifier performs automatic fault-tolerant control on the negative sequence superposition command when correcting the input voltage, based on the critical output criterion.

[0045] In this embodiment, the automatic fault-tolerant control of the negative sequence superposition command of the rectifier when correcting the input voltage based on the critical output criterion can be achieved by the following steps: The critical output criterion is compared with the negative sequence component of the input voltage acquired in real time to generate a negative sequence superposition command to cancel the voltage imbalance. The disturbance intensity of the rectifier midpoint potential is adaptively adjusted according to the negative sequence superposition command to obtain the fault-tolerant control information of the rectifier when correcting the input voltage. The space vector modulation synthesis process of the input voltage is corrected based on the fault-tolerant control information, and an automatic fault-tolerant control switching signal is output. The rectifier is adaptively controlled using the switching signal.

[0046] In practical implementation, firstly, the input voltage signal is acquired at a frequency of 10kHz using a three-phase voltage sensor. After being converted into a digital signal by a 16-bit analog-to-digital converter, the amplitude and phase of the negative-sequence component of the input voltage are separated using the symmetrical component method. Then, the safe threshold for the negative-sequence component in the pre-stored critical output criteria is retrieved, and the real-time negative-sequence component is compared with the threshold. If the threshold is exceeded, the instruction generation process is initiated. Substituting the negative-sequence compensation formula, the amplitude and phase parameters of the instruction are calculated with the goal of "canceling the negative-sequence component," and integrated to generate a negative-sequence superposition instruction used to cancel voltage imbalance. Next, a rectifier simulation model can be built using MATLAB / Simulink. After inputting the negative-sequence superposition instruction, the change in the midpoint potential during instruction execution is simulated to calculate the disturbance intensity of the instruction on the midpoint potential. A safe threshold for the disturbance intensity is preset. If the threshold is exceeded, adaptive adjustment is initiated. A proportional-integral controller is used, taking the disturbance intensity as input and outputting the correction amount of the instruction amplitude and phase. The corrected instruction parameters, adjustment timing, and trigger conditions are integrated, and the integrated result is used as the fault-tolerant control information of the rectifier when correcting the input voltage. Then, the core algorithm of the rectifier's space vector modulation synthesis process is extracted, and the instruction correction parameters in the fault-tolerant control information are substituted as correction terms into the algorithm to recalculate the voltage vector action time of each sector. Combining this with the switching characteristics of the rectifier's power switching devices, the corrected action time is converted into the duty cycle of a pulse width modulation signal. The duty cycle signal is then converted into high and low level switching signals via a drive circuit, with each switching signal corresponding to the on / off state of a power switching device, ultimately outputting an automatic fault-tolerant control switching signal. Finally, the switching signal is transmitted to the rectifier's power switching device driver board, which controls the on / off state of devices such as IGBTs and MOSFETs based on the high and low levels of the signal. During the control process, parameters such as the rectifier's output voltage and midpoint potential are acquired at 100μs intervals and compared in real-time with the critical output criteria. If the parameters are close to the criteria, the duty cycle and frequency of the switching signal are further adjusted; if the parameters return to a safe range, the current switching signal is maintained, thus achieving adaptive control of the rectifier.

[0047] It should be noted that, in this application, the negative sequence superposition command refers to the control command used to cancel the negative sequence component of the input voltage and balance the three-phase voltage; automatic fault-tolerant regulation refers to the control method that automatically adjusts the command parameters and corrects the modulation process when the negative sequence superposition command may cause the output to exceed the critical criterion; the negative sequence component of the input voltage refers to the voltage component in the three-phase input voltage that has a phase difference of 120° but whose amplitude or phase deviates from the ideal state; the disturbance intensity of the neutral point potential refers to the degree of interference of the negative sequence superposition command on the neutral point potential of the rectifier; the fault-tolerant regulation information refers to the negative sequence superposition command parameters and execution rules adjusted according to the disturbance intensity; the space vector modulation synthesis process refers to the calculation process by which the rectifier converts the voltage control command into the on / off signal of the power switching device; and the switching signal refers to the electrical signal that controls the on and off of the rectifier's power switching device.

[0048] Therefore, this application demonstrates that when existing adaptive rectifier regulation supporting multiple input voltage modes suffers from input voltage control lag, it can adaptively regulate the rectifier. Specifically, by responding to the changing characteristics of the voltage signal in multiple input voltage modes and monitoring the rectifier's input voltage control quantity in real time, it solves the problems of inaccurate response to voltage signal changes, input voltage control lag, and susceptibility to misjudgment in existing technologies. By determining the order of regulation actions and implementing graded control based on the input voltage control quantity—that is, determining the voltage equalization strategy after obtaining the voltage amplitude level—it can reduce device losses and improve the adaptability of multiple input modes. By adjusting the equivalent compensation error under fluctuating operating conditions and judging load condition jumps, it obtains the voltage jump vector and then switches the gain to obtain the critical output criterion, which can improve the output accuracy and risk avoidance reliability under fluctuating operating conditions. By automatically performing fault-tolerant regulation on negative sequence superposition commands based on the critical output criterion, it can compensate for the lack of a perfect fault-tolerant mechanism for negative sequence superposition commands, improving the rectifier's operational reliability in unstable grid scenarios.

[0049] In summary, the technical solution adopted in this application can perform precise fault-tolerant adjustment of the negative sequence control of the rectifier under multiple input voltage fluctuation conditions, thereby improving the adaptive control stability of the rectifier.

[0050] Example 2: This application provides an adaptive rectifier control system that supports multiple input voltage modes, referencing... Figure 4 As shown in the figure, this is a block structure diagram of an adaptive rectifier control system supporting multiple input voltage modes according to this embodiment of the present application. The control system includes: The feature monitoring module 100 is used to respond to the changing characteristics of the voltage signal in the multi-input voltage mode, and to monitor the input voltage control quantity of the rectifier in real time according to the changing characteristics; The hierarchical control module 200 is used to determine the order of regulation of the rectifier's midpoint voltage within the current control cycle based on the input voltage control quantity, perform hierarchical control on the regulation order, obtain the voltage amplitude level of the rectifier's midpoint potential in the adaptation range, and then determine the voltage balancing strategy corresponding to the current input voltage mode based on the voltage amplitude level. The voltage jump determination module 300 is used to adjust the equivalent compensation error of the input voltage under fluctuating conditions, perform voltage jump determination on the load conditions corresponding to the equivalent compensation error, obtain the voltage jump vector of the rectifier under the matching load conditions, and then use the voltage equalization strategy to switch the gain of the voltage jump vector to obtain the critical output criteria of the rectifier under different switching operating states. The fault-tolerant control module 400 is used to automatically perform fault-tolerant control on the negative sequence superposition command of the rectifier when correcting the input voltage based on the critical output criterion.

[0051] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0052] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, including read-only memory (ROM), random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), one-time programmable read-only memory (OTPROM), electrically-Erasable Programmable Read-Only Memory (EEPROM), compactdisc read-only memory (CD-ROM) or other optical disc storage, disk storage, magnetic tape storage, or any other computer-readable medium capable of carrying or storing data.

[0053] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

Claims

1. An adaptive rectifier control method supporting multiple input voltage modes, characterized in that, The control method includes the following steps: The system responds to the changing characteristics of the voltage signal in multiple input voltage modes and monitors the input voltage control quantity of the rectifier in real time based on the changing characteristics. The rectifier's regulation sequence within the current control cycle is determined based on the input voltage control quantity. The regulation sequence is then graded to obtain the voltage amplitude level of the rectifier's midpoint potential in the adaptation range. The voltage amplitude level is then used to determine the voltage balancing strategy corresponding to the current input voltage mode. Adjust the equivalent compensation error of the input voltage under fluctuating conditions, perform jump judgment on the load condition corresponding to the equivalent compensation error, obtain the voltage jump vector of the rectifier under the matching load condition, and then switch the gain of the voltage jump vector by the voltage balancing strategy to obtain the critical output criterion of the rectifier under different switching operating states. The rectifier performs automatic fault-tolerant control on the negative sequence superposition command when correcting the input voltage based on the critical output criterion.

2. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, The input voltage control quantity refers to the control condition that suppresses the input voltage within a preset reasonable range.

3. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, Determining the order of rectifier regulation of the midpoint voltage within the current control cycle based on the input voltage control quantity specifically includes: The voltage vector sector of the rectifier is determined based on the input voltage control quantity, which is within the current control cycle where the midpoint voltage can be balanced. Extract the voltage balance error of the rectifier at the midpoint voltage within the current control cycle; The rectifier's control sequence for the midpoint voltage within the current control cycle is determined based on the voltage vector sector and the voltage balance error.

4. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, The aforementioned "balanced current control cycle" refers to the range within a single switching control cycle of the rectifier where the midpoint voltage is corrected to a preset balance range by executing adaptive control actions.

5. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, The voltage equalization strategy corresponding to the current input voltage mode, determined by the voltage amplitude level, specifically includes: The voltage equalization amount containing the zero-sequence voltage component in the current input voltage mode is determined based on the voltage amplitude level. Separate the modulated wave component that dominates the midpoint potential from the voltage equalization quantity; The voltage equalization strategy corresponding to the current input voltage mode is determined based on the modulated wave components.

6. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, The equivalent compensation error refers to the difference between the theoretical compensation amount of the input voltage under fluctuating operating conditions and the actual compensation amount performed by the rectifier.

7. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, The voltage jump determination of the rectifier under matched load conditions by performing a jump judgment on the load condition corresponding to the equivalent compensation error specifically includes: Real-time monitoring of the rate of change and threshold of the equivalent compensation error is used to determine the timing direction of the load condition jump. Determine the instantaneous voltage increment required to maintain neutral potential balance at the moment of load transition; The voltage transition vector of the rectifier under matched load conditions is determined based on the transition timing direction and the instantaneous voltage increment.

8. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, The gain switching mentioned above refers to the process of dynamically adjusting the gain parameters of the control algorithm in the voltage equalization strategy based on the characteristics of the voltage jump vector.

9. The adaptive rectifier control method supporting multiple input voltage modes as described in claim 1, characterized in that, The automatic fault-tolerant control of the rectifier's negative sequence superposition command during input voltage correction based on the aforementioned critical output criterion specifically includes: The critical output criterion is compared with the negative sequence component of the input voltage acquired in real time to generate a negative sequence superposition command to cancel the voltage imbalance. The disturbance intensity of the rectifier midpoint potential is adaptively adjusted according to the negative sequence superposition command to obtain the fault-tolerant control information of the rectifier when correcting the input voltage. The space vector modulation synthesis process of the input voltage is corrected based on the fault-tolerant control information, and an automatic fault-tolerant control switching signal is output. The rectifier is adaptively controlled using the switching signal.

10. An adaptive rectifier control system supporting multiple input voltage modes, used to execute an adaptive rectifier control method supporting multiple input voltage modes as described in any one of claims 1 to 9, characterized in that, The control system includes: The feature monitoring module is used to respond to the changing characteristics of the voltage signal in the multi-input voltage mode, and to monitor the input voltage control quantity of the rectifier in real time according to the changing characteristics; The hierarchical control module is used to determine the order of regulation of the rectifier's midpoint voltage within the current control cycle based on the input voltage control quantity, perform hierarchical control on the regulation order, obtain the voltage amplitude level of the rectifier's midpoint potential in the adaptation range, and then determine the voltage balancing strategy corresponding to the current input voltage mode based on the voltage amplitude level. The voltage jump determination module is used to adjust the equivalent compensation error of the input voltage under fluctuating conditions, perform voltage jump determination on the load conditions corresponding to the equivalent compensation error, obtain the voltage jump vector of the rectifier under the matching load conditions, and then use the voltage equalization strategy to switch the gain of the voltage jump vector to obtain the critical output criteria of the rectifier under different switching operating states. The fault-tolerant control module is used to automatically perform fault-tolerant control on the negative sequence superposition command of the rectifier when correcting the input voltage, based on the critical output criterion.

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