Three-phase photovoltaic inverter system and single-phase micro-inverter

Abstract

The application relates to the field of power electronics, and discloses a three-phase photovoltaic inverter system, which comprises an impedance analysis module for collecting three-phase output voltage and output current data, a state sensing module for detecting system operation state variables in real time, an adaptive control module for receiving impedance error signals and feedback signals, a power driving module for receiving control signals and acting on inverter bridge arms to realize modulation control of the three-phase inverter, and a closed-loop updating module for feeding back voltage and current in the power driving result to the impedance analysis module and the state sensing module. The application also discloses a single-phase micro inverter, which comprises an impedance sensing module, an information interaction module, a matching coordination module and a grid-connected driving module. The application realizes high stability and adaptive regulation and control capacity of inverter output by constructing a closed-loop feedback control link and a dynamic impedance adjustment mechanism.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to a three-phase photovoltaic inverter system and a single-phase micro-inverter. Background Technology

[0002] With the rapid development of new energy grid connection, microgrids, and electrified equipment, the requirements for inverter output quality and system stability are increasing. Especially in three-phase power supply scenarios, impedance matching between the supply and demand ends has a significant impact on energy transmission efficiency, safety, and grid connection compliance. Impedance mismatch can lead to current distortion and increased harmonics, or even equipment malfunction or damage. Therefore, achieving stable, efficient, and dynamically adaptable impedance control has become a key issue in power electronic system design.

[0003] In existing technologies, common three-phase inverter control schemes typically employ static control or fixed-parameter model strategies, resulting in relatively simple system structures, clear modulation logic, and ease of engineering implementation. These schemes exhibit good steady-state output characteristics under rated operating conditions, meeting the voltage and current requirements of most loads. Furthermore, some optimized designs integrate high-frequency PWM modulation technology to improve the smoothness of the output waveform and suppress low-order harmonic interference.

[0004] However, these existing control structures generally lack real-time closed-loop feedback capabilities. Key signals such as voltage and current cannot be effectively transmitted back to the upstream control module, making it difficult to detect system state changes in a timely manner. A disconnect exists between control behavior and actual output, especially under conditions of sudden load changes and power grid fluctuations, where impedance matching adjustment lags, significantly reducing output accuracy. Furthermore, many systems operate solely based on initial model settings, unable to dynamically correct for nonlinear disturbances during operation, resulting in poor adaptability of the control strategy. Moreover, while traditional modulation can achieve a certain degree of control accuracy improvement, without synchronous feedback support, it easily leads to a situation where "accurate modulation results in unstable control." Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a three-phase photovoltaic inverter system and a single-phase micro-inverter, solving the problems of lack of real-time closed-loop feedback, lag in impedance matching response, and poor adaptability of control strategies in existing inverter control systems.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a three-phase photovoltaic inverter system, comprising: an impedance analysis module, used to collect three-phase output voltage and output current data, calculate the dynamic output impedance of the three-phase inverter based on the collected three-phase output voltage and output current data, and simultaneously acquire and set the system target output impedance, thereby generating an impedance error signal;

[0007] The state awareness module is used to detect system operating state variables in real time, including DC bus voltage, d-axis current and q-axis current, and use them as feedback signals.

[0008] An adaptive control module is used to receive the impedance error signal and the feedback signal, and generate a control signal for driving the inverter based on a state feedback control strategy and an error adjustment algorithm. The control signal includes an adaptive adjustment factor for dynamically matching the output impedance and the target impedance.

[0009] The power drive module is used to receive the control signal and act on the inverter bridge arm to realize the modulation control of the three-phase inverter so as to output three-phase AC power that matches the grid requirements.

[0010] The closed-loop update module is used to feed back the voltage and current in the power drive results to the impedance analysis module and the state sensing module to form a closed-loop circuit for impedance matching control.

[0011] Preferably, the impedance analysis module includes:

[0012] The sampling subunit is used to synchronously acquire the three-phase output voltage and output current signals at a preset sampling period;

[0013] Impedance calculation subunit, used to calculate output impedance based on Fourier transform or complex impedance method;

[0014] The reference impedance setting subunit is used to extract the target impedance value from the external microinverter system, grid parameters and operating strategies and store it as a system matching reference.

[0015] Preferably, the impedance error signal includes:

[0016] Based on the actual output impedance Z o (s) and the reference target impedance Z ref The impedance error signal E is formed by the difference between (s). z (s), which is calculated as follows:

[0017] E z (s)=Z o (s)-Z ref (s);

[0018] in, V(s) and I(s) are the Laplace transforms of the three-phase output voltage and current, respectively.

[0019] Preferably, the state feedback control strategy includes the following linear state feedback control formula:

[0020] u(t) = -Kx(t);

[0021] Where u(t) represents the vector form of the initial control signal of the controller, K represents the state feedback gain matrix, and x(t) represents the column vector of the system's state variables, including:

[0022]

[0023] Among them, i d (t) represents the d-axis current, i q (t) represents the q-axis current, v dc (t) represents the DC bus voltage;

[0024] The gain matrix K can be set offline through pole placement and optimal control methods.

[0025] Preferably, the error adjustment algorithm includes the following adaptive control formula with disturbance feedforward compensation:

[0026]

[0027] Among them, u ′ x(t) represents the final output control signal, K represents the state feedback gain matrix, x(t) represents the system state variable column vector, α is the impedance error adjustment gain factor, and E is a positive real number. z (t) represents the impedance error signal. This represents the external disturbance term estimated by the disturbance observer.

[0028] Preferably, the control signal includes:

[0029] The state feedback subunit is used to generate the first control component based on the system state variables, providing basic regulation capabilities for system current and voltage.

[0030] The impedance compensation subunit is used to generate a second control component based on the impedance error signal to compensate for the dynamic deviation between the output impedance and the target impedance.

[0031] The disturbance suppression subunit is used to fuse external disturbance estimates and superimpose them into a feedforward suppression signal;

[0032] The output integration subunit is used to synthesize the above control components and finally generate a complete control signal for the bridge arm drive.

[0033] Preferably, the power drive module includes:

[0034] The modulation subunit is used to convert the control signal into a pulse width modulation signal to drive the three-phase inverter bridge arm switching devices; the drive signal synchronization subunit is used to ensure that the generated signal maintains a 120-degree phase difference between the three phases to meet the three-phase symmetrical output requirements.

[0035] Preferably, the closed-loop update module includes:

[0036] The electrical parameter extraction subunit is used to collect the latest three-phase voltage and current information from the output of the inverter.

[0037] The state refresh subunit is used to calculate the latest state variables based on the voltage and current information and periodically update them to the state sensing module.

[0038] The closed-loop synchronization subunit is used to ensure that the impedance analysis module and the adaptive control module obtain the state variables synchronously, thus maintaining a stable closed-loop control section for the system.

[0039] Preferably, the three-phase output voltage includes:

[0040] The voltage acquisition unit is used to acquire the voltage signals of phase A, phase B and phase C at the three-phase output terminals respectively;

[0041] The voltage processing unit is used to filter, amplify, and convert the three-phase voltage signals A, B, and C.

[0042] The voltage vector construction unit is used to construct the processed three-phase voltage signal into a voltage vector form for use as the Laplace transform input of the impedance analysis module and the state feedback input of the controller.

[0043] This invention also provides a single-phase microinverter, comprising:

[0044] The impedance sensing module is used to collect the voltage and current signals at the output of the micro-inverter and calculate the current output impedance based on the complex impedance method. The output impedance serves as a characterization parameter of the dynamic operating state.

[0045] The information interaction module, based on the output impedance information obtained by the impedance sensing module, sends it to the three-phase photovoltaic inverter system via wired or wireless communication, and receives the target impedance parameters and grid status fed back by the system.

[0046] The matching and coordination module dynamically adjusts its output control strategy based on the coordination signal fed back by the three-phase photovoltaic inverter and the grid operation parameters, so that the output impedance of the micro-inverter is consistent with the target impedance.

[0047] The grid-connected drive module is used to drive the micro-inverter bridge arm according to the control signal generated by the matching and coordination module, so as to achieve impedance coordination output and grid connection with the three-phase photovoltaic inverter system.

[0048] This invention provides a three-phase photovoltaic inverter system and a single-phase micro-inverter. It offers the following advantages:

[0049] 1. This invention employs a fusion architecture of "closed-loop update + state awareness + impedance analysis" to achieve dynamic matching and adjustment of the output impedance, effectively improving the system's adaptive response capability under rapid load changes. Compared with the fixed impedance control strategy used in existing technologies, it no longer relies on static parameter adjustment, avoiding the problems of response lag and large matching errors.

[0050] 2. This invention introduces a closed-loop update module to feed back the actual voltage and current signals to the front-end control in real time, achieving the goal of refined closed-loop control. Compared with traditional segmented or open-loop control methods, this approach significantly enhances the integrity of the control loop and solves the technical shortcoming of unstable control caused by the lack of feedback paths in existing systems.

[0051] 3. This invention employs a power drive module based on the SVPWM strategy, resulting in precise modulation signals and minimal output waveform distortion. Compared to commonly used sinusoidal pulse width modulation methods, the system is more stable under medium- and high-frequency operating conditions, solving the problems of distortion and overmodulation that easily occur when the switching frequency is increased in existing technologies.

[0052] 4. This invention employs a closed-loop approach of "feedback-analysis-modulation," ensuring that the output impedance always matches the power grid and can quickly and adaptively recover even under external disturbances. Compared to some existing systems that rely on preset parameter control, this effectively avoids instability caused by parameter drift during operation. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the system architecture of the present invention;

[0054] Figure 2 This is a framework diagram of the impedance analysis module of the present invention;

[0055] Figure 3 This is a framework diagram of the power drive module of the present invention;

[0056] Figure 4 This is a diagram of the module closed-loop update framework of the present invention;

[0057] Figure 5 This is a schematic diagram of the single-phase micro-inverter of the present invention. Detailed Implementation

[0058] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Please see the appendixFigure 1 - Appendix Figure 4 This invention provides a three-phase photovoltaic inverter system, comprising:

[0060] The impedance analysis module is used to collect three-phase output voltage and output current data, calculate the dynamic output impedance of the three-phase inverter based on the collected three-phase output voltage and output current data, and at the same time obtain and set the system target output impedance, thereby generating an impedance error signal.

[0061] The three-phase photovoltaic inverter system uses an impedance analysis module to collect three-phase output voltage and current data in real time, and calculates the inverter's dynamic output impedance based on this data. The module's design goal is to generate an impedance error signal through accurate dynamic impedance calculation and target impedance setting, providing a basis for subsequent control systems, thereby optimizing inverter performance and achieving efficient grid connection. This module is not merely a data acquisition unit; it also integrates signal processing and real-time feedback control, and its function is fundamental to the stability and high efficiency of the entire system.

[0062] In this embodiment, the sampling subunit synchronously acquires the three-phase output voltage and output current signals at a preset sampling period. The three-phase output voltage and output current signals originate from the inverter's output terminals. Precise sampling technology ensures the accuracy and timeliness of the signals. Generally, the sampling frequency is selected based on system requirements and actual applications. Typically, the sampling period is on the order of microseconds to ensure that the acquired voltage and current signals accurately reflect the inverter's operating status.

[0063] Alternatively, the sampling subunit can employ a high-speed analog-to-digital converter (ADC) to digitize the voltage and current signals, achieving a conversion accuracy of 12 bits or higher, thus ensuring high-precision signal acquisition. This acquired data will then serve as input for further processing and analysis by the impedance calculation subunit.

[0064] The impedance calculation subunit is responsible for calculating the dynamic output impedance of the three-phase inverter based on the acquired three-phase output voltage and current signals. This calculation employs either Fourier transform or the complex impedance method. Through Fourier transform, the time-domain signals of the three-phase voltage and current are converted into frequency-domain signals, allowing for a clearer analysis of the inverter's output characteristics. The complex impedance method analyzes the frequency-domain signals of the voltage and current to derive the inverter's output impedance.

[0065] The formula is as follows:

[0066]

[0067] Among them, Z oV(s) is the output impedance, V(s) is the Laplace transform of the output voltage, and I(s) is the Laplace transform of the output current.

[0068] The calculated output impedance reveals the inverter's dynamic response characteristics and provides a basis for setting the target impedance. In this embodiment, the output impedance not only includes a component related to the AC characteristics of the power grid but also automatically adapts to load changes, thus providing necessary information for system optimization.

[0069] In this embodiment, the setting of the reference target impedance depends on the external grid conditions, the inverter's operating strategy, and the parallel system parameters of the microinverter system. Generally, the target impedance value can be determined through system design parameters or through the operating strategies of the external microinverter system and the grid. Specifically, the target impedance is calculated by coordinating the grid requirements with the system settings.

[0070] Specifically, under grid-connected conditions, the target impedance needs to take into account the grid's voltage amplitude, frequency, and impedance characteristics. These grid parameters directly affect the power quality of the inverter's output. Therefore, the target impedance setting must match the grid requirements to ensure that the inverter's output impedance can match the grid's impedance.

[0071] In one possible implementation, the reference target impedance value can be obtained from online parameters of the power grid or from a parallel microinverter system via an automated system. This target impedance value is stored and used as a reference for impedance error calculation. The difference between the stored target impedance and the actual output impedance is the impedance error signal.

[0072] The impedance error signal is calculated based on the difference between the dynamic output impedance and the set target impedance. Specifically, the impedance error signal is a complex error signal representing the deviation between the actual output impedance and the target impedance. This error signal will be used as an input signal in the subsequent adaptive control module to adjust the inverter's control strategy.

[0073] The formula is as follows:

[0074] E z (s)=Z o (s)-Z ref (s);

[0075] Among them, E z (s) Impedance error signal, Z o (s) represents the actual output impedance, Z ref (s) represents the reference target impedance.

[0076] The impedance error can be further adjusted based on the system's feedback signal. By providing real-time feedback on the error signal, the system can dynamically adjust to achieve precise matching between the output impedance and the target impedance.

[0077] The impedance analysis module is closely related to the subsequent state sensing module, adaptive control module, and power drive module. In the previous stage, by acquiring voltage and current signals and calculating the dynamic output impedance, the impedance analysis module feeds back the generated impedance error signal to the adaptive control module. The adaptive control module dynamically adjusts the control signal based on this signal to ensure that the system can perform optimal adjustment according to the grid conditions, thereby maintaining the output impedance consistent with the target impedance.

[0078] The state awareness module is used to detect system operating state variables in real time, including DC bus voltage, d-axis current and q-axis current, and use them as feedback signals.

[0079] During the operation of the entire three-phase photovoltaic inverter system, the impedance analysis module provides basic dynamic feedback on the output impedance. However, to achieve refined adaptive control, impedance information alone is insufficient for accurately adjusting the control input. Therefore, this invention further introduces a state sensing module as a key component for system state monitoring and feedback regulation. This module can assist the control system in accurately identifying the current operating condition based on real-time sampling of core state variables, and, combined with impedance error signals, achieve more comprehensive closed-loop adjustment of the control strategy.

[0080] In this embodiment, the state perception module is used to detect system operating state variables in real time, mainly including the DC bus voltage V. dc d-axis current i d q-axis current i q Three key parameters. These parameters will be input as feedback signals to the control system to achieve rapid response and dynamic adjustment of the inverter's operating status. In one possible implementation, the state sensing module acquires these parameters by connecting to the voltage and current sensors inside the system. Typically, this module is positioned between the power conversion unit and the control processing unit, capable of completing a full data refresh at a high rate (e.g., every 50 μs), ensuring the control system's high responsiveness to state changes.

[0081] Alternatively, this module can employ a dual-channel sampling circuit to simultaneously acquire voltage and current, avoiding error accumulation due to delay and improving feedback accuracy. The DC bus voltage is detected using a voltage divider network in conjunction with a high-precision ADC for conversion, yielding V. dc The digital signal reflects the stability of the power supply on the DC side.

[0082] Specifically, the detection of d-axis and q-axis current signals requires the three-phase AC current i a i b i c This is converted to components in a synchronously rotating coordinate system. This transformation is typically calculated using the Park transformation, as shown in the following formula:

[0083]

[0084] Among them, i a The three-phase output current is θ; the synchronous rotating coordinate angle is i. d (t) represents the d-axis current; i q (t) represents the q-axis current.

[0085] In this embodiment, the above calculations are performed in real time in the control processor, through continuously updated i d and i q This enables dynamic sensing of the inverter's power control status. Simultaneously, changes in the DC bus voltage provide crucial information about input-side power stability, particularly useful for evaluating system response performance under conditions of rapid power changes or load disturbances.

[0086] In some embodiments, the three types of state variables collected by the state-aware module, together with the aforementioned impedance error signal, serve as the multi-input signal source for the controller. This information fusion structure allows the controller to make more accurate judgments about the inverter's state, avoiding instability or misjudgment problems caused by single-signal control.

[0087] In the control logic, the following state feedback regulation function can be constructed:

[0088] u(t)=f(E z (s),V dc (t),i d (t),i q (t));

[0089] Where u(t) represents the control output, E z (s) Impedance error signal, V dc (t),i d (t),i q (t) represents the real-time detected state variables, and f is the system control law function, the structure of which varies depending on the type of controller.

[0090] In another implementation, the state-aware module can also be equipped with a filtering unit to perform low-pass filtering on the original voltage and current signals, removing high-frequency interference and improving the stability of the feedback signal. Furthermore, to prevent system oscillations caused by sudden changes in the state signal, a dead zone or saturation function can be introduced to limit the rate of change of the feedback signal.

[0091] The adaptive control module receives impedance error signals and feedback signals, and generates control signals for driving the inverter based on state feedback control strategy and error adjustment algorithm. The control signals include adaptive adjustment factors for dynamically matching output impedance and target impedance.

[0092] In the overall closed-loop regulation structure of a three-phase photovoltaic inverter system, the impedance analysis module provides dynamic output impedance information, and the state sensing module provides feedback signals of operating state variables. To achieve effective matching between the output impedance and the target impedance, the above information must be comprehensively processed to generate precise control signals to drive the inverter. Therefore, this invention proposes an adaptive control module, which constitutes the core decision-making unit in the system control link. This module is responsible for receiving impedance error signals and feedback signals, and based on these, generating control signals containing adaptive adjustment factors according to the state feedback control strategy and error adjustment algorithm, thereby achieving real-time dynamic adjustment and matching of the output impedance.

[0093] In this embodiment, a stable data interaction relationship exists between the adaptive control module, the impedance analysis module, and the state sensing module. This module receives the impedance error signal E from the impedance analysis module. z (s), and simultaneously receive the DC bus voltage V output by the status sensing module. dc d-axis current i d With q-axis current i q The above inputs together constitute the input signal set of the controller.

[0094] In one possible implementation, this module employs a state feedback control strategy, which involves jointly modeling multiple state variables of the system and constructing a state-space control law to derive the real-time update values ​​of the control variables. The state feedback control strategy includes the following linear state feedback control formula:

[0095] u(t) = -Kx(t);

[0096] Where u(t) represents the vector form of the initial control signal of the controller, K represents the state feedback gain matrix, and x(t) represents the column vector of the system's state variables, including:

[0097]

[0098] Among them, i d (t) represents the d-axis current, i q (t) represents the q-axis current, v dc (t) represents the DC bus voltage.

[0099] The error adjustment algorithm includes the following adaptive control formula with disturbance feedforward compensation:

[0100]

[0101] Among them, u ′ x(t) represents the final output control signal, K represents the state feedback gain matrix, x(t) represents the system state variable column vector, α is the impedance error adjustment gain factor, and E is a positive real number. z (t) represents the impedance error signal. This represents the external disturbance term estimated by the disturbance observer.

[0102] With the above structure, the system improves the adjustment sensitivity to enhance the response capability when the impedance error changes rapidly; when the error is stable, the adjustment factor tends to stabilize to reduce the oscillation risk of the control system.

[0103] In some embodiments, the adaptive control module also embeds a nonlinear limiting processing unit to set upper and lower boundaries for the control output signal u(t) to prevent signal overshoot. The limiting control strategy is typically represented by a saturation function as follows:

[0104]

[0105] Among them, u sat (t) is the control signal, u max u min These are the upper and lower limits of the control output signal, set according to the safe operating range of the inverter.

[0106] Furthermore, in this embodiment, the generated control signal u sat (t) will be transmitted as input to the power drive module to modulate the inverter's drive pulse signal, thereby acting on the three-phase bridge arm switching devices to achieve inverter output regulation. This regulation is ultimately reflected in the real-time change of the inverter's output impedance to match the set target impedance Z. ref (s).

[0107] As an alternative, to enhance the controller's adaptability, the adaptive control module can also introduce an online gain adjustment mechanism. That is, during operation, the system can fine-tune the gain matrix K based on the changing trends of the state variables to adapt to the control requirements of different operating scenarios. For example, under high power fluctuation conditions, the weight of K is increased to improve the system response speed; under steady-state conditions, the gain is reduced to avoid system oscillations.

[0108] The power drive module is used to receive control signals and apply them to the inverter bridge arm to realize the modulation control of the three-phase inverter so as to output three-phase AC power that matches the grid requirements.

[0109] In the closed-loop control path of a three-phase photovoltaic inverter system, the front-end adaptive control module comprehensively processes the impedance error signal and the feedback status signal to generate a control signal for driving the inverter. This control signal needs to be converted by the power drive module into a modulation control signal that directly acts on the inverter bridge arm, thereby realizing power conversion and modulation output. The power drive module plays a crucial role in the system by amplifying signals, performing logic transformations, and matching drive capabilities; it is a key link in the execution of the control signal.

[0110] In this embodiment, the power drive module is used to receive the control signal u output by the adaptive control module. sat (t) is modulated, analyzed, and pulsed to drive the power switching devices in the three-phase inverter bridge arm. This module supports a control mode based on SVPWM (Space Vector Pulse Width Modulation) strategy, aiming to improve the inverter output waveform quality and reduce harmonic distortion rate.

[0111] In one possible implementation, the control signal u sat (t) contains reference voltage vector information, defined as follows:

[0112] in: As the reference voltage vector, V α (t), V β (t) Two-phase stationary coordinate system components obtained from the three-phase system by Clarke transformation.

[0113] The voltage vectors mentioned above are used by the SVPWM module for spatial region identification and sector allocation, and then the effective conduction times T1, T2, and T0 of the three-phase bridge arms are calculated. The specific calculation process is as follows:

[0114] T s =T1 + T2 + T0;

[0115]

[0116] Among them, T s For PWM period, As the reference voltage vector, V dc θ is the DC bus voltage, θ is the synchronous rotating coordinate angle, and T0 is the zero vector action time, used to balance the conduction time and maintain modulation symmetry.

[0117] Specifically, the power drive module maps T1, T2, and T0 to the switching sequences of each bridge arm through logic allocation, generates control signals suitable for the upper and lower arm drivers, and completes energy isolation and drive capability amplification with the gate driver through isolation circuit.

[0118] Generally, high-voltage, high-frequency devices such as SiC or IGBTs are selected for power switching, and the drive module needs to provide a pulse signal with sufficient voltage swing and current push-pull capability. In this embodiment, the drive voltage amplitude is typically ±15V, and the turn-on and turn-off edge times are strictly controlled within 100ns to avoid bridge arm short-circuit faults.

[0119] As an alternative, the power drive module also integrates dead-time insertion logic to prevent the upper and lower bridge arms from conducting simultaneously within the same control cycle. Dead time t dead The settings are based on device characteristics and switching frequency:

[0120] t dead =f(T) rise ,T fall V th ,R g );

[0121] Among them, T rise V represents the rise / fall time. th R is the gate threshold voltage. g This is the external gate resistor.

[0122] In some embodiments, to improve the system's response to high-frequency disturbances, the power drive module operates in high-frequency chopping mode, which can increase the modulation frequency to above 20kHz, thereby improving the inverter's dynamic control performance and reducing output current ripple.

[0123] In addition, the power drive module in this embodiment also includes an overcurrent detection and shutdown logic module, which is used to quickly shut down all drive signals when an overcurrent risk in the bridge arm is detected, thereby achieving soft shutdown protection and ensuring system safety.

[0124] The closed-loop update module is used to feed back the voltage and current from the power drive results to the impedance analysis module and the state sensing module, forming a closed-loop circuit for impedance matching control.

[0125] The power drive module generates drive signals for the inverter arms through modulation control to achieve grid-matched output. However, to ensure the accuracy and stability of impedance matching control, the inverter's voltage and current feedback signals must be fed back to the impedance analysis and state sensing modules to achieve closed-loop adjustment of the error between the output impedance and the target impedance. The closed-loop update module, through this feedback process, completes real-time updates and state optimization of the voltage and current signals, constructing a complete impedance matching closed-loop circuit.

[0126] In this embodiment, the closed-loop update module, as the core of the feedback signal processing, is responsible for feeding back the voltage and current at the inverter output to the front-end impedance analysis module and state sensing module. This module receives the voltage V measured at the inverter. out(t) and current I out (t), by comparing with the set target value, a feedback signal E is generated. fb (t), and the system control parameters are corrected by passing them to the impedance analysis module and the state awareness module.

[0127] Specifically, the closed-loop update module calculates the feedback error signal E from the voltage and current signals using the following formula. fb (t):

[0128] E fb (t)=[V target (t)-V out (t),I target (t)-I out (t)];

[0129] Among them, V target (t) represents the target voltage value, I target (t) represents the target current value, V out (t) represents the actual output voltage value, I out (t) represents the actual output current value.

[0130] After the feedback error is calculated, the closed-loop update module transmits this feedback information to the impedance analysis module, which then updates the impedance error signal E using an impedance estimation algorithm. z (s). Typically, the impedance analysis module performs dynamic evaluation based on the following impedance calculation formula:

[0131]

[0132] Among them, V out (t) represents the actual output voltage value, I out (t) represents the actual output current value, Z out (s) represents the output impedance.

[0133] Through this calculation, the impedance analysis module can adjust the impedance matching strategy in real time, thereby ensuring that the difference between the output impedance and the target impedance is minimized. Feedback signal E fb (t) enables the system to continuously optimize its control strategy and correct any possible impedance deviations.

[0134] Alternatively, the closed-loop update module can also include a high-order filter design to filter out high-frequency noise in the voltage and current signals, improving the accuracy and stability of the feedback signal. The filter typically uses a low-pass filter to ensure that the feedback signal contains only valid dynamic information and that noise does not affect the system's accuracy.

[0135] In some embodiments, the closed-loop update module also has a delay compensation function, which uses a feedforward control strategy to correct errors caused by signal propagation delay. This function can improve the response speed of closed-loop control, especially under conditions of frequent load changes, ensuring that the system can adjust its output in a timely manner to adapt to changing load demands.

[0136] In this embodiment, the closed-loop update module, under the action of the inverter's voltage and current feedback signals, forms a closed-loop control loop with the impedance analysis module and the state sensing module. This not only ensures the accuracy of impedance matching but also improves the dynamic response performance of the system, guaranteeing the stability of the three-phase inverter output and its compatibility with the power grid.

[0137] The single-phase microinverter described below can be referenced in correspondence with the three-phase photovoltaic inverter system described above.

[0138] Please see the appendix Figure 5 The present invention also provides a single-phase micro-inverter, comprising:

[0139] The impedance sensing module is used to collect the voltage and current signals at the output of the micro-inverter and calculate the current output impedance based on the complex impedance method. The output impedance serves as a characterization parameter of the dynamic operating state.

[0140] The information interaction module sends the output impedance information obtained by the impedance sensing module to the three-phase photovoltaic inverter system via wired or wireless communication, and receives the target impedance parameters and grid status fed back by the system.

[0141] The matching and coordination module dynamically adjusts its output control strategy based on the coordination signal fed back from the three-phase photovoltaic inverter and the grid operating parameters, so that the output impedance of the micro-inverter is consistent with the target impedance.

[0142] The grid-connected drive module is used to drive the micro-inverter bridge arm according to the control signal generated by the matching and coordination module, so as to achieve impedance coordination output and grid connection with the three-phase photovoltaic inverter system.

[0143] The device in this embodiment can be used to execute the above system embodiment, and its principle and technical effects are similar, so they will not be described again here.

[0144] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A three-phase photovoltaic inverter system, characterized in that, include: The impedance analysis module is used to collect three-phase output voltage and output current data, calculate the dynamic output impedance of the three-phase inverter based on the collected three-phase output voltage and output current data, and at the same time obtain and set the system target output impedance, thereby generating an impedance error signal. The state awareness module is used to detect system operating state variables in real time, including DC bus voltage, d-axis current and q-axis current, and use them as feedback signals. An adaptive control module is used to receive the impedance error signal and the feedback signal, and generate a control signal for driving the inverter based on a state feedback control strategy and an error adjustment algorithm. The control signal includes an adaptive adjustment factor for dynamically matching the output impedance and the target impedance. The power drive module is used to receive the control signal and act on the inverter bridge arm to realize the modulation control of the three-phase inverter so as to output three-phase AC power that matches the grid requirements. The closed-loop update module is used to feed back the three-phase output voltage and current from the power drive results to the impedance analysis module, and to feed back the DC bus voltage, d-axis current and q-axis current to the state sensing module, so that the impedance analysis module can update the impedance error signal and the state sensing module can update the feedback signal, thus forming a closed-loop circuit for impedance matching control.

2. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The impedance analysis module includes: The sampling subunit is used to synchronously acquire the three-phase output voltage and output current signals at a preset sampling period; Impedance calculation subunit, used to calculate output impedance based on Fourier transform or complex impedance method; The reference impedance setting subunit is used to extract the target impedance value from the external microinverter system, grid parameters and operating strategies and store it as a system matching reference.

3. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The impedance error signal includes: Based on actual output impedance With reference target impedance The impedance error signal formed by the difference between them The calculation method is as follows: ； in, , and These are the Laplace transforms of the three-phase output voltage and current, respectively.

4. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The state feedback control strategy includes the following linear state feedback control formula: ； in, This represents the vector form of the initial control signal of the adaptive control module. Represents the state feedback gain matrix. The column vector representing the system's state variables includes: ； in, For d-axis current, For q-axis current, This is the DC bus voltage; The gain matrix Offline configuration can be achieved through pole configuration and optimal control methods.

5. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The error adjustment algorithm includes the following adaptive control formula with disturbance feedforward compensation: ； in, This represents the final output adjustment and control signal. Represents the state feedback gain matrix. Represents the column vector of system state variables. Let be the adaptive adjustment factor, and be a positive real number. This is the impedance error signal. This represents the external disturbance term estimated by the disturbance observer.

6. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The adaptive control module includes: The state feedback subunit is used to generate the first control component based on the system state variables, providing basic regulation capabilities for system current and voltage. The impedance compensation subunit is used to generate a second control component based on the impedance error signal to compensate for the dynamic deviation between the output impedance and the target impedance. The disturbance suppression subunit is used to fuse external disturbance estimates and superimpose them into a feedforward suppression signal; The output integration subunit is used to synthesize the above control components and finally generate a complete control signal for the bridge arm drive.

7. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The power drive module includes: A modulation subunit is used to convert the control signal into a pulse width modulation signal to drive the three-phase inverter bridge arm switching devices; The drive signal synchronization subunit is used to ensure that the generated signal maintains a 120-degree phase difference between the three phases, meeting the three-phase symmetrical output requirements.

8. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The closed-loop update module includes: The electrical parameter extraction subunit is used to collect the latest three-phase voltage and current information from the output of the inverter. The status refresh subunit is used to calculate the latest status variables based on the three-phase voltage and current information, and periodically update them to the status sensing module. A closed-loop synchronization subunit is used to ensure that the impedance analysis module obtains the three-phase voltage and current information, the state sensing module obtains the latest state variables, and maintains a stable closed-loop control section for the system.

9. The three-phase photovoltaic inverter system according to claim 1, characterized in that, The impedance analysis module further includes: The voltage acquisition unit is used to acquire the voltage signals of phase A, phase B and phase C at the three-phase output terminals respectively; The voltage processing unit is used to filter, amplify, and convert the three-phase voltage signals A, B, and C. The voltage vector construction unit is used to construct the processed three-phase voltage signal into a voltage vector form, which is used as the Laplace transform input of the impedance analysis module and the state feedback input of the adaptive control module.

10. A single-phase micro-inverter, comprising a three-phase photovoltaic inverter system according to any one of claims 1-9, characterized in that, include: The impedance sensing module is used to collect the voltage and current signals at the output of the micro-inverter and calculate the current output impedance based on the complex impedance method. The output impedance serves as a characterization parameter of the dynamic operating state. The information interaction module, based on the output impedance information obtained by the impedance sensing module, sends it to the three-phase photovoltaic inverter system via wired or wireless communication, and receives the target impedance parameters and grid status fed back by the system. The matching and coordination module dynamically adjusts its output control strategy based on the coordination signal fed back by the three-phase photovoltaic inverter and the grid operation parameters, so that the output impedance of the micro-inverter is consistent with the target impedance. The grid-connected drive module is used to drive the micro-inverter bridge arm according to the control signal generated by the matching and coordination module, so as to achieve impedance coordination output and grid connection with the three-phase photovoltaic inverter system.

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