219 results about "Composite controller" patented technology

A composite anti-jamming attitude control method for a flexible spacecraft, which is characterized in that it includes the following steps: First, by considering the vibration of the flexible attachment, the change of the spacecraft moment of inertia caused by the expansion of the flexible attachment and the space environment disturbance torque on the attitude In order to control the influence of control, a flexible spacecraft dynamics model including neutral uncertain dynamic items and external equivalent disturbance variables is established; secondly, in view of the serious influence of structural vibration on the stability of the spacecraft, and the large existence of flexible accessories such as sailboards, With the characteristics of flexibility and low damping, the PPF active vibration controller is constructed to reduce the impact of vibration modes on the spacecraft body; thirdly, the H∞ anti-jamming controller is designed to suppress vibrations from flexible mechanisms such as sailboards and extension rods. The disturbance caused by the change of the spacecraft rotational inertia caused by the deployment and the bounded disturbance such as the space environment disturbance moment; finally, based on the convex optimization algorithm, the composite anti-jamming output feedback attitude and the vibration composite controller are solved; Design and other advantages, can be used for high stability control of flexible spacecraft.

The present invention provides a method for disturbance compensation based on a sliding mode disturbance observer for a spacecraft with a large flexible appendage, comprising steps of: a) building a spacecraft attitude control system; b) constructing an external system, the external system being incorporated with an uncertain portion of a damping matrix of a flexible appendage of the spacecraft; the external system being incorporated with an uncertain portion of a rigidity matrix of the flexible appendage of the spacecraft and describing a sum of flexible vibration and environmental disturbance; c) configuring a sliding mode disturbance observer for estimating the value of the sum of flexible vibration and environmental disturbance; d) compounding a nominal controller with the sliding mode disturbance observer in step c) to obtain a compound controller; the compound controller compensating for the sum of flexible vibration and environmental disturbance.

The invention discloses a track and posture composite control method in a shield tunneling process. The method comprises the following steps of: performing control by setting threshold values for a posture and a track; immediately adjusting the posture as long as the posture deviates to exceed the limit even though the track does not reach a deviation correction threshold; solving current positional deviation Si and angular deviation theta I of a shield machine through measurement and calculation when a shield works; continuously propelling the shield machine when the Si is less than or equal to a positional deviation threshold value Scmin of a track and posture composite controller and theta i is less than or equal to an angular deviation threshold value theta cmin of the track and posture composite controller or when the Si is less than or equal to positional allowable deviation Smin of actual tunnel construction and theta i is equal to 0; contrarily, automatically adjusting propelling pressure of a hydraulic cylinder of each sub-region and propelling displacement to simultaneously eliminate the positional deviation and the angular deviation generated in a tunneling process. Thus, an actual tunneling route of the shield machine is controlled within a design axial range of a tunnel, unnecessary overbreak and underbreak are avoided, and the forming quality of the tunnel is improved.

The present invention provides a method for attitude control based on finite time friction estimation for a flexible spacecraft. The control method includes the following steps: a. introducing spacecraft flywheel friction disturbance into a spacecraft dynamics system, and establishing a flexible spacecraft dynamics system with flywheel friction disturbance; b. converting the flexible spacecraft dynamics system with flywheel friction disturbance into a state-space form; c. constructing a flywheel friction disturbance estimator; d. constructing a flexible appendage vibration disturbance observer; and e. combining the flywheel friction disturbance estimator in the step c and the flexible appendage vibration disturbance observer in the step d with a nominal controller to obtain a compound controller; the compound controller compensating for flywheel friction according to an estimated value of a flywheel friction moment; and the compound controller compensating for flexible appendage vibration disturbance according to an estimated value of flexible appendage vibration disturbance.

The invention discloses a trajectory tracking controlling method of a six-rotor-wing air vehicle, and belongs to the field of controlling of spacecraft instrumentation. The method includes the steps: building a kinematics model of the air vehicle and a dynamics model in which the air vehicle has compound jamming situations based on a Newton-Euler equation; utilizing a second order sliding mode compound jamming motion estimation algorithm of a sign functional integration to offer a continuous jamming compensation term; then adopting a method that a linear differentiator and a nonlinear differentiator are combined to design a nonlinear differentiator with rapid convergence; combining the compound jamming motion estimation algorithm, the nonlinear differentiator and backstepping to design a compound controller of a gesture system of the air vehicle; finally adopting a PD method, designing a position controller of the air vehicle, calculating out gesture angle information needed for tracking a preset trajectory and controlling lift force. According to the trajectory tracking controlling method of the six-rotor-wing air vehicle, under the situation of compound jamming, the air vehicle still has good stability and control performance, and the preset trajectory can be accurately tracked.

The invention provides a large flexible spacecraft interference compensation method based on a sliding mode disturbance observer. The compensation method comprises the following steps of a) establishing a spacecraft attitude control system [sigma1]; b) establishing an external system [sigma3], wherein the external system [sigma3] adopts an uncertain part of a spacecraft flexible appendage damping matrix and describes the sum of flexible oscillation and environment interference; c) designing a sliding mode disturbance observer, wherein the sliding mode disturbance observer estimates the value of the sum of flexible oscillation and environment interference; and d) combining a nominal controller and the sliding mode disturbance observer in the step c) to obtain a combined controller, wherein the combined controller compensates the sum of flexible oscillation and environment interference through the estimation value of the sum of flexible oscillation and environment interference.

The invention discloses a hierarchical dynamic inverse control method for a flight vehicle based on a sliding mode interference observer. The hierarchical dynamic inverse control method comprises the steps of: 1, by considering multi-source interference suffered by the flight vehicle, building a multi-source interference system model based on an flight vehicle longitudinal dynamics model; 2, designing a sliding mode interference observer and estimating multi-source interference based on the multi-source interference system model built in the first step; the third step, constructing a hierarchical dynamic inverse composite controller based on the sliding mode interference observer in the second step, thus enabling speed and height of the flight vehicle to highly follow a reference instruction while compensating multi-source interference. The hierarchical dynamic inverse control method for the flight vehicle based on the sliding mode interference observer has the advantages of strong anti-interference capability, fast tracking speed, high control precision and the like, thus being applicable to tracking and controlling height and speed of the flight vehicle.

The invention discloses a multisource disturbance actuator saturation integrated spacecraft relative attitude control method. The method includes: starting from spacecraft relative attitude kinematicand kinetic equations to perform characteristic analysis and classification of multisource disturbances in a system; then, estimating disturbances with different characteristics by taking advantages of estimation performances of a disturbance observer, a radial basis function neural network and an extended state observer; next, designing an anti-saturation compensator to avoid damages caused by saturation upper limit exceeding of a spacecraft execution mechanism; finally, designing a composite controller according to a backstepping method on the basis of multisource disturbance observation values and anti-saturation compensation items. Therefore, adverse effects of multisource disturbances on the system are avoided, system robustness is improved, accurate spacecraft relative attitude control in a saturation range is guaranteed by the execution mechanism, and smoothness in space operation task completion is guaranteed.

The invention relates to a support vector machine inverse system composite controller based on a bearingless synchronous reluctance motor. Two expandable current hysteresis loop PWM (Pulse-Width Modulation) inverters and a bearingless synchronous reluctance motor to be controlled are used as a whole to form a composite object to be controlled; a support vector machine inverse system controller is constructed according to a mathematical model of the object to be controlled and is connected in series before the composite object to be controlled of the bearingless synchronous reluctance motor so as to realize the decoupling control between the electromagnetic torque and the radial levitation force of the motor as well as the radial levitation force in two vertical directions; on the basis, a rotating speed closed loop linear controller and two rotor position closed loop linear controllers are respectively designed for the rotating speed of the motor and the rotor positions to form a linear closed loop controller; an finally the linear closed loop controller, the support vector machine inverse system controller and two expandable current hysteresis loop PWM inverters commonly form the support vector machine inverse system composite controller for dynamically decoupling control on the bearingless synchronous reluctance motor. The control speed, the control precision and the dynamic and static performances of the system can pass parameters for adjusting the linear closed loop controller.

The invention provides a sliding mode and active disturbance rejection based composite control method of a tank gun controlling system. Dynamic shooting performance and stability of the tank gun controlling system can be improved. The method includes: firstly, building a tank gun high-low stabilizer control model, secondly, designing a sliding mode variable structure switching function and a control law thereof according to the control model, thirdly, designing an active disturbance rejection controller according to the control module, and finally designing a composite controller of the tank gun controlling system according to the switching function, the control law and the active disturbance rejection controller. The active disturbance rejection controller comprises a tracking differentiator, an extended state observer and a nonlinear feedback control law.

The invention discloses an attitude control method for a spacecraft networked system based on event trigger, belonging to the field of system servo control for space robot networked control systems. The method comprises the following steps: firstly arranging a suitable transition process for the desired attitude of the system by designing a tracking differentiator to avoid a serious overshoot on the output of the system caused by an over-large initial error, and at the same time, acquiring a differential signal of the desired value for preparation for subsequent controller design; then, considering the network transmission signals, designing an event-triggered expansion state observer by using an attitude-angle measurement signal output by an event trigger mechanism, estimating the nonlinear uncertainties formed by the state in the spacecraft system, coupling, external disturbances and the like in real time, and compensating the estimated values of the nonlinear uncertainties into an error feedback control rate to form a composite controller. Finally, the method provided by the invention prevents nonlinear factors such as internal and external interferences from adversely affectingthe system, improves the robustness of the system, and provides guarantee for the smooth completion of space operations tasks.

A simplified self noise-immunity controller formation method of PMSM (permanent magnet synchronous motor) is applicable to the high performance control of PMSM. It constructs the expanding voltage-controlled inverter (2) by the voltage control voltage source inverter (1) and space vector pulse width modulation; it constructs a composite controlled object (10) by the expanding voltage-controlled inverter and current controller (3), the coordinate transformation (4), the permanent magnet synchronous motor (7), the workload (8) and the photoelectric encoder (9); it constructs the second-order state observer (52) by compositing the input and output signals of the controlled object; It constructs the composite speed feedback (54) by the weighted sum of the two speed measurement value; it constructs the composite controller (53) by the superposition of the generalized rate error square controller (51) and the compensation value of the system perturbation (-z2 / b); it series connects the composite controller before the composite controlled object, and finally, it constructs the simplified self noise-immunity controller (5) by the composite controller and the expanding second-order state observer.

The embodiment of the invention provides a PWM (Pulse-Width Modulation) rectifier controlling method and a PWM rectifier. The PWM rectifier controlling method is a passivity control method based on repeated control and compensation, and comprises the following steps: a control law of the PWM rectifier based on the interconnection and damping configuration of port controlled dissipation Hamilton models is obtained with a Lagrange-Charpy integral method; and a composite controller including repeated control and passive control is used as a controller of the PWM rectifier, and the passive control is compensated by the repeated control according to the control law so as to suppress periodic interference. According to the embodiment of the invention, PWM rectification of a unit power factor can be realized, and at the same time the harmonic interference of a power grid is better suppressed under the condition of not detecting load harmonic current so as to improve power quality. Compared with the conventional PWM rectifier, the PWM rectifier disclosed by the invention has the functions of harmonic suppression and reactive compensation under the condition of not increasing hardware cost.

The invention discloses a novel photovoltaic inverter control method based on BP neural network and dual-mode structure repetitive control. According to the invention the output of the photovoltaic grid-connected inverter is connected to a power network after LCL filtering to carry out a sampling link. The phase theta extracted by the improved PLL is fed into the dqalpha beta transform. The difference between the reference voltage of the DC side and the actual voltage of the DC side is inputted into the PI controller; Obtaining the actual current signal ig through abcalpha beta transformationfrom the sampled current of the power network side. The difference between the reference grid-connected current ig and the actual current signal ig in the alpha beta coordinate system after the dqalpha beta transformation is subjected to the alpha beta abc transformation, and then is fed into the composite controller together with the actual current signal ig and the reference grid-connected current ig. The signal processed by the composite controller is sent to the notch filter for processing, and then the processed signal is sent to the SVPWM module, so as to generate periodic switching signals for controlling the grid-connected photovoltaic inverter, thereby suppressing the harmonics of the grid-connected photovoltaic inverter into the power grid. The compensation effect of the invention is superior to the traditional photovoltaic grid-connected inverter.

A combined scheme of identification and torque control is provided for rotary hydraulic actuators. The composite controller consists of a dynamic feedback linearizing inner loop cascaded with a robust linear feedback outer loop. The proposed controller allows the actuator to generate desired torque irrespective of the actuator motion. In fact, the controller reduces significantly the impedance of the actuator as seen by its external load, making the system an ideal source of torque suitable for many robotics and automation applications. An identification method to extract the parameters of non-linear model of actuator dynamics and to estimate a bound for modeling uncertainty, used for synthesis of the outer optimal controller, is also presented. Results are illustrated experimentally on a pitch actuator of a Schilling industrial robot.

The invention relates to a low rotating speed high precision control method of a control moment gyro gimbal servo system. The method solves the problems of friction interference and a disturbing moment caused by unbalanced rotor vibration of the control moment gyro gimbal servo system in a low speed operation process. The method comprises the steps of establishing a control moment gyro gimbal servo system kinetic model containing the friction interference and an unbalanced rotor vibration interference moment, performing control design on a frame servo system current loop via vector control andPI (proportional-integral) control methods, designing an interference observer to estimate equivalent interference formed by the friction interference and the disturbing moment caused by the unbalanced rotor vibration at a frame servo system speed loop, allowing the interference observer to offset an equivalent interference estimated value via a feedforward channel and designing a composite controller. The method has the advantages of high engineering practicability, high interference immunity and the like.

The invention discloses a small-sized unmanned rotary-wing aircraft high-precision control method based on an adaptive neural network, and relates to the design of a composite controller with the combination of the construction and optimization of the feedback control and non-sample training adaptive neural network of a small-sized unmanned rotary-wing aircraft. Firstly, as for a small-sized unmanned rotary-wing aircraft dynamical model, a feedback control coefficient matrix is constructed through a pole assignment method to ensure the preliminary stability of a system. Secondly, the adaptive neural network with independent updating weight features is designed, an adaptive network weight updating matrix is constructed based on error messages to update a weight matrix of the neural network in an online mode, and estimation and restraint of disturbance are achieved. An adaptive threshold value optimizing strategy is designed, online updating is carried out on a control residual error upper limit threshold value of the adaptive neural network on the basis of the mean square error between the actual position and the expectation position in a time window, and the small-sized unmanned rotary-wing aircraft high-precision attitude control under the complex environment is achieved. The small-sized unmanned rotary-wing aircraft high-precision control method has the advantages of being good in real-time performance, fast in dynamic parameter response, strong in multi-source interference adaptability and the like, can be used for the high-precision control over the small-sized unmanned aircraft under the complex multi-source interference environment and the like.

The invention relates to a D-axis and A-axis current vector composite controller of a permanent-magnet synchronous motor. The D-axis and A-axis current vector composite controller is characterized by comprising a position sensor, a speed measurement feedback link, a counter potential feed-forward compensator, a rotational speed closed-loop controller, an A-axis current composite controller, a D-axis current composite controller and a vector converter. By the D-axis and A-axis current vector composite controller, decoupling composite control is separately carried out on i<d> and i<q> under a dq coordinate, the speed regulation range is wide, phase shift of a phase current closed-loop control structure caused by limited bandwidth of the controller is prevented, and the D-axis and A-axis current vector composite controller has favorable performance in all ranges of speed regulation; through the adoption of a composite controls structure with combination of feed-forward and feedback, the dynamic characteristic is improved, the feedback control gain is reduced, and the gain margin of the system is improved; feed-forward is designed on the basis of the dynamic characteristic of an object, and D-axis and A-axis current vector composite controller is clear in physical concept, simple in structure and stable in working, and is easy to be implemented; and meanwhile, feedback control is introduced, the control precision is improved, and an error caused by model inaccuracy and disturbance is overcome.

The invention discloses an advanced control method for direct-current boost converter system, applicable to high precision control of the direct-current boost converter system. The method adopts a current tracking mode based on extended state observers and a limit time control technology, and specifically includes the steps of: firstly, respectively observing disturbance of voltage change and resistive load by designing two extended state observers, based on the above, designing the limit time controller, and thereby obtaining a composite controller to control the direct-current boost converter system such that the direct-current boost converter system can quickly track target voltage with high precision under the presence of voltage change and resistive load disturbance. The method is simple to implement and relatively less in parameter adjustment, not only can improve the tracking speed of the direct-current boost converter system for reference signals, but also can effectively reduce steady-state wave motion of the power electronic direct-current boost converter and meet the application of high-performance power electronic direct-current boost converter systems.

A multi-transformer push-pull type photovoltaic inverter comprises a DSP, a DC / DC convertor, a DC / AC convertor and a filter, wherein the DC / DC convertor, the DC / AC convertor and the filter are sequentially connected, and a composite controller which is composed of a PI controller of the DC / AC convertor, an artificial neural network model and a feed-forward arithmetic unit is arranged in the DSP. The input end of the artificial neural network model is connected with the state variable of the DC / AC convertor in the kappath sampling period, a predicted value of the output voltage which is outputted by the artificial neural network model in the (kappa+1)th sampling period is connected with the negative input end of the feed-forward arithmetic unit, the positive input end of the feed-forward arithmetic unit is connected with a set value of voltage at the kappa moment, and an output signal of the feed-forward arithmetic unit is connected with an output signal of he PI controller and then controls the duty ratio of the DC / AC convertor. According to the multi-transformer push-pull type photovoltaic inverter, the output voltage of the inverter at the next moment is predicted through the neural network model, compensation for the duty ratio at the present moment is timely conducted through the feed-forward arithmetic unit, and therefore the hysteresis quality of the PI controller is overcome, and the robustness of the inverter system is improved.

The invention relates to a spacecraft attitude control method for a sensor under attack in a space confrontation environment. The method aims at attitude control for the spacecraft sensor under attackin a complex space environment. The method comprises the steps that first, a spacecraft attitude control system model with sensor attack and external environment interference is established; secondly, a disturbance observer is designed to estimate the external environment interference received by a system without considering the sensor attack; again, based on the external environment interferenceestimation value, an output filter and an unknown input learning observer are designed to estimate an attack signal in the sensor information; and finally, the attack signal estimation value and theexternal environment interference estimation value are combined to design a composite controller to construct the spacecraft attitude control method for the sensor under attack in the space confrontation environment. The method provided by the invention has the characteristics of high anti-interference, high reliability and high engineering practicability, and is suitable for high-precision andhigh-reliability control of the spacecraft attitude control system under the condition that the sensor information is attacked.

The invention provides a bi-axis inertially-stabilized platform high-precision control method based on a self-adaptive backstepping sliding mode, and relates to design of a composite controller for backstepping sliding mode control based on an auxiliary integral sliding mode surface and adaptive neural network construction and optimization. The method is characterized by, to begin with, designing a backstepping sliding mode control method based on the auxiliary integral sliding mode surface according to a bi-axis inertially-stabilized platform dynamical model, and generating a control command according to state error information to realize suppression of indeterminacy and interference of dynamical model parameters; and then, constructing an adaptive neural network, constructing an adaptive neural network weight updating matrix based on the error information to update a weight matrix of the neural network online, estimating upper bound of interference error in real time, and realizing bi-axis inertially-stabilized platform high-precision control under complex environment. The method has the advantages of good real-time performance, fast dynamic parameter response and high multisource interference adaptability and the like, and can used for high-precision control and the like under the complex multisource interference environment.

The invention discloses an active suspension support vector machine generalized compound inverse controller and a construction method thereof. The controller comprises an active suspension system, an optimal controller and a linear motor support vector machine generalized composite inverse controller. The construction method includes forming a compound control target by cascading a current inverter before a linear motor, forming a support vector machine inverse system by the support vector machine and two integration elements, and combining a linear controller with the support vector machine inverse system and the current inverter to form the support vector machine generalized compound inverse controller. A sensor of the active suspension system is used for extracting suspension vibration signals online, and the optional controller is used for calculating the optimal control force and the vibration velocity. The support vector machine compound inverse controller controls the linear motor to output corresponding electromagnetic force and velocity in real time according to the control force and the suspension vibration velocity given by the optimal controller and the electromagnetic thrust and velocity fed back by the linear motor, thereby realizing system linearization, decoupling and degree reduction while achieving good effect and real-time performance of the active suspension.

The invention discloses a method for realizing a feedback linearization double hysteresis composite controller of an active power filter, and the method comprises the following steps of: building a mathematical model which is connected with an active power filter system in parallel in a rotating coordinate system, calculating a reference value of a compensating current, decoupling the model into a pseudo-linear system, taking controlled variables of a main circuit switch function as input variables of the model, determining a reference voltage vector and an error current vector at the alternating current side of a main circuit as well as space regions at which the two vectors are located by virtue of the main circuit switch function, selecting a double hysteresis pulse width modulation method for an output voltage space vector to control the change rate of the error current vector, and adopting a DSP (digital signal processer) chip to realize the feedback linearization double hysteresis composite controller of the active power filter. By adopting the method disclosed by the invention, the problem of parameter coupling in a compensating current component in a system model is solved, thus a system can still rapidly respond under the condition that load parameters are disturbed or suddenly changed; meanwhile, the switching frequency of a main circuit inverter can be effectively reduced, and the switching loss can be reduced.

The invention discloses a system and method for controlling a unit power factor single-level AC-DC converter. The system comprises a composite controller, and the composite controller receives a secondary side direct current bus voltage and current signal and a secondary side direct current reference voltage and current signal of the single-level AC-DC isolation converter and converts the received voltages and the currents into an effective alternating current reference value. The effective alternating current reference value and the voltage value are calculated through a multiplying unit into a primary side current reference signal, and the primary side current reference signal, a primary side current signal, a primary side voltage signal and a secondary side voltage signal are input into a current controller. According to the system and method, both-way and single-level AC-DC or DC-AC isolation converting can be achieved, the system is conveniently used in battery charging / discharging or photovoltaic grid connection generating, the cascading modularization single-level isolation AC-DC conversion can be achieved, and the system serves as a power electronic transformer to be applied to high-voltage alternating current input application occasions.

The invention discloses a continuous sliding mode zero current sensor control method of a DC voltage reduction converter. The method is based on a voltage reduction average state model, the continuous sliding mode control theory and a limited time observer are utilized to design a composite continuous controller, a reference input voltage can be precisely tracked by the voltage reduction converter even under the condition of having no current sensor, system hardware cost is reduced, system fault tolerance is improved, moreover, interference of a converter system caused by parameter perturbation, input voltage fluctuation and load abrupt change can be further estimated through the limited time observer, and anti-interference capability of the system is improved. The reference voltage can be precisely tracked by the designed zero current sensor composite controller even when the DC voltage reduction converter is under the conditions of parameter perturbation, input voltage fluctuation and load abrupt change. The method is advantaged in that a sliding mode shivering phenomenon can be eliminated through the proposed composite controller, and a closed loop system is made to have an excellent response speed and anti-interference capability.

The invention provides an improved Smith estimator-based H-infinity control method of an aero engine, and belongs to the technical field of aero engine control and simulation. The improved Smith estimator-based H-infinity control method comprises the steps of building a reasonable small deviation linear model for an aero engine non-linear model, and selecting data of a state space model in a certain working condition as a controlled object designed by a controller; selecting an appropriate performance index weighting function parameter, solving an H-infinity output feedback controller, and adjusting the parameter to basically achieve control requirement; and designing an improved-structure Smith estimation compensator according to a closed-loop feedback control system designed according toan H-infinity control law so as to form a composite controller, additionally arranging a deviation correction controller, designed according to a PID control law, in the control system according to relatively large deviation between an estimation model and the parameter of the controlled object and a true model and the parameter, employing the deviation correction controller to stabilize the controlled object, making adaptability correction according to comparison between the controlled object and a model output signal so as to further improve robustness of the system.

The invention relates to a spacecraft anti-interference attitude control method in a condition of a damaged actuating mechanism. The method provides a spacecraft anti-interference attitude control system for conditions that a spacecraft actuating mechanism is physically attacked by an opponent in a space confrontation and a spacecraft platform has an external environment interference and a systemnon-modeling dynamic influence. The method includes: firstly, establishing a spacecraft attitude control system model in conditions of the damaged actuating mechanism, the external environment interference and the system non-modeling dynamic influence; then designing an interference observer, and estimating an equivalence interference caused by the external environment interference and the systemnon-modeling dynamics; designing a learning observer for an actuating mechanism failure fault, caused by an attack, of the actuating mechanism, and reconstructing the actuating mechanism fault; and finally designing a composite controller according to an equivalence interference estimate and actuating mechanism fault reconstruction information, and constructing the spacecraft anti-interference attitude control method in the condition of the damaged actuating mechanism. The method is applicable to high-precision and high-reliability control of the spacecraft attitude control system.

The invention discloses a compound control method of a photovoltaic grid-connected inverter. The compound control method comprises the steps of performing 3s / 2r transformation on input current and establishing a grid-connected inverter model under a d-q coordinate system; and utilizing a compound controller to control output current to eliminate even harmonic component disturbance in the output current, wherein the compound controller comprises a proportional plus integral (PI) controller and a repetitive controller which are connected in parallel. By means of the technical scheme that the 3s / 2r transformation is performed on the input current, and the compound controller composed of the PI controller and the repetitive controller which are connected in parallel is utilized to eliminate the even harmonic component disturbance in the output current, dynamic response of a system is increased, accuracy and stability are high, harmonic component disturbance can be controlled well, steady-state errors can be eliminated, and the grid-connected current control effect is good.

The invention discloses a positive- and negative-sequence combined control method for a three-phase PWM current transformer when a power grid is imbalanced. The combined control of positive-sequence and negative-sequence currents is realized in a positive-sequence dq synchronous rotating reference frame, the control system is simplified, and the normal and stable operation of the PWM current transformer is ensured when the voltage of the power grid is imbalanced. To solve the problem of separation of positive-sequence and negative-sequence vectors of the power grid voltage, a novel positive-sequence and negative-sequence vector separation method in the positive-sequence dq synchronous rotating reference frame is provided such that only a primary positive- and negative-sequence voltage extraction module is needed, and a positive- and negative-sequence extraction module is omitted. For the inner-loop control of current, a PI+R type composite controller method is provided, and a resonant frequency of a resonance controller is configured to be 2[omega], so that zero steady-state error control for the negative-sequence component in the dq synchronous rotating reference frame is realized. Besides, in order to increase the response speed of the control system, a voltage feedforward control method is adopted according an output voltage and current vector model of the PWM current transformer, so that the dynamic performance of the control system is improved.