Outer-loop Control Scheme Research Articles

M3C outer loop control strategy based on variable universe fuzzy PI control

M3C outer loop control strategy based on variable universe fuzzy PI control

Research on the Control Method of Micro-gas Turbine Power Supply Modulation System for Primary Energy in Electromagnetic Launch Technology

Combining the advantages of micro-gas turbine generation system (MTGS) and power converters, moreover, comparing the various design ideas for the primary energy of electromagnetic launch technology, we design a primary energy to meet the reliability, stability, safety and portable of electromagnetic launch technology. We discuss the control ideas and methods to be adopted in this system, the first step is to output a stable DC bus voltage through rectification, and then to step up the voltage through a series resonant converter to achieve the desired output voltage. Through theoretical analysis and simulation, it reveals the effect of this load on the performance of MTGS, and the parameter optimization design is combined with the voltage outer loop control strategy to achieve the purpose of outputting stable voltage. We used a ARM controller to implement the control of this system to measure the response curve of the system under different input commands. According to the theoretical analysis, numerical simulation and experimental results, the control strategy designed in this paper can better meet the performance index requirements of micro-gas turbine engine (MTE) and power converter as well as the control method is simple and easy to implement in engineering. The results of this paper confirm the feasibility of this primary energy application for electromagnetic launch technology.

Research on the simulation of SVG for online de-icing on distribution lines

The distribution network connects with families, more branch circuit breakers, more and more users rely on power in winter, which requires higher and higher reliability requirements for power supply. The power supply department is facing greater pressure to stop distribution line for de-icing. In view of the above reasons, this paper first briefly introduces several measures of de-icing without power failure, and selects the technical route of injecting reactive power at the end of the line for online de-icing; secondly, it introduces the principle of SVG device generating reactive power, which uses reactive power to generate heat loss in the distribution network line for on-line de-icing, and then proposes an improved reactive power outer loop control strategy to make it equivalent to current source De-icing device; Finally, a simulation model is built in PSCAD. Taking a 5km ACSR (LGJ-120) line with 5.4Mvar reactive power injected at the end of the line as an example, it can be seen that the line current reaches more than 500A due to the injected reactive power. The simulation results prove the effectiveness of the method. Considering its economy, it provides a feasible way for the distribution network with important loads Electric deicing scheme.

Trajectory Tracking of Underactuated VTOL Aerial Vehicles With Unknown System Parameters Via IRL

This article studies the optimal control policy learning for underactuated vertical take-off and landing (VTOL) aerial vehicles subject to the unknown mass and inertia matrix. A novel off-policy integral reinforcement learning (IRL) scheme is presented for simultaneously unknown parameter identification and optimal trajectory tracking. In the outer loop of the VTOL vehicles, a novel off-policy IRL scheme is proposed, where the fixed control policy for data generation is chosen to be different from the iterated control policy and the feedforward term with an unknown mass can be learned along with the optimal control policy. In the inner loop, a hybrid off-policy IRL algorithm is developed to tackle the optimal attitude control policy learning and inertia matrix identification under the hybrid control scheme introduced by the employed inner–outer loop control strategy. A simulation study is finally provided to demonstrate the effectiveness of the proposed algorithm.

PV Panel to PV Panel Transfer Method for Modular Differential Power Processing

This article proposes a realization of the photovoltaic (PV) panel to PV panel (P2P) method for the modular differential power processing (mDPP). The approach is modular and permits panels to be added to or removed from either series strings or paralleled connections. A voltage inner loop and power outer loop control strategy tracks the individual maximum power point of the PV panel, as well as converts only the differential power. The proposed method decouples the control loop performance of each PV module, making design simple. Simulation results validate the plug and play function for scalable PV system and MPPT accuracy. Hardware prototype is also built, and both indoor and outdoor experiments are provided to exhibit the advantage of this P2P method. Drawbacks and limitations are also discussed.

Continuous Control Set Model Predictive Control for Three-Level Flying Capacitor Boost Converter With Constant Switching Frequency

In this article, two continuous control set model predictive control (CCS-MPC) methods with one-step prediction horizon for three-level flying capacitor boost converter (FCBC) that can provide constant switching frequency are presented. The first one is explicit model predictive control (EMPC), which can provide explicit solution. In order to further reduce the complexity and the computational burden of EMPC while meeting the control requirements, a simple model predictive control (SMPC) is proposed as the second CCS-MPC method. The proposed CCS-MPC will be used as the inner-loop controller to control the inductor current and flying capacitor (FC) voltage. Besides, a suitable outer-loop control strategy for the output voltage is proposed to provide a suitable inductor current reference to improve the dynamic response of the output voltage while avoiding overcurrent. Compared with the previous control method for three-level FCBC, the proposed control method has good dynamic performance and stronger ability to resist input voltage disturbance. The effectiveness of the proposed method is verified by simulation and experimental results.

A three-level support method for smooth switching of the micro-grid operation model

Smooth switching of micro-grid between the grid-connected operation mode and off-grid operation mode is one of the key technologies to ensure it runs flexible and efficiently. The basic control strategy and the switching principle of micro-grid are analyzed in this paper. The reasons for the fluctuations of the voltage and the frequency in the switching process are analyzed from views of power balance and control strategy, and the operation mode switching strategy has been improved targeted. From the three aspects of controller’s current inner loop reference signal, voltage outer loop control strategy optimization and micro-grid energy balance management, a three-level security strategy for smooth switching of micro-grid operation mode is proposed. From the three aspects of controller’s current inner loop reference signal tracking, voltage outer loop control strategy optimization and micro-grid energy balance management, a three-level strategy for smooth switching of micro-grid operation mode is proposed. At last, it is proved by simulation that the proposed control strategy can make the switching process smooth and stable, the fluctuation problem of the voltage and frequency has been effectively improved.

A Robust Inner and Outer Loop Control Method for Trajectory Tracking of a Quadrotor.

In order to achieve the complicated trajectory tracking of quadrotor, a geometric inner and outer loop control scheme is presented. The outer loop generates the desired rotation matrix for the inner loop. To improve the response speed and robustness, a geometric SMC controller is designed for the inner loop. The outer loop is also designed via sliding mode control (SMC). By Lyapunov theory and cascade theory, the closed-loop system stability is guaranteed. Next, the tracking performance is validated by tracking three representative trajectories. Then, the robustness of the proposed control method is illustrated by trajectory tracking in presence of model uncertainty and disturbances. Subsequently, experiments are carried out to verify the method. In the experiment, ultra wideband (UWB) is used for indoor positioning. Extended Kalman Filter (EKF) is used for fusing inertial measurement unit (IMU) and UWB measurements. The experimental results show the feasibility of the designed controller in practice. The comparative experiments with PD and PD loop demonstrate the robustness of the proposed control method.

Guidance and nonlinear control system for autonomous flight of minirotorcraft unmanned aerial vehicles

AbstractSmall unmanned aerial vehicles (UAVs) are becoming popular among researchers and vital platforms for several autonomous mission systems. In this paper, we present the design and development of a miniature autonomous rotorcraft weighing less than 700 g and capable of waypoint navigation, trajectory tracking, visual navigation, precise hovering, and automatic takeoff and landing. In an effort to make advanced autonomous behaviors available to mini‐ and microrotorcraft, an embedded and inexpensive autopilot was developed. To compensate for the weaknesses of the low‐cost equipment, we put our efforts into designing a reliable model‐based nonlinear controller that uses an inner‐loop outer‐loop control scheme. The developed flight controller considers the system's nonlinearities, guarantees the stability of the closed‐loop system, and results in a practical controller that is easy to implement and to tune. In addition to controller design and stability analysis, the paper provides information about the overall control architecture and the UAV system integration, including guidance laws, navigation algorithms, control system implementation, and autopilot hardware. The guidance, navigation, and control (GN&C) algorithms were implemented on a miniature quadrotor UAV that has undergone an extensive program of flight tests, resulting in various flight behaviors under autonomous control from takeoff to landing. Experimental results that demonstrate the operation of the GN&C algorithms and the capabilities of our autonomous micro air vehicle are presented. © 2009 Wiley Periodicals, Inc.

Asymptotic Stability of Hierarchical Inner-Outer Loop-Based Flight Controllers

In this paper, we present a hierarchical controller for autonomous aerial vehicles control and navigation. For autonomous rotorcraft flight, it is common to separate the flight control problem into an inner loop that controls attitude and an outer loop that controls the translational trajectory of the rotorcraft. The resulted nonlinear controller is thus, easy to implement and to tune. Although satisfactory results have been reported in the literature and various navigational tasks have been achieved using this hierarchical control technique, this control scheme suffers from the lack of the stability proof and analysis of the closed-loop system. Here, we propose a 3D flight controller which is based on the inner- and outer-loop control scheme, and we prove the asymptotic stability property for the connected closed-loop system.

Optimum Multivariable Wind Tunnel System Control

The control of multivariable system models following input set point and load disturbance changes is considered. An inner and outer loop control strategy is proposed, for analysis purposes, enabling targeted recovery rates, off-set attenuation and constrained steady state interaction to be achieved. Proportional control and passive network compensation alone are employed. Gain ratio selection, ensuring energy efficient confinement of output perturbations, following low frequency load disturbances and reference input changes, is exercised. Disturbance suppression and transient recovery rate adjustment, via outer loop feedback advancement, is advocated. An application study is presented for purposes of illustration, confirming the theoretical predictions thereby.

Lagrangian Modeling and Passivity-Based Control of Three-Phase AC/DC Voltage-Source Converters

In this paper, we investigate the dc-bus voltage regulation problem for a three-phase boost-type pulsewidth-modulated (PWM) ac/dc converter using passivity-based control theory of Euler-Lagrange (EL) systems. The three-phase PWM ac/dc converters modeled in the a-b-c reference frame are first shown to be EL systems whose EL parameters are explicitly identified. The energy-dissipative properties of this model are fully retained under the d-q-axis transformation. Based on the transformed d-q EL model, passivity-based controllers are then synthesized using the techniques of energy shaping and damping injection. Two possible passivity-based feedback designs are discussed, leading to a feasible dynamic current-loop controller. Motivated from the usual power electronics control schemes and the study of Lee, the internal dc-bus voltage dynamics are regulated via an outer loop proportional plus integral (PI) controller cascaded to the d-axis current loop. Nonlinear PI control results of Desoer and Lin are applied to theoretically validate the proposed outer loop control scheme. The PWM ac/dc converter controlled by the proposed passivity-based current control scheme with outer loop PI compensation has the features of enhanced robustness under model uncertainties, decoupled current-loop dynamics, guaranteed zero steady-state error, and asymptotic rejection of constant load disturbance. Experimental results on a 1.5-kVA PC-based controlled prototype provide verification of these salient features. The experimental responses of a classical linear PI scheme are also included for comparative study.

Input-output linearization and zero-dynamics control of three-phase AC/DC voltage-source converters

Nonlinear differential-geometric techniques are proposed for the design of a feedback controller for three-phase voltage-source pulsewidth modulation (PWM) AC/DC boost converters under a cascade control structure. The input-output linearizability of the system modeled in d-q synchronous reference frames is examined. The results lead to a decoupled d-q current control scheme. For the internal DC-bus voltage dynamics (zero dynamics), by considering the d-axis current command as control input and using a square transform on DC-bus voltage, it is shown that this remaining system contains an input memoryless nonlinearity of conic sector type and satisfies the conditions for a Lur'e plant. This suggests a new outer-loop control strategy to control the square of the DC output voltage, rather than DC output voltage itself, utilizing a simple proportional plus integral (PI) controller cascaded to the d-axis current loop. Since most results do not consider the control of zero dynamics, the strategy for the control of zero dynamics via cascade control structure may provide valuable insight for the design of input-output linearized systems in which zero dynamics contain some desired control variables. The absolute tracking concept for Lur'e plants is introduced to prove the global tracking capability with zero steady-state error of the voltage loop. The controlled PWM AC/DC converter has the features of global stability, fast (exponential) tracking of DC-bus voltage command with zero steady-state error, asymptotic rejection of load disturbance, robustness against parameter uncertainties and decoupled dynamical responses between d and q current loops. Also, measurement of load current is not required. All these features are confirmed via laboratory experiments on a 1.5 kVA PC-based controlled prototype.