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In order to improve the dynamic performance of three-phase voltage type PWM rectifiers predictive direct capacitor power control, in view of the deficiencies of slow response and poor dynamic performance of present PI control of load disturbance, the fractional order PID controller of the DC side voltage control section is introduced to the capacitive power control. The new predictive direct power capacitor control strategy has been proposed. It consists of two parts: the outer loop of voltage square model of fractional order PID and the inner loop of capacitor power and the reactive power in network side. Through decoupling control with the prediction control of the inner loop and the voltage outer loop of fractional PID, the dynamic performance of a direct power control has been improved. The Matlab/Simulink simulation results prove that the system has better dynamic performance, robustness and response speed of direct power control.

Proportion, integration and differential gain of nonlinear PID Controller is nonlinear function of controlling error. This paper performed the non-linear PID controller parameter optimization of vertical take-off and landing stage for tilt rotor aircraft using the genetic algorithm. Dual loop control is used. Inner loop is angular velocity loop. Outer loop is angular position loop. According to the features of stability control of vertical take-off and landing stage of tilt rotor aircraft, system ascend time, steady error, and weighted overshoot are chosen as objective function of optimization. Simulation results show that controller designed by the present method can meet the requirement of control.

PID control (fuzzy control) is one of the earliest and most widely used control laws in process control applications. It can obtain satisfactory control results for most industrial objects. People use PID control (or PI, PD control) in a variety of controllers in frequency control system. However, with the rapid development of modern large-scale industry, and the degree of automation is getting higher and higher, the scope of applications in frequency control technology has been continuously expanding, while it has wider and deeper requirements for the performance of speed control system. AC drive system has uncertain factors, such as the existing parameter variability, load disturbance, nonlinear and strong coupling in under controlled AC motors, they will seriously affect the performance of speed control system. The traditional PID control seems a little powerless. The fuzzy control is a nonlinear control in essence, it can significantly improve the robustness of the system comparing to linear PI controller, and it can more effectively overcome various nonlinear factors in transmission system. For a multi-loop speed control system, the outer loop is the fundamental factor in determining the system performance. Inner loop is mainly for changing object properties in order to facilitate the controlling actions of the outer loop. The sampling frequency of inner loop is lower than the one in outer loop, which is facilitating for the realization of intelligent control.

The primary goal of this research is the development of software system about functional gradient material process by laser. The system can be divided into several modules such as STL file loading and viewing, model slicing, filling path planning and process controlling. Path planning of FGM area is one key technology of system development because of one path must contain material information of functional gradient material. The material information planning methods of one-dimension and two-dimension functional gradient material were described respectively in this article. The material information of one-dimension FGM changes by layer along Z-axis, and the material information of two-dimension FGM changes by path in X-Y plane, especially, there is different change direction of FGM between inner loop and outer loop.

Grid-connected inverter topologies and control methods are analyzed and compared on the basis of two non-isolated PV grid-connected inverter circuit topology as 3kVA grid connected PV systems. In this paper, the current control method, the DC bus voltage outer grid current inner loop of the dual closed-loop PI control method. Sampled signal through the system circuit for processing, resulting in a SPWM drive signal to control the conduction of the power devices off the grid current control.

The flow field of the traditional inner loop biological fluidized bed reactor (ILBFBR) and a new biological fluidized bed reactor set ring-type baffle was calculated by computational fluid dynamics. The results show that the gas holdup of drop zone in ILBFBR set the ring-type baffle can increase significantly, the flow rate of drop zone in ILBFBR with the ring-type baffle is faster than that in traditional ILBFBR, and turbulence intensity distributed more evenly all in rising zone and drop zone in ILBFBR set the ring-type baffle than that in traditional ILBFBR, but static pressure difference of ILBFBR set ring-type baffle is higher than that of the traditional ILBFBR.

A novel double-loop control approach for reducing excess torque of the servo loading system based on disturbance observer is proposed.The mathematical model of the loading system is established by mechanism theory and the reasons causing the excess torque are analyzed, the nominal model and disturbance weighting function are determined based on an approximate method. Dis-turbance observer based the inner loop controller is designed by H ∞ mixed sensitivity method and the external-loop controller is designed as the classical PID contro ller. Both the simulation and experi-ments results show that disturbance observer is feasible and effectiv e to eliminate the excess torque, accuracy of the loading system is improved.

This paper presents modeling and dual-loop control of a non-linear hydraulic actuator applied on the quadruped robot. The pure position control of the actuator is hard to achieve because it’s a three-order system. So we propose the dual-loop control method to decompose it. The controller structure of the system is composed of two loops namely outer position control loop and inner force control loop. Outer loop controller is used to calculate the optimum target force to reject the errors of the position control, while, the inner loop controller is used to keep the actual force close to this desired force.

According to the aircraft control load power model, using electric power servo loading approach in designing the aircraft simulator electric control loading system, introduced a control loading system works as well as excess power causes. According to the direct driving torque control servo motor applied characteristics of double by force, and the compensation of hybrid control strategy. Using force is the inner loop, current loop using. At the same time as manipulate load system, we can adopt " Structure invariability principle " compensation strategies that speed compensation measures to abate force to influence on the performance of the control system. Experiment measures to eliminate that speed compensation system of plus torque, and good results have been achieved. Simulation results show that, using the hybrid control strategy can effectively eliminate the surplus torque control steady-state error, tracking precision, to force the requirements for the construction, performance control principle prototype system load provides data parameters and the control strategy.

According to characteristics of unidirectional flow of energy in permanent magnet wind power system, the paper proposes a two-quadrant three-level converter topology. Combined with method of the optimum tip speed ratio for tracking the maximum wind energy, the generator-side converter uses the double closed-loop control, speed outer loop and stator current inner loop control, whose control objective is to track the given generator speed. Grid-side converter uses the direct power control strategy based on virtual flux-linkage orientation. On the basis of MATLAB simulation platform, the permanent magnet wind power system simulation model was established. The simulation results show that the grid- and generator-side converter can operate with unity power factor, furthermore, verifies that the proposed converter structure is feasible.

This paper summarizes the defects of both OPA model and its improved models and then proposes a new model in order to simulate real power system roundly. There is an inner loop based on DC power flow optimization to minimize the change in generation or load shed and an outer loop based on the risk theory. In the outer loop, whether to improve the line capacity and how to improve are determined by risk index of line improvement (RILI) and line improvement degree function, respectively. A new prevention strategy against cascading failure is proposed by identifying the high-risk lines and determining optimal RILI which minimize line improvement cost and load loss. In the end, simulation based on 39-bus New England System reveals that new model is closer to real power system than the original one by comparing outage probability and load loss between the two models, and risk-based assessment interval and line improvement delay play important roles in prevention against power system outages, and improvement based on risk assessment can reduce outage probability to varying degrees, which illustrates the practical significance of optimal RILI.

The converters connected to the power grid, including rectifier and inverter. The rectifier uses DC voltage outer loop control method and the input current inner loop control method, three-phase inverter output current uses SPWM modulation. With the capacity of the system increasing, the capacity of a single converter can no longer meet the requirements, for improving the system's power grid, reliability and efficiency, converters can be paralleled. Parallel operation generates loop current; one of the effective methods of suppressing the loop current is to connect limiting inductance in the inverter AC side. Through simulation, gets the suitable inductance value, and researches the dead zone time affecting on the loop current. When the dead zone times of two modules are not equal, the loop current increases.

The design of Digital Double Close-loop DC Speed Regulation System which we introduce in this article is based on the numeric control scheme, and using ATMega8 as the main controller, also with PI arithmetic, so as to construct a double close-loop DC Speed Regulation System with inner loop of current feedback and outer loop of speed feedback. The approach of motor speed regulation is through the voltage regulation. Experimental results show that the system has robustness, fast and good tracking performance.

A new improved multidiscipline feasible (MDF) strategy based on the updating approximate function constructed by Response Surface Method (RSM) is firstly pointed out and denoted as MDF-update-RSM which involves double cycles. Before the start of inner loop on MDF-update-RSM strategy, the approximate function is initialized by RSM on a set of sampling points which are generated from the Design of Experiment (DOE). With the process of outer loop, the coefficients and one high-order term of polynomial are updated and upgrade by the Least Square Regression. The ability of this new strategy promotes the efficiency and saves huge calculational cost incurred by the MDF strategy which always runs on the multidisciplinary analysis (MDA). The MDF-update-RSM is good procedure to ameliorate the accuracy that has been tested by the Rosenbrock function in this paper. Finally, the optimization strategy is employed on executing the low pressure turbine shrouded blade design and provides a true optimal result compared to the classical MDF strategy.

PWM inverter, as the main part of wind power grid-connected system, directly determines the quality of the power sent finally to grid. It has become the focus of research to develop a high-performance inverter control system. Based on the analysis and establishment of the mathematical model of the grid inverter system, the vector control strategy based on the voltage directional technique is analyzed in this paper. It consists of two closed loops. The fluctuation of direct voltage is suppressed due to the existence of voltage outer loop. Current inner loop realizes the independent control over meritorious electric current and reactive current through the feedforward of grid voltage and the decoupling of grid-connected current, which makes the inverter power factor close to 1.

The first of all, the multidisciplinary modeling and analyzing for the electric power steering system (EPS) is made. The design method based on the model is proposed and the EPS control system is analyzed. On the basis of deeply observing and studying S/T singular value curves, a robust control algorithm of back-calculation is put forward. After analyzing the deficiency in the single-loop control structure of the EPS, the dual-loop control structure of the EPS is developed. The inner loop controller is designed using the single neuron PID algorithm, and the new robust control algorithm is proposed to design the outer loop controller. The simulation results in the frequency-domain S/T curves of the EPS system and the hand force step input of the steering wheel show that the designed controller is simple and effective, and has good robust stability and robust performance.

That the dynamic model is characteristic of nonlinearity and that linear equation design approach based on small perturbations of linear system has failed to meet the design requirements cause the study of the dynamic inversion control. Integrating the dynamic inversion theory and the UAV nonlinear mathematical model, the paper, in accordance with the speed of status variable change, has designed respectively the UAV inner-loop fast variable and outer-loop slow variable controllers and thus, found the dynamic inversion flight control law applicable to UAV and conducted the simulation study. A conclusion can be drawn that the control law is satisfactory in flight control.