Applied Mechanics and Materials Vols. 668-669

Abstract: The impacts of grid voltage on grid current in distributed generation grid-connected inverters are analyzed, and a control strategy that can compensate harmonics and suppress DC bias is proposed. In comparison with traditional PR controller, the proposed PRI controller with an additional integral part obtains a higher gain in low frequency, and the controller has an apparent effort especially for suppressing DC bias. Finally the PRI controller is verified in a 50KW. The experimental results show that the PRI controller not only can reduce harmonics of grid current in the steady state but also can suppress DC bias rapidly in a dynamic process. The PRI controller is suitable for DGs since they typically contain low order harmonics which caused by nonlinear l three-level inverter loads.

Abstract: This paper achieved the realization to apply a hybrid fuzzy control algorithm to control the rotorcraft, which can it fly stably, load heavy things, carry easily and complete complex flight movements. The operation show that control system is effective and valuable.

Abstract: According to the flexibility relationships of the 3-RRR compliant parallel micromotion platform along the X, Y direction and the rotation around the Z axis, using the Taguchi Design and Monte Carlo Simulation methods, considering the strong robustness of the flexibility in X direction and the existence of errors of the flexible hinge geometrical sizes, the flexibility iterative optimization for the compliance of the micromotion platform along the translation in Y-direction and the rotation around the Z axis are carried out respectively, the best geometry sizes of flexible hinge are find out, which provides a new solution of robust optimization design with multiple response problems of compliant mechanism consider uncertainty disturbance situation. Finally the correctness and validity of the method are verified with an example.

Abstract: In this paper, the state space model of neutral point clamped three-level grid-connected inverter is detailed derived and an Robust Predictive Control (RPC) method is proposed. In the proposed method, the total 27 switching vectors composed of a finite set from which the optimal switching vector is selected according to a cost function. The robust performance is improved just by increasing switching frequency. Experimental results show that the proposed method has a flexible control purposes and we can optimize the synthesize performance just by adjusting weighting coefficients of cost function. In addition, RPC controller has a robust performance in tracking output reference current and balancing neutral point voltage.

Abstract: Vibration suppression of the launcher is an important way to improve the firing accuracy of Multiple Launch Rocket System (MLRS). In order to get a better control result from the course that pulse control mechanism generates pulses to restrain the vibration of MLRS launcher, this paper analyzed the process that pulse thruster control the vibration of launcher under the modulation of pulse width and pulse frequency (PWPF) modulator. And the simulation model of the control system is established through the SIMULINK software in MATLAB. Under repeated modifications of the structural parameters of PWPF modulator, the influence laws of these parameters are found out, and the best structure parameter values are obtained. The final simulation result shows that the vibration in the pitch and lateral direction is greatly reduced. It is a big help to improve the firing accuracy of MLRS.

Abstract: Under three-phase grid asymmetric fault conditions, use traditional PI controller of PV inverters to inject symmetric current positive sequence into the grid, ignoring the impact of the negative sequence current on LVRT, thus traditional PI controller does not apply to three-phase grid asymmetric faults. The paper proposes the decoupling dual synchronous current controller to reject positive, negative sequence current into the grid simultaneously and adopt positive and negative sequence flexible control to determine the active current reference and reactive current reference, avoiding the various drawbacks such as power control, totally positive sequence control bringing. Experiment verify the science and feasibility that decoupling dual synchronous current controller applies to asymmetric faults riding-through.

Abstract: This design makes the anemometer verification automatic and realizes the management of equipment information through the establishment of wind tunnel laboratory automatic verification software system. It integrates fan control device owned by the apparatus, data acquisition system and equipment information management to achieve the goal that we can record or select the information of inspected instruments, standard devices and verified data, and make data acquisition and calculation automatic by using the software platform. The system also has the function of generating verification log sheet automatically. The establishment of the system can reduce the error prone by manual operation of verification staff and enhance working efficiency thereby improving the efficiency and quality of the anemometer verification work.

Abstract: According to the contradiction between the large stroke and high precision of positioning mechanism, in order to solve the high precision positioning problem of large stroke motion system in precision machining and precision measurement fields, the macro-micro positioning mechanism based on electrohydraulic-piezoelectric hybrid servo was presented with the advantages of the electrohydraulic servo driven and the piezoelectric precision driven. Its combined simulation model based on AMESim and MATLAB/Simulink software was built. On this basis, its fuzzy PID control simulation research was done. The simulation results showed that compared with traditional PID, the positioning mechanism static and dynamic performance could be improved by using the fuzzy control method. This will provide control theoretical basis for practical engineering applications.

Abstract: An improved cooperative method to control a nonlinear uncertain system is raised in this paper. First, the optimal control law is introduced to attain the desired dynamics of the linear part of original system. Then, a nonlinear PI controller is used to remove the influence of uncertain unit. It is proved by simulation that this method is effective to control this special system and is easy to be carried in applications.

Abstract: To realize maneuvering target terminal effective intercept and control, at the expense of the miss distance function, using pursuit-evasion differential game strategy analyze the effective intercept conditions of bilateral optimization strategy. Select different parameters to simulate the interception effect, the comparison shows that the method is not subject to specific target maneuver values, which can minimize the flexible of the potential role.