A four-leg Matrix converter is built based on conventional Matrix converter. It is required to provide a path for the zero-sequence load current when the added midline bridge connects the neutral point of load. In thi...
详细信息
ISBN:
(纸本)9781467371896
A four-leg Matrix converter is built based on conventional Matrix converter. It is required to provide a path for the zero-sequence load current when the added midline bridge connects the neutral point of load. In this paper, a model predictive control method for a four-leg matrix converter under unbalanced load condition is described. The predictive control method is based on the optimal selection among the valid switching states of the converter by evaluating a cost function. Compared with the conventional method, the predictive control method is simple to implement without coordination transformation and duty ratio calculation. To support the theoretical analysis, the feasibility and reliability of the proposed method are verified by simulation results.
In a study, researchers consider trajectory generation as an optimal control problem, allowing the direct incorporation of performance metrics and state–control constraints. In particular, they present a rapid feasib...
详细信息
In a study, researchers consider trajectory generation as an optimal control problem, allowing the direct incorporation of performance metrics and state–control constraints. In particular, they present a rapid feasible trajectory generation approach for fixed-wing UAVs in which the trajectory is defined as a function of points x, y, and z in three-dimensional (3D) space and velocity v. The definition of a feasible trajectory with four optimization parameters leads to a faster solution time than for the original optimal control problem with more than four optimization parameters. A similar idea appears where a semi-analytical method for generating an initial guess was proposed for aircraft landing trajectory generation in the absence of obstacles. In contrast, they consider the scenario of flying from a start point to a goal point in the presence of stationary and moving obstacles, with the goal of staying close to a reference flight path.
Because of the large domestic civil aircraft projects started in China a decade ago, there is a greater need to control the accuracy of the Mach number in aerodynamic tests, especially near the designed cruise point o...
详细信息
Because of the large domestic civil aircraft projects started in China a decade ago, there is a greater need to control the accuracy of the Mach number in aerodynamic tests, especially near the designed cruise point of large commercial aircraft. Nowadays the control accuracy of China Aerodynamics Research and Development Center 2.4-meter transonic wind tunnel Mach number is in the range of +/- 0.002 to +/- 0.003 when M <= 0.9, which is far from the measurement accuracy of drag coefficient required for testing advanced aircraft. This value should result in a better-than-one drag count. As a consequence, it is imperative to improve the control accuracy of Mach number urgently. The nonlinearity, large time delays, and strong coupling of wind tunnel flowfield control, along with the variation of the model angle of attack, could cause the Mach number to deviate from the expected value. To solve these problems, a model predictive control method based on dynamic matrix control algorithm is proposed. This method builds a prediction model based on step response test. The accuracy of Mach number predictivecontrol can be efficiently improved by performance optimization in the form of vector norms, rolling optimization, and feed-forward compensation. This control strategy has been successfully tested in the wind tunnel, and the control accuracy of Mach number has been remarkably enhanced, to the point where it can be controlled to within +/- 0.0015. This value satisfies the requirements of aerodynamic aircraft testing.
暂无评论