Liu Daming

The Optimization-Sliding Mode Control For Three-Phase Three-Wire DSP-based Active Power Filter

Based on the time-domain analysis, a time-domain mathematical model of three-phase three-wire active power filter (APF) current control loop is established; Predictive control equation and its optimal feasible solution with minimum objective function value are gotten, and the sliding-mode control strategy of current control loop is deduced. A novel optimization-sliding mode control strategy is proposed, with this control strategy the current tracking error can be reduced quickly and the chattering can be reduced effectively. The control performance under the proposed control strategy is analyzed. The proposed control strategy can improve current tracking speed and accuracy, provide both robustness response and a good dynamic response of the current tracking control, and has the characteristics of simple computation and easy application. The simulation and experiment results show its validity and feasibility

Uniform magnetic field under rectangle coil system based on differential evolution algorithm

The uniform magnetic fields are correlated with the region relative to coil systems, the arrangement of coils, the dimensions of coil systems and the number of ampere-turns. It has been the very considerable difficulty encountered in the past in attempting the numerical solution of the equations involved, especially a region under coil systems. The paper considers the uniform degree of magnetic field of the region given as the objective function and uses differential evolution algorithm to search the position for arranging coil systems, the dimensions of coil systems and the number of ampere-turns to make the objective function reach the optimum. The result shows that the problem of uniform magnetic fields produced by rectangle coil systems can be solved effectively with differential evolution algorithm.

Study on the Modeling of Ship Induced Magnetic Field

A novel model on the calculating of ship induced magnetic field with hybrid finite element-boundary element method of double scalar potentials is presented. The full scalar potential and linearity element are adopted in ferromagnetic region. Reduced scalar potential and hybrid element mesh are adopted on the boundary surface. The coupling relationship between variables on the interface and the formulas to computing element coefficients are deduced. The degenerate transforms combination is used in deeling with singular boundary integrals. An equivalent magnetic model is proposed to compute ship mockups induced magnetic field. The three dimensional model of the ship mockup was drawn and meshed. Through the hysteresis during the magnetization of ship ferromagnet, it is pointed out that the induced magnetic field will be a bit high with the slope of basic magnetization curve as the permeability of the material. Based on that, the equivalent permeability of the material was calibrated through the curve of average relative error-relative permeability. The results of ship model experiment testify that the calculating model have good applicability to the calculating of ships induced magnetic field.