| 1 | PMSM Vector Control Optimization Based on Fractional PI^(λ) of Rotational Speed Outer Loop of Dragonfly Algorithm显示文摘Aiming at the problems of slow dynamic response and weak robustness of integer-order proportional integral(PI)controller in double closed loop vector control system of permanent magnet synchronous motor(PMSM),a method of combining dragonfly algorithm with fractional order PI control is proposed for off-line parameter tuning for the outer loop of speed of the system.The parameter to be optimized is used as the spatial position of the optimal individual searching for food sources in the search space,and the error performance index integrated time and absolute error(ITAE)is used as its target fitness function.The motor speed regulation performances of traditional engineering experience setting integer order PI,particle swarm optimization algorithm tuning fractional order PI and dragonfly algorithm tuning fractional order PI are compared,respectively.Results show that the fractional order PI controller optimized by dragonfly algorithm can improve the dynamic response performance of the system,reduce overshoot and enhance robustness,which proves the feasibility and superiority of the optimization strategy. | ZENG Guohui FU Xiuwei LIU Jin HUANG Bo DU Tao ZHU Xiangchen | 2021 | Wuhan University Journal of Natural Sciences2021，26，5： | 3 |
| 3 | High quality crystal growth and characterization of ferroelectric Ba_(0.77)Ca_(0.23)TiO_(3) single crystal显示文摘Ba_(0.77)Ca_(0.23)TiO_(3)(BCT)single crystal has been widely studied as a promising lead-free ferroelectric material.In this work,high-quality BCT crystal was successfully grown by the Czochralski(CZ)method.The as-grown crystal is crack-free and shows black coloration.It possesses a high dielectric stability over a wide temperature range,while the dielectric loss is rather small below 90℃.Furthermore,it possesses excellent ferroelectric properties with residual polarization strength(Pr)and coercive field(Ec)of 17.93μC/cm^(2) and 8.47 kV/cm,respectively.Besides,BCT crystal shows large electromechanical coupling factors,with kt,k31,k33 and k15 of 0.535,0.254,0.714 and 0.721,respectively.The piezoelectric coefficients d31,d33 and d15 are measured to be−36.5,130 and 246 pC/N,respectively. | Lei Liu Fangyi Yin Guiyuan Zhao Limei Zheng Xiuwei Fu Zhitai Jia Xutang Tao | 2023 | Journal of Advanced Dielectrics2023，13，2： | 0 |
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