The finite element dynamic model for integrated structures containing distributed piezoelectric sensors and actuators ( S/As ) is formulated with a new piezoelectric plate bending element in this paper. The problem of...The finite element dynamic model for integrated structures containing distributed piezoelectric sensors and actuators ( S/As ) is formulated with a new piezoelectric plate bending element in this paper. The problem of active vibration control and suppression of integrated structures is investigated under constant gain negative velocity feedback control law. A general method for active vibration control and suppression of integrated structures is presented. Finally, numerical example is given to illustrate the validity of the method proposed in this paper.展开更多
Based on the Theodorsen’s Theory of the aerodynamic forces on wing-aileron, the Scanlan’s Theory is expanded considering a deck-flap system. It is suggested that a new forced vibration method can acquire aerodynamic...Based on the Theodorsen’s Theory of the aerodynamic forces on wing-aileron, the Scanlan’s Theory is expanded considering a deck-flap system. It is suggested that a new forced vibration method can acquire aerodynamic derivatives of this deck-flap system theoretically. After obtaining the wind induced forces, a deck-flap equation of motion in time domain is established to investigate its control law. Numerical simulation results indicate suboptimal control law of the deck-flap system can suppress the flutter effectively, and the flutter speed can be increased for desirable purpose.展开更多
A flux linkage compensation field oriented control (FOC) method was proposed to suppress the speed and torque ripples of a brushless wound-field synchronous motor in its starting process. The starting process was anal...A flux linkage compensation field oriented control (FOC) method was proposed to suppress the speed and torque ripples of a brushless wound-field synchronous motor in its starting process. The starting process was analyzed and the model of wound-field synchronous electric machine was established. The change of field current of the electric machine was described mathematically for simplified exciter and rotate rectifier. Based on the traditional field control, the flux linkage compensation was introduced in d-axis current to counteract the flux ripple. Some simulation and preliminary experiments were implemented. The results show that the proposed method is feasible and effective.展开更多
电网换相换流器型高压直流输电(line commutated converter-based high voltage direct current,LCC-HVDC)系统若发生后续换相失败,将严重影响交直流混联电网的安全稳定运行。文中首先针对LCC-HVDC系统故障恢复过程中电流偏差控制作用...电网换相换流器型高压直流输电(line commutated converter-based high voltage direct current,LCC-HVDC)系统若发生后续换相失败,将严重影响交直流混联电网的安全稳定运行。文中首先针对LCC-HVDC系统故障恢复过程中电流偏差控制作用阶段易再次发生换相失败的问题,对电流偏差控制参数与换相失败之间的关系进行理论分析,发现此阶段系统若不发生换相失败,逆变侧LCC直流电压和交流换相电压须满足一定的约束关系,且该约束关系受电流偏差控制参数的直接影响。然后,基于理论分析结果,提出一种电流偏差控制参数整定方法,可改善系统故障恢复过程中对直流电压恢复速度和程度的控制要求,使系统更易满足直流电压与交流换相电压稳定运行约束关系,以降低后续换相失败概率。最后,利用PSCAD/EMTDC仿真平台CIGRE标准测试模型验证了理论分析的正确性以及参数整定方法的有效性。展开更多
文摘The finite element dynamic model for integrated structures containing distributed piezoelectric sensors and actuators ( S/As ) is formulated with a new piezoelectric plate bending element in this paper. The problem of active vibration control and suppression of integrated structures is investigated under constant gain negative velocity feedback control law. A general method for active vibration control and suppression of integrated structures is presented. Finally, numerical example is given to illustrate the validity of the method proposed in this paper.
文摘Based on the Theodorsen’s Theory of the aerodynamic forces on wing-aileron, the Scanlan’s Theory is expanded considering a deck-flap system. It is suggested that a new forced vibration method can acquire aerodynamic derivatives of this deck-flap system theoretically. After obtaining the wind induced forces, a deck-flap equation of motion in time domain is established to investigate its control law. Numerical simulation results indicate suboptimal control law of the deck-flap system can suppress the flutter effectively, and the flutter speed can be increased for desirable purpose.
基金Sponsored by the NSFC General Project (51177135)the Key Project of Natural Science Foundation of Shaanxi Province (2011GZ013)
文摘A flux linkage compensation field oriented control (FOC) method was proposed to suppress the speed and torque ripples of a brushless wound-field synchronous motor in its starting process. The starting process was analyzed and the model of wound-field synchronous electric machine was established. The change of field current of the electric machine was described mathematically for simplified exciter and rotate rectifier. Based on the traditional field control, the flux linkage compensation was introduced in d-axis current to counteract the flux ripple. Some simulation and preliminary experiments were implemented. The results show that the proposed method is feasible and effective.
文摘电网换相换流器型高压直流输电(line commutated converter-based high voltage direct current,LCC-HVDC)系统若发生后续换相失败,将严重影响交直流混联电网的安全稳定运行。文中首先针对LCC-HVDC系统故障恢复过程中电流偏差控制作用阶段易再次发生换相失败的问题,对电流偏差控制参数与换相失败之间的关系进行理论分析,发现此阶段系统若不发生换相失败,逆变侧LCC直流电压和交流换相电压须满足一定的约束关系,且该约束关系受电流偏差控制参数的直接影响。然后,基于理论分析结果,提出一种电流偏差控制参数整定方法,可改善系统故障恢复过程中对直流电压恢复速度和程度的控制要求,使系统更易满足直流电压与交流换相电压稳定运行约束关系,以降低后续换相失败概率。最后,利用PSCAD/EMTDC仿真平台CIGRE标准测试模型验证了理论分析的正确性以及参数整定方法的有效性。
