电动桥式起重机负载升降过程的系统动力学模拟

从系统的角度考虑电动桥式起重机起升机构工作过程中的动力学模拟问题。首先,由系统的拉格朗日函数、约束条件和电机的磁共能定义修正的拉格朗日函数;随后,应用Hamilton原理和三相感应电机瞬态模型得出起升机构工作过程中电动桥式起重机系统的运动方程。为验证模型的效果,本文还进行了转子串电阻速度控制系统控制下的32t电动桥式起重机吊运额定负载下降过程的数值模拟,分析了高速浮动轴扭转刚度以及制动过程中转子电阻的配置方案对系统动力响应的影响。模拟结果表明,制动过程中起升机构高速浮动轴所受载荷远大于起动过程中所受载荷,制动开始时在电机转子电路中增加一级较大的外串电阻有利于减小下降制动阶段系统中的动载。

Simulation of system dynamics of electric cranes during operation of lifting mechanism

The dynamics of electric overhead cranes during the lowering operation of the lifting mechanism were studied in a systematic view.By means of the transient model of the three-phase induction motor controlled by a speed control system and Hamilton's principal with a modified Lagrangian which consists of the ordinary Lagrangian and constraints of the crane system,and magnetic co-energy of the motor in the lifting mechanism,the equations of motion of the electric overhead cranes during the operation of the lifting mechanism were derived.The numerical simulations of the normal process for lowering a rated payload of an electric overhead crane of 32t are presented.The effects of the torsional stiffness of the floating shaft in the high-speed link of the lifting mechanism and rotor resistance of the driving motor on dynamic responses of system are discussed.It is seen that the peak load acting on the high-speed link of lifting mechanism during braking is much greater than that when starting during a normal lowering operation for a rated payload and a bigger rotor resistance at the start of the braking process is favorable to decrease the dynamic loads applied to the electric overhead crane during braking.