组合载荷作用下动车牵引电机转子系统弯扭耦合振动特性

Bending-torsional coupling vibration characteristics of EMU traction motor rotor system under combined loads

为了研究组合载荷作用下动车组用牵引电机转子弯扭振动机理和识别典型故障特征,依据动车牵引电机结构特点,将其转子结构离散化为集总质量盘轴系统,得到了电机转子系统的10自由度弯扭力学模型;考虑定转子静动气隙偏心引起的不平衡磁拉力、转子质量偏心引起的机械不平衡力、转子重力以及电机驱动转矩和负载转矩等径向和扭转载荷作用,利用拉格朗日方程法建立了牵引电机转子系统弯扭耦合运动微分方程;基于Runge-Kutta法求解和分析了不同组合载荷工况作用下的转子系统弯扭振动特性。分析结果表明:由转子质量偏心造成的系统弯扭自由度耦合关系,使得牵引电机转子系统的弯扭振动特性受到转子径向和扭转载荷的共同影响,且影响规律符合转子质量偏心耦合规律;在全部径向和扭转载荷作用下,牵引电机转子的径向振动包含零频、转频、二倍转频、弯振固有频率、二倍供电频、二倍供电频与转频组合、脉动转矩频率与转频组合等频率成分,其中转频成分对应的弯振幅值最大,而脉动转矩频率与转频的组合频率的振幅非常小,说明脉动转矩对牵引电机转子径向振动的贡献并不明显;在全部载荷作用下牵引电机转子的扭转振动包含转频、二倍转频、弯振固有频率与转频组合、二倍供电频与转频组合、脉动转矩频率等频率成分,其中脉动转矩频率成分对应的扭振幅值最大,其次由重力和不平衡磁拉力引起的转频成分对应的扭振幅值也较大,且基本具有同一数量级,表明它们对扭振的贡献均不能忽略。

To investigate the bending-torsional vibration mechanism of EMU traction motor rotor and identify their typical fault features under the action of combined loads, the rotor structure was lumped into a rigid-disk-massless-shaft system according to the actual structure configuration of EMU traction motor, and a bending-torsional mechanical model of motor rotor system with ten degrees of freedom was established. The differential equation of bending-torsional coupling motion of traction motor rotor system was built by using Lagrange’s equation method under the action of multiple radial and torsional loads, such as the unbalanced magnetic pull caused by the static and dynamic air-gap eccentricity, the mechanical unbalanced force caused by the mass eccentricity, the rotor gravity, the driving torque and the load torque of motor. The bending-torsional vibration characteristics of rotor system under different combined load cases were calculated and analyzed based on the Runge-Kutta method. Analysis result shows that the coupling relationship of bending and torsional degrees of freedom caused by the mass eccentricity of rotor makes the bending and torsional vibration characteristics of traction motor rotor system affected mutually by the radial and torsional loads of rotor, and the influence results conform to the law induced by the mass eccentricity coupling of rotor.Under the action of all radial and torsional loads, the radial vibration of traction motor rotor includes the frequency components such as the zero frequency, the rotation frequency, the double rotation frequency, the bending natural frequency, the double power frequency and its combinations with rotation frequency, the combination of pulsating torque frequency and rotation frequency, and so on, and among them the bending vibration amplitude corresponding to the rotation frequency component is the largest, while the vibration amplitude of the combination of pulsating torque frequency and rotation frequency is very small, which means that the contribution of pulsating torque to the radial vibration of traction motor rotor is not obvious. The torsional vibration of traction motor rotor under the action of all loads consists of the frequency components such as the rotation frequency, the double rotation frequency, the combination of bending natural frequency and rotation frequency, the combination of double power frequency and rotation frequency, and the pulsating torque frequency, and so on, and among them the torsional vibration amplitude corresponding to the pulsating torque frequency is the largest, and the torsional vibration amplitude corresponding to the rotation frequency caused by the gravity and unbalanced magnetic pull is also larger, and both them basically have the same order of magnitude, which means that their contributions to the torsional vibration cannot be ignored. 3 tabs, 6 figs, 30 refs.