磁悬浮高速电机转子非线性低频振动机理研究

Mechanism of nonlinearity low frequency oscillation for active magnetic bearing-rotor systems

本文针对磁悬浮电机高速旋转时转子出现低频振动的现象开展研究。文中建立了磁悬浮控制系统各环节的非线性模型,分析了电磁力、开关功率放大器、电流输出限幅等非线性因素导致低频振动的机理,并在此基础上,基于描述函数及扩展奈奎斯特判据方法分析了含有非线性环节的磁悬浮系统稳定性。文中建立了基于Matlab的仿真模型,并研制了100 kW磁悬浮高速永磁电机样机,通过仿真与试验对提出的结论进行了验证,结果表明当磁悬浮电机高速旋转时,除同频振动外,转子确实产生了与转速无关的低频振动,该低频振动与系统中的非线性因素有关,其中电流饱和与限幅是导致该低频振动的主要原因,所得结论能够为磁悬浮技术在高速电机中的应用提供理论依据。

Mechanism of nonlinearity low frequency oscillation for active magnetic bearing-rotor systems at high speed is investigated.Firstly,the nonlinear models of the electromagnetic force,power amplifier and amplitude limiter were built,and the relevance of low frequency oscillation was analyzed.Then the stability of the AMBs control system were studied based on the extended nyquist stability criterion.For verification,the experiments regarding to low frequency oscillation were carried out with a 100 kW high-speed magnetic levitation PMSM.The results show that the rotor produces low frequency oscillation independent of the speed,and the nonlinear saturated exciting current due of the amplitude limiter is the major factor of the low frequency oscillation of the AMBs.