基于改进自适应陷波器的电磁轴承支承转子自动平衡控制

Automatic balance control of a rotor supported by magnetic bearings based on an improved adaptive notch filter

针对转速信息未知情况下的电磁轴承支承转子不平衡振动抑制问题,提出一种基于改进自适应陷波器(adaptive notch filter,ANF)的自动平衡控制算法。首先,对传统ANF的结构和工作原理进行分析,讨论了相关控制参数的选取原则,并针对电磁轴承闭环系统嵌入ANF导致的低转速区失稳,设计了最优相位补偿器,在保证全转速范围稳定的情况下进一步优化陷波性能;然后,根据相位补偿ANF输入输出信号之间的相位关系,设计了转速估器,通过变增益和归一化处理,不仅平衡了算法收敛速度和估计精度之间的矛盾,同时保证了各转速下的收敛特性一致;最后,通过仿真分析和试验研究对提出的算法进行验证。结果表明,设计的算法能对未知的转子转速进行快速准确的估计,从而消除控制电流和电磁力中的转速同频分量,大幅抑制传递到基座上的振动力。该方法简化了轴承结构、降低了生产成本、实现了无转速传感器的自动平衡控制,在工业磁轴承领域有很好的应用前景。

An automatic balance control algorithm based on an improved adaptive notch filter(ANF)was proposed to suppress the unbalance vibration of a rotor supported by active magnetic bearings without the information of the rotation speed.Firstly,the structure and principle of the typical ANF were introduced,and the method to select the control parameters was discussed.In order to solve the instability problem of the system in low-speed range which was caused by the embedded ANF in the closed-loop system of the magnetic bearings,an optimal phase compensator was presented and the performance of the ANF was improved further while keeping the stability of the whole system in the full speed range.Then,a rotor speed estimator was designed according to the phase relationship between the input and output signals of the ANF.The contradiction between the convergence speed and the estimation accuracy was balanced through normalization of parameters of the estimator and the variable gain algorithm.The convergence property of the estimator was consistent at different rotation speeds.Finally,the proposed method was verified by simulation and experiments.Results show that the speed estimator can quickly and accurately estimate the rotor speed from the displacement signals of the rotor,and the ANF can effectively eliminate the synchronous components in the control currents and the bearing forces.This method can realize the automatic balance control without a speed sensor.It not only simplifies the bearing structure but also reduce the cost of the system,and has a good prospect in the industrial application of magnetic bearings.