实心磁路磁轴承的分数阶系统辨识

Fractional-order System Identification of a Solid-core Active Magnetic Bearing

由于受涡流效应的影响,实心磁路磁轴承(solid-coreactive magnetic bearing,AMB)系统表现出分数阶特性,用传统磁路模型进行描述存在较大误差。以往磁轴承的辨识多集中在对整数阶模型中参数的辨识,对未知模型结构的分数阶模型辨识很少涉及。为了辨识出实心磁轴承的精确分数阶模型,在等比例分数阶模型基础上推导了一般形式分数阶模型辨识的加权最小二乘算法;提出了模型结构的确定原则、步骤及获取最优模型的误差准则,并对一台实心同极磁轴承进行了闭环频域辨识。结果表明,辨识的分数阶模型与实际系统误差很小,可为设计高性能控制器提供有价值的参考。

Due to the eddy current effect,a solid-core active magnetic bearing（AMB） will show some fractional order characteristics and the traditional magnetic equivalent circuit model has significant amounts of error when predicting the actual system.The past AMB identification mostly focuses on the estimation of parameters in integer model and rarely involves the fractional model of unknown model structure.For the latter identification,a weighted least-squares method was derived for the general fractional model based on the widely studied commensurate-order fractional model.Moreover,the principles and procedures for determining the model structure and the error criteria for deriving the optimal model were proposed.Finally,the closed-loop frequency domain identification was carried out for a solid-core homopolar AMB.The final results show that the identified fractional model is very close to actual system and could provide a valuable reference for designing high-performance controllers.