电流驱动和电压驱动下实心磁路磁轴承的系统辨识

System Identification of Solid-core Active Magnetic Bearings Under Current Drive and Voltage Drive

与叠片结构的磁轴承相比,实心磁路磁轴承除了能简化工艺外,还能保证结构强度,但实心材料中会有明显的涡流。用等效磁路法建立磁轴承模型时忽略了涡流的影响,导致理论模型和实际系统之间有较大的误差。为了获取磁轴承的精确模型,该文对一个实心磁路主动磁轴承在电流驱动和电压驱动下都做了系统辨识。磁轴承的理论模型在电流驱动下是二阶的,在电压驱动下是三阶的,但辨识结果是两者都需要用一个三阶模型来描述。涡流改变了电流驱动下模型的阶次,却只修正了电压驱动下模型的系数,说明电压驱动下建立的数学模型能更好地描述实际系统。

Compared with laminated active magnetic bearings（AMB）, the solid-core AMB can simplify mechanical process as well as guarantee the strength of the structure, but eddy currents are evident in solid-core materials. The effect of the eddy currents is omitted when setting up the model of an AMB using the equivalent magnetic circuit method, leading to a significant error between the theoretical model and the real system. In order to obtain the accurate model of a solid-core AMB, system identification is carried out under both current drive and voltage drive. The theoretical model of an AMB is a second-order model under current drive while a third-order one under voltage drive, but the result of identification shows that a third-order model is required to describe the real system under both drives. The eddy currents change the order of the model under current drive while they only modify the parameters of the model under voltage drive. The conclusion is that the theoretical model based on voltage drive can describe the real system better.