Diagnostics of Magnetic Bearings via Identification of Its Physical Parameters

Identification of physical parameters of unstable system is an important problem, for example in the design of its diagnostic system. In the diagnostics, there are usually observed trends in physical parameters changes. An identification method of the state-space model resulting from the physics laws is presented in the paper. The method is a modification of the OKID method [3] and it works exactly in the case when the sum of the input number and output number equals to the dimension of the state vector. The existing estimator is replaced by the deadbeat state observer, and the ARX model of the observer/controller is computed. This model is used to obtain the physical state-space model of the open-loop system for voltage controlled magnetic bearing.