Abstract: The stability of electromagnetic bearing system (EMBS) is an important problem which has to be solved before sending it into application. There are a lot of factors which make the system unstable, but, the electronic controller is a key factor. A method to analysis the relation with Routh method based on a conventional PID regulator is mentioned and the margin of the parameters is presented, meanwhile, the margin of the parameters liminated by the bandwind of the controller loop is disccussed also.

Key words: Control, EMBS, Parameter, PID regulator, Stability