A Nonlinear Switching Control Method for Magnetic Bearing Systems - Minimizing the Power Consumption -

In this paper, a nonlinear switching control method is proposed for a magnetic bearing system which has a strong nonlinearity in the magnetic actuator. The main purpose is to use minimal electrical power to achieve good response. By focusing on the structure of this system, it is found that the rotor part of the system can be stabilized by a virtual magnetic force first, which is given by a linear feedback. Then, the minimal currents necessary for the realization of this magnetic force is determined. As a result, it is discovered that the minimal currents are given by a set of switching rules. After that, the electromagnetic part is stabilized by using either backstepping method or high-gain feedback. The control input obtained is simpler compared with other related approaches, and the response of the rotor can be assigned directly. No bias current is used. Finally, numerical simulations are implemented and the numerical simulations show that this method is extremely effective.