LQG Control of an Active Magnetic Bearing with a Special Method to Consider the Gyroscopic Effect

It could be very difficult to find an acceptable feedback path for coupled differential equations like a FIVE degree of freedom (DOF) AMB system. This paper describes a linear quadratic Gaussian (LQG) approach on this problem. Due to the time variant gyroscopic part of the AMB system equation the controller could only be optimized for a specific angular velocity. For this reason a time variant state feedback is developed and added to the LQG controller in a way that the system is nearly equal for all angular velocities. The feedback matrix which is the result of the LQG problem uses all feedback terms. Compared to a decentralized controller which only uses the diagonal terms, the LQG method also uses the cross feedback terms which are able to provide instability. After developing the LQG method was compared to a decentralized PID controller.