Stabilization of Magnetic Suspension System by using First-Order-Reset Element without Derivative Feedback

The stabilization of a magnetic suspension system is achieved by using only a nonlinear integrator without other element. The proportional-derivative (PD) feedback is the simplest control method for the magnetic suspension system. The proportional element gives restoring force, and the derivative element gives damping to the system. However, the derivative feedback element needs to be carefully designed because unnecessary high-frequency signals generate an adverse effect. Meanwhile, installing a first-order-reset element (FORE) has been proposed to reduce the vibration. The element is a first-order low-pass filter (LPF) with reset functions. This paper proposes to stabilize a magnetic suspension system with a FORE only. However, the magnetic suspension system cannot be stabilized by the basic FORE. Therefore, the FORE is modified as to the reset conditions. A magnetic suspension system is stabilized by the modified FORE. The characteristics of the stabilized magnetic suspension system are studied experimentally.