The development process of an axial active magnetic bearing

The purpose of this paper is to motivate and inspire students to investigate and understand fundamental principles of electrical engineering such as magnetic levitation, control theory and sensor design. This paper describes the development process of an axial active magnetic bearing (AMB) system. The objective is to design, build, and control a magnetic levitation test bed. This test bed must be capable of levitating a 2 kg steel disc at a stable working distance of 3 mm and a maximum attraction distance of 6 mm. The levitation is accomplished by two electromagnets producing upward and downward attraction forces to support the steel disc. An inductive sensor measures the position of the steel disc and relays this to a PC based controller board (dSpace® controller). The control system uses this information to regulate the electromagnetic force on the steel disc. The intent is to construct this system using relatively low-cost, low-precision components and still be able to stably levitate the 2 kg steel disc with high-precision. The dSpace® software, Controldesk® will be used for data acquisition. In this paper an overview of the system design will be presented, followed by the axial AMB model design, inductive sensor design, actuating unit design and controller development and implementation. The paper ends with results obtained with the dSpace® controller and evaluation of the AMB system