Embedded controller for a fully suspended active magnetic bearing system

Abstract

The industrial application of active magnetic bearings is expanding. This expansion is a driving force in the integration of AMBs. The Magnetic Bearing Modelling and Control (MBMC) research group in the School of Electrical, Electronic and Computer Engineering, North-West University is accordingly compelled to expand their research to the application of embedded control systems. The aim of this study is to develop an embedded controller for an active magnetic bearing in order to establish a DSP platform for future research in embedded control systems. The embedded controller developed during this study is required to be capable of actively controlling a spindle with a rotational speed of 60 000 rpm. It is further required that the embedded controller is capable of stand-alone operation, scalable in terms of the number of axes controlled and flexible in terms of the control algorithm implementation. A TMS320F2812 DSP is selected for its processing speed, on-chip peripherals and available development tools such as the eZdsp® TMS320F2812 DSP Starter Kit, VisSim® Embedded Controls Developer and Code Composer Studio®. The interface of the embedded controller is designed for an existing double radial AMB model, which allows for the performance of the embedded controller to be compared to the existing PC-based controller. The AMB system exhibits a slightly higher second order equivalent stiffness and damping when using the embedded controller as opposed to the existing PC-based controller. The AMB system is also slightly less sensitive when using the embedded controller. This embedded controller establishes a DSP platform which can be used for further research into embedded control systems and advanced control algorithms. The knowledge gained and controller developed for this study serves as essential stepping stones towards the ultimate goal of AMB integration through the progression from a DSP to an FPGA and eventually an ASIC.