Improvements of the integration of active magnetic bearings Norbert Skricka, Richard Markert * Department of Applied Mechanics, Darmstadt University of Technology, Hochschulstrasse 1, D-64289 Darmstadt, Germany Abstract Functional and structural integration are tools to improve active magnetic bearing systems. In this paper two aspects of the integration of electromagnetic bearings are presented: (1) The non-linearity of the magnetic force is compensated by software integrated in the digital con- troller. (2) In self-sensing bearings the rotor position is identified from the electric state variables directly at the power amplifiers. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Magnetic bearings; Compensation; Non-linearity; Non-linear control; Self-sensing magnetic bearing; Integration 1. Introduction Today, most active magnetic bearing systems (AMB) are assembled of separate components (controller, power amplifiers, electromagnets, sensors, signal condi- tioning). This has some inherent disadvantages like high sensitiveness, high main- tenance expenditure, expensive production and limited capacity, which considerably hinder a general acceptance and greater dissemination. These disadvantages of conventional magnetic bearing systems can be reduced significantly with the aim of functional and structural integration. Integrated magnetic bearing systems include also improved and completely new functions that could not realize before as well as the realization of a compact, reliable and low-priced unit. A first type of integration is the structural or hardware integration as described in [3]. As an example the rotor position is identified by integrating the sensing system into the actuator using a micro computer. Mechatronics 12 (2002) 1059–1068 * Corresponding author. Tel.: +49-6151-162785; fax: +49-6151-164125. E-mail address: markert@mechanik.tu-darmstadt.de (R. Markert). 0957-4158/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0957-4158(02)00013-2