Precise Digital Control of Active Magnetic Bearings

This book presents a step by step approach in developing a test rig for the acoustic noise study of induction machines using Active Magnetic Bearings (AMB). The possibility of developing a DSP based digital control system for this purpose is presented. The AMB system is initially modeled using first principles using manufacturer data. Controller designs are carried out first at simulation level. Successful implementation of the digital controller opens up several opportunities for further research. One of them is the model validation using system identification tests. Under this, the mathematically developed AMB model is validated in time domain and frequency domain by conducting system identification experiments. Periodic disturbances occur in the position feedback signals, when the motor is rotated. An adaptive periodic disturbance cancellation method is employed to overcome this problem. This further improves the performance of complete control strategy. As such, the modeling and control strategies used in this book can be used as the basis for anybody entering into the area of AMB.