Research On Bidirectional Digital Power Amplifier Of Active Magnetic Bearings

This thesis is about the research on bidirectional digital power amplifier of active magneticbearings, which is applied to new current biased magnetic bearings and permanent magnetic biasedmagnetic bearings. A way of establishing the closed-loop system model of the bidirectional poweramplifier was presented based on the period average method. From this transfer function we can tellthat the system is a second order system with a zero point which is depended on the PI parameters.The expression of the system’s step response is derivated and simulated to evaluate the influence ofthe parameters.In terms of the hardware and software, it proposes the improved IGBT drive circuit to restrainthe current and voltage surge in the previous version involved. And a combination of anti-integralsaturation and integral separation algorithms is introduced to improve the dynamic performance. Thetwo level of overflow protection plan can afford reliable protection. According to the result of test, thepower amplifier has a good static and dynamic performance.The experiments using this digital power amplifier on current biased magnetic bearing andpermanent magnetic biased magnetic bearing have been carried out.Both of the test-beds haveachieved static suspension and the displacement of rotor in each degree of freedom is less than9μm.