Research On Position Detection And Drive System For Active Magnetic Suspension Pushing Bearing

Active magnetic suspension bearing which use controlled magnetic force is a high-performance bearing, there is no contact between stator and rotor, it has characteristics of frictionless, pollution-free, low cost, low noise and long-life, it has been used widely in all kinds of high-tech fields. This thesis does research on position detection and drive system for active magnetic suspension pushing bearing, it contains displacement sensor and hybrid power amplifier. The main work has been divided into several parts as follow:First, It introduces the whole structure and axial,radial structure of active magnetic suspension bearing and their operating principle. Based on model of electrical magnetic force of axial magnetic bearing and motion equations, the mathematic model of axial single-degree-of-freedom of magnetic bearing was deduced. Position detection and drive system for active magnetic suspension pushing bearing will be discussed in this thesis.Then, According to the structure characteristic of active magnetic suspension push bearing, a novel differential transformer displacement sensor is designed. It can measure axial displacement of rotor in radial direction. Establish equivalent circuit and the mathematic model of sensor and rotor, then calculation to the circuit and simulation analysis to this model separately in the way of magnetic circuit and with engineering electrical magnetic field finite element analysis software Ansoft. The results indicate that the output voltage of sensor is in proportion to axial displacement of rotor, and this sensor has characteristics of high linearity and sensitivity and low cost. Because this axial displacement sensor is set in the frame of radial sensor, the structure of all magnetic bearing system will be more simply.It also provided the structure and control strategy of a novel hybrid power amplifier, it can regulate the supply voltage of linearity power amplifier with lopper and keep the collector voltage of transistor constant. Simulation results indicate that this novel hybrid power amplifier not only has characteristics of small current ripples of linearity power amplifier and quick dynamic response, and under the same dynamic response, its power loss is smaller than linearity power amplifier largely.At last, give a conclusion to the whole thesis and take a view to the future.