| The Hybrid Magnetic Bearing (HMB) has the advantages such as low power consumption, small weight and volume since it uses permanent magnets to create the bias magnetic By using the HMB, the machines’speed and the power density can get increased, which will help them to be more competitive in the aeronautics, astronautics and the manufacturing applications with the requirement of high speed drive. This dissertation focuses on the basic research of the HMB system in the high-speed motor, including the design and optimization of the HMB parameters, digital control strategies for the control system and the switching power amplifier system.This dissertation proposed a new design method for HMB’s parameters, which was based on the iteration of the leakage and magnetoresistance coefficient. By using the finite element and analytic method, the leakage and the magnetoresistance coefficients can be obtained through the iteration, which can improve the precision of the parameter design and optimization. Using this method, a 3-DOF HMB was designed and the corresponding FEA software was used to verify the design result. Moreover, a 5-DOF HMB prototype was also built, and the experimental result has proved that the system can realize the 30000 r/min stable suspension. The effectiveness of this method got proved by both the simulation and the experiments.This dissertation studies the H∞ and the improved H∞ control in 5-DOF HMB The H∞ control was designed using the rules of the weighting function derived by the singular value graph. The simulation and experimental results have shown that H∞ controllor has advantages than traditional PID controller in terms of system stability and disturbance rejection. In the conventional H∞ control design, the order of the controller is much higher than that of the plant, making it difficult for engineering applications. To solve this problem, this dissertation designed a simple structure-specified magnetic bearings controller with low order for the high-speed magnetic levitation motor by using the approximation characteristics of BP neural network function. The controller was applied in a high-speed magnetic levitation motor platform, and the experimental results have verified that the starting, stable and dynamic levitation and the anti-disturbance character of this system was improved.This dissertation proposed One-cycle control (OCC) digital control strategy for the current-mode full-bridge switching power amplifiers. The mathematical models of OOC in unipolar and bipolar modes were established respectively so that the design of OCC for switching power amplifiers was realized, and the simulation results validated this method’s feasibility and validity A prototype was built and the control strategy under the two models was conducted, the experimental results showed that the system with the OCC method get the acceptable features.In order to reduce the cost and make it easier for application, this dissertation used the five-phase six legs switching power amplifier as the power circuit. The traditional current control algorithm in the multi-leg switching power amplifier was complicated since different phase currents were coupled. To address this problem, a novel control strategy based on OCC was proposed, which can enforce the average current of each phase be equal to the reference in each control cycle. This method that set the duty cycle of the neutral leg as a constant has the advantages such as quick dynamic response, easy control and decoupling of the phase currents. Taking a five-phase six-leg switching power amplifier for example, the high speed system using the magnetic bearing was constructed to test this method. Both the simulation and experimental results have demonstrated the simplicity and the effectiveness of this method. |
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