Optimal Design And Flux-Weakening Control Of Interior Permanent Magnet Synchronous Motors

Interior Permanent Magnet Synchronous Motors (IPMSM) have been widely used in AC speed regulating system and traction applications for their merits such as small volume, reliability and the wide range of speed regulation. Based on the recent research on weak magnetic extender speed and the flux-weakening control strategy, the thesis takes the issue that flux-weakening control of PMSM is hard to realize as the research subject and discusses it from two aspects, its design and control strategy.Firstly, the thesis chooses IPMSM as the research object, which are more suitable for the flux-weakenking control. Based on the Clark and Park coordinate transformation principle and the mathematical model of PMSM, the vector control and space vector pulse width modulation technology are introduced, and the advantages and disadvantages of various stator current vector control strategies are analyzed in detail.Secondly, the thesis gives the optimal design and the size calculation of the IPMSM. From the view of increasing d-axis inductance, the electromagnetism design of IPMSM is done by using the Finite Element Analysis (FEA) software Ansoft. Some parameters are selected to analyze the effect on flux-weakening performance, such as slots shape of stator, structure of windings, air gap and structure of permanent magnet. A further analysis is to study the air gap flux density harmonic of the IPMSM and its cogging torque by using the simulated annealing algorithm. The electrical parameters of the designed IPMSM are given in the end.Thirdly, the two-dimension model of IPMSM is analyzed under static state and dynamic state in Maxwell2D. This paper analyzes the precise inductance computation of IPMSM with a new method, by analyzing the line of magnetic force, induced voltage, current and torque curve in transient field, the field results prove the rationality of the model and reflects the validity of the FEA method.Finally, considering the effect of the motor parameters on PI parameters with the speed increasing, the current controller completes decoupling control by the feedback compensation method in this paper. In order to improve the dynamic performance of the flux-weakening control, PID algorithm of alteration in rate and fuzzy self-adaptive PI controller of flux-weakening control loop is designed to replace the conventional PI controller. Both of the two methods can enhance the dynamic response speed and reduce the overshoot of flux-weakening control system, which have been validated by the simulation of this thesis. Furthermore, the dynamic performance of PID algorithm of alteration in rate is much more evident.