| Compared with other Motors, Permanent Magnet Synchronous Motor(PMSM) has no much redundant device, so it has strong and simple structure. The PMSM has many advantages, such as high power factor, high power density, high efficiency, low consumption, and small structure. The PMSM can meet the requirement of high performance control system, meanwhile it has gradually become the first choice of the energy saving. The PMSMs have been widely applied to the electric car, robot, aerospace and other control fields. In order to get accurateinformation of rotor position and speed, sensors and photoelectric encoder need to be installed. However this increases the motor volume and the cost of the system. Meanwhile it can reduce the stability and accuracy of the motor. Another disadvantage is that its internal parameters or external load mutation also limit the application of permanent magnet synchronous motor. So many scholars begin to research the sensorless PMSM based on disturbance compensation. And using the method of vector control and direct torque control can achieve the speed and rotor position estimation. Besides it has good robustness to the changing of parameters.In this paper, there were three different strategies to be used to study the position control for sensorless PMSM. These were the robust adaptive control method, expansion observer control method and model reference adaptive controlmethod. These methods can achieve better precision and stability of the system. The main work is explained as follows:Firstly, by reading lots of related literature on PMSM control, the research purpose and the prospects for development had been analyzed. On the basis of reading, the mathematical modeling of PMSM had been established. And it was simulated in Matlab. By this method, the principle of vector control and the principle of coordinate transformation had been studied as well.Secondly, the robust adaptive control method was applied to implement sensorless position control of PMSM. The mathematical model of PMSM contained six unknown parameters, where output current and voltage constituted the measurements of the system. The control law was designed to make the system linearized, while the adaptive law was proposed to achieve the speed tracing under internal and external unknown parameter disturbance. Furthermore, stability and convergence analysis of the closed-loop control were given based on the Lyapunov stability theory. Simulation results verified the asymptotic convergence of the robust adaptive speed controller.Thirdly, theexpansion observer control method was applied to implement sensorless position control of PMSM. In this method, the signals of speed and position can be obtained from counter electromotive force. So it canachieve the goal of no sensor position control.Meanwhile, this controller can achieve real-time feedback compensations to dynamic compensations of various parameterschanges, which caused by some external and internal interferences. Stability and convergence analysis of the closed-loop control are given based on the Lyapunov stability theory. Simulation results verify the asymptotic convergence of the expansion observer controller.Fourthly, the model reference adaptive controlmethod was applied to implement sensorless position control of PMSM. In this method, the current's estimated values and errors were the input values. Using POPOV stability theorem, a proper adaptive rate was designed to estimate speed signals effectively. Meanwhile, considering the change of resistances when the motor run, it was necessary to estimateresistancesreal-timely ensure the system performance and the stabilityin the process of motor running caused by the changes of the resistances.Matlab simulation's results showed that this method was effective and feasible.Finally, these three control methods were summed up and compared with each other. The existing research deficiencies in this paper were analyzed and the corresponding solving ideas were put forward. |
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