Design And Implementation Of Position Sensorless PMSM Control System In The Low And Medium Speed

Position sensorless permanent magnet synchronous motor control system has been widely used in various types of products, but in the present control system there are lots of problems about instability in the range of low and medium speed. Factors affecting the speed stability include the start reliability, closed loop handover success rate, current loop and closed-loop transfer stability. Therefore, to solve the problem in speed stability is important for the application of permanent magnet synchronous motor.Based on this, new position sensorless permanent magnet synchronous motor control system in the low and medium speed has been designed in this thesis. For the speed stability problem, the traditional sensorless control algorithms are optimized to achieve a full-order state observer based on vector control algorithm. Three major improvements has been made, including:Firstly, to safeguard the reliability of start, pretargeting way has been adopted; Secondly, in order to improve the stability of the current loop and speed closed-loop, full-dimensional state observer algorithm has been improved; Thirdly, for the aim to improve the success rate of the closed-loop switching, the rotor position estimation algorithm is optimized using a phase locked loop instead of the traditional arctangent way. Improved algorithm is modeling and simulation in Matlab, and the feasibility of the algorithm is verified. Finally, the hardware and software of the improved control system is completed, then the present system is performed functional tests. The test results show that the designed control system starts reliably with no jitter; opening-loop can be smoothly switched to the closed loop with high stability; closed-loop speed is stabilized, and the motor can be operated within ± 5% of the predetermined range; Closed-loop current is stabilized, and the motor can be also operated within ± 15% of the predetermined range;This design of the control system can be directly applied to meet the requirements of the fan coil, the balance of the car, water pumps, washing machines, air conditioners and other applications. So this design has some practical value.