The Research On Dricet Torque Field Weaking Control Of Synchronous Reluctance Motor

Synchronous Reluctance Motor has a long history,but its development has been limited due to the limitations of power inverter technology at that time.With the continuous development of power electronics technology and the need of energy economy,synchronous reluctance motors have attracted increasing attention due to their special rotor structure,which has the advantages of easy speed increase and low loss.They are used in high-speed machine tools and locomotives.Synchronous reluctance motors has no permanent magnets on the rotor,which makes it easy to run at high speeds.However,at high speeds,they are susceptible to saturation of the magnetic circuit and the inductance parameters change,which affects the stable operation of the system.Direct torque control technology is simple and reliable,and it is widely used in the field of AC speed control.In this thesis,a series of research work on the direct torque control of synchronous reluctance motor has been conducted.Firstly,the internal structure and basic operation principle of the synchronous reluctance motor is analyzes.Then the mathematical model of the synchronous reluctance motor in different coordinate systems is analyzed,and the mathematical model of the motor considering magnetic saturation is researched.Based on the research of the direct torque control of the interior permanent magnet synchronous motor,the direct torque control system of the synchronous reluctance motor is established,which is compared with the vector control by the simulation.Secondly,the operating state of the synchronous reluctance motor in the full speed range is analyzed.Using the appropriate control strategy,a direct torque field weakening control system of synchronous reluctance motor considering magnetic saturation is designed and verified by simulation.We find that the torque ripple is too large.To solve this problem,the main cause of torque ripple is analyzed.The ripple is reduced by using the optimal method to calculate the duty cycle.The method is verifies by the simulation.There are two problems in the field weakening zone: the utilization of the DC bus voltage is too low,and the electromagnetic torque limit value depends on the motor parameters.To solve these two problems,the stator flux adaptive control and torque limit adaptive control system is designed in this thesis.And the correctness of the system is verified through simulation.Finally,a direct torque-weakening control hardware platform for synchronous reluctance motor is set up with DSP28335 as the control core,and the designed control system was verified experimentally.The results show that the direct torque field weakening control system of the synchronous reluctance motor runs stably.