Research On DTC Strategy For PMSM

Permanent magnet synchronous motors(PMSM)compared with other types of motors has the advantages of high efficiency small volume,low noise,high power density and is widely used in industrial production and intellectual control field.In the field of motor control,direct torque control(DTC)has the advantages of short response time,low sensitivity to parameter perturbation,simple and reliable structure and so on.It is a hot research topic in the field of motor drive control technology.In this paper,the related research results of DTC are deeply analyzed,and the design problems of PMSM DTC system of sensorless are studied by combining the higher order sliding mode(HOSM)and the simulation analysis and the result discussion are also carried out.Firstly,in this paper,we model the permanent magnet synchronous motor in rotating two-phase coordinate system,static two-phase coordinate system and static three-phase coordinate system,and then we give a brief overview of the principle of direct torque control of the motor.Secondly,direct torque control of conventional Permanent Magnet Synchronous Motors greatly fluctuate in Flux and torque and difficultly control its high and low speed.To solve the above problems,DTC Controller Strategy Based on Super Spiral Sliding Mode can be designed according to the theory of second – order sliding mode and DTC control and combined with built-in permanent magnet synchronous motor mathematical model based on direct torque control.Compared with the traditional DTC control strategy,the designed method can effectively control the flux and torque of the DTC and have a strong robustness with the load of the parameters of the changes and greatly enhance the stability of the system dynamic and static operation.The simulation results show that the method can obtain good control effect.At last,PMSM DTC position sensorless control system based on SMO(Sliding mode observer,SMO)can be designed combined with Space Voltage Vector Pulse Width Modulation based on sliding mode variable structure theory.Mechanical sensor can be measured the speed while its installation with high maintenance costs and its application of the motor is limited.Motor rotor speed,rotor position can be determined On-line and real-time through a sliding mode observer.The state equation under the coordinate system can be established on the basis of deep analysis of the working mechanism of sliding mode observer,and the speed calculation accuracy can be improved by variable boundary layer function to replace the switching function.