Research On Direct Torque Control Of Permanent Magnet Synchronous Motor For Electric Vehicles

Electric vehicles have the advantages of automobiles and environmental protection,energy saving,has become the world's competing development of the industry.As a driving form of electric vehicle,the Permanent Magnet synchronous motor(PMSM)system has the advantages of high power density and efficiency,small volume,low inertia,fast response and wide speed Regulation range.Direct torque control algorithm is relatively simple to implement stator magnetic field orientation,does not need complex coordinate transformation,stator flux estimation only involves stator resistance,reducing the dependence on motor parameters.However,there are some problems in direct torque control,that is,there is a large flux and torque pulsation in direct torque control.In order to solve this problem,based on the analysis of the principle of direct torque control(DTC),a PMSM-DTC model is built in Matlab/Simulink environment,and the role of 0 vectors in the direct torque control system of Permanent magnet synchronous motor is analyzed.On this basis,the simulation results of two kinds of DTC,0 vectors and no 0 vectors,are compared in the control table.The simulation results show that the DTC control with 0 vectors has the advantages of less torque ripple and low switching frequency of power electronic switch tube.In this paper,the spatial vector PWM(SVPWM)control model of Permanent magnet motor is established,which uses the idea of synthetic voltage vector to generate target voltage vector based on vector error to control the torque and flux error during cycle.The target voltage vector is then combined with two adjacent non-0 voltage vectors to achieve precise torque control and flux coupling.In this paper,the simulation results of SVPWM and the control results of DTC model are compared,and the two control methods of DTC and SVPWM are combined,which can not only fix the switching frequency of power electrons,but also reduce the fluctuation of torque.Finally,the paper verifies the feasibility of the theory through experiments.