| The key to the energy conversion of electric vehicles lies in the driving motor,which determines the operating performance and power requirements of electric vehicles.Permanent magnet synchronous motor(PMSM)has developed rapidly in the field of electric vehicles because of its small size,strong adaptability and easy speed regulation.Permanent magnet synchronous motor(PMSM)control technology has two methods:vector control and direct torque control(DTC).The earliest electric vehicle drive system mainly uses vector control technology,but direct torque control(DTC)control method is gradually replacing vector control technology,domestic and foreign scholars began to introduce(DTC)algorithm into the control system.Although the direct torque control technology has the advantages of simple modeling,fast control speed and stable control of motor parameters,it still has some shortcomings such as large electromagnetic torque and flux ripple,large switching frequency fluctuation and harmonic interference.Based on the above discussion,combined with the requirements of the motor drive system,this paper uses the permanent magnet synchronous motor as the driving motor of the system,and uses the three-level inverter direct torque control method to build the control system model.The control model is supplied by diode-clamped three-level inverter.First,the theoretical analysis is carried out according to the structure of permanent magnet synchronous motor,and then the direct torque control of three-level inverter is theoretically analyzed.The mathematical model is analyzed,and for the purpose of reducing torque and flux ripple,the method of voltage space vector synthesis is described in detail to solve the problems of neutral point voltage imbalance,voltage jump,switching frequency and switching loss.Then the simulation model of the control method is built under Matlab/Simulimk,and the different effects brought by the simulation waveforms are analyzed and studied,and it is concluded that the three-level inverter direct torque control method has the advantages that the former does not have,and further verify the superiority of the three-level inverter direct torque control technology.According to the above specific theoretical methods and simulation verification,the control chip used in this paper is TMS320F2812,and the control chip is applied to the hardware and software design of the control system,and the flow chart of the three-level inverter permanent magnet motor DTC control system is designed.according to the implementation of the hardware and software design,the accuracy and practicability of the three-level direct torque control system can be verified.It provides the basis for the improvement and promotion of the motor control system. |
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