Based On The Current Vector Of The Matrix Converter - Direct Torque Control System

Matrix converter can produce an output voltage with adjustable amplitude, phase and frequency, and the bidirectional switches can make the power flow in two ways.The excellent matrix converter is applied in direct torque control (DTC) system of asynchronous motor. It is called matrix converter-DTC bombined system. The input current of this system is with poor quality. An easy and effective control strage is proposed to improve the input current of this systemThe mathematical model of the induction motor and the structure of DTC system are analyzed, the work principle and control strategies of matrix converter are introduced, and the working processes of the voltage space vector are analyzed in detail.The voltage vector is divided into high, middle and low level according to the amplitude. To improve the voltage usage, high and middle levels are selected as control signal to realize SVPWM.Current vector control was introduced to improve the quality of input current of matrix converter. The control strategy that coordinate voltage vector with current vector can keep the performance of DTC and maintain the input current performance.The availability and superior performance of the system are verified through emulation in platform of MATLAB/Simulink. Both ideal characteristics of matrix converter and the good dynamic and static performance of DTC are retained, and the input current waveform is improved.Besides, a new vector control list is added to realize the brake and motor energy feedback. The mechanical energy of synchronous motor can be reverse circulate to the grid, and stop asynchronous motor quickly, which is of great significance to save energy.