Research On Three-level Three-switch Rectifier Based On Hysteresis Space Vector Control

The three-level three-switch rectifier(VIENNA rectifier)is an excellent three-phase PWM rectifier topology.VIENNA rectifier has the advantages of high power factor,less switching devices required,low voltage stress on the power tube,no need to set dead time and no bridge arm straight-through problem,etc.It is especially suitable for three-phase high-power applications.Hysteresis current control and SVPWM(Space Vector Pulse Width Modulation)control are commonly used control methods for VIENNA rectifiers.However,hysteresis current control has the problems of unstable switching frequency and large harmonic content,and SVPWM control has the problems of large calculation and complex control process.For the problems of the above two control strategies,hysteresis space vector control combining hysteresis current control and SVPWM control is applied to VIENNA rectifier.It is found that in the implementation of the traditional hysteresis space vector control,the error current vector cannot be transformed into the two-level space from the three-level space,and the position of the error current cannot be judged,so it is not suitable for VIENNA.Rectifier.Therefore,a new hysteresis space vector control method is proposed to be applied to the VIENNA rectifier.The specific control strategies are as follows:set the acceptable error current smaller than the hysteresis width,use hysteresis current control when the error current is larger than the hysteresis width;use SVPWM control when the error current is larger than the acceptable error current and smaller than the hysteresis width;keep the switch state unchanged when the error current is smaller than the acceptable error current.The new hysteresis space vector control has the characteristics of fast dynamic response,high power factor,small THD and good midpoint voltage balance.Three simulation models of hysteresis current control,SVPWM control and hysteresis space vector control based on VIENNA rectifier are built on the simulation platform of MATLAB/Simulink software,and the corresponding simulation analysis is carried out.The simulation results show that hysteresis space vector control achieves better performance in midpoint voltage balance,harmonic content,response time and output voltage overshoot while maintaining the respective advantages of hysteresis current control and SVPWM control.