Novel Double Closed-loop Control Strategy For Three-phase Three-wire Vienna Rectifier

With the increasing emphasis on energy conservation and environmental protection in society,electric power devices are widely used in various occasions,which brings convenience to people’s lives.However,the problem of harmonic pollution of power grids cannot be ignored.Reducing the input current total harmonic distortion(THD)of rectifier equipment and improving the power factor of rectifiers have always been the key research direction in power electronics applications.The three-phase Vienna rectifier is a three-phase three-level boost rectifier.Compared with other three-level rectifier circuits,this topology has high power factor,low voltage stress of the switching transistor,low input current THD and high application value.And in this paper,the three-phase three-wire Vienna rectifier topology is taken as the research object.A novel double closed-loop control strategy is designed to further reduce the harmonic content of the input current and improve the overall performance of the rectifier.In order to reduce the complexity of the system structure and improve the stability of the rectifier,this paper proposes a novel voltage and current double closed loop control strategy.The voltage outer loop adopts a sliding mode variable structure control strategy based on the improved reaching law,which can effectively suppress the switching jitter.At the same time,the phase-locked loop based on adaptive notch filter is introduced to accurately obtain the grid voltage information,ensuring that the outer loop can accurately output the reference command current for the current inner loop.The current inner loop adopts an improved predictive current control strategy,combining the idea of finite control set model predictive control with space vector pulse width modulation(SVPWM),so that the optimal switching state obtained by the predictive controller passes through the modulator to generate a switching signal.Therefore,the switching frequency is controlled by adjusting the frequency of the carrier,which fixes the switching frequency while preserving the advantages of the model prediction control.A simulation model is established in the Matlab/Simulink simulation software.And the the three-phase three-wire Vienna rectifier prototype is designed and tested.Theoretical simulation and experimental analysis verify the correctness of the performance analysis of the Vienna rectifier and the rationality and effectiveness of the proposed double closed-loop control strategy.