Model Predictive Current Control Of Non-ideal Grid Connected Rectifier With Fewer Sensors

In recent years,the application of a large number of power electronic devices and non-linear loads has brought harmonics pollution to the grid.Reasonable control of power electronic interface converters is conducive to preventing the spread of harmonics and achieving reliable grid connection of electrical equipment,therefore,it is of great significance to research the control strategy of power electronic converters under non-ideal grid situation.PWM rectifier is a widely used AC-DC converter device,which has the advantages of high power factor,low line-side current distortion and bi-directional power flow.Among the control methods for PWM rectifier,Model Predictive Control(MPC)has been widely used in recent years because of its fast dynamic response,intuitive modelling and high robustness.Considering the fact that the actual grid voltage is subject to frequency fluctuations,distortions and unbalance,and that the use of sensors increases the hardware cost and reduces the reliability of the control system.Selecting single-phase PWM rectifier and three-phase PWM rectifier as research objects,this study proposes a sensor-less model predictive control strategy for PWM rectifier in non-ideal grid voltage condition based on state observer.The method is able to reconstruct the grid voltage quickly and accurately even the grid voltage is in a non-ideal state.The proposed method could reduce the hardware cost and improve the environmental adaptability of the control system.Compared with other sensor-less control methods,the proposed method is able to detect not only the fundamental component of the input voltage,but also both harmonic and DC components.Reconstructing the grid voltage is helpful to improving the modelling accuracy of MPC which a topology model-based control method,and thus improving the control performance.In addition,the observer is adaptive to frequency fluctuation because it is combined with a phase detection algorithm.This study also proposes a method to alleviate the influence of 2ω oscillation on line-side current.Finally,several sets of simulations and experiments are set up to validate the proposed method under different grid conditions.The effectiveness of proposed strategy get proved.