Finite Control Set Model Predictive Control Study And Application Of Three-phase Voltage Source Inverters

Power electronic converters play a very important role in energy conversion and making new energy grid is controllable,efficient and reliable operation.The control performance directly affects the power quality of the system output.Considering the inherent characteristics of power electronic converters,Finite Control Set Model Predictive Control(FCS-MPC)has become a hot topic in the field of inverter control because of the advantages of flexible control,no modulator and decoupling operation,multi-objective nonlinear control and so on.In FCS-MPC system,control actions are implemented by a single controller.this controller can choose a state from all effective state on line,and the control state is calculated can minimize the cost function which is made pre-defined and can represent system expected performance.Therefore,appropriate cost function can also optimize many important parameters(such as switching frequency,switching loss,reactive power,motor torque ripple,etc.).In this way,predictive controller can replace traditional modulation unit in the system and cascade loop PI control,at the same time,it can provide multiple target which must be satisfied the occasion required of industrial flexibility,simplicity,and based on the optimal solution of the software.In this article,taking three-phase inverter for the control object detail the control principle of FCS-MPC.The basic thought,prediction model,cost function and weight coefficient design and rolling optimization are discussed respectively in this paper.Firstly,the advantages and disadvantages of FCS-MPC and traditional control methods are compared.In this paper,the traditional hysteresis current control and the linear control method based on pulse width modulation(PWM)are introduced.Moreover,the control comparison of the hysteresis current control method and FCS-MPC method under the same conditions is given by Matlab/Simulink simulation.Secondly,a problem of FCS-MPC is analyzed,which is the effect of time delay on the system.Traditional FCS-MPC uses Lagrange extrapolation method to modify the future reference on delay compensation problems.But the peak is bigger in the event of the step change.After considering the vector representation of the three-phase system variables,which can be based on the change a sampling time vector Angle to estimate future reference value.and improve the problem,In addition,this article gives the comparison between having delay without compensation,having delay using Lagrange extrapolation method to compensation and having delay using the vector Angle compensation method to compensation.Finally,the improved FCS-MPC strategy is applied to the photovoltaic grid-connected and motor drive,and the feasibility and validity of this method are further verified by Matlab/Simulink simulation.