Digital Control of Grid-connected Inverter with LCL-filter Using Multi-rate Sampling Technique

A digital control method is proposed on the basis of multi-rate output sampling(MROS) and deadbeat control technique to solve the shortcoming of multi-sensor and high switching frequency in the control design of grid-connected inverter with LCL-filter.Firstly,the discrete mathematic model and state predictive algorithm of grid-connected inverter with LCL-filter is deduced using MROS,and then state values of LCL-filter is predicted by state predictive algorithm,and finally the control input is computed by using deadbeat control with integral and optimal control.The state predictive algorithm can provide an output sampling interval control algorithm for the actual project implementation and accurately predict state values of LCL-filter,and reduce the number of sensors.Simulation results show that the system has good control performance and lower switching frequency.