Multi-function multi-level grid tied inverter based on a new combined logic-analog controller with capacitors balancing ability

In this paper, a modified hysteresis band logic-analog controller with capacitors balancing ability is proposed. A multi-function five-level grid-tied inverter is investigated, which can be used to inject power into the grid and act as an active filter, simultaneously. It is also capable of absorbing active power to act as a storage system using batteries on the DC link and reactive power compensation to some extent. The new hysteresis band controller has been implemented on a conventional 5-level converter, based on the current injection method. In addition, this controller is also capable of balancing the voltage of the capacitors by selecting appropriate switches related the desired voltage vector. The proposed controlling method acts in the time domain and no need for complex transformations; furthermore, it has a high processing speed due to the utilization of logic gates. Moreover, due to the lack of need for a microcontroller or DSP, there is no halt phenomenon or delay in the execution of software loops. In this paper, power injection into the grid and active filtering ability have been investigated. To verify the proper operation, the simulation results as well as the laboratory 350 W prototype results are presented.