Full digital control of three-phase DC/AC inverter

This paper presents a design of full digital controller for three-phase DC/AC inverter to meet the dynamic specification. The three-phase inverter system including a LC output filter becomes a MIMO system due to the coupling terms. These coupling terms make the controller design difficult and complicate. In this paper, through RGA and simulation process, it is shown that the coupling terms can be ignored to represent the system as a SISO one firstly. And then the full digital voltage controller is designed directly in z-domain. It is a very simple structure of single loop and has a good performance caused by including no zero. Gains of designed controller are assigned by MATLAB according to the time response such as overshoot and settling time automatically. The simulation results using DLL block of PSiM simulator is almost same as the design specification. Finally, the full digital controller is verified by the experiment using TMS320VC33 DSP.