Performance analysis and improvement of digital controlled inverter

Inverter performances with conventional digital PI, PD, and PID controllers are analyzed. It is found why conventional digital controllers fail to achieve better performances than analog ones. The reasons are the effect of discretization process besides delay time caused by A/D conversion and computation time. The effect of discretization is analyzed quantificationally and the conclusion that can instruct design of an inverter controller is indicated. A digital feedback control scheme, in which the number of state variables is increased, is proposed in this paper. Theoretical analysis shows that it can provide good dynamic and steady state performances. Simulation and experimental results on an inverter controlled by a TMS320F240 are given to verify the theoretical analysis.