Improvement of the output voltage waveform technology for single-phase inverter

In this paper, to achieve high-precision steady state waveform and fast dynamic performance, a new control method is introduced, namely, a two-tier structure, the traditional digital PID controller and repetitive controller working in parallel. We name it as hybrid controller. Response speed between the two kinds of control methods is different and the time is decoupled. This control method can restrain the change of output voltage caused by load disturbance. In addition, to improve dynamic performance, two kinds of methods to improve dynamic response are proposed. One is load current feed-forward control; the other is to change the modulation ratio. Both of them improved the output voltage waveform. Finally, the proposed methods are verified by simulation and experiment.