Repetitive Control with State Feedbck on A Single-Phase Five-Level Inverter for Power Quality Improvement

In this paper, a novel single-phase five-level inverter only using five power switches is presented to alleviate harmonic components of the output voltage. The derivation of the topology and its modulation methods are analyzed in the paper. In AC system, nonlinear loads are major sources of total harmonic distortion (THD), so the repetitive control system is given to keep the output voltage being sinusoidal; and the feedback of the capacitor current is added to the control system to quicken the dynamic response. In order to expediently observe the capacitor current, the author uses a digital dimensionality reduction observer. The design methods of the system are discussed in the paper, the feasibility of the system is justified by the simulation and experiments results. The output waveform is perfect, even when the load is nonlinear, the waveform just distorts a little