Low frequency current reduction using a quasi-notch filter operated in two-stage DC-DC-AC grid-connected systems

For a single-phase grid-connected power system, output power is pulsated instantaneously with a double-fundamental frequency. Accordingly, the current drawn from renewable energy sources tends to be pulsated and contains low frequency ripple components, which causes several issues including a power harvesting deterioration and energy source´s life shortening. This paper proposes a novel power pulsation decoupling scheme to reduce low frequency ripple current with a fast voltage loop. Proper control design based the small-signal model of two-stage dc-dc-ac converter is presented in a frequency domain analysis, and its experimental waveforms are provided to verify the effectiveness.