Grid-connected inverter with digital dual-polar frequency-limited current hysteresis control

A hysteresis control strategy of grid-connected current is proposed for single-phase grid-connected inverter, which samples the actual grid-connected current at a fixed period and compares it with the reference current to generate the control signal of switching component for controlling the actual grid-connected current. The distribution law of switching cycle and current ripple corresponding to the electrical angle of grid-connected current is derived and the principle of filter parameter design is given. The steady-state and dynamic simulative and experimental waveforms of grid voltage and grid-connected current, as well as the working states of switching component, are shown, which indicates that, without complicated linear close-loop control algorithm, the grid-connected current is well controlled by properly selecting the sampling frequency, the maximum switching frequency of switching component is effectively limited, and the implementation of the proposed strategy is simple, with high reliability.