Compared with voltage source-type photovoltaic grid-connected inverters

current source-type inverters have fewer passive components

higher power density

and boost characteristics. However

to prevent open-circuit faults of the DC-side inductor current

it is necessary to introduce turn-off delay in the drive signals of current source-type inverters

resulting in two devices on the same bridge arm being in the on-state simultaneously. This period is called the overlap time

which causes significant harmonic distortion in the inverter-side and grid-side currents. To address this issue

an equivalent circuit was established for the overlap-time state

the relationship was analyzed between the inverter-side current error caused by the overlap time and the AC-side three-phase capacitor voltages

and derives the mathematical expression for the grid-side current harmonic distortion caused by the overlap time. Then

to improve the compensation accuracy

a high-precision digital filter was introduced to obtain the fundamental component of the capacitor voltage

and a lookup table-based current error compensation strategy in the d-q coordinate system was proposed. Finally

simulation and experimental verification were carried out. The results show that the proposed compensation method can effectively reduce the harmonic distortion rates of the inverter-side and grid-side currents introduced by the overlap time

fully demonstrating correctness and effectiveness of the theoretical analysis and the proposed overlap-time compensation scheme.