A transformerless Z-Source photovoltaic grid-connected inverter with
coupled inductor coil
Abstract
The quasi-Z-source H-bridge grid-connected inverter (QHGCI) is well
known with its advantages of the void of shoot-through problem and the
high DC-voltage utilization. But the existence of the common-mode
leakage current in the power frequency cycle, lower power density and
higher thermal stress makes it hardly applicable to the grid-penetrating
application. Thus with a purpose to conquer the problem relating to the
QHGCI, an innovative transformerless Z-Source photovoltaic
grid-connected inverter with coupled inductor coil (TZPGCI-CIC) is
proposed. The circuitry topology and an unipolar SPWM strategy are
firstly introduced in short. And thereafter the common-mode voltage in
the whole working process is derived and evaluated through the detailed
operating mode analysis, in which a constant value of it has been
theoretically revealed. Lastly, a prototype platform of TZPGCI-CIC is
setup and its good performance on leakage current suppression, lower
thermal stress are validated with the experimental results.