The transformerless H-bridge, also known as an H4 inverter (shown in a two- stage configuration with a boost dc–dc stage), gets rid of the low f requency transformer by splitting the grid inductor into the phase and neutral wires of the systems and using a bipolar PWM (two-level) to solve the issues of the switched common-mode voltage and leakage currents and by using a boost stage for a wider input voltage range. The downside is that the two-level modulation reduces the power quality at the grid connection and lowers the efficiency since there is a reactive current flow between the passive elements of the circuit at zero voltage through the free wheeling diodes as the dc-link capacitor is not isolated from the grid at any time.