Bi-Directional Clamping Based H5, HERIC and H6-Type Transformerless Inverter Topologies with Improved Modulation Technique

TLDR: An improved H5, Heric, and H6-type topologies with bi-directional clamping branch are proposed to maintain constant common-mode voltage (CMV) during the freewheeling period to develop an inverter with reactive power capability and minimum leakage current.

Abstract: Transformerless inverters (TLIs) are well commercialized for Photovoltaic applications due to its small in size, less cost and high power conversion efficiency. However, the major challenge is to develop an inverter with reactive power capability and minimum leakage current. Therefore, in this paper, an improved H5, Heric, and H6-type topologies with bi-directional clamping branch are proposed to maintain constant common-mode voltage (CMV) during the freewheeling period. Thus, high-frequency variations due to switch junction capacitances in CMV are diminished and it further reduces the leakage current. Besides, an improved pulse width modulation scheme (PWM) provides a bidirectional current path during zero state to enhance the output waveform quality of the grid-connected inverter at different power factor conditions. Finally, the proposed concept is examined through the simulation results using Matlab software.