Tan Kheng Suan Freddy, June-Hee Lee, Hyun-Cheol Moon, Kyo-Beum Lee, and Nasruding Abd Rahim, "Modulation Technique for Single-Phase Transformerless Photovoltaic Inverters with Reactive Power Capability," IEEE Transactions on Industrial Electronics, vol. 6 > Paper

This paper underpins the principles for generating reactive power in single-phase transformerless photovoltaic (PV) inverters. Two

mainstream and widely adopted PV inverters are explored, i.e., H5 and HERIC. With conventional modulation techniques, reactive

power cannot be realized in H5 and HERIC due to the absence of freewheeling path in negative power region. Based on the study,

modulation techniques are proposed to provide bidirectional current path during freewheeling period. With proposed modulation

technique, reactive power control is achieved in H5 and HERIC inverters, without any modification on the converter structures. The

performances of the proposed modulation techniques are studied via MATLAB simulation and further validated with experimental

results.