A novel transformerless current source inverter for leakage current reduction

High-frequency common mode voltage elimination is one of the most important issues for transformerless PV grid-connected inverters. Many interesting single-phase inverter topologies have been reported to reduce the common mode voltage. However, most of them are voltage-source inverters, which suffer from a limited lifetime and reliability. In order to solve the problem, a new single-phase six-switch current source inverter is proposed. A one-dimensional space vector modulation strategy is also presented so as to eliminate the high-frequency common mode voltage. The proposed topology yields lower total harmonic distortion (THD). The experimental results reveal that the maximum value of leakage current can be significantly reduced from 1.3A to 0.14 A with the proposed solution. And, the RMS value of leakage current for the proposed solution is 28.1 mA, which complies with VDE-0126-1-1 standard. In this paper, the theoretical analysis and experimental evaluation tests are carried out to verify the effectiveness of the proposed solution.