Ground leakage current in a power converter is a major concern, which has stringent limitations due to safety concerns. Presence of high-frequency pulses, with high dv/dt due to switching actions in common-mode (CM) voltage, result in injection of current waveforms with large di/dt spikes into the ground and causes high electromagnetic interference (EMI) noise level. In this study, a new method is proposed to make the CM voltage, of a single-phase grid-connected inverter, sinusoidal and free of high-frequency pulses. The proposed method consists of two parallel connected H-bridge power converters, which uses unipolar pulse width modulation (PWM) with carrier interleaving angle of 180°. The proposed method reduces the ground leakage current by more than an order of magnitude. A novel modification to the LCL filter is proposed which further reduces the leakage current by 48%. It is shown that these modifications make the overall system insensitive to circuit non-idealities. Experimental results based on ground leakage current measurements on a 7.5 kW parallel single-phase PWM rectifier are presented. These results validate the effectiveness of the proposed method.
|Number of pages||7|
|Journal||IET Power Electronics|
|Early online date||23 Mar 2017|
|Publication status||Published - 30 Jun 2017|