Leakage Current Suppression of Single-Phase Power-Decoupled Current Source Inverters

Abstract

Recently, single-phase power-decoupled current source inverters (PD-CSIs) have been proposed to eliminate the use of electrolytic capacitor (E-cap) having a short lifespan. This type of inverter also features a high-efficiency and compact circuit design via multiplexing use of circuit components. However, it is found in this paper that component sharing inevitably renders coupled switching states for incorporating charging and discharging phases of decoupling buffers, e.g. film and ceramic capacitors. The resultant effect will be a significant increase in common-mode voltage, which may lead to unpleasant leakage current. In this paper, a generalized modulation technique is proposed for the PD-CSIs to perform active power decoupling (APD) operation without generating much leakage current. The generic operating principles of the PD-CSIs are analyzed synthetically. The formation of leakage current in the coupled switching states is analyzed. The design of the proposed modulation technique, as well as the power-decoupling controller is provided. Simulation and experimental results of typical types of PD-CSIs in an 110 V AC grid are performed to verify the effectiveness of the proposed modulation scheme. With the proposed modulation scheme, the leakage current of the PD-CSI can be reduced by 56%.