Abstract
We developed a transformer-less inverter for photovoltaic power system. This has a unique chopper circuit of multiple-switching method and small inductor. The reduction and detection of earth-leakage current is serious probrew in transformer-less system. To clear this, We cleared the relation between switching behaviors in chopper and inverter circuits, voltage from ground level, and earth-leakage current. We solved the probrem by using synchronization of chopper PWM with inverter, high impedance filter inductor, and flux-gated current sensor.
