First realisation of a Golomb ruler staircase inverter for photovoltaic applications

Abstract

This paper proposes a new direct-conversion, dc to ac multi-level inverter for photovoltaic applications based on the previously unexploited Golomb (and sparse ruler) number theorems. This allows individual panel outputs to be aggregated in an optimal fashion to produce low-distortion, approximate sine wave outputs with the option of panel blocking in the event of shading. The main advantages of the Golomb structure over the conventional contiguous block arrangement is that it provides 36% less series resistance loss, is transformer-less and runs at the order of 1000 times lower frequency; hence virtually eliminating switching losses. Here we describe a low power prototype which shows just 2% or 16.9dB power distortion with 6 levels compared to the 17.2dB theoretical value.