Series Connected Open-End Winding Generator for Higher Voltage DC Supply

High-voltage dc is popular for transmission of large volume of power over long distances due to several advantages. Medium voltage dc transmission are becoming de facto standard in offshore wind generation and in similar cases where long cable lengths are required for transmitting power from the source to the usable destination. Several schemes have been proposed for generating the high dc bus voltage from the lower voltage ac generators at the offshore platform. However, size, weight, and maintenance are the major deciding factors. This article proposes a scheme of generating suitable dc voltage from a lower voltage synchronous generator without using transformers or boost converters. It uses an open end winding permanent magnet synchronous generator. The voltage outputs from each winding are converted to boosted dc by individual 1-phase pulsewidth modulation converters, whose dc bus are connected in series to convert to a higher dc bus voltage. This permits conversion to much higher voltage dc employing semiconductor switches of lower voltage rating. Simulation and experimental verification are presented to validate the proposed scheme.