Medium to low voltage DC/DC resonant converter with SiC SCRs and nanocrystalyne magnetic core transformer

Abstract:
Offshore wind farms can benefit from direct connection of their wind turbines to medium voltage DC distribution lines. The power converter cost can be low if the connection is unidirectional and only diodes are used in the high voltage side. However the wind turbines require electric power to operate their control electronics and pitch and yaw systems. This paper presents a power converter to feed wind turbines from a medium voltage bipolar DC distribution line using high voltage SiC SCR-s operating in resonant mode at high frequencies. The maximum switching frequency is only limited by the circuit commutated turn off time, tq, of the SiC SCR-s. With the introduction of SiC semiconductors devices, Medium Voltage High Frequency Nanocrystalyne Core Transformers are a future promising solution for the different power network levels (generation, transportation and distribution) and smart grid applications. Compact size, high reliability and more efficiency are promising features that could be provided by such devices. Analytical and simulation results are explained and validations with experimental results of a low power prototype are presented.