Double input AC/AC nine-switch converter for multiple-generator drivetrain configuration in wind turbines

Split drivetrain configurations with multiple generators are one of the solutions for increasing the reliability and reducing the cost of wind turbines. The split drivetrain technology gives the ability to introduce multiple generators and by that reduces the gear size and facilitate variable-speed operation. This paper proposes a double input AC/AC nine-switch converter for direct conversion of low-frequency AC from the generators to high-frequency AC square wave for input to a high frequency transformer used for isolation purposes. The high frequency transformer in connection with a diode rectifier will give a high voltage DC output. With the nine-switch topology a pair of generators can then share one converter and thus reduce the cost of the power electronics. Performance and operation are explained and illustrated in this paper through simulations.