High Efficiency and High Power Quality Electrical Power Conversion

The proposed shipboard medium voltage AC to DC converter system will allow for various input and output levels based on a power dense, efficient, low cost, high quality output, and modular design expandable up to 6MW. A 450kW power conversion module uses advanced power switching devices and a uniquely designed isolation transformer. The 13.8kV module front-end is connected across a series cascade of H-Bridges that are switched at a low frequency to reduce losses, synthesize a high quality sine wave, operate at unity power factor, and meet low current distortion per MIL-STD-1399-680. Each DC output of the H-Bridge section acts as an input for a Series Loaded Resonant DC/DC converter that includes high frequency transformer isolation. The SLR converter uses Super Gate Turn Off devices from Silicon Power Corporation operating at a high frequency to minimize the transformer. Low output DC ripple is realized by full wave rectifying and interleaving each SLR output to form a single DC output. Multiple paralleled modules combine to achieve a ripple voltage of 0.1% rated up to 6MW. Each module output is regulated to handle transient load conditions and can be adjusted between 800-to-1000V as influenced by the transformer turns ration.