Mainstream develops lightweight and compact portable power supplies for military and DoD applications. We have developed AC-DC, DC-DC, and DC-AC converters for high current (500 A), low voltage (28 VDC) systems, and prime power 208/230 and 460 VAC systems. Thermal management ranges from natural convection systems where external fan circulation is impractical to liquid-cooled systems (up to 100°C) to direct refrigerant cooling systems. Example applications include 60 Hz to 400 Hz solid-state frequency conversion, pulsed power supplies with hybrid energy storage, high-efficiency integrated fuel cell electronics, and portable battery chargers.