PERFORMANCE OF A CLOSED-LOOP-CONTROLLED HIGH VOLTAGE DC-DC CONVERTER AT CRYOGENIC TEMPERATURES

摘要

A 1 kW, 80-110V/500V closed-loop-controlled full-bridge dc-dc converter was designed to operate from room temperature to -190°C using commercially available components. The converter design was based on that of a beam supply for a space electric propulsion system, with the added capability of being able to operate over a very wide low temperature range. In order to design a circuit to operate at cryogenic temperatures, specific attention was paid to the selection of the components used. In particular, most bipolar-type devices were avoided and were replaced with CMOS-type devices which have been shown to work well at cryogenic temperatures [1]. In addition, MOSFET switches were used because of their capability to operate quite well at low temperatures [2]. Finally, only certain types of resistors, capacitors and magnetics (which were known to have desirable characteristics at low temperature) were selected. The closed-loop-controlled full-bridge dc-dc converter was tested and operated successfully from room temperature to -190°C. The performance of the closed-loop control was verified by measuring the efficiency, output regulation and switching behavior over changing load, and input voltage at various operating temperature conditions.