A 2.5 KV high-reliability TWT power supply: Design techniques for high efficiency and low ripple

A power supply designed to operate a high-efficiency, ten-watt TWT used as the power amplifier in a communications satellite is described. The electrical environment in which the power supply must operate and the required functional outputs are defined. Emphasis is placed on efficiency and regulation of the high-voltage converter. Operation is outlined by use of a functional block diagram and description of the primary power-handling circuits. Command, monitoring, and fault control, while vital to the proper operation of the amplifier, are not topics of this paper. The high-voltage converter achieves primary regulation through pulse-width modulation. The basic relationships which control its design, and the base drive circuit used to modulate the pulse width are described. An energyrecovery system using a two-winding inductor is employed in conjunction with the buck-mode converter. The principal sources of dissipation in the supply, contained in the highvoltage converter, are described. Relationships governing the dissipative loss in each are developed, and solved by use of a computer program. The results are presented in terms of graphs showing the effect on overall loss of varying critical parameters. Control of ripple, both externally imposed and internally developed, is a primary consideration of the power supply design. Its accomplishment is described in terms of the primary regulator, supplemental regulation by means of a linear regulator, and filtering at both input and output. Results of the design effort are summarized by a presentation of operational characteristics, and a brief description of the packaging.