Design and realization challenges of power supplies for space TWT

Abstract

Traveling Wave Tubes (TWTs) are extensively used in the satellite payloads as RF power transmitting amplifiers. TWT requires a highly sophisticated power supply; often known as High Voltage Electronic Power Conditioners (HV-EPC) in space community. Both the units put together make a Traveling Wave Tube Amplifier (TWTA). HVEPC is a regulated power supply used to provide conditioned and isolated voltage rails, with stringent regulation / ripple requirements, to various electrodes of TWT and make the TWT RF performance independent of solar bus variations that occur due to varying sunlit and eclipse conditions. Apart from this, HV EPC will have precisely timed protection and control circuits to safeguard the TWT against all vacuum phenomena like corona, arcing, micro-discharges etc. HV EPC consists of DC-DC Converters, DC-AC Converter, EMI filters, Protection circuits and associated Tele command-Telemetry circuits to suit a satellite platform. Satellite systems are designed for maximum efficiency, minimum mass and size for being state of the art. Rationalizing the design philosophies, analyses, manufacturing and process controls ensure the reliability of the systems. This helps not only to ensure a long and reliable operation onboard (usually satellite operational life is more than 15 years) but also helps in avoiding any problems during early stages of manufacture. Being a closed loop multi converter high voltage system (3KV-6KV); HV EPCs need special attention regarding the Design and Configuration, closed loop stability of multi converter system, Energy limiting of HV outputs Component selection, Material selection, HV Potting, fabrication & process control etc. This paper addresses all these critical technologies involved in realizing a state of the art HV EPC required for a space TWTA.