Development of a radiation hardened 600 watt switchmode power converter

The purpose of this investigation was to develop a radiation hardened switching power supply. The power supply will be used in a nuclear fuel reprocessing environment, supplying power to other instrumentation. The supply was required to have three DC voltage outputs, with a total output power capability of 600 watts. Complete isolation of the AC line input and each of the voltage outputs was also required. Each output was to be short-circuit protected and capable of sensing over and under voltage conditions.

The power supply circuit was designed to withstand a total absorbed gamma dose of at least ten megarad. The implications of this requirement were discussed.

In addition, the results of specific testing of parts for this application were reviewed along with the radiation hardness of the completed prototype.

In addition to the radiation hardness requirements, frequency and transient response of the various sections were computer simulated and measured. Various circuit topologies for implementation of the switching power supply were discussed in terms of relative advantages and applicability to various applications.

A magnetic amplifier was also discussed and implemented for secondary regulation of two of the output sections. The magnetic amplifier circuit was discussed and computer models for the closed loop response were illustrated.

Complete results for the constructed prototype were presented and discussed. Also included was a complete parts list for the prototype power supply.