Characterisation of radiation effects on power system components for cubesats

Abstract

Front-end power converters for nanosatellite applications demand better performance in accurate reference tracking because of the wide-range input voltage of the solar panels. The very tight output voltage requirements demand a robust, reliable, and high-efficiency converter. The control of such a converter is very complex and time consuming to design. Two commonly used control modes are current and voltage control. The design and implementation of a voltage controller for DC–DC power converter is simpler but compared to current mode controller, does not do provide for overcurrent protection. A single-ended primary inductance converter (SEPIC) was selected for this research work because of its ability to buck or boost the input voltage coupled with the ability to provide noninverting polarity with respect to the input voltage. Parameter values for the converter studied are used to analyse and design both the voltage and the current mode controllers for the nanosatellite front-end power converter. Output voltage reference tracking with step and ramp changes in the input voltage is evaluated in terms of the time taken to reach steady-state after the induced disturbances and either the overshoot or undershoot of the output voltage reference. The design of analogue pulse width modulation (PWM) study was carried out in order to drive the metal-oxide-semiconductor field-effect transistor (MOSFET) switch. For the two controllers, changes in the reference output voltage in response to load changes are also studied. An examination of the effects of solar radiation on the MOSFET switch was conducted; this switch is the main component of the front-end DC–DC power converter for a nanosatellite. At the more general level the examination also provided information on the response of the semiconductor technology in space application. The overall purpose of studying the MOSFET switch was to investigate the mechanisms that will facilitate its ability of switching ‘on’ and ‘off’ without failure as a result of solar radiation. The effects of solar radiation on MOSFET device in space, has resulted in more malfunctions of these devices in the past five years than over the preceding 40 years.