A computer program to estimate the weights and volumes of space borne power systems has been written. The program runs on a Zenith Z-100 microcomputer. The weight and volume of the system is calculated based on component data stored in the form of databases. An executive program which provides maximum flexibility to the user in terms of specifying the desired characteristics of the target system has been written. Constraints on the weight and volume of the system may also be specified. Some of the characteristics that may be specified are power requirement, orbit, duty cycles, etc. A complete User's Manual which describes the working methods to create new databases and enter new data, and includes error handling techniques has been generated. The result is an interactive, menu driven, user friendly software package to estimate the parameters of a space borne power system. / M.S.

Maintaining and improving innovation is vital to any organisation.There are many challenges organisations are faced with, both internally and externally when it comes to maintain and improving innovation. Eskom is such an organisation. The employees, both non-managerial and managerial, of Eskom are faced with various challenges in their daily activities. The quest for innovation advantages requires increased creativity to assist employees in adopting an intrapreneurial outlook to provide proactive solutions. Intrapreneurship is an autonomous process. Eskom which bulk suppliers South Africa mission is to provide electricity reliably at a low cost to all South African. This seems less reachable with high operating cost, slow capacity growth and aging infrastructure. This study focused and contributed to the innovation environment of Eskom, with the area of study being confined within the Eastern Cape. The study objectives sought to review Eskom Distribution’s business plan and innovation policy, while identifying if employees have intrapreneurial trait, if organisational culture, system and managerial styles are conducive for intraprenuership, if the external environment will promote intrapreneurship within the organisation, and which ideas have best adoption rates of innovation within the organisation, these factors may hinder the success of innovation in the organisation, based on the theoretical findings of the literature study. Employees, at both managerial and non-managerial levels participated in a research study. The research instrument used comprised of questions that covered the various objectives listed above. This provided the basis for a quantitative study to be done. Using statistical methods to identify any special relationships or trends, the research was conducted and recommendations were made based on the objectives of this study in relation to the organisation under study, Eskom Distribution, Eastern Cape Operating Unit. Based on the findings, recommendations to improve innovation, through intrapreneurship methods were made.

Thesis presented in ful lment of the requirements for the degree of Magister Technologiae in Electrical Engineering at the Cape Peninsula University of Technology, 2013 / The power system is essentially one of the most critical subsystems to any satellite, without some form of power system a satellite would simply cease to function. The research within these pages investigates the areas pertaining to satellite power systems with the main focus towards the CubeSat platform. The end objective of this research was the development of a reliable analogue based switch-mode power system for a CubeSat. The research began with an investigation into the CubeSat platform, the space environment and a basic overview of a satellite and its systems. The research then focussed on satellite power systems, focussing primarily on satellite power system topologies and switch-mode power systems. Various components and concepts surrounding the satellite power system were investigate and included the photovoltaic (PV) solar cell, batteries, satellite power system topologies, protection concepts and typical CubeSat power systems. The nal part of the literature review included research into typical CubeSat power systems. The space environment complicates the design of satellite systems. The developed electrical power system harnessed electrical power from a PV solar panel by means of a fractional opencircuit voltage (FOCV) based maximum power point tracker (MPPT) with the use of a SEPIC DC-DC converter. The use of a SEPIC DC-DC converter allowed the system to operate at a greater e ciency than could be expected from linear designs. The requirement for an e cient system was important as the heat generated by the power system could bring rise to dissipation issues, resulting in over-heating of various components. The design took into account component sizing, as larger components would be more prone to damage during the high accelerations and vibrations associated with being launched into space. The use of a MPPT allowed the power system to better utilise the available PV solar panel power, by maintaining the PV solar panel near its optimum operating voltage. The design slid between MPPT and voltage regulation to harness as much power as possible while not over-charging the Lithium polymer battery. The power system consisted of battery under-voltage protection as well as over-current protection for the attached payloads and satellite subsystems. The SEPIC DC-DC converter was selected over other SMPS topologies, as this topology could be used in a 1U and 3U CubeSat with a wide variety of PV solar panel cell con gurations. The bene ts of this SMPS topology are due to the SEPIC DC-DC converter's ability to produce an output voltage greater than, less than or equal to the input voltage (National Semiconductor, 2008; Texas Instruments, 2008a). This, along with the operation of the FOCV based MPPT, allowed the power system to be very exible. The designed FOCV based MPPT could be pre-set to di ering PV solar cell technologies due to the adjustable ratio between the maximum power point voltage, Vmpp, and the open-circuit voltage, Voc of the PV solar panel. It was decided not to select a Buck or Boost DC-DC converter based power system as this would limit the exibility of the system. Additionally, the SEPIC DC-DC converter brings with it the ability to isolate the input and output voltage upon shut down. This isolation is due to the SEPIC DC-DC converter's coupling capacitor and this topologies operation as described by National Semiconductor (2008) and Texas Instruments (2008a). The prototype was versatile allowing a wide variety of PV solar cell technologies to be used. The wide operating voltage of the prototype allowed the design to be connected to a series or parallel combination of solar cells with an operating voltage of 3 V to 20 V. The power handling capability of the prototype per solar panel channel allows the design to be applied to a 1 U or 3 U CubeSat given that the channel did not exceed 10 W. All components of the prototype operated without fault, e ectively charging the Li-poly battery safely while protecting payloads and subsystems. The SEPIC DC-DC converter utilised by the MPPT achieved an e ciency of 71 % under full load and with an input voltage of 10 V.