In this thesis, an approach to design a space-based shunt voltage-regulator is presented in which a microprocessor is used as a controller. The proposed system meets the demands of space-missions, i.e., reliable, efficient, flexible, low weight, low volume, and less development time. Such system responds to future demands by permitting real-time modification of system parameters for system optimization which has a special importance in the event of an anomaly. The design and performance of the individual components of such a regulator system are discussed in detail with a particular reference to 30 W prototype. However, the prototype design is such that it can be easily expanded to higher ratings. The bus voltage regulation is achieved by two stages. First, coarse regulation is done by switching the solar array sections on and off via a solar array switching unit (SASU). Second, fine regulation is done using a small PWM shunt that is designed to regulate the output of one solar array section. Thus, power losses are reduced and assembly of the unit is simplified. The design reliability of the system is enhanced further by constructing a second (Standby) regulator system to come into action in case of the original (Active) regulator becomes faulty. As the microprocessor needs not be dedicated to control the SASU and PWM, it can simultaneously be used for the entire power system monitoring and housekeeping. Hence, a single-integrated power conditioning and control unit (PCCU) to achieve various jobs that are required by the space-based systems can be implemented. The power stage design of the PWM shunt regulators is based on power MOSFET as the main switching device and a simple switching-aid network to ensure safe and reliable operation. The behavior and performance of this stage are analyzed theoretically by deriving a mathematical model. The validity of proposed model is examined by comparing the predicted regulator performance with that measured experimentally. A reasonable correlation between the predicted and measured performance is obtained at various operating conditions.