Power condition unit (PCU) regulates thewhole power of man-made satellites, spacecrafts and etc.The greater the total power of spacecrafts becomes, thegreater that of the PCU becomes. This paper is to analyzethe basic operation principle of the non-isolated WeinbergConverter, which is also called the Battery discharge regulator (BDR) used in the PCU for High-Power Bus Satellites. According to the ac small-signal modeling and analysis based on this operation principle, we get the voltagecontrol mode and current control mode transfer functionsrespectively. Moreover, a regulator system has been designed to meet the requirements of the transient response,and stability, which is to be used in a 9kW communicationsatellite, adopting six modules with the power of 1.5kW foreach. Work of this kind has been studied from the open andclose loop control curves under the voltage control modeand current control mode respectively, and the practicalwaves of a high-effciency non-isolated 1.5kW Weinbergconverter with the current control mode are also givenpartly. Simulation using Saber and experimental resultswill be employed to verify our theoretical work.