Pulse Adjustment, a Novel Digital Control Technique, for Control of a DC-DC Buck-Boost Converter Operating in Discontinuous Conduction Mode and Driving Constant Power Loads

Multi-converter power electronic distribution systems are being considered for advanced vehicles. The stability of the DC power electronics based power distribution systems is a significant design consideration because of the potential for negative impedance induced instabilities. In order to mitigate the problem of negative impedance instability, this paper presents a novel digital control technique for converters operating with constant power loads (CPLs). This novel digital control treats the converter as a digital system and regulates output voltage with the help of two predefined state variables. A comparator compares actual output voltage with reference voltage and then switches between appropriate states. Thus, task of the digital control is to deliver right amount of energy to the converter by right numbers of state operations so that the average power delivery matches the required power. It needs few logic gates and comparators to implement, thus, making it extremely simple and easy to develop a low cost application specific integrated circuit (ASIC) for converters driving CPLs. Simulation and analytical results are presented to describe and verify the proposed technique.