Electronic systems are continuously growing nowadays in every ambit and application; concepts like mobile systems, domotic, wireless monitoring are becoming very common, and the reason is the continuous reduction of the energy and time needed to collect, process and send information and data to the end user. The energy management complexity of these systems is increasing in parallel both in terms of efficiency and reliability, in order to increase the lifetime of the application and try to make it energy-autonomous, thus also the power management should not be seen only as an efficient energy conversion stage, but as a complex system which can now manage different energy sources, and ensure an uninterrupted power supply to the application. The problems that must be overcome increase as the number of scenarios where the end applications have to be used: this thesis aims to present some complex power distribution systems and provide a detailed analysis of the strategies necessary to make the solution reliable and efficient.