Design and Simulation of a Direct Current Distribution System

Much effort is spent on regulating the power quality in alternating current power supplies for electronic devices. Many electronic devices however, do not use alternating current, but rather direct current. The output of most small scale renewable energy systems are also direct current, therefore it can be connected to the loads more efficiently by eliminating the inverter stage. In a circuit with a number of rectification stages the conversion losses can add up to a significant amount. By reducing the number of conversion stages or possibly eliminating some of the stages the overall system could be more efficient. The purpose of this paper is to present the simulation design and results of a direct current distribution system, containing common household appliances connected to a direct current grid supply and a renewable energy source. A bottom-up design approach is used where a list of household appliances with their voltage needs is identified and the distribution voltage is then selected based on the voltage needs. The distribution system is modeled using Matlab and Simulink software. Results show that common household loads can be supplied directly with direct current from either a main direct current supply or from a renewable energy system with direct current output. A full-load efficiency of 94.9 percent was recorded for the main supply and 78 percent for the renewable energy supply. Future recommendations are the transient state modeling of appliances and building a practical set-up in order to analyze the practical aspects of a residential direct current distribution system.