Power quality improvement in a low-voltage DC ceiling grid powered system

Power quality is an important issue in low-voltage DC (LVDC) grids which drives light-emitting diode lighting system and many other DC loads in residential applications. The requirement of high-quality power to the lighting system necessitates power factor correction (PFC). This study presents a three-phase modular AC-to-DC converter with a simple controller for PFC in LVDC grids under balanced and unbalanced supply voltage conditions. The proposed circuit consists of three separate single-phase boost converter modules. Each module includes a diode rectifier at the front end, followed by a boost converter. The main advantage of this converter is module loss operation where the DC supply given to the lighting system and other DC loads will be continued even in case of failure of one module. The 24 V DC output voltage is regulated using an outer proportional-integral controller and the input current wave shape in each phase is improved by three individual hysteresis controllers. The controller works successfully in tracking the reference voltage changes in order to vary the regulated DC output voltage. The effectiveness of the controller has been verified by the results obtained through MATLAB/SIMULINK. A prototype model has been developed to validate this system and tested using dSPACE1104 processor.