Uma Dharmalingam

The demand for electricity is rapidly growing and renewable energy sources such as solar, wind and tidal energy can compensate the demand to a substantial level. Among these, solar energy is abundant, scalable and is cheaper. The generated energy can be used in an efficient way if the DC output is directly supplied to the load instead of converting it to AC. Every electrical system is capable of operating in DC and, for example, energy efficient Light Emitting Diode (LED) lights have become popular as they provides more lumens with less power consumption and also can be directly operated from DC. LED lighting system in large commercial buildings has irradiance levels which vary sigificantly during operation. Extracting maximum power from the energy system and maintaining constant voltage output at different loads is another challenge. This paper proposes a solar Photo Voltaic (PV)-based energy system including Battery Energy Storage System (BESS) for supplying LED lamps to a commercial building through a modified high gain Luo converter. The Perturb and Observe control algorithm has been used for maximum power extraction from a PV cell whereas PI (Proportional Integral) controllers maintain constant output voltage from PV–BESS against different irradiance levels. To supply the desired voltages to the LED lighting system, a modified high gain Luo converter is designed. To make the output voltage constant at different load currents, PI and Sliding Mode Controllers (SMC) are designed with the help of the state-space average model. It is found that the sliding mode controller outperforms the PI controller in terms of behavior in the transient period and tracking capability. The system is simulated using MATLAB/Simulink^®. The Sliding Mode Controller has a 95% less transient period and is 75% faster in tracking capability when compared to other controllers. The system could be incorporated with the PV source to obtain green energy.

Multilevel inverter (MLI) is the recent advancement in power electronics which employed to synthesize a high-quality output voltage waveform. This paper focuses on developing a single phase modified nine-level inverter with the reduced number of switches for improving the quality of output voltage waveform. Single carrier and multireference Pulse Width Modulation (PWM) technique is utilized for generating the switching pulses. The proposed topology consists of a single DC source, level generation part (balancing capacitor and bidirectional switches) and polarity generation part (H-Bridge). The operation of the proposed topology is examined for generating 9-level output voltage using MATLAB/SIMULINK. The result of the proposed topology is verified through laboratory-based prototype model. For experimental setup, the switching pulses are generated by PIC16F877A microcontroller. This proposed lab experimental and simulation can be used to study the value of %THD at output side of the inverter.