An Adaptive Fractional Voltage MPPT With the Exponential Sliding AC Voltage and Current Controllers for Enhanced Power Processing Integrity

In this work, a novel adaptive fractional open circuit voltage (AFOCV) MPPT algorithm is devised for a grid-connected inverter, aiming to optimize power processing integrity and enhance energy yield amid fluctuating irradiance and temperature. The proposed algorithm incorporates adaptive solar constant updates to accommodate environmental uncertainty. Additionally, a novel control mechanism is introduced for voltage and current controllers to improve grid-injected current quality while minimizing voltage deviations on the DC side. This mechanism employs a modified exponential reaching law to approach the proposed sliding surface. The modified control tracks the voltage and current error based on the designed sliding surface to achieve the steady-state voltage and current reference. The proposed sliding surface additionally enhances coordination between inner and outer loops, ensuring smoother operation. It also improves dynamic response when tracking voltage and current references. Further, the effectiveness of the proposed algorithm, coupled with the novel controller, is compared with conventional methods, showcasing its superior performance under diverse environmental conditions. Moreover, the effectiveness of the AFOCV algorithm, coupled with the proposed controller for the solar grid-connected inverter, is experimentally validated on the developed prototype in the laboratory. This validation involves replicating various environmental conditions using a solar emulator.