Fast Maximum Power Point Tracking Technique With 4-Bits/Cycle SAR ADC For Photovoltaic Energy Harvesting System

This paper presents a photovoltaic(PV) energy-harvesting system with fast maximum power point tracking (FMPPT) circuit that utilizes 4-bit successive approximation register analog to digital converter (SAR ADC) suitable for solar cells. Solar Panel's output power depends on switch duty ratio of inductive-boost DC/DC converter. Usability of 4-bit/cycle SAR ADC to adjust duty ratio is proved through the measurement, using conventional Pulse Frequency Modulation (PFM) boost converter. This circuit achieves short tracking time of 4-cycle in order to reach the MPP and high MPPT efficiency of 99.5 %, while consuming the low power. The switches and control stages were implemented into 0.18-um CMOS process, and a chip size is 2.13 x 1.66 mm(2).