An Accurate Time-Based MPPT Circuit With Two-Period Tracking Algorithm and Convergence Range Averaging Technique for IoT Applications

Abstract

This article proposes a highly efficient Time-Based Maximum-Power-Point-Tracking (TB-MPPT) integrated-circuit. Conventional TB-MPPT circuit shows unstable status (oscillation) near the Maximum Power Point (MPP), which causes the degradation of the overall power tracking efficiency. To overcome this critical issue, the proposed circuit separates the tracking operation into two periods, and it utilizes convergence range averaging technique with an adaptive perturbation step according to each control signal to accurately extract the current power level without oscillation problem. This work is fabricated in 180 nm CMOS process to demonstrate advantages of the proposed scheme. With 0.47V 12mW Photovoltaic (PV) cell, the measurement results show 94.2% of MPPT efficiency and 91.6% of power conversion efficiency (PCE). It occupies silicon chip area of 1.69 mm2.

Keywords

• Convergence range averaging technique
• dc-dc converter
• energy harvesting system
• time-based MPPT
• two-period tracking algorithm