Adaptive Maximum Power Point Tracking With Model-Based Negative Feedback Control and Improved V–f Model

Abstract

This brief presents the model-based negative-feedback-control (NFC) for maximum power point tracking (MPPT), with an improved V- f model including the switch turn-on resistance in the switched-capacitor (SC) converter. The method is more efficient than the conventional simulation-based method to obtain the target V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> T</sub> - f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> T</sub> curve of the solar energy harvesting system (EHS). Meanwhile, this brief compares two different MPPT schemes: maximum input PPT (MIPPT) and maximum output PPT (MOPPT). We find that MOPPT is more suitable for maximizing the utilization of solar energy. This design, implemented in 0.18 μm CMOS and measured with a 4 ×4 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> solar cell, exhibits an improved V- f model with an average tracking error of 0.47% for the MOPPT. MOPPT transfers more power to the load circuits than MIPPT and achieves a peak efficiency of 90.3% at 3k lux.