A Time-Based Direct MPPT Technique for Low-Power Photovoltaic Energy Harvesting

Abstract

This letter introduces a maximum power point tracking (MPPT) technique for photovoltaic (PV) energy harvesting (EH) systems to enhance the end-to-end efficiency (ηE-E) when the output power of PV cell (PPV,MAX) is low. A ripple-based PV cell current sensing and a time domain multiplication are proposed to monitor the PV cell power delivered to the charger, which reduces the controller power consumption (PCTR). The PV EH system with the proposed MPPT method is implemented in a 180-nm CMOS process. The PCTR is 1.34 μW. The measured ηE-E at low PPV,MAX (13 μW) is 88%. The measured peak ηE-E is 94.4% at 82 μW. IEEE