A Thermoelectric Energy-Harvesting Interface With Dual-Conversion Reconfigurable DC–DC Converter and Instantaneous Linear Extrapolation MPPT Method

Abstract

This article presents a thermoelectric (TE) energy- harvesting interface with a reconfigurable dc–dc converter and a time-based instantaneous linear extrapolation (ILE) maximum power point tracking (MPPT) method. The proposed reconfigurable dc–dc converter comprises five switches for buck–boost operation and an additional switch for a dual- conversion mode in which battery power and TE generator (TEG) power are extracted in one cycle; therefore, the improved power density is achieved. The proposed ILE MPPT algorithm does not require TEG disconnection from the dc–dc converter, ensuring continuous TE energy extraction. The proposed MPPT method modulates the open-circuit voltage of TEG by performing linear extrapolation with a fully integrated circuit based on the steady-state voltage ripple information. The proposed interface is fabricated using a 180-nm CMOS process. The peak end-to-end efficiency of 90.48% is achieved with 0.2-V input voltage. The MPPT errors are measured up to 2.0% for the input capacitance variation and up to 1. 067% for the equivalent resistance of TEG variation.