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

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.