20.6 Electromagnetic vibration energy harvester interface IC with conduction-angle-controlled maximum-power-point tracking and harvesting efficiencies of up to 90%

An electromagnetic vibration energy harvester (EMH) is an electromechanical mass-spring-damper system transducing electrical energy out of ambient vibrations. Resistive load matching [1] as well as maximum power point (MPP) AC-DC conversion [2] are highly suitable techniques for enhancing the electrical energy output of an EMH. The presented interface IC (Fig. 20.6.1) enables MPP AC-DC conversion by tracking the optimum conduction angle and by employing a hysteretic input voltage controlled inductive DC-DC boost converter. All control signals are derived from the harvester voltage itself. Thus, no additional sensor, harvester disconnection, or DC-DC converter duty-cycle control are needed. Additionally, the implemented voltage conditioning provides over-voltage protection (OVP) and application voltage regulation (VR).