A High-Efficiency Energy Harvesting System for Low-Power Vibration Energy Sources

With the booming development of the Internet of Things (IoT), environmental energy harvesting technology has become increasingly vital. As a widely available energy source, the vibration energy harvesting system has been extensively researched in recent years. For high-voltage, low-power vibration energy sources, this article presents a self-powered energy harvesting system. We employed a piezoelectric energy transducer as vibration energy harvester, which has a relatively high-energy conversion efficiency and a small size. The presented system incorporates an active full-bridge rectifier for efficient ac–dc conversion. Compared with traditional diode-based rectifier circuits, the maximum voltage conversion efficiency (VCE) increase is 22.27%. Furthermore, to improve environmental adaptability, the design employs adaptive on time (AOT) control loop to ensure system frequency stability. Besides, when the vibration energy is weak, the proposed design can continue to harvest energy by under-voltage lockout technology. This work is implemented on an integrated circuit (IC), which is manufactured in a 180 nm bipolar-CMOS-DMOS (BCD) process. The chip area is 1.7 × 1.8 mm. The vibration energy harvesting system can drive the load directly. The experimental results show that the load regulation is 0.015% and the maximum power conversion efficiency of converter can reach 95.33%. The system is well suited for vibration energy harvesting and exhibits a high-power conversion efficiency.