Investigation of the Rectifiers Responses Affecting the Operational Bandwidth in the Electromagnetic Vibration Energy Harvester

Wireless sensor nodes (WSNs) have attracted much attention in recent years as a device that can be used for structural health monitoring. Most of the WSNs are used battery as a source of power supply and the energy will be depleted over the time. The self-power WSNs play an important role and electromagnetic vibration energy harvesters (EMVEHs) is one of the options for the continuous energy supply. As an important component of the electromagnetic vibration energy harvesting system, rectifiers play an important role in the entire system which convert the AC power generated by vibration into DC power. The basic half-wave rectifier consists of a rectifier diode, a filter capacitor, and a load, while the basic full-bridge rectifier is composed of four rectifier diodes, a filter capacitor, and a load. Compared to commonly adopted full-bridge rectifiers, half-wave rectifiers are often not favored by researchers due to their inability to obtain full cycle AC power. However, limited researchers focused on the cantilever beam type electromagnetic vibration energy harvester, half-wave rectifiers may exhibit more advantages than full-bridge rectifiers in some cases. This paper presented an equivalent circuit model of the harvester derived from mechanical parameters, and then verifies the feasibility of the rectifier circuit applied to the harvester using finite element simulation software. The experimental results present the performance of two circuits under different sweep mode condition and the comparative analysis on the maximum power and bandwidth is studied. The results indicate that although the ripple coefficient of the half-wave rectifier is greater than that of the full-bridge circuit, it exhibits certain advantages in bandwidth and maximum power. Finally, a preliminary analysis of the mechanism of the experimental phenomenon is provided.