Power conservation is an important factor in many electrical systems, such as but not limited to, wireless sensor networks (WSNs) that operate according to low power requirements and low data rates. Long battery life (e.g., up to 10 years) is essential in such systems where line power is not available or if the system is mobile in nature. In many applications, however, utilizing and replacing batteries, even long-lived battery types, is impractical due to factors such as, but not limited to, hard-to-access locations, and labor and replacement battery costs. Accordingly, solutions have been sought for harvesting or extracting electrical power from the environment.
Energy harvesting devices can be utilized to collect and convert environmental energy into electric energy for supporting electrical components, devices and/or systems, thereby eliminating the need for batteries. One example of an energy harvesting device or system is a cantilever(s) with Lead-Zirconate-Titanate (PZT) film(s), which can convert vibration energy in an environment into electrical energy. Piezoelectric materials can be utilized as a means for transforming ambient vibrations into electrical energy, which can be stored and used to power other devices. With the recent surge of microscale devices, piezoelectric power generation can provide convenient alternative to traditional power sources used to operate certain types of sensors/actuators, telemetry and MEMS devices. The energy produced by these materials in many cases, however, is much too small to directly power an electrical device. Therefore, the majority of research into power harvesting has focused on techniques for accumulating the energy until a sufficient amount is present, thereby allowing the intended electronics to be powered.
One single cantilever can only function in a single frequency and produces a very limited power output. The cantilevers must be connected to a cantilever array to overcome these problems. When the cantilevers are electrically connected directly, however, the AC electrical power from different cantilevers can be counteracted as they have different phases. The connection method thus cannot achieve ideal results.
A prior art representation of a connection configuration currently used in electrical connection circuitry of an energy harvesting system 100 is illustrated in FIG. 1A. The block diagram depicted in FIG. 1A shows a capacitor 101 connected in series with one or more other capacitors 107, 109 and so forth. A signal can be provided to an AC/DC converter 102 to attain a high voltage output 103. In the prior art configuration depicted in FIG. 1A, the output from different cantilevers counteract.
Another prior art connection configuration currently utilized in the electrical connection circuitry of an energy harvesting system 100 is illustrated in FIG. 1B. Note that in FIGS. 1A-1B, similar or identical parts are generally indicated by identical reference numerals. Thus, a block diagram depicted in FIG. 1B illustrates capacitor 101 connected in parallel with capacitors 107, 109 and so forth. A signal can be provided to the AC/DC converter 102 to attain a high voltage output 103. In the configuration of system 100 depicted in FIG. 1B, the output from different cantilevers can also counteract.
Based on the foregoing, it is believed that a need exists for an energy harvesting device that overcomes such problems. It is believed that the system and method disclosed herein provides a solution to these problems by offering a configuration in which a DC output can be attained by rectifying an AC output from a cantilever array and DC output terminals are connected in parallel or in series to achieve a higher voltage or current output such that the output from different cantilevers cannot be counteracted.