Contactless battery charger controller for wireless sensor node

Wireless sensor network nodes have been used to collect data from processes in several different areas. In most cases, these sensors and their batteries need to be recharged regularly. However, these sensors are often deployed in harsh environments that can damage them with moist and dust particles. Therefore this work aims to present a contactless inductive charger developed to avoid jack or plug holes on the sensor casing in order to prevent damage to its circuitry. This battery charger uses a resonant topology circuit and an algorithm to adjust the resonant frequency. Unlike a previous work, it measures the current through the primary coil to determine the optimal point, which yields a simpler solution. The concept has been proven to be effective while keeping low cost and simplicity, which are important aspects to wireless sensor networks.