Quick self-start and minimum power-loss management circuit for impact-type micro wind piezoelectric energy harvesters

This paper proposes a new minimum power-loss management circuit with a quick self-start function, for effective power use from an impact-type micro wind piezoelectric energy harvester. The free tip of the piezoelectric cantilever harvester is excited by a miniaturized wind blade. A smart power management strategy is required for efficient saving and use of the energy generated from the random natured and small scaled wind. We propose a new small scale power management circuit composed of three sub-circuits. First, we have taken a resistive impedance matching strategy because the transient response of the harvester vibrates at the natural frequency and the corresponding impedance is almost time invariant. Second, we have designed a wake-up circuit with quick self-start function, for the timely activation from sleep mode. When the circuit detects the input energy, it rapidly self-starts, adaptively controls the operation mode, and charges load battery. Lastly, an overvoltage protection circuit with sleep function is designed for effective power storage. Measurement results demonstrate that the start-up time is approximately 1 ms for a wind speed of 1.5 m/s and that the maximum efficiency of the proposed circuit is 77% for a wind speed of 3.5 m/s. A commercial wireless sensor is successfully powered with the proposed energy harvesting system, demonstrating its potential application to the Internet of Things.