An Autonomous Power Supply System Supporting Low-Power Wireless Sensors

This paper presents a complete autonomous power supply generation system which can find application in a wireless sensor network. Every part of the system is powered only by the energy harvested by an electromagnetic transducer. Besides the transducer, the system comprehends an integrated electronic interface working as step-up ac/dc converter, a high-efficiency step-down dc/dc voltage regulator, and, finally, a load which closely replicates the characteristics of the Analog Devices ADF7242 2.4-GHz low-power transceiver, Texas Instruments MSP430 16-bit microcontroller, and Analog Devices AD7814 temperature sensor with 10-bit digital output. The core of the autonomous power supply system is the transducer's dedicated electronic interface which is designed for transferring the harvested energy to a storage capacitor and is able to process every voltage pulse coming from the transducer, providing the supply voltage for itself and the rest of the circuitry. The system will be analyzed and experimental results demonstrating the possibility of supporting a wireless communication with the harvested energy will be presented for two situations: in the first one the transducer is driven at its mechanical resonance frequency, and in the second one the same transducer is activated through the body movements of a person.