Hybrid start-up strategy for low voltage electromagnetic energy harvesting systems

In this paper, a new strategy to provide start-up energy for low voltage energy harvesting systems is presented. There has been a lot of interest in electromagnetic microgenerators due to their high energy density for low power harvesting. However, they exhibit extremely low voltages of the order of few hundred millivolts AC. In recent years, a number of converters have been presented that can boost such low voltages to satisfy the load end requirements (1.8-3.3V DC). A key limiting factor has been a lack of proper start-up strategy for such systems. The present work involves the use of a hybrid set-up consisting of a piezo-strip to provide sufficient voltage for the start-up operation of the converter. An auxiliary DC supply is designed for the boost converter. The operation of this circuit is verified first using a battery and then, using the hybrid set-up. Simulation and experimental results are presented to verify the proposed system.