Vibration and Thermal Energy Harvesting System for Automobiles with Impedance Matching and Wake-up

This paper presents a system for vibration and thermal energy harvesting from automobiles, and it intends to power wireless sensor nodes. Two main features of the proposed circuit are impedance matching to extract maximum power and wake-up to incorporate sleep mode. Two separate buck-boost converters in discontinuous conduction mode are used for impedance matching. A wake-up circuit senses the vibration energy generated by a piezoelectric cantilever (PZT). When a car is turned off, the wake-up circuit deactivates the two converters, and the entire circuit goes into sleep mode to save power. The proposed circuit charges a capacitor to power a wireless sensor node, and is able to cold start. The proposed circuit is prototyped with discrete components. Experimental results show that the proposed system harvests peak power of 3.4 mW and these results also demonstrate that a wireless sensor node can be powered by the proposed system.