Energy Harvesting Circuit Using Variable Capacitor with Higher Performance

Abstract

The search for compact autonomous devices has been increasing in the microelectronics industry. These devices have the capacity to generate their own energy in order to be charged. One of the ways of harvesting environmental energy for charging such devices is by using mechanical vibrations through the use of variable capacitor. Taking this principle into account, this work presents a behavioral analysis of a system model of harvesting vibratory energy for low power, made up of a circuit which includes a variable capacitor. An architecture of a circuit which improves the relation concerning the amount of harvested energy/circuit area in relation to conventional architectures is also presented as well as a comparison between the circuit with the proposed architecture and the conventional circuit. In this way, it was verified that, under the same functioning conditions, the conventional circuit harvested a maximum power of 4,5 μW whereas the circuit with the new architecture harvested a 6,25 μW power.

Theoretical analysis of electrostatic energy harvester configured as Bennet's doubler based on Q‐V cycles

“…Among electronic interface circuits for MEMS capacitive energy harvesters, 25,26 the charge pump circuit 6 and its varieties are widely investigated. A well-known charge pump variation that combines with an inductive flyback circuit was developed by Yen et al 8 An alternative technique to implement flyback is to use a load resistance, which was first introduced in Florentino et al 27 and thoroughly analyzed in O'Riordan et al 23 Comparing the results reported in the literature with those obtained in the first sections of this paper, it is worth noting that the Q-V cycle for the charge pump circuit with resistive flyback is very similar to that of Bennet's doubler circuit. Both the charge pump and voltage doubler can be approximated by a rectangular conversion cycle in the ideal circumstance in that the electrical loss is neglected.…”

“…Among electronic interface circuits for MEMS capacitive energy harvesters, 25,26 the charge pump circuit 6 and its varieties are widely investigated. A well‐known charge pump variation that combines with an inductive flyback circuit was developed by Yen et al 8 An alternative technique to implement flyback is to use a load resistance, which was first introduced in Florentino et al 27 and thoroughly analyzed in O'Riordan et al 23 …”