Research And Design Piezoelectric Energy Harvesting ICs

The dependence on the battery as the only power source has become a major bottleneck for wide deployment of wireless sensor nodes.Harvesting energy from the mechanical vibration to power the nodes by using piezoelectric cantilever beam is an effective way to extend battery lifetime or to completely replace the battery.The design of a high-efficiency and low-power piezoelectric energy harvesting circuit is the key to the obtainment of the net energy,providing voltage and current levels to the load electronic devices.The major role of the energy harvesting circuit is to extract and manage the harvested energy and able to be self-powered by the energy.With the advancement of integrated circuit technology and the emergence of new ultra-low power circuit techniques,it further improves the efficiency of the electronic circuits and is a driving force of development of the integrated circuit for piezoelectric energy harvesting.This paper focuses on the piezoelectric energy harvester with the structure of the cantilever beam.From the perspective of extracting and delivery piezoelectric energy efficiently,the paper conducts research on a self-powered piezoelectric energy harvesting integrated circuit,especially in-depth study a piezoelectric energy extraction method based on a nonlinear technique and corresponding circuit.After study on the characteristics of a piezoelectric energy harvester and various commonly used piezoelectric interface circuits,a variety of self-powered integrated circuits for piezoelectric energy harvesting are designed and implemented,three of which have been taped-out and verified.The innovative works of this paper are as follows:(1)In order to solve the problem that has difficulty in controlling the synchronous switch timing accurately for the nonlinear technique,this paper presents a self-powered and optimal Synchronized Switch Harvesting on Inductor(SSHI)circuit integrated with an active rectifier for piezoelectric energy harvesting.The proposed SSHI circuit inserts an active diode on each resonant loop,which ensures flipping of the capacitor voltage at optimal times and eliminates the need to tune the switching time.The diodes of the SSHI circuit are also used as a rectifier to further simplify the controller.The circuit is implemented and verified by taped-out.Extending the circuit technique by the proposed circuit,other two integrated circuits for piezoelectric energy harvesting are presented and designed.The first circuit inserts the body diode instead of the active diode to achieve optimal flipping time to reduce the power dissipation of the diode in certain applications.The second circuit implements the proposed idle scheme of the SSHI circuit to extract energy from an ultra-low-voltage piezoelectric energy harvester.(2)A self-powered piezoelectric vibration energy harvesting circuit with an optimal flipping time SSHI and Maximum Power Point Tracking(MPPT)is presented,which integrates a SSHI circuit and a MPPT circuit.The proposed circuit has three different operation modes and it is capable of self-starting up and self-powered even if the storage elements are drained.When the piezoelectric energy harvester can provide sufficient energy,both the SSHI circuit and the MPPT circuit are activated to extract and transfer the piezoelectric energy efficiently.To reduce the power consumption of the energy harvesting circuit,five schemes are adopted including adopting asynchronous control fashion,PSM modulation,DCM operation,the use of nA level current bias and low supply voltage,and the use of dynamic circuits and active diode with ultra-low quiescent current.The circuit was implemented and verified by taped-out.(3)In order to solve the problem that the output power of the piezoelectric energy harvester is inevitably limited by the full-bridge rectifier with a filter capacitor,a self-powered integrated SSHI technique and direct AC-DC conversion piezoelectric energy harvesting circuit is proposed.The circuit achieves the SSHI operation,a direct resistive matching and AC to DC conversion.The proposed circuit was designed and simulated using the CMOS process,employing the circuit modules that have been verified in(1)and(2).The experimental results show the feasibility of the circuit.Compared to a typical SSHI circuit,the proposed circuit can increase the output power with a sufficiently high DC voltage.