Novel power conditioning circuits for piezoelectric micro power generators
generators (MPGs) to replace the batteries to power them. Due to the trend in
decreasing integrated circuit (IC) supply voltages, power supply designers are facing
more and more serious challenges. The objective of this research is to design a power
conditioning circuit (PCC) for use in conjunction with low voltage
microelectromechanical systems (MEMS)-based Palouse Piezoelectric Power (P3)
micro heat engine power generation systems. The PCC enables maximum power
extraction from a piezoelectric MPG. The proposed PCC includes a rectifier stage and
a regulator stage. The rectifier stage is based on the synchronous rectification
technique. The dc-dc regulator is a charge pump-based step-down converter.
Interleaved discharge (ID) is proposed to reduce the output voltage ripple
significantly, without sacrificing the converter efficiency. The proposed step-down
charge pump is analyzed with state-space averaging.
In order to facilitate the PSpice simulation of the lead zirconate titanate (PZT)
membrane, a simplified PZT model was developed. Both the rectifier and the charge
pump are simulated with PSpice. Simulations show that the interleaved discharge method takes full advantage of the step-down charge pump structure, and provides
flexibilities to the design of step-down charge pumps. The designed 200mW 5V/1.2V
charge pump has an efficiency of 92.2%, with reduced output ripple. Proof-of-concept
demonstration of the proposed PCC includes a 4-stage completely passive charge
pump driving an analog wristwatch, proving proper operation of the entire P3 micro
A maximum output power of 18.8mW has been extracted from a single
piezoelectric MPG, with 92% efficiency in the rectifier stage. Arbitrary waveform
generator representation (AWGR) of the piezoelectric membrane is also presented.
AWGR facilitates ongoing tests and demonstrates the feasibility of cascading many
MPGs to extract additional power.
Advisor:von Jouanne, Annette; Dietterich, Thomas G.; Mayaram, Karti; Liu, Huaping; Wallace, Alan K.
School:Oregon State University
School Location:USA - Oregon
Source Type:Master's Thesis
Keywords:electric generators power electronics microelectonics microelectomechanical systems
Date of Publication:10/31/2003