| With the development of wireless sensor networks(WSN)and wireless body area networks(WBAN),micro-electronic systems are becoming more and more complex and the size of the system is becoming smaller and smaller.Traditional battery power supply is difficult to meet the long-term requirements of micro-electronic systems.In the future,the self-powered technology that harvests the energy from the surrounding environment and converts it into electricity will become one of the main power supply methods of micro-electronic systems.Among many environmental energy sources,piezoelectric energy source is often used as the main energy source of self-powered supply technology because of its high power density.Piezoelectric energy harvester(PEH)has attracted more and more researchers' attention.The design of rectifier interface circuit is the most important for piezoelectric energy harvester.However,the existing piezoelectric energy harvesting interface circuit is difficult to achieve high rectification efficiency over a wide input range,and the volume of the rectifier interface circuit is also difficult to further reduce.Therefore,the key of piezoelectric energy harvesting system is to design a rectifier interface circuit with wide input range,high efficiency and small volume.A wide input range and high efficiency parallel synchronized switch harvesting on inductor(P-SSHI)rectifier interface circuit is proposed in this thesis.The rectifier interface circuit consists of a negative voltage converter and an adaptive on-resistance active diode and combines a precise switch on-time controlled P-SSHI circuit.The traditional active two-stage synchronous rectifier has lower current detection accuracy and hardly achieves high efficiency rectification over a wide input current range.An adaptive on-resistance active diode(AOR active diode)is proposed to replace the traditional active diode to achieve higher current zerocrossing detection accuracy,improve the input current range and the output power of the rectifier.The AOR active diode allows the rectifier to maintain high rectification efficiency over a wider input current range.Further,the P-SSHI technology is also used in the thesis to realize the precise control of the turn-on time of P-SSHI circuit by detecting the switch current zero-crossing point with comparator.It achieves higher voltage flipping efficiency and improves the power extraction capability of the rectifier.The proposed circuit is fabricated in a SMIC 0.18?m standard CMOS technology and simulated under Cadence platform.The simulation results indicate that the proposed circuit achieve more than 80% power converting efficiency and its peak efficiency is 85%.The proposed P-SSHI rectifier interface circuit extracts up to 3.09 times more output power compared with a traditional rectifier.The voltage flipping efficiency of the P-SSHI circuit is up to 90%.In addition,the proposed circuit is selfpowered and capable of cold startup.The volume of the traditional P-SSHI rectifier interface circuit is difficult to miniaturize due to the usage of the off-chip inductance.Implemented in SMIC 0.18?m standard CMOS process,a rectifier interface circuit based on parallel synchronized switch harvesting on capacitor(P-SSHC)is also proposed.Switch capacitor are used in the P-SSHC circuit to replace the inductor to flip the parasitic capacitor voltage.It improves the power extraction ability of rectifier interface circuit,greatly reduces the volume of rectifier interface circuit,and is favorable for miniaturization of piezoelectric energy harvester.The post simulation results show that the voltage flipping efficiency of the P-SSHC circuit is up to 83%,the peak power converting efficiency of the P-SSHC rectifier interface circuit is 91.5%.Compared with a traditional rectifier,the proposed P-SSHC interface circuit extracts up to 2.97 times more output power.When the open circuit voltage of the piezoelectric transducer is greater than 1V,the P-SSHC circuit can realize cold start. |
PDF Full Text Request