This paper presents a low-profile and autonomous piezoelectric energy harvesting system consisting of an extraction rectifier and a maximum power point tracking (MPPT) circuit for powering portable electronics. Synchronized switch harvesting on capacitor-inductor (SSHCI) technique with its unique two-step voltage flipping process is utilized to downsize the ponderous external inductor and extend application areas of such harvesting systems. SSHCI implementation with small flipping inductor-capacitor combination enhances voltage flipping efficiency and accordingly attains power extraction improvements over conventional synchronized switch harvesting on inductor (SSHI) circuits utilizing bulky external components. A novel MPPT system provides robustness of operation against changing load and excitation conditions. Innovation in MPPT comes from the refresh unit, which continually monitors excitation conditions of piezoelectric harvester to detect any change in optimum storage voltage. Compared with conventional circuits, optimal flipping detection inspired from active diode structures eliminates the need for external adjustment, delivering autonomy to SSHCI. Inductor sharing between SSHCI and MPPT reduces the number of external components. The circuit is fabricated in 180 nm CMOS technology with 1.23 mm ² active area, and is tested with custom MEMS piezoelectric harvester at its resonance frequency of 415 Hz. It is capable of extracting 5.44x more power compared to ideal FBR, while using $100~\mu $ H inductor. Due to reduction of losses through low power design techniques, measured power conversion efficiency of 83% is achieved at 3.2 V piezoelectric open circuit voltage amplitude. Boosting of power generation capacity in a low profile is a significant contribution of the design.

中文翻译：

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压电微发电机的薄型自主接口电路

本文提出了一种薄型自主压电能量收集系统，该系统由提取整流器和最大功率点跟踪（MPPT）电路组成，用于为便携式电子设备供电。电容器电感器上的同步开关收获（SSHCI）技术及其独特的两步电压翻转过程可用于减小繁琐的外部电感器的尺寸并扩展此类收获系统的应用范围。与小型翻转电感器-电容器组合一起使用的SSHCI实现提高了电压翻转效率，因此与使用大型外部组件的电感器（SSHI）电路上的常规同步开关采集相比，功率提取得到了改善。一种新颖的MPPT系统提供了针对变化的负载和励磁条件的鲁棒性。MPPT的创新来自刷新单元，该单元不断监控压电收割机的激励条件，以检测最佳存储电压的任何变化。与传统电路相比，由有源二极管结构激发的最佳翻转检测消除了对外部调整的需要，从而为SSHCI提供了自主权。SSHCI和MPPT之间的电感器共享减少了外部组件的数量。该电路采用1.23 mm的180 nm CMOS技术制造 SSHCI和MPPT之间的电感器共享减少了外部组件的数量。该电路采用1.23 mm的180 nm CMOS技术制造 SSHCI和MPPT之间的电感器共享减少了外部组件的数量。该电路采用1.23 mm的180 nm CMOS技术制造 ^2个有源区域，并使用定制的MEMS压电采集器在415 Hz的谐振频率下进行了测试。在使用时，与理想的FBR相比，它能够提取出5.44倍的功率 $ 100〜\ mu $ H电感器。由于通过低功耗设计技术降低了损耗，因此在3.2 V压电开路电压幅度下可实现83％的测量功率转换效率。薄型地提高发电能力是该设计的重要贡献。