Self-Powered 30 µW to 10 mW Piezoelectric Energy Harvesting System With 9.09 ms/V Maximum Power Point Tracking Time

Abstract

A piezoelectric (PE) energy harvesting system with one-cycle maximum power point (MPP) sensing is presented. The one-cycle MPP sensing method uses a very small size sensing capacitor and it can make the transducer output voltage reach the open circuit voltage within one cycle. The proposed MPP sensing block can sense the open circuit voltage with a proposed peak detector and stores the MPP voltage using charge sharing blocks. The one-cycle MPP sensing approach simplifies the design of an MPP tracking algorithm and greatly reduces the tracking time. All control blocks are self-biased and choose the higher voltage between the input or output voltages of the switching converter as a supply voltage (V $_{DD}$ ). Therefore, a voltage multiplexer and a low-power ramp generator with V $_{DD}$ independence are also proposed to control the system without additional DC to DC converter. The entire system has been implemented in a 0.35 µm BCDMOS process. It operates at 90 kHz with a 10-mH inductor. The total power dissipation of the controller is 10 µW at a V $_{DD}$ of 2.7 V. The MPP tracking time is only 9.09 ms/V when the input voltage of the switching converter is changed from 3.4 V to 1.2 V.