Research And Design Of Continuous MPPT Optimized High-efficiency Piezoelectric Energy Harvesting System

With the increasing demand for the technical requirements of portable products and the number of devices,the Internet of Things technology has developed rapidly.Among them,the battery-based power supply system cannot meet the users’ requirements due to its large size,high cost and the need for regular replacement.Thus,an energy harvesting system with low power consumption has gradually shown its necessity.Piezoelectric energy,as a typical energy widely existing in the natural environment and human activities,has a huge market prospect when it is collected and used to supplement or replace batteries through energy harvesting technology.In this paper,the energy harvesting system is researched and designed for piezoelectric energy.The designed system uses a BUCK-BOOST converter as a power stage to adapt to the large input energy source range,and it has an optimized continuous maximum power point tracking function.The traditional MPPT module works every few cycles or a fixed time to detect and track the maximum power point.This method cannot closely follow the changes of the input,and will produce relatively large power consumption when the input energy source is stable for a long time.This paper proposes an event-driven mechanism,which will trigger the MPPT module to re-track the maximum power point only when the input energy source’s state changes.It can follow the changes of input source continuously and in real time,which greatly saves power consumption.The traditional open-circuit voltage method needs to disconnect the connection between the input source and the power stage at regular intervals for opencircuit voltage sampling,resulting in switching loss and energy loss during the switch-off period,and cannot respond to changes in the input source in time.In this paper,the ripple correlation related control scheme for the BUCK-BOOST converter is used instead of the traditional open-circuit voltage method and a specific circuit is designed and implemented without intermittently disconnecting the switch,avoiding power loss and speeding up the response.The piezoelectric energy harvesting system studied and designed in this paper is implemented in circuits with low power consumption.Therefore,the MPPT module,the main topology circuit structure and other sub-module circuits such as rectifier interface circuit,differentiator,operational amplifier,comparator,current-limit module,reference module and event-driven module all adopt low-voltage and low-power structure for design improvements to reduce the system’s power consumption and improve the efficiency.This paper uses the Spectre simulation tool for overall topology design and construction,and based on the 180 nm BCD process for system detail design and submodule construction.Finally,each module and the overall system are simulated and verified.The simulation results show that the system achieves a real-time performance and adaptive MPPT technology.The tracking time is about 30 ms,the average tracking accuracy of the maximum power point is as high as 87.0%,and the transmission efficiency of the system is 84.2%.It also verifies the design concept that the MPPT module only works when the input source changes.A piezoelectric energy harvesting system with low power consumption and high efficiency is truly realized.