Research On AC-DC Circuits Of Self- Powered Wireless Sensor Network Nodes

Wireless sensor networks have been rapidly developed due to their advantages such as high efficiency,wide coverage,ease of deployment,and self-management,while power supplies have restricted the development of wireless sensor network nodes.Batteries are not suitable for wireless sensor nodes because of their limited capacity and they are not easily replaced.Although self-powered wireless sensor nodes can continuously source energy from the surrounding environment and convert it into electrical energy,the output power of the energy harvesting device is limited in a limited space.Therefore,the node's power conversion circuit becomes a determinant factor for whether the node can work stably for a long time.It is of great significance to study highperformance and high-efficiency power conversion circuits.In this paper,for the self-powered sensor node of AC power generation,the ACDC circuit for wireless sensor network node is developed,and a control chip for AC-DC circuit is designed.This paper focuses on the characteristics of low operating voltage and low power in wireless sensor nodes.It adopts a flyback structure and uses PWM loopback control to improve system stability and response speed based on PWM modulation mode.At the same time,it uses primary feedback technology to improve system integration degree.Based on this,this paper designs the solution of AC-DC circuit,designs and analyzes the peripheral devices of AC-DC circuit,puts forward the design structure and design index of converter chip.And according to the actual application of converter chip,the 0.35 ?m BCD process was selected.Afterwards,the main module circuits inside the converter chip are designed and analyzed.These include low-temperature bandgap reference voltage modules,linear low-dropout regulators without off-chip compensation capacitors,undervoltage-latch modules,the secondary side conduction time detection circuit of the side feedback,the temperature compensation and over-temperature protection module used simultaneously for feedback voltage temperature compensation and chip overtemperature protection,and the oscillator module with oscillating frequency load adjustable.The simulation results show that each module circuit meets the design index requirements.Based on the selected 0.35 ?m BCD process,the AC-DC integrated circuit designed in this paper was simulated using Cadence software's Spectre tool.In a typical application,the maximum output ripple is 133.7mV,the linear regulation is 0.41%/V,the load regulation is 13.02%/V,and the conversion efficiency is up to 87% at 12 V AC input.The overall simulation results are in line with the overall circuit design specifications.Finally,the layout of the circuit that has passed the simulation verification is designed.