Ultra Low Voltage Boost Converter Design For Energy Harvesting With Synchronous Rectification

With the rapid development of the Internet of Things and wireless sensor network,the limitation of battery power supply system are more obvious.Since wireless sensor nodes may be applied in remote places,the replacement of battery power supply system is inconvenient and potentially dangerous.Therefore,harvesting energy from the environment could be a wonderful solution.Moreover,compared with the traditional battery charging systems,energy harvesting utilizes renewable energy sources such as vibration,heat,friction and solar,which are more environmental friendly.As a result,energy harvesting has been paid more and more attention.Based on the previous researches and innovation,this paper proposes a transformer-based with high-efficiency energy collection circuit,which combines transformer and synchronous rectification to collect and convert the energy from environment into electricity for wireless sensor networks.This design is suitable for the collection of heat and solar.The input voltage ranges from 200 mV to 800 mV.Self-starting is realized through resonant oscillation in the system.This paper adopts parallel MOS control mechanism which utilizes one depletion MOS and one enhancement MOS to reduce the mean current for self-resonant oscillation.At the same time,as the input voltage reaches to a fixed value,the system will be shifted to synchronous rectification mode which can reduce the loss of the process.Compared with Schottky diode modulation in conventional design,a negative feedback loop is used to realize output modulation to avoid energy waste when the energy source is sufficient.Therefore,the energy harvesting system can reach a high conversion efficiency during the whole input voltage range.Meanwhile,an energy storage block is added.When energy from the external environment is enough,the excess energy will be stored to Cstore in advance.The stored energy will be supplied to the output for a short time when the energy supply is out of order.to ensure the reliability and practical application of the system.This paper uses VIS 0.40 ?m BCD technology.It focuses on the conversion efficiency of the system during the whole input voltage range.The control system is composed of self-resonant oscillation control,energy storage control and synchronous rectification control.Candence Virtuoso software is used to simulate the system results.Through simulation,it can be concluded that the design within the range of 200mV-800 mV input voltage,can realize 3V output voltage,20 mA maximum output current.Meanwhile,the overall efficiency of the system can reach to 53%.