A Multi-mode Boost Converter For TEG Energy Harvesting

Wireless sensor networks(WSNs)are widely used and rapidly developed.They monitor and collect various information.The information is analyzed and processed through WSNs nodes.Finally,this information is transmitted to the smart terminal through a radio frequency transceiver.WSNs nodes are mostly powered by traditional batteries,but this method gradually exposes problems such as poor endurance,large size,and serious pollution.Therefore,the acquisition of environmental energy instead of batteries to power WSNs nodes has become a research hotspot.The energy in the environment includes thermal energy,solar energy,vibration energy and radio frequency energy.The thermal energy density is relatively stable and large,which is very suitable for wearable applications.However,when the temperature difference between the person and the environment is low,the energy obtained by the system is extremely small.The open circuit voltage of a thermoelectric generator(TEG)can be as low as a few ten millivolts.Therefore,it is necessary to design a high-performance Boost converter.At present,the research focus of scholars is mainly on reducing the open-circuit voltage,improving the peak efficiency and solving the problem of self-start.This paper proposes a multi-mode low-power Boost converter for thermoelectric energy harvesting,which minimizes the minimum input voltage,reduces power loss,and improves power conversion efficiency.According to the different input voltages,the converter can work in three working modes,which are discontinuous conduction mode(DCM),critical conduction mode(CRM)and continuous conduction mode(CCM).The maximum power point tracking circuit(MPPT)corresponding to the operating mode is designed to maximize energy transmission and improve power conversion efficiency.When the converter input voltage range is 10 m V-40 m V,the circuit adopts DCM working mode,and MPPT adopts constant peak current control.When the input voltage range is 40 m V-100 m V,the converter adopts CRM mode for transition,and MPPT adopts constant on-time control.When the input voltage range is 100 m V-500 m V,the converter adopts CCM working mode,and MPPT adopts multiplexing mode with CRM mode MPPT.In order to improve the circuit robustness and reduce the design complexity,this paper designs a high-performance offset calibration comparator for inductor current detection,which can be multiplexed in the three working modes of DCM,CRM and CCM.Finally,the combination of solar pre-charging and low voltage startup solves the startup problem of Boost converter.This article is based on SMIC 0.18?m standard CMOS process and uses Cadence Spectre simulation tool to perform post-simulation verification on the designed Boost converter.The post-simulation results show that the input voltage range of the Boost converter designed in this paper can reach 10 m V-500 m V,and the output voltage regulation is about 1.4V.The input range of the converter in DCM mode is 10 m V-40 m V.The load current at 10 m V input voltage is 1.33?A.The static power consumption is 1.5?W,and the conversion efficiency can reach 39%.The input range of the converter in CRM mode is 40 m V-100 m V.The load current at 60 m V input voltage is 112.2?A.The static power consumption is 12?W,and the conversion efficiency can reach 80.6%.The input range of the converter in CCM mode is 100 m V-500 m V.The load current at 280 m V input voltage is 2.41 m A.The static power consumption is 41?W,and the conversion efficiency can reach a peak value of 93.6%.