Research And Design Of Very Low Voltage Boost DC-DC Converter Chip For Thermoelectric Energy Harvesting

With the advancement of the Internet of things(Io T),the number of small devices such as wearable devices and wireless sensor nodes is increasing rapidly and the volume is smaller,which makes users put forward higher requirements for power supply schemes.The traditional lithium battery power supply has the disadvantages of difficult replacement,inconvenient main-tenance and so on.Therefore,the power management scheme of self-power supply through energy harvesting has gradually become a research hotspot.Because the energy that can be col-lected by the energy collector is often weak,and the voltage generated by it is low and unstable,it can not be directly used as the power supply voltage of subsequent electrical appliances.It is necessary to use a boost converter as a bridge between the energy source and the power supply equipment.Based on the thermoelectric energy harvesting for passive Io T,this paper proposes a very low voltage boost DC-DC converter,analyzes the circuit implementation,power loss and work-ing mode.The innovations about the challenges of an ultra-low-voltage start-up,high effi-ciency,and minimum working voltage are as follows:Firstly,the circuit adopts a two-stage pre-boost auxiliary boost converter structure with single inductor multiplexing,which can boost quickly from 155-m V low voltage to 520-m V output within 22-ms.Without additional special devices,the proposed circuit have a output sufficient power,a higher integration and lower cost.Secondly,the open-circuit voltage method is used for the MPPT circuit.The fully digital adaptive coarse and fine frequency modulation circuit reduces power consumption,and the average tracking accuracy is greater than 94%.The wide voltage tracking range of 30m V-300m V is realized,so that the boost DC-DC converter can still extract the maximum energy from the energy source under changeable environment and load.At the same time,a fixed time sampling circuit is proposed to reduce the ripple of V_{OU T}.With the output power of 125?W,the output voltage ripple is only 22-m V.Thirdly,the clock with multiple duty cycle output circuit is proposed,which is applied for the zero current sensing(ZCS)circuit.While stabilizing the output,it can effectively suppress the reverse current.The structure of step-by-step boost is proposed to reduce the loss,which improves the energy conversion efficiency with the constraint of very low voltage.Based on Globalfoundries 0.18?m CMOS process,this paper has carried out simulation results and layout drawing of the proposed boost DC-DC converter,which has been sent to the process factory for production.The circuit realizes the minimum starting voltage of 155-m V.After the system is started,it can operate as low as 15m V.Besides,the ZCS scheme combined with MPPT obtains high efficiency of 71%at the 80m V input voltage.When the input voltage is300m V,it outputs the maximum power of 540?W,and finally stably outputs a voltage of 1.25-V to supply power to other subsequent devices.The boost DC-DC converter proposed in this paper has the characteristics of low-voltage self starting,high integration and low power consumption.It is suitable for thermoelectric energy harvesting system and has a wide application prospect in the field of energy management of passive Io T.