Research And Design Of Reverse Polarity Input Multimode DC-DC Converter

The rapid development of Internet of Things（IoT）technology in the past decade has increased the demand for self-powered,long-life,and small wireless sensor systems,which has led to extensive research on device energy harvesting solutions.Wearable and implantable biomedical electronic devices typically require energy self-sufficiency,miniaturization,biocompatibility,and high energy efficiency.However,for most biomedical systems,the design of energy harvesting solutions is still challenging due to their limited size and relatively low available energy extracted from the environment.Among the energy collection systems applicable to the biomedical field,thermoelectric energy collection systems（TEGs）can provide the highest output power density^[39]（100μW/cm³）at the micro-scale compared to other energy source collection systems（RF energy collection,piezoelectric energy collection,photovoltaic energy collection）,but the energy provided by the system cannot be sustained stable against unpredictable changes in external environmental temperature.Therefore,this paper presents a reverse polarity input multi-mode DC-DC thermoelectric energy collection converter.Traditional thermoelectric cells can only collect positive input voltages,which means that one end of the thermoelectric cell must be at a higher temperature.To address this issue,a compatible positive and negative temperature difference thermoelectric energy collection architecture is proposed,solving the problem of single polarity input voltage in traditional weak energy collection systems in biomedicine.This improves the energy collection density of the power management system per unit time,expands the input power range through reverse polarity input,consolidates the stability of the equipment in complex temperature environments,and effectively broadens the application of thermoelectric energy collection devices.The reverse polarity input multi-mode converter proposed in this paper extends the traditional Harvest-Use architecture to the Harvest-Use and Store architecture,enabling continuous energy collection.Under light or no load conditions,excess energy is stored in a supercapacitor for use when the input source energy is insufficient.Under heavy load or overload conditions,intermittent discharge of the supercapacitor ensures the stability of the output power supply.This effectively improves the output power range of the thermoelectric energy collection system.The circuit design of reverse polarity input multi-mode DC-DC converter is completed based on 0.18μm CMOS process.SPICE software simulation shows that the conversion efficiency is higher than 60%when the input internal resistance of TEG is 210Ωand the input open circuit voltage is in the range of-300m V to 300m V and the peak conversion efficiency is 90.1%(V_TEG=300m V,R_TEG=210Ω).Compared with the traditional Harvest-Use architecture,the conversion efficiency is significantly improved in the full power range.Using a bipolar oscillator,the minimum starting voltage is as low as±100m V,and the minimum input voltage is±50m V,which meets the ultra-low voltage requirements of the thermoelectric energy collection system.The maximum tracking efficiency of the bipolar maximum power tracking system is 99.5%(V_TEG=-300m V),which meets the requirements of low power consumption.The output voltage ripple is less than 20m V under both light and heavy loads,indicating that the designed energy harvesting system meets the efficient power management requirements of wearable devices.