Design Of Power Management Circuit With Maximum Power Point Tracking For Indoor Photovoltaic Energy Harvesting

With the rapid development of Internet of Things technology(Io T)and integrated circuit industry,wireless sensor network has been widely used in various fields.The electronic products used in the application of the Internet of Things tend to be low power consumption and miniaturization,especially in the special application scenarios where it is impossible to replace batteries frequently,such as intelligent security and building manufacturing monitoring,etc.,the chip size and power consumption requirements are more stringent,therefore the power supply and battery life become the key factors limiting the performance,size and life cycle of such electronic products.Because the light energy is abundant and easy to obtain in the indoor environment,the photovoltaic energy harvesting is the most widely studied scheme in the world.Among them,the design of maximum power point tracking(MPPT)and power management circuit to improve the efficiency of indoor photovoltaic energy harvesting has very important research significance and application value.Aiming at the characteristics of weak indoor light intensity and low energy generation,this paper designs a maximum power point tracking and power management chip for indoor photovoltaic energy collection.In order to realize the simulation of the whole circuit system in the IC simulation platform,the photovoltaic cell was first modeled,and according to its I-V and P-V characteristic curve,the open circuit voltage of photovoltaic cell is controlled at the maximum power point by the improved open circuit voltage proportional coefficient method;at the same time,the supercapacitor model suitable for circuit simulation is studied to improve the accuracy of circuit simulation;finally,The DC-DC converter with synchronous rectification is used to stabilize the voltage,so as to improve the power conversion efficiency and reduce the energy loss and chip area.This paper adopts the Silterra 0.18μm CMOS process,under the Cadence Virtuoso software platform,to design and simulate the circuit and layout of the maximum power point tracking and power management chip core module of indoor photovoltaic energy harvesting.Finally,the chip taping and testing were carried out.Under the input current of 100μA～500μA,the output power of the photovoltaic cell can reach 94.38%of the theoretical maximum output power after MPPT control;the tracking accuracy of MPPT control circuit can reach 93.66%～98.32%;the maximum average error between the simulation curve obtained by the proposed supercapacitor simulation model and the actual supercapacitor charging and discharging measurement curve is 1.655%;the input voltage of the designed DC-DC converter is 4V～5V,the output voltage is 1.8V,and the efficiency can reach 93%.Finally,the chip area designed in this paper is 1.669mm~2.