The Research Of The Passive TPMS For Automobile Based On Electromagnetic Coupling

Tires are the most important security components of the vehicle run system,and its performance has a direct impact on the performance of the vehicle and traffic safety.Keeping normal pressure ,a vehicle will run steadily,safely,using lesser fuel and so it will be a comfortable trip,at the same time ,a longer life-span tire,and lower cost.To achieve these,TPMS—automobile tire pressure monitoring system is the best tool beyond all doubt.Basically,lithium batteries supply energy to emitter of the sensor in current TPMS,which is setted inside of tires.It is complex inside tires:160 0 C temperature and 507~810KPa pressure as high-speed rotation.So TPMS is related to many factors like Centrifugal Acceleration,Dynamic Blance of tires,high temperature , life-span and capacitance of batteries and so on,that result in many abuse such as limited life-span of tires,decreased capacitance of batteries when temperature decreases,environment problems made by castoff of batteries.If the moudule inside tires have no batteries,all of above problems can work out.Of all the passing passive projects,electromagnetism coupling has nothing to do with the mysterious high-end technology and it has a low efficiency of energy transfer,but it very suit for passive TPMS development for its mature theory base, the cheap material and it has no impact on the object state that transferring energy by wave.Because of the above reasons,I had a systemic study about TPMS's passive project by electromagnetism coupling.I analyse and compare coupling characteristics of every frequency band through learning from the theory of distant coupling IC card of the noncontact IC cards in the base of studying about RF reader and labels in the paper.At last,combining the complex electromagnetic environment .And the I designed the electromagnentism coupling TPMS passive system being dead against low frequency.First power consumption of the existing module was analyzed,and lower power consumption system was weaved in the paper.And then the no battery part was designed emphasizely aim at the plan.Energy transfers of coupling antenna was designed and analyzed emphasizely aiming at finding the best coupling coefficient and the best quality submultiple that can improve the efficiency of energy transfers.Lastly simulation experiment of designed hardware system was done. Main contents listed below:1. The study of low power consumption TPMSThe system project was fixed on through studying the existing module and comparing the performance and consumpation on emission,take-over and controlling department of a number of manufacturers and types.SP12 adding MCU adding TDK5100 is the tire module. MCU is PIC16F628A which come from Microsoft (SOIC encapsulation).2. The designing of hardware circuit of no battery part of TPMSWheras the project is in its beginning,predigested designing method was chosed.Only design the signal generator which can have a magnetic field for the antenna to couple.I chosed the Function Generator ICL8038 to produce sine wave which is then magnified by magnifier of D and meet the resonpance loop in series.Looking like this ,it would have a strong current to emission the electromagnetic wave and produce the need magnetic field.The power part contains coupling antenna,Rectifier filter circuit,Limiting circuit and Supercapacitor.The antenna was designed more detailed in the paper.3. Simulation experimentsThrough creating equivalent circuit model of passive electromagnetic coupling circuit and combining selection parameters, simulation experiments table is built,and the simulation is done. Adjusting parameters of the hardware circuit by observing the wave that created in simulation experiments, would make it to be the best.4. Energy programmeTPMS operation of the system by the time the calculation and tire rotation of the reported non-energy radio frequency system and the continuity of low efficiency of energy transfer restrictions , that must use the use of storage elements. By comparing the performance of the storage elements choose a new super-capacitor energy storage devices. Ultracapacitor then calculated the necessary capacity, the initial choice of super capacitor model, then the different models and super capacitor parallel super capacitor charging and discharging performance tests, to further define the use of the super capacitor models and methods.5. The realization of the structureBy studying tire structure and the surrounding environment, and decided to the installation location of launch module and coupling module.Conmining with the installation position,I considered anti-jamming measures on hardware and software.