Electrical Characteristics Analysis And The Model Research Of Electric Vehicle Power Battery

Automobile, related closely to the production and our daily life, is the symbolof modern industrial civilization. At present, the electric vehicles industry has entered aperiod of rapid development. Though there have been great improvements on thetechnical performance of pure Electric Vehicle (EV), Hybrid Electric Vehicle(HEV),and Fuel Cell Electric Vehiecle (FCEV), lots of crucial problems concerning thepower cell, the motor and its driving and controlling system, the energy managementsystem, etc., which weaken the competitiveness of electric vehicles when comparedwith conventional gas-powered cars, are to be solved. Among them, the performanceand cost of the power cell which actually has become the bottleneck counts most,calling for emergent studies on its properties and application,NI-MH battery, the energy storage device with light pollution, high specificenergy, relatively high specific power, long cycle life and which is maintenance-free, isa hotspot in the new energy vehicles promotion nowadays. Power cell, as the powersource for electric vehicles, must posses the properties that guarantee the rideabilityand safety performance. Based on a project on HEVs of a domestic brand, this thesisinvestigated on the NI-MH battery for HEVs through experiment combined withcomputer simulation.The research methods of Ni-MH power battery in this paper canbe used on other power battery research and promotion.Firstly, the causes for the dynamic hysteresis of NI-MH battery were addressed. arevised open-circuit voltage measurement method (ROCVMM) on SOC estimationdiminishing the influence of dynamic hysteresis which was neglected by the traditionalOCVM was raised up. Fast-charging method for NI-MH battery was explored based onrelated theories, with its feasibility testified by experiment. The discharge capacity ofNI-MH battery was calculated with introduction of the Peukert formula whichaddresses the influence of discharge current on discharge capacity for battery. KiBaMmodel was constructed to display the consequences of the non-liner effect of thebattery capacity and the recovery effect in its use. Combined with the revised Thevenin,it also displays the V-I feature of NI-MH battery. Revised ampere-hour measurementmethod, also called the integrated ampere-hour measurement method (AHMM) whichemploys the ROCVMM on basis of equivalent-circuit model, was adapted to estimatethe SOC of the battery. Correction factors were added to the new model when factors affecting the accuracy of SOC estimation being considered. The validity and veracityof the new model was assessed through comparison with the traditional AHMM insimulation. In the end, the role of battery at system-level electromagnetic compatibility(EMC) was observed form the perspective of battery compatibility of automobiles. Asa link in the high voltage electrical apparatus system, power batteries system is acoupling path for interference in transmission. Thus, it is necessary to study of highfrequency impedance characteristics for the power cell. This thesis started withindividual battery cells and finally built an assembled series-parallel batteries system.The model proved effective through test in Lab.