| With the reduction of non-renewable resource like oil gradually and worse andworse air environment, electric vehicles (EVs) at the advantage of low pollution andlow energy consumption are become more and more popular by different countriesand automobile factories. The developed countries such as USA, Europe and Japanhave introduced the policies to promote the development of EVs, in the meantime, thefew biggest automobile factories of global is carrying out R&D work of EVs actively.However, EVs still exist some questions, like the short driving range and the longcharge time. That is to say, power battery, driving motor and electric control system isstill the technology need to solve. EV with in-wheel motors gets more and moreattention because it have the simple structure and the high energy utilization rate. Thekinetic energy of vehicle is made good use of and dissipated as heat. RegenerativeBraking is obviously significant especially complex conditions of downtown area likemore traffic lights, more condition of low speed drive and braking very frequently.Currently Regenerative Braking technology is mainly Flywheel Energy Storage brakeenergy recovery, Hydraulic Energy Storage brake energy recovery, ElectrochemicalEnergy Storage brake energy recovery. Electrochemical Energy Storage brake energyrecovery has infinite prospect of development potential because of the way of electricenergy, simple structure and the easier control. Battery and driving motor of EVsprovide convenience for Electrochemical Energy Storage brake energy recovery.Super capacitor is of great significance as a brand-new energy storage item.Compared with battery, super capacitor has quicker charge and discharge rating andlarger power density. So it can recover the energy quickly.The paper proposed a brand-new composite regenerative braking device basedon the advantage of EVs with in-wheel motors achieving regenerative braking of fullconditions. Battery and super capacitor are energy storage units of the device. In chapter1, the paper described the features of EVs, wheel motor drivetechnology and regenerative braking and the domestic and international developmentstatus on the basis of references and the development situation of global in detail.In chapter2, the paper analyzed the existed problem of regenerative braking ofEV in-wheel motors. Firstly, the paper analyzed the dynamic characteristics and thenlisted dynamic equations. Secondly, it also illustrated the property of super capacitorand the determination of super capacitor’s parameters in detail.In chapter3, the paper introduced the control algorithm of regenerative braking.The fuzzy control was introduced and then the property and way of DC/DC choppercontrol was described. Lastly PID control to braking current of in-wheel motor wasillustrated.In chapter4, the paper proposed the strategy of regenerative braking. Thestrategy and energy storage system were built by means of MATLAB, meanwhile, thevehicle model with in-wheel motors was built by AVL CRUISE.In chapter5, the paper carried out off-line simulation under low strength ofbraking, medium strength of braking, high strength of braking and FTP-75cycleconditions according to the theory of regenerative braking of in-wheel motors. Interms of simulation results, the paper analyzed the validity of proposed compositeregenerative braking.In chapter6, the paper concluded the current results and pointed out the outlook.The designed composite regenerative braking device can achieve regenerative brakingto EVs with in-wheel motors and can promote energy utilization rate. At the sametime, the paper also proposed the disadvantage of work and then pointed out theoutlook of future work. |
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