| Confronted with increasing depletion of global oil resources and environmental pollutionproblems, environmental and energy saving-vehicle has become the research emphasis oftoday’s world auto industry. As a key energy-saving technology of environmental and energysaving-vehicle, regenerative braking technology can effectively improve the vehicle fueleconomy effectively and prolong the mileage. Especially in driving cycle for city road withquite frequent starting and braking, designing a highly efficient regenerative braking systemand supporting a reasonable braking control strategy will greatly improve the contribution ofregenerative braking to the improvement of vehicle fuel economy, which has importanteconomic benefits and social benefits.Combined with the commend of developing add-on breaking energy recovery system—parallel regenerative braking system for electrical storage system of vehicle, based onXQ6103 bus matching with regenerative braking system for electrical energy storage, thispaper developed regenerative braking control strategy, built the theoretical model ofregenerative braking system, made simulation, and analyzed the engagement control forelectric clutch. The main works are as follows:(1) Combined with the characteristics of driving cycle for typical city, according to thefunctional requirements of parallel regenerative braking system for electrical storage systemof vehicle, the transmission speed ratio and the characteristic parameters of motor andsuper-capacitor stacks were matching designed, and the matched-type of main parts weredone.(2) According to analyzing the relationship between front and rear tire braking force distribution and drawing braking force distribution curve, this paper determined synchronousadhesion coefficients both at full load and no-load, which verified the rationality of brakingforce distribution. Based on the requirements of the braking regulations by ECE, under thepremise of braking performance and braking stability, the braking force distributioncoefficient range was determined from 0.4 to 0.5, which provided a theoretical basis fordeveloping regenerative braking control strategy.(3) Based on the analysis of three typical regenerative braking control strategies and thestructural characteristics of regenerative braking system, mainly taking into account threeconstraints of regenerative braking: the motor peak torque, ECE braking regulations andsuper-capacitor stacks SOC, this paper proposed a regenerative braking control strategy basedon parallel control theory, the control strategy can give full play to the braking ability of themotor and recover braking energy in maximum under the premise of meeting therequirements of the braking regulations by ECE, at the same time, the braking effect is betterthan that of mechanical braking obviously, which improved the braking stability.(4) A simulation model of regenerative braking system for electrical storage system hasbeen built under the environment of Matlab/Simulink, mainly including motor model,super-capacitor stacks model, the vehicle dynamics model, control strategy model and drivingcycle model, which provides the platform to verify the regenerative braking control strategy.(5) Based on the model of regenerative braking system built above, this paper verifiedthe regenerative braking control strategy. The simulation results of driving cycle for routinebraking showed that the error of deceleration is lower than 1m/s2, which has a little influenceon the braking sense of drives and comfort of occupants, at the same time, braking distanceand braking time are shortened, thus the braking stability and braking safety are furtherimproved. The simulation results of driving cycle for typical cities showed that the energyrecovery efficiency of regenerative braking system is greatly affected by driving cycle, whichdecreases as the speed increases, thus the regenerative braking control strategy is suitable fordriving cycle for low-speed, and has an ideal effect of energy recovery; for driving cycle for high-speed, the recovery effect of energy can be effectively improved by increasing energyoutput of super-capacitor stacks and other measures .(6) This paper analyzed the electric clutch engagement process of regenerative brakingsystem and clutch performance indicators, proposed a control strategy of clutch engagementin the process of regenerative braking. Then the clutch simulation model was built based onMatlab/Simulink platform, according to the problems of simulation results, this paperproposed an improved scheme of theΔω-ΔT based on closed-loop control, the analysis ofsimulation results show that theΔω-ΔT closed-loop control strategy can meet theperformance requirements of the clutch engagement process and the control effect of clutchengagement is satisfied. |
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