A regenerative braking control strategy for pure electric bus with compound power supply
To improve the braking energy recovery efficiency of electric buses, with the consideration of the limitation of motor speed and battery charging power and the calculation of the maximum regenerative braking force of the motor under constrained conditions, this paper presents a regenerative braking control strategy which makes full use of motor characteristics with the integration of the I curve to determine the braking force distribution of front and rear wheels and the distribution ratio of friction braking force to regenerative braking.Given the low power density and short cycle life of a single power battery, a composite energy system composed of power battery and supercapacitor is designed.A real-time wavelet control strategy is proposed for energy management, which decomposes the demand power into high-frequency components and low-frequency components.The high frequency power of this strategy is borne by the super capacitor to avoid the impact of the power battery, and the low frequency power is borne by the power battery.To verify the effectiveness of the control strategy, Matlab/Simulink software is employed to build the simulation model under typical urban cycle conditions in China.Our simulation results show when the single energy source of the power battery is used, the battery SOC is increased by 19.03％, the braking energy recovery rate is up by 13.10％; when the composite power supply is employed, the current, power and voltage of the battery are significantly reduced and their fluctuations are more gentle.The battery SOC and the braking energy recovery rate are increased by 17.51％ and 10.24％ respectively.The strategy effectively improves the power battery' s lifespan and the electric buses' economy.
electric buscompound energyregenerative brakingsliding windowwavelet transformation
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