一种复合电源纯电动公交车再生制动控制策略

A regenerative braking control strategy for pure electric bus with compound power supply

为了提高纯电动公交车制动能量的回收效率,考虑电机转速特性与电池充电功率的限制,计算电机在约束条件下能提供的最大再生制动力,结合I曲线确定前、后轮制动力分配,以及摩擦制动力与再生制动的分配比例,提出了一种充分利用电机特性的再生制动控制策略。针对单一动力电池功率密度低、循环寿命短等问题,设计了由动力电池与超级电容组成的复合能源系统,并提出利用实时小波控制策略将需求功率分解成高频成分与低频成分,其中高频功率由超级电容承担,避免动力电池受到冲击,低频功率则由动力电池承担。最后,利用Matlab/Simulink软件建立仿真模型,在中国典型城市循环工况下进行仿真,仿真结果表明:采用动力电池单一能量源时,电池SOC增加了19.03%,制动能量回收率提高了13.10%;采用复合电源时,电池的电流、功率与电压明显减小,波动更加平缓,电池SOC增加了17.51%,制动能量回收率提高了10.24%,可有效提高纯电动公交车的动力电池寿命与整车经济性。

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 realtime wavelet control strategy is proposed for energy management,which decomposes the demand power into highfrequency components and lowfrequency 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.