ISG混合动力汽车起动及加速策略

Start and Acceleration Strategies of an ISG Parallel Hybrid Electric Vehicle

混合动力车的怠速停机功能既增加了起动次数又会减缓催化器起燃,对排放产生不利的影响,因此必须对混合动力起动过程进行专门的优化.为了满足驾驶性和加速性能,传统车辆加速时发动机提供的瞬态燃油必然会恶化排放性能,因此加速过程的瞬态排放成为排放控制的另一难点.基于ISG电机的快速响应特性以及性能参数,对ISG混合动力车的起动及加速策略进行了优化.对冷机及热机的起动空燃比进行控制;提出了ISG快慢转矩的概念,以ISG转矩代替传统车的瞬态燃油,确定了理想的混合动力起动及加速的ECU和VCU参数.对混合动力车以不同模式进行NEDC循环测试,试验结果表明,混合动力起动避免了传统车起动时的过浓喷油,ISG转矩有效地取代了传统车加速时的瞬态燃油,使混合动力车在节油的同时较大地改善了排放性能.

The idle-stopping function of hybrid electric vehicle（HEV）not only increases the starts,but also postpones three-way catalyst（TWC）activation,bringing unfavorable influence on engine emission.So start process of hybrid is worth of studying.To satisfy the drivability and acceleration performance,extra fuel is required for engine at conventional vehicle acceleration.Transient fuel will deteriorate emissions dramatically,and it is hard to control the transient emissions.Hybrid start and acceleration strategies were developed based on the ISG characteristic.The air-fuel ratio（AFR）at cold start and hot start is under control.The concept of ISG ＂fast＂ and ＂slow＂ torque to overcome the conventional engine transient fuel is proposed.Reasonable ECU and VCU parameters are determined.Tests at NEDC driving cycle were conducted both on conventional and hybrid modes.Result shows that the conventional start fuel reduces with aid of ISG motoring.The transient fuel at acceleration is replaced by the ISG torque.The HEV can simultaneously realize reduction in fuel consumption and emissions.