4.3.2. High-efficiency operation in Engine drive modeIn Engine drive mode, the engine and wheels are coupled via a fixed reduction gear, so the engine speed is determined uniquely with respect to the vehicle speed. The relationship between the engine speed and the torque when cruising on a flat road is shown by the dashed line in Fig. 6. Engine drive mode is used in the high-speed cruising area, but when driving on a flat road the engine operating point deviates to the low torque side of the minimum BSFC line. In this case, the engine torque is increased so that the engine operates at a more efficient operating point, and this increase in torque is absorbed by the regeneration operation of the motor. Conversely, under conditions where the engine operating point deviates to the high-torque side of the minimum BSFC line, the engine torque is reduced and the difference is compensated by motor drive. In this manner, control is performed to converge the engine operating point to the higher-efficiency area by motor regeneration and motor drive'
简单翻译来说 就是高速巡航下的发动机模式,发动机和车轮是以固定齿比连接的,所以发动机转速相对于某一个车速是唯一固定的...但由于为了保证燃效(BSFC ),而发动机在输出的扭矩不一定适时满足当前工况,如果发动机当前转速下的最大扭矩高于当前工况的情况下(比如下坡),多余的扭矩由电动机发电存入电池中.....而相反的当发动机输出扭矩不能满足当前工况比如上坡,不足的扭矩则由电机来进行补偿,以这种方式来保证发动机始终工作在最佳燃效区间附近...