2.2.2　Series Hybrid

Text（课文）

The configuration of a series HEV as shown in Figure 2.7 is simpler than that of a parallel HEV.Only the electric motor provides all the propulsion power.An ICE on board drives a generator which can charge the battery when the state of charge（SOC）of the battery drops below a certain level.Beyond the ICE and the generator the propulsion system is the same as in an EV.The series HEV has advantages including flexibility of location of engine-generator set and simplicity of drivetrain，but meanwhile，due to its intrinsic structure，the series HEV needs more propulsion components（i.e.，ICE，generator and motor）.The fact that no mechanical link exists between the engine and mechanical transmission can have the engine operate in its most efficient region by adjusting its speed and torque.The electric motor has to be designed for the maximum power required by the vehicle.For long-distance missions，the three propulsion components need to be sized for maximum power.

Figure 2.7　Configuration of a series HEV

New words and expressions（单词和短语）

1.New words（单词）

2.Expressions（短语）

Notes to the text（难点解析）

★1.An ICE on board drives a generator which can charge the battery when the state of charge（SOC）of the battery drops below a certain level.当电池的荷电状态（SOC）下降到低于设定值时，车载发动机会驱动发电机对电池进行充电。

★2.The fact that no mechanical link exists between the engine and mechanical transmission can have the engine operate in its most efficient region by adjusting its speed and torque.在发动机和机械传动之间不存在机械连接，可通过调整发动机速度和转矩使其工作在最大效率区。

Exercises（练习）

◆1.Translate the following passages（expressions）into Chinese（英译汉）

（1）Only the electric motor provides all the propulsion power.

（2）The electric motor has to be designed for the maximum power required by the vehicle.

◆2.Translate the following passages（expressions）into English（汉译英）

（1）串联式混合动力电动汽车

（2）最大功率

◆3.Directions:Answer the following questions briefly according to the text

Please draw the configuration of a series HEV.

Reading material（阅读材料）

Based on the vehicle operating conditions，the propulsion components on a series HEV can operate with different combinations:

1）Battery alone:When the battery has sufficient energy，and the vehicle power demand is low，the I/G set is turned off，and the vehicle is powered by the battery only.

2）Combined power:At high power demands，the I/G set is turned on and the battery also supplies power to the electric motor.

3）Engine alone:During highway cruising and at moderately high power demands，the I/G set is turned on.The battery is neither charged nor discharged.This is mostly due to the fact that the battery's state of charge（SOC）is already at a high level but the power demand of the vehicle prevents the engine from turning off，or it may not be efficient to turn the engine off.

4）Power split:When the I/G is turned on，the vehicle power demand is below the I/G optimum power，and the battery SOC is low，then a portion of the I/G power is used to charge the battery.

5）Stationary charging:The battery is charged from the I/G power without the vehicle being driven.

6）Regenerative braking:The electric motor is operated as a generator to convert the vehicle's kinetic energy into electric energy and charge the battery.