2.2.3　Series-parallel Hybrid

Text（课文）

Considering the advantages of both series and parallel configurations，manufacturers and researchers have developed series-parallel hybrid electric vehicles.These HEVs can operate by either using electric motor alone or with the assistance of the ICE.The configuration of the seriesparallel HEV is shown in Figure 2.8.In this configuration，power of the ICE and the electric motor is coupled to drive the vehicle in parallel operation，while power flow from engine to generator and then to the electric motor can be considered series.

There are many choices to design the“mode selection”device.The simplest one is clutches to select which shaft is connected to the ICE，i.e.，to connect either the final drive or the electric generator to the ICE.Another choice is to have a power split device such as a planetary gear train to split the ICE power to the drive shaft and the electric generator.

Figure 2.8　Configuration of a series-parallel HEV

The battery can be charged by the power of the generator.The electric motor can also supply power to the front wheels in parallel with the ICE.A control unit is in charge of driving mode selection.When short bursts of power are needed，the ICE and the electric motor together provide the power required by the vehicle demand.

The Toyota Prius，shown in Figure 2.9，is a typical series-parallel HEV where a small series element is placed in addition to the primarily parallel HEV.In Toyota Prius，the battery remains charged in prolonged waiting periods such as traffic lights or in traffic jam.According to the report from the United States Environmental Protection Agency，the 2008 Prius is the most fuel-efficient car sold in the US.

Figure 2.9　Toyota Prius

New words and expressions（单词和短语）

1.New words（单词）

Notes to the text（难点解析）

★1.In this configuration，power of the ICE and the electric motor is coupled to drive the vehicle in parallel operation，while power flow from engine to generator and then to the electric motor can be considered series.在此结构中，内燃机和电动机的功率耦合驱动汽车运行在并联模式下，但是功率由发动机到发电机再到电动机的过程可以看作是串联的。

★2.Another choice is to have a power split device such as a planetary gear-train to split the ICE power to the drive shaft and the electric generator.另外一种选择是釆用一种功率分流装置（例如行星齿轮组）将发动机的输出功率分流到传动轴和发电机。

Exercises（练习）

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

（1）The battery can be charged by the power of the generator.

（2）traffic lights

（3）a planetary gear-train

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

Please draw the configuration of the series-parallel HEV.

Reading material（阅读材料）

Prius is a Latin word meaning“to go before.”When the Prius was first released，it was selected as the world's best-engineered passenger car for 2002.The car was chosen because it is the first hybrid vehicle that seats four to five people plus their luggage，and is one of the most economical and environmentally friendly vehicles available.Then in 2004，the second-generation Prius won the prestigious Motor Trend Car of the Year Award and Best-engineered Vehicle of 2004.