5.3.1　Components of Electronic Converters

Text（课文）

The electronic static inverters which equip electric or hybrid vehicles to modify the electrical energy presentation mode，use associations of electronic power semiconductors，diodes，thyristors，IGBT，which work in commutation i.e.they operate in on or off mode to limit the losses.

If we take a closer look at the operation of power semiconductors，we observe that it is the role they play during commutations which constitutes the main feature of these components.We can distinguish as follows:

non-controllable components:the diodes；

components controllable only with the setting in a thyristor conducting state.These semiconductors can be put in a state of conduction by a control impulse sent onto their“trigger”during an arbitrary moment but they cannot return to the blocked state following a blocking sent onto the trigger.To return to the blocked state，the current crossing them must be cancelled under the very effect of the source or the load，thus causing a“natural”current commutation；

components controllable when placed in conducting state and in blocked state.

For this type of current the change from blocked to conducting state and vice versa is caused by a current impulse sent onto their control electrode:

①trigger for the GTD and other IGCT；

②gate for IGBT，and field-effect transistors of the MOS type；

③base for the bipolar transistors.

In electric vehicles，the most used semiconductors are diodes，IGBT and MOS.Thyristors are used only in rectifying assemblies.

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.These semiconductors can be put in a state of conduction by a control impulse sent onto their“trigger”during an arbitrary moment but they cannot return to the blocked state following a blocking sent onto the trigger.在任意时刻发送一个控制脉冲到触发器，这些半导体可以切换为导通状态，然而发截止指令到触发器时这些半导体并不能回到截止状态。

Exercises（练习）

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

（1）For this type of current the change from blocked to conducting state and vice versa is caused by a current impulse sent onto their control electrode.

（2）non-controllable components

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

（1）截止状态

（2）场效应晶体管

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

How can we distinguish the semiconductor from commutations which constitutes the main feature of these components？

Reading material（阅读材料）

In this operating mode，the semiconductor can:

sometimes be“conducting”i.e.equivalent to a closed mechanical switch which lets the current pass with a direct voltage drop between weak terminals；

sometimes be“blocked”i.e.equivalent to an open mechanical switch supporting a voltage between terminals，raised with a virtually-zero leakage current；

pass very quickly from the“conducting”state to“blocked”state；these are in fact the different changes of state seen at the component or on the circuit，which includes the component that we call“commutation.”