電氣專業英語（簡體書）

《普通高等教育"十二五"創新型規劃教材?高等教育課程改革項目研究成果:電氣專業英語》編者從實際應用角度出發，結合電氣專業所學課程，從國外原版教材、專著、相關網站及產品說明書等材料中均精心挑選課文內容，并結合自己的教學體會給出了相關注釋和練習。《普通高等教育"十二五"創新型規劃教材?高等教育課程改革項目研究成果:電氣專業英語》可作為高等院校電氣專業及相近專業的專業外語教材，也可供電氣專業的工程技術人員閱讀參考。

Chapter 1 Electronic Components
Unit 2 Diodes
Unit 3 Transistors
Unit 4 Operational Amplifiers
Unit 5 Digital Logic Circuits
Chapter 2 Power Electronics and Motors
Unit 6 Introduction to Power Electronics
Unit 7 How Electric Motors Work
Unit 8 DC Motor Control with PWM and H-Bridge
Unit 9 Variable Speed AC Drives and How They Work
Unit 10 Induction Motor Control Circuits
Chapter 3 Industrial Automation
Unit 11 PLC Systems
Unit 12 PLC Programming
Unit 13 Introduction to Fieldbus
Unit 14 Why HMls Are Everywhere
Unit 158051 Microcontroller Architecture
Unit 16 How to Start Working with a Microcontroller
Chapter 4 Principles of Automatic Control
Unit 17 Introduction to Control
Unit 18 Transfer Functions
Unit 19 Modes of Control
Unit 20 Control Loops
Unit 21 PID Controller
Chapter 5 Process Control Systems
Unit 22 Importance of Process Control
Unit 23 Process Control Loops
Unit 24 Advanced Control Loops
Unit 25 Computers in Control
Unit 26 Introduction to Sensors

A regular magnet
Before talking about electromagnets, let's talk about normal "permanent" magnets like the ones you have on your refrigerator and that you probably played with as a kid.
You likely know that all magnets have two ends, usually marked "north" and "south," and that magnets attract things made of steel or iron. And you probably know the fundamental law of all magnets: Opposites attract and likes repel. So, if you have two bar magnets with their ends marked "north" and "south," the north end of one magnet will attract the south end of the other. On the other hand, the north end of one magnet will repel the north end of the other （and similarly, the south end will repel the south end of the other）.
An electromagnet is the same way, except it is "temporary"——The magnetic field only exists when electric current is flowing.
An electromagnet
An electromagnet starts with a battery （or some other source of power） and a wire. What a battery produces is electrons.
If you look at a battery, say at a normal D-cell from a flashlight, you can see that there are two ends, one marked plus （+） and the other marked minus （—）. Electrons collect at the negative end of the battery, and, if you let them, they will gladly flow to the positive end. The way you "let them" flow is with a wire. If you attach a wire directly between the positive and negative terminals of a D-cell, three things will happen:
Electrons will flow from the negative side of the battery to the positive side as fast as they can.
The battery will drain fairly quickly （in a matter of several minutes）. For that reason, it is generally not a good idea to connect the two ternunals of a battery to one another directly. Normally, you connect some kind ofload in the middle of the wire so the electrons can do useful work. The load might be a motor, a light bulb, a radio or whatever.