ELE 454 Power Electronics. Lecture Notes Chapter I

Transcription

1 Hacettepe University Electrical and Electronics Engineering Department ELE 454 Power Electronics Lecture Notes Chapter I Instructor: Dr. Işık Çadırcıadırc

2 OUTLINE I. INTRODUCTION II. POWER SEMICONDUCTOR DEVICES III. LOSS CALCULATIONS AND COOLING OF POWER SEMICONDUCTORS IV. RECTIFIER CIRCUITS (AC-DC Converters) V. CONVERTER OPERATION IN FOUR-QUADRANTS VI. AC VOLTAGE CONTROLLERS VII. CHOPPERS (DC-DC Converters) VIII. INVERTERS (DC-AC Converters) IX. PROTECTION OF POWER CONVERTERS

3 Power Electronics is a branch of electrical / electronics engineering that is concerned with the conversion and control of electrical power for various applications. Block diagram of a power electronic system

4 Utility systems usually generate, transmit, and distribute power at a fixed frequency (50 or 60 Hz), and a fixed voltage is maintained at the consumer terminals. A consumer, however, may need power at DC or AC, at the same, higher or lower or variable frequency. Frequently, the power is to be controlled with precision. A A power electronics system interfaces between the utility system and consumer load to satisfy this need. Power electronics may be defined as the applications of solid-state state electronics for the control and conversion of electrical power.

5 I. INTRODUCTION POWER ELECTRONICS is concerned with static power conversion, or interconversion of electrical energy The core of a power electronics apparatus consists of a converter built on a matrix of power semiconductor switching devices, and electronic control circuitry: Utility Grid Constant V,f POWER ELECTRONICS APPARATUS * Converter * Controller LOAD Needs DC or AC power usually at variable V, and f

6 The goals of Power Electronics: To process, and control the flow of electrical power by supplying voltages and currents in a form that is optimally suited for user loads, To convert electrical energy from one form to another with highest efficiency, high availability, and high reliability, with the lowest cost, smallest size, and weight.

7 The power converters can be classified as: RECTIFIERS (AC to DC Converters) CHOPPERS (DC to DC Converters) INVERTERS (DC to AC Converters) AC POWER CONTROLLERS (AC to AC Converters) AC Voltage Controllers, and Direct Frequency Changers

8 Power electronics systems applications + AC to AC: AC Power Controllers, Direct Frequency Changers

9 Power electronics an interdisciplinary technology The study of power electronics encompasses many fields within electrical engineering

10 Combining the knowledge of these diverse fields makes the study of power electronics challenging as well as interesting. There are many potential advances in all these fields, that will improve the prospects for applying power electronics to new applications. It is difficult to draw the bondaries for the application of power electronics; especially with the present trends in the development of power devices and microcontrollers.

11 Power Electronics is a branch of electrical / electronics engineering engineering, that is concerned with the conversion and control of electrical power for various applications such as: heating and lighting control electrochemical processes switch-mode power supplies dc and ac electrical machine drives, active power line filtering, static VAr compensation systems, AC power controllers electrical welding

12 Power electronics systems applications Solid-state circuit breakers Induction heating Photovoltaic systems Transportation (electric car, trains) Variable-speed, constant-frequency generating systems, Power generation and transmission (HVDC) and many more...

13 Power electronics systems applications Power electronics systems applications

14 Application of power semiconductor devices Application of power semiconductor devices

15 At present, POWER ELECTRONICS seems to have been polarized in two directions: Low-power, high frequency electronics - need for switch mode power supplies - circuit miniaturization Moderate to high power electronics - covers motor drives, UPS, lighting, heating control, power quality etc. - Cost, efficiency, size, and other performance improvements are the main criteria

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17 Power electronics systems applications Power electronics systems applications

18 Motor drives I. INTRODUCTION Power electronics systems applications

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20 A 200 W SMPS: A dc-dc converter:

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22 Bilsat 1 Power Supply I. INTRODUCTION

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24 Commercial electric motor drives