49270407-Introduction-2002

49270407-Introduction-2002 - Chapter 1 INTRODUCTION...

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Power Electronics and Drives (Version 2). Dr. Zainal Salam, 2002 1 Chapter 1 INTRODUCTION • Definition and concepts of power electronics and electronics power conversion • Application • Power semiconductor switches • Gate/base drivers • Losses • Snubbers • Links to useful websites
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Power Electronics and Drives (Version 2). Dr. Zainal Salam, 2002 2 POWER ELECTRONIC • DEFINITION: To convert, i.e to process and control the flow of electric power by supplying voltage s and currents in a form that is optimally suited for user loads . • Basic block diagram shown in Figure 1. Power Processor Controller Load measurement reference POWER INPUT POWER OUTPUT v i , i i v o , i o Figure 1
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Power Electronics and Drives (Version 2). Dr. Zainal Salam, 2002 3 Goal of electronics power conversion systems • To convert electrical energy from one form to another, from the source to load with highest efficiency, high availability and high reliability with the lowest cost, smallest size and weight. • Static and applications – involves non-rotating or moving mechanical components. – E.g rectifiers, inverters, choppers, cycloconverters. • Drive applications – intimately contains moving or rotating components such as motors. – E.g. DC drives, AC drives, Permanent magnet motor drives.
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Power Electronics and Drives (Version 2). Dr. Zainal Salam, 2002 4 Conversion concept: example Supply from TNB: 50Hz, 240V RMS (340V peak). Customer need DC voltage for welding purpose, say. TNB sine-wave supply gives zero DC component! We can use simple half-wave rectifier. A fixed DC voltage is now obtained. This is a simple PE system. time V TNB (Volt) V o time V dc + V o _ + V TNB _ π m o V V = : tage output vol Average
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Power Electronics and Drives (Version 2). Dr. Zainal Salam, 2002 5 Concept-cont’d + v o _ + v s _ i g i a ω t v s v o i a α i g t () [] α π ω ω π π α cos 1 2 sin 2 1 : tage output vol Average + = = m m o V t d t V V How if customer wants variable DC voltage? More complex circuit using SCR is required. By controlling the firing angle, α ,the output DC voltage (after conversion) can be varied. . Obviously this needs a complicated electronic system to set the firing current pulses for the SCR.
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Power Electronics and Drives (Version 2). Dr. Zainal Salam, 2002 6 Applications • Power generation and transmission (HVDC) • Uninterruptable power supplies (UPS) • DC power supplies • Energy conservation (ballast, pumps, compressors, air- condition) • Transportation (Electric car, trains) • Process control and factory automation • Electroplating, Welding • Heating,cooling • Utility-related application
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Power Electronics and Drives (Version 2). Dr. Zainal Salam, 2002 7 Current issues related to power electronics: Energy scenario • Energy Scenario. – Need to reduce dependence on fossil fuel (coal, natural gas, oil) and nuclear power resource (uranium). Depletion of these sources is expected – Effort to tap renewable energy resources such as solar, wind, fuel-cell etc. need to be increased.
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This note was uploaded on 09/10/2011 for the course SDSD 24 taught by Professor Ahmadi during the Spring '11 term at Akademia Rolnicza w Wrocławiu.

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49270407-Introduction-2002 - Chapter 1 INTRODUCTION...

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