Advances in Power Electronics - Its Impact on the Environment

(Invited Plenary Address)

Bimal K. Bose, Life Fellow, IEEE Condra Chair of Excellence in Power Electronics

Department of Electrical Engineering The University of Tennessee

Knoxville, TN 37996-2100, USA Tel: (423) 974-8398, Fax: (423) 974-5483

bbose@utk. edu

Power Electronics is one of the fastest changing and evolutionary technologies in electrical engineering in the recent years. This last decade of the 20th Century can be truly defined as the era of power electronics - or more truly, power electronics and information era. The solid state power electronics revolution (often called second electronics revolution) started by the invention of thyristor in the late 1950's, and then continued ceaselessly by invention of many power devices, such as GTOs, Triacs, BJTs, Power MOSFETs, IGBTs, SITS and MCTs. The advent of new devices and the dramatic improvement of their ratings and characteristics gave solid foundation of power electronics which resulted the development of many Converter topologies, analytical and simulation techniques, variable frequency drives, and their control and estimation methods. As a result, the cost of power electronics apparatus fell significantly and their performance improved considerably, which correspondingly, spurred the dramatic surge of power electronics applications everywhere. This contributed to the present era of global industrial automation. Besides the improvement of industrial productivity and product quality, we are recently realizing another dimension of importance of power electronics - energy conservation and the corresponding control of environmental pollution.

Availability of abundant energy has contributed to the present advancement of our industrial civilization with high living standard. Since the beginning of industrial revolution around two centuries ago, the global energy consumption has increased by leaps and bounds. Now, the per-capita energy consumption is considered as a barometer of a nation's economic prosperity. It may be mentioned here that the USA has the world's highest living standard, and with 5% of world population, it consumes 25% Of total energy. Unfortunately, we have so far ignored the adverse effect of this increased energy consumption on the environment.

As indicated in Fig. 1, globally, 87% of total energy comes from fossil fuel (coal, oil and natural gas), 6% comes from nuclear power, and the rest is obtained &om renewable sources (hydro, solar and wind). The total energy consumption in USA approximately follows the same pattern. The USA is ever hungry for oil. The 42% of US energy comes from oil most of which is consumed in automobile transportation. In USA, 37% of total energy is consumed in

electrical form, of which 55% comes from coal and 20% comes fiom nuclear plants. It is interesting to note that the world's two largest populous countries (China and India) generate most of their electricity from coal (74% and 71%, respectively).

Unfortunately, environmental problems are recently becoming dominating issues in our society. The nuclear energy has safety problem, and the nuclear plant waste remains radio - active for thousands of years. Burning of fossil fuel gives polluting gases, such as CO, , SO,, NO,, HC and CO. Particularly, the accumulation of CO, in the atmosphere causes global warming (green house effect). A definite way to improve the environmental pollution is to consume most of the energy in electrical form (and controlling emission in central generating stations) and use the electrical energy more efficiently. Power electronics can play a vital role in the efficient use of electricity and thus saving of energy. Of course, promotion of wind and solar energy, that heavily uses power electronics, can also help cleaner environment. It is interesting to note that affluent societies like USA, typicaly wastes one-third of the total energy, and thus aggravating the environmental pollution problem.

Electrichybrid vehicles can play a dominant role in environmental pollution control - particularly in the urban area. Fig. 2 shows the fuel chains for gasoline-fbelled ICE vehicle and EV charged with coal-based power. The calculation indicates that around 20% of the gross energy goes to the wheels of EV, whereas only 10% goes to the wheels for ICEV. Besides energy saving, EV helps to shift the urban pollution to that of central power station located in remote country-side area.

As mentioned before, the recent advances in power electronics have been possible by fast evolution of power semiconductor devices, converter topologies, PWM techniques, analytical and simulation methods, control and estimation methods, advancement of personal computers, digital processors, ASIC chips, and control hardware and software. Undoubtedly, the present revolution of power electronics is mainly due to advent of new and advanced power semiconductor devices. Fig. 3 shows the power semiconductor progress in the present decade. The advent of advanced power devices with Sic material will usher a new era of power electronics in future. The soft-switched phase-

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controlled converters and hard-switched PWM type converters have established firmly for different applications. In the recent years, we have seen enormous growth of soft- switching technology for PWM type converters. They provide many advantages at the expense of additional components. The evolution of electrical machines has been very slow compared to that of devices and converters. The converter-fed variable frequency ac drives are now being increasingly popular in various industrial applications. Fig. 4 shows the application trends[3] of industrial ac drives. For high performance drives, vector or field-oriented control is invariably used, whereas for low performance applications, simple open loop voltsEh control is popular. ,Recently, speed sensorless vector-controlled induction motor drives have been introduced commercially. Of course, zero speed or near zero speed operation of the drive yet remains a challenge. There has been extensive R & D in various advanced control techniques, such as sliding mode or variable structure control, direct torque and flm control (DTC), H- infinity control, and model referencing adaptive control. The intelligent control techniques based on expert system, fuzzy logic, artificial neural network and genetic algorithm show a lot of promise for high performance control and estimation of ac drives. Power electronics and variable frequency drives will undoubtedly play a key role in the global industrial automation in the 2 1 It century.

REFERENCES

B.K. Bose, "Energy, Environment and Progress in Power Electronics", Japan IEE - IAS Conference, Nagaoka, August 7,1998. L. Lorenz, :"Trends in power integration", PCIM Magazine, pp. 14-18, Issue 1, 1998. S. Tadakuma and M. Ehara, "Historical and predicted trends of industrial ac drives", IEEE-IECON Con$ Rec.,

B. K. Bose (Ed), Power Electronics and Variable Frequency Drives, IEEE Press, 1997. S. Rahman and A. D. Castro, "Environmental impacts of electricity generation: a global perspective", IEEE Trans. On Energy Conversion, vol. 10, pp. 307-313, June 1995. B. J. Baliga, "Trends in power semiconductor devices", IEEE Trans. On Electron Devices, vol. 43, pp. 1717- 1723, October 1996. B. K. Bose, "High performance control and estimation in ac drives", IEEE IECON Con$ Rec., pp. 377-385, 1997. B. K. Bose, "Power electronics and motion control - technology status and recent trends", ZEEE Tram. Ind. Appl., vol. 29, pp. 902-909, Sept./Oct. 1993.

pp. 655-661, 1993.

US TOTAL ENERGY

NATURAL GA 2 4 %

F E N E W A B L E 5%

NUCLEAR 6%

GLOBAL TOTAL ENERGY

Fig. 1: World and USA Energy Generation

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ICE Vehicle ..................................................

oil well ~ ~ f i ~ ~ ~ Transportation : & Distribution : Engine Wheels

1 (FUDS) Transmission

..................................................

Electric Vehicle .................................................. Coal Mine Utility Transponarion :

& Distribution ' : Charger Controller . Wheels f

Battery and Motor Transmission

..................................................

Fig. 2: Fuel Chains for Gasoline-Fuelled ICE Vehicle and Electric Vehicle with Coal- Based Power

I990

P(kVA)

Thyristor GTO BPT IGBT

102 MOS tl?FiF 1Crj- 10' e?- 10" 100 io1 i~f, io1 i o 5

' 4 , - f(kHid

2000 Power swi tchable (kVA)

Thyristor GTO IGBT

MOS

lol T!T 10'

10" 100 10' lo' 10' 10' 10' __* f(kH.4

Fig. 3: Power Semiconductor Progress in a decade

'60 '65 '70 '75 '80 '85 '90 '95 2000 1 I I I

n I n Devices Thyristor Micro-proc. GTR GTO IGBT

I Static and/or Brushless I Large Scale and I lmprovemenl 01 Power Factor Targels 1 Drives. I Sinusoidal Drives j (Incl Harmonlcs)

I , I _---- __---- I _ _ - - I * - I __----

__--- ___ - - - I

780 6 5 1'90 1'95

Rolling Mills

Traction Drives

-. I

I 1

, t I L _

Vector Controlled I M

.I

SM System

Linear SM Drive

Rolling _ _ _ Slock

- - - - - - - I

I I I I

I (, Non Circulating Current CIC f IM I c i Test 8 1 Medium I 2X3000kW

I I I 1 (NPC Inv -k- IM

Plpe Pierce( ~ ~ 1 1 (CirCUlatlng CUrrenl C / c -k I M { - - -_---

(SM) (4800kW-230/1380 rpm elc) ------- L - - - - - - , ( Load Commutated Inv f SM {

Wire 8 Rod Mill (2X3600kW-700/1200 rpm) (6000kW-485/1360 rpm)

Non Cir Curr C C Cir Curr CIC XPWM Inv (GTO) 11 Miyazakt (2) 16MVA-60HU33Hz

( GTO - Inv i- IM

Yamanashi (40MVA) Miyazakr ( 1 ) 9 6MVA- 120HU33Hz

New Tokaido Lme

(pwMc.. / I .v +IM

-r-- I I r (3000kW / Unrt) .._-__ SubwayIUrban

Fig. 4: Application Trends of Industrial AC Drives

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