전기회로 과목개요 과목명 : 전기회로 (059분반) 담당교수 : 김욱 ( 특공관 318호, kimwook@pusan.ac.kr) 주교재 Fundamentals of Electric Circuits, 6 th Ed. (Alexander & Sadiku) 평가방법 1차고사 : 30%, 2차고사 : 30%, 기말고사 : 30%, 리포트 / 태도 : 10% (1,2차중간고사및기말고사의최종점수는표준정규화후반영 ) 출석미달자는무조건 F처리 1,2차중간고사및기말고사평균 20점이하는무조건 F처리 수업시간중핸드폰사용자는퇴실조치 전체태도점수반영 1
전기회로 과목학습목표 전자기장과회로이론은전기공학의가장중요한기초과목 전기회로와관련된제이론 (Node & Mesh 해석법, 테브난 & 노턴정리, 중첩원리등 ) 을이해하고실제회로를해석하는데활용 전기회로의대표적인소자 (R, L, C, OP-Amp) 의특성을이해하고회로를해석하는방법 1 st 및 2 nd -order Circuit 해석법 회로이론 (I) 에서는주로직류 (DC), 회로이론 (II) 에서는교류 (AC) 에대한이론을다룸 2
주요강의내용 1주 전기회로기본개념이해 (Ch.1) 2주 전기회로의기본법칙 (Ohm s law, Kirchhoff s Law) (Ch.2) 3-4주 Nodal 및 Mesh 해석법의이해 (Ch.3) 5주 1차중간고사 6-7주 Thevenin 및 Norton 정리를이용한회로해석 (Ch.4) 8주 Operational Amplifier의원리 (Ch.5) 9주 회로소자 (Capacitors & Inductors) 의특성이해 (Ch.6) 10주 2차중간고사 11-12주 First-Order Circuits의이해 (Ch.7) 13-14주 Second-Order Circuits의이해 (Ch.8) 15주 Final Exam 3
전기회로 과목의활용 Advanced Course( 회로이론, 전자회로, 전력공학, 전력전자, 전기기기, 반도체, 컴퓨터설계등 ) 의수강을위한필수이수과목 각종시험, 자격증의필수과목 ( 대학원입학, 전기기사등의자격증시험, 입사시험등 ) 하드웨어관련직종취업시가장많이활용되는지식 일상생활및취미활동에활용 ( 예 : 오디오제작 ) 4
Ch.1. Basic Concepts
전기회로의정의 전기회로의정의 : 전기소자의상호연결 (Interconnection of electrical elements) 대표적인전기소자 -전원 -저항(Resistance) -인덕터(Inductance) -콘덴서(Capacitor) -Switch 6
SI Units (Int l System of Units) 기본적인 SI Units SI Prefix 7
System of Units The derived units commonly used in electric circuit theory Quantity Unit Symbol Electric charge Coulomb C Electric potential Volt V Resistance Ohm Ω Conductance Siemens or Mho S, Inductance Henry H Capacitance Farad F Frequency Hertz Hz Force Newton N Energy, Work Joule J Power Watt W 8
전하와전류 전하 (Electric Charge) : 어떤물체또는물질이가지고있는전기적성질또는전기의양을의미함 - Unit : 쿨롱 (Coulomb, 표기 : C) - 전자및양자의전하량 : 1.6021773349x10-19 C 일반적으로자연에서발견되는전하량은 1.602x10-19 C 의정배수 - 전하량보존의법칙 의성립 - 도체에서는전하가자유롭게이동할수있으며음전하 ( 전자 ) 이동의반대방향을전류방향으로정의 (Benjamin Franklin s convention) 9
전하와전류 전류 (Electric Current) : 단위시간당전하량의변화 (Time rate of change of electric charge) dq t - 수학적표현 : i or q dt i () t dt t 0 - Unit : ampere[a] = coulomb / second [C/sec] 직류와교류 - 직류 (DC, direct current) : a current that remains constant - 교류 (AC, alternating current) : a current that varies sinusoidally 직류는일반적으로 italic 대문자로, 교류는 italic 소문자로표시 11
전하와전류 Example 1.1 How much charge is represented by 4,600 electrons? Example 1.2 The total charge entering a terminal is given by q=5t sin4πt [mc]. Calculate the current at t = 0.5 sec. Example 1.3 Determine the total charge entering a terminal between t=1 and t=2 if the current passing the terminal is i=(3t 2 t) [A]. 10
전하와전류 전류의방향 - Direction of positive charge movement - Positive & negative current 12
전압 전압또는전위차 (Voltage or Electric Potential Difference) : The energy required to move a unit charge through an element dw - 수학적표현 : v dq - Unit : [V] = [Joule / Coulomb] = [Newton meter / Coulomb] 전압의방향 - ( 그림 a) point a의전압은 point b 보다 9V 높다 - ( 그림 b) point b의전압은 point a 보다 9V 낮다 13
전압 Example 1.4 An energy source forces a constant current of 2A for 10sec to flow through a light bulb. If 2.3kJ is given off in the form of light and heat energy, calculate the voltage drop across the bulb. 14
전력과전력량 전력 (Power) : the time rate of expending or absorbing energy dw dw dq -수학적표현 : p v i dt dq dt - Unit : [Watt] = [Joule / Sec] = [Volt Ampere] 전력의부호에대한 convention - ( 그림 a) p>0이면 element에의하여전력이소비됨을의미 - ( 그림 b) p<0이면 element가전력을공급함을의미 15
전력과전력량 전력의부호에대한 convention (2) 16
전력과전력량 전력량 (Energy) : 일정기간동안 element에의하여흡수 / 공급된전력 (the capacity to do work) - 수학적표현 : w p () t dt vi dt t0 t0 - 단위 : [Watt sec] or [Watt hour] t t 전력량보존의법칙 (law of conservation of energy) : p 0 공급된전력량 (energy supplied) = 흡수된전력량 (energy absorbed) 17
전력과전력량 Example 1.5 Find the power delivered to an element at t=3 ms if the current entering its positive terminal is i=5 cos60 πt [A] and the voltage is : (a) v=3i, (b) v = 3 di/dt Example 1.6 How much energy does a 100-W electric bulb consume in two hours? 18
회로소자 (Circuit Elements) 회로소자의구분 - Active element : Energy를생성할수있는소자예 ) Generator, Battery, Op-Amp - Passive element : Energy를생성할수없는소자예 ) Resistor, Inductor, Capacitor 19
회로소자 (Circuit Elements) Ideal Independent Voltage / Current Source an active element that provides a specified voltage or current that is completely independent of other circuit element Ideal Independent Voltage sources Ideal Independent Current sources 20
회로소자 (Circuit Elements) Ideal Dependent (Controlled) Voltage / Current Source an active element in which the source quantity is controlled by another voltage or current ( 대부분 OP-Amp로구현 ) - VCVS : Voltage controlled voltage source - CCVS : Current controlled voltage source - VCCS : Voltage controlled current source - CCCS : Current controlled current source 21
회로소자 (Circuit Elements) Example 1.7 Calculate the power supplied or absorbed by each element. 22
회로소자 (Circuit Elements) Example 1.8 The electron beam in a TV picture tube carries 10 15 electrons per second. Determine the voltage Vo needed to accelerate the electron beam to achieve 4W. 23
회로소자 (Circuit Elements) Example 1.9 23