Ch 1 slides

Introduction to Power ElectronicsECEN 4797/5797Robert W. EricksonUniversity of Colorado, BoulderFall 2013

#1.1 Introduction to Power ProcessingDc-dc conversion:Change and control voltage magnitudeAc-dc rectification:Possibly control dc voltage, ac currentDc-ac inversion:Produce sinusoid of controllable magnitude and frequencyAc-ac cycloconversion:Change and control voltage magnitude and frequency

The switching converter is the brain of the power system, allowing conversion of voltage and current levels with high efficiency, plus control#Control is invariably required

Traditional analog feedbackSophisticated control using inexpensive digital microcontrollers#Electric VehicleTesla Model SFunctions of the power electronics:1. Convert the DC battery voltage to the variable AC required to drive the AC motor240 V batteryVariable-frequency, variable-voltage AC drives the motorAC motor propels the rear axleUp to 330 kW (acceleration)Up to 60 kW regenerative braking

2. Control charging of the batteryInterface to 240 V 60 Hz 1 100 A circuit in garageControl AC current waveform to be sinusoidal, unity power factorControl charging of battery to maximize life

#Hybrid VehiclesPrius

Power Electronics Module:Convert the DC battery voltage to the variable AC required to drive the AC motorIncludes dc-dc boost converter and dc-3ac inverterControl system can operate in all-electric mode or in hybrid gas+electric modePartial-power electronicsUnder the hood:Gas enginePower electronics module#Variable-Speed Wind Turbine Systems

AC generator produces wild ac: frequency and amplitude change with wind speedUtility operates with constant frequency (60 Hz) constant voltage acPower electronics changes the frequency and voltage, and also implements control functionsCycloconverter, orDC link system: rectifier, boost dc-dc, inverter

#Photovoltaic Solar Power Systems

Grid-tied solar: inverter converts dc of solar panels to ac for gridStand-alone solar: dc-dc converter interfaces solar panels to batteriesA solar roof shingle system#A standalone photovoltaic power system

The system constructed in ECEN 4517/5517 Power Electronics and Photovoltaic Systems Laboratory#Computer power supply systemsBattery-powered and servers

Laptop power systemiPhone power system and chargerComputer serversServer farms#High Efficiency is EssentialHigh efficiency leads to low power loss within converterSmall size and reliable operation is then feasibleA good measure of converter performance is the ratio of output power to loss:

Converters generally are loss-limited, and technologies that can produce large output power while incurring small loss result in small size and low cost

Large input powerLarge output powerSmall converter#

Devices available to the circuit designer#

Devices available to the circuit designerSignal processing: avoid magnetics#

Devices available to the circuit designerPower processing: avoid lossy elements#Power loss in an ideal switchSwitch closed:v(t) = 0Switch open:i(t) = 0In either event:p(t) = v(t) i(t) = 0Ideal switch consumes zero power

#A simple dc-dc converter exampleInput source: 100VOutput load: 50V, 10A, 500WHow can this converter be realized?

#Dissipative realizationResistive voltage divider

#Dissipative realizationSeries pass regulator: transistor operates in active region

#Use of a SPDT switch

#The switch changes the dc voltage levelD = switch duty cycle0 D 1

Ts = switching period

fs = switching frequency = 1 / Ts

DC component of vs(t) = average value:

#Addition of low pass filterAddition of (ideally lossless) L-C low-pass filter, for removal of switching harmonics:Choose filter cutoff frequency f0 much smaller than switching frequency fsThis circuit is known as the buck converter

#Addition of control systemfor regulation of output voltage

#The boost converter

#A single-phase inverterH-bridgeModulate switch duty cycles to obtain sinusoidal low-frequency component

#Introduction to Power ElectronicsECEN 4797/5797Instructor: Prof. Bob EricksonOffice: ECOT 356Telephone: (303) 492-7003Email: rwe@colorado.eduOffice hours: To be announcedTelephone office hours: To be announcedCourse web site:http://ece.colorado.edu/~ecen5797Includes lecture slides, handouts, homework assignments, links to online lecture filesTextbook:

Erickson and Maksimovic, Fundamentals of Power Electronics, second edition, Springer, ISBN 0-7923-7270-0.Prerequisite:A 3-4 semester sequence of undergraduate EE circuits and electronics courses(at Univ. of Colorado: ECEN 3250) #Coursework in Power Electronicsat the University of ColoradoPower electronics coursesECEN 4797/5797 (this course): Intro to power electronics (Fall)ECEN 5807 Modeling and Control of Power Electronics Systems (Alt Spring semesters, including S 15)ECEN 5817 Resonant and Soft-Switching Techniques in Power Electronics (Alt Spring semesters, including S 14)ECEN 4517/5517 Power Electronics Laboratory (Spring)Professional Certificate in Power ElectronicsECEN 5797, 5807, and 5817Formats for this courseOn-campus, for senior or graduate creditWeb-based lectures: recorded with ECHO 360 system, with viewing through the Flash viewer. For technical help, contact help@cuengineeringonline.colorado.edu (CAETE)

#GradingHomeworkDue at beginning of class on date listed on Lecture Schedule web pageSubmit online via D2L dropbox; late homework not acceptedHomework counts 50% of gradeYou may speak with others about the homework, but turn in your own workHomework and exam problems of additional depth and complexity for those earning graduate credit; separately graded ExamsMidterm exam: one-week take-home exam, 17% of gradeFinal exam: five-day take-home exam, 33% of gradeSee course schedule page for datesSee course vitals page for details#Desire-2-Learn (D2L) Sitelearn.colorado.eduLog on with your campus IdentiKey

Dropbox for submission of homework and examsScan, save as pdf, then upload to the D2L dropboxFor on-campus students: a scanner is available within the SRCAutomatic deadline at beginning of classA log of your grades for all assignmentsWhen grading is complete, your grade will appear onlineRunning total of your overall course gradeGrader will post comments and annotations onlineHomework solutionsPosted within D2L after submission deadlineStudent discussion forumYou can post questions and discussions with your classmatesNormally questions will not be answered by Prof. EricksonPosting of homework solutions in the forum is prohibited#Off-campus studentsViewing of lecturesLectures are normally available online by the end of the day of the on-campus lectureAssignmentsUse the D2L site to upload your pdf file: same as for on-campus studentsGenerally, by Friday the lectures will finish covering the material needed for the homework assignment due the following Friday. So you can work the homework over the weekend.Check out the D2L student forumsDue dates and times are the same as for the on-campus studentsEducational OfficersNot neededSee course vitals pageLink to academic calendar for CAETE students, including add/drop deadlines

#Key datesDrop deadlinesSeptember 11: last day to drop the course and receive full tuition refund, with no W grade appearing on transcriptNovember 1: last day to drop the course via MyCUInfoTentative exam datesMidterm exam: 1 week take-home exam. Available through D2L on Oct. 18, due on Oct. 25.Final exam: Four day take-home exam. Available through D2L on Dec. 13, due on Dec. 17.Grades assigned in December appear on your permanent university transcriptCampus holidaysLabor day: Sept. 2Fall break / Thanksgiving holiday: Nov. 25-29

#1.3 Elements of power electronicsPower electronics incorporates concepts from the fields ofanalog circuitselectronic devicescontrol systemspower systemsmagneticselectric machinesnumerical simulation

#Part I. Converters in equilibrium

Inductor waveformsAveraged equivalent circuit

Predicted efficiencyDiscontinuous conduction modeTransformer isolation#Switch realization: semiconductor devices

The IGBT

Switching loss#Part I. Converters in equilibrium2. Principles of steady state converter analysis3. Steady-state equivalent circuit modeling, losses, and efficiency4. Switch realization5. The discontinuous conduction mode6. Converter circuits#Part II. Converter dynamics and control

Closed-loop converter systemAveraging the waveformsSmall-signal averaged equivalent circuit#Part II. Converter dynamics and control7.Ac modeling8.Converter transfer functions9.Controller designInput filter designAc and dc equivalent circuit modeling of the discontinuous conduction mode12.Current-programmed control#Part III. Magnetics

transformer designtransformer size vs. switching frequencythe proximity effect#Part III. Magnetics13.Basic magnetics theory14.Inductor design15.Transformer design#