![Page 1: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/1.jpg)
EEL 5245 POWER ELECTRONICS I
Lecture #9: Chapter 3
Power System Basics and Sinusoidal Systems
![Page 2: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/2.jpg)
EEL 5245 Objectives
• Review of Basic Power Concepts – Efficiency-Practical Example – Average and RMS Calculations
• Commonly observed waveform • Sinusoidal Systems
– Load Types – Average, Reactive, and Apparent Power – Power Factor – Power Factor Correction – 3 Phase, 4 Wire Neutral Currents
![Page 3: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/3.jpg)
EEL 5245 Efficiency in Power Electronic Converters
• Efficiency is one of the most significant figures of merit – Can be used to judge overall performance of topology in many cases
• Modern Power Electronic Converters have efficiencies approaching 100% • For in-class analysis, if power electronic circuit consists of ideal switches, transformers, and energy elements
(L&C) efficiency is 100% • In Real World Circuits, losses play a significant role:
– Dominate Loss Mechanisms • Semiconductor Switch Loss: Conduction and Switching
– Losses are a function of operating point
![Page 4: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/4.jpg)
EEL 5245 Efficiency in “Real World” Power Electronics Circuits
Example – Power Factor Connections
![Page 5: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/5.jpg)
EEL 5245 Average and RMS Calculations
• In modern power electronics converters, electrical parameters have periodic and nonlinear waveforms (steady state)
– Switch Current, Diode Voltage, Inductor Current, etc.
• Both average and RMS values of these highly, nonlinear wave shapes are often needed for design
– Average is area under curve divided by period – RMS used for power loss calculation
Given Periodic Function f(t): Average of f(t):
Rms of f(t):
![Page 6: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/6.jpg)
EEL 5245 Average and RMS Calculations Nonlinear/Piecewise Wave shapes
Example of Boost DC-DC Converter
![Page 7: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/7.jpg)
EEL 5245 Instantaneous and Average Power
• Instantaneous power is point for point product of voltage and current
• “Useful” power is average of Instantaneous, Pavg (aka Real Power)
• RMS definition can be derived from instantaneous power average
• Apparent Power is product of RMS values of voltage and current
![Page 8: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/8.jpg)
EEL 5245 RMS & Average Value Calculation
• RMS & Average Value Calculation
• Examples of Commonly observed P.E. waveforms
• DCM Induced Current
![Page 9: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/9.jpg)
EEL 5245
![Page 10: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/10.jpg)
EEL 5245
![Page 11: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/11.jpg)
EEL 5245
![Page 12: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/12.jpg)
EEL 5245
![Page 13: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/13.jpg)
EEL 5245
![Page 14: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/14.jpg)
EEL 5245
![Page 15: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/15.jpg)
EEL 5245
![Page 16: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/16.jpg)
EEL 5245 Sinusoidal Systems
• Recall that the RMS value of any pure sinusoidal is peak divided by root 2
• Phase shift in this diagram a result of reactive elements – In this case, a capacitive load
as I leads V • Real power is maximized when
v(t) and i(t) are in phase since overlap is maximized – Any relative shift between
the two means real power is less than maximum while RMS is unaffected
02
== avgs
rms VV
V
02
== avgs
rms III
2.
.ss IV
RMSRMSapparent IVP ==
phaseshiftiv θθφ −=
![Page 17: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/17.jpg)
EEL 5245 Sinusoidal Systems Purely Resistive Load
V(s)
I(s)
P(t)
![Page 18: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/18.jpg)
EEL 5245 Sinusoidal Systems Resistive-Inductive Load
V(s)
I(s)
P(t)
![Page 19: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/19.jpg)
EEL 5245 Sinusoidal Systems Resistive-Capacitance Load
V(s)
I(s)
P(t)
![Page 20: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/20.jpg)
EEL 5245 Sinusoidal Systems Purely Inductive Load
V(s)
I(s)
P(t)
![Page 21: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/21.jpg)
EEL 5245 Sinusoidal Systems-Power Factor
• For the resistive load (Θ=0), both real and apparent power are Vrms*Irms
• Irms is current load and power distribution system • For resistive load, power system capacity is most
efficiently utilized • For any relative phase shift (i.e. Θ Not equal to 0), power
system capacity more stressed that what is strictly necessary to deliver required real power to load
• Power Factor is measure of how effectively power system is being utilized
![Page 22: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/22.jpg)
EEL 5245 Sinusoidal Systems-Reactive Power
• What makes up difference between apparent power and real power when pf<1 • For any relative phase shift (i.e. Θ not equal to 0), additional circulating energy due
to charging and discharging of system reactive elements • Reactive Power passed back and forth from source to load using system capacity
but provides no real power to load (i.e. performs no work)
![Page 23: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/23.jpg)
EEL 5245 Sinusoidal Systems
Real, Reactive, and Apparent Power Related
• Power Triangle above drawn for R-L load so if 0< Θ <90 we say power factor is “lagging”, since I lags V with an inductive load
![Page 24: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/24.jpg)
EEL 5245 Sinusoidal Systems Power Factor Correction
• Utility wants to provide minimum current necessary to meet customer Real (Average) power requirements – Transmission lines have maximum capacity – Higher current means more I2*R losses
• Utilities will place capacitor banks in parallel with user loads at the remote location to make load look resistive to their generators
![Page 25: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/25.jpg)
EEL 5245 Exercise 3.10
![Page 26: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/26.jpg)
EEL 5245
![Page 27: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/27.jpg)
EEL 5245
![Page 28: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/28.jpg)
EEL 5245
![Page 29: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/29.jpg)
EEL 5245
![Page 30: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/30.jpg)
EEL 5245
![Page 31: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/31.jpg)
EEL 5245 P.F. Example
![Page 32: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/32.jpg)
EEL 5245
![Page 33: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/33.jpg)
EEL 5245
![Page 34: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/34.jpg)
EEL 5245 Sinusoidal Systems Power Factor Correction
Exercise 3.10
![Page 35: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/35.jpg)
EEL 5245 Sinusoidal Systems Power Factor Correction
I - Correct PF to 0.97
![Page 36: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/36.jpg)
EEL 5245 Sinusoidal Systems Power Factor Correction
II - Correct PF to 1.0
![Page 37: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/37.jpg)
EEL 5245 Sinusoidal Systems Power Factor Correction
![Page 38: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/38.jpg)
EEL 5245 Sinusoidal Systems Power Factor Correction
![Page 39: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/39.jpg)
EEL 5245 Sinusoidal Systems Neutral Currents in
3 Phase 4 Wire Systems
• A balanced three phase load draws equal currents, each separated by 120 degrees as the source voltages are separated by 120 degrees
![Page 40: EEL 5245 POWER ELECTRONICS I Lecture #9: Chapter 3 …fpec.ucf.edu/teaching/EEL 5245 Lectures/Lecture9_Chapter3...• Review of Basic Power Concepts – Efficiency-Practical Example](https://reader030.vdocument.in/reader030/viewer/2022040202/5e6b72c8d858456dc06bd3f4/html5/thumbnails/40.jpg)
EEL 5245 Sinusoidal Systems
Neutral Currents in 3 Phase 4 Wire Systems
• The neutral current (by KCL) is the sum of the three phase currents for wye connected load • If the three loads are “balanced”, neutral current is zero