SWITCH-MODE POWER SUPPLIES AND SYSTEMS

1
SWITCH-MODE POWER SUPPLIES AND SYSTEMS
Lecture No 1

• Silesian University of Technology
• Faculty of Automatic Control, Electronics
• and Computer Sciences
• Ryszard Siurek Ph.D., El. Eng.

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Program of the course

• Lecture No 1 - General overview of power
  supplies, basic func-
• tions, static and dynamic parameters related
  to
• the output
• Lecture No 2 - protection circuits (overcurrent,
  overvoltage etc.),
• additional functions and indications,
  paralleling of
• power supplies, redundancy
• Lecture No 3 - Input parameters specified for
  power supplies,
• Electomagnetic Noise emission, Power Factor,
• Immunity against electromagnetic disturbances,
• general overview of power supply systems
• Lecture No 4 - Linear regulator in comparison to
  switching one,
• analysis of basic topology step-down
  switching
• regulator, general equations and waveforms
• Lecture No 5 - Analysis of step-up and flyback
  switching topolo-
• gies, basic equations and waveforms, problem
  of
• discontinuous current (magnetic flux) flow
• Lecture No 6 - Switching converters, pulse power
  transformer,
• analysis of single-ended forward converter,
  trans-
• former reset circuits, transformer saturation

3
Lecture No 7 - Push-pull converter analysis,
transformer opera- tion explanation on
hysteresis curve, core satu- ration problems,
bridge an half bridge converters Lecture No
8 - Single-ended flyback converter analysis,
parasitic (leakage) inductance problems,
multi-output power supplies Lecture No
9 - Output filter components - capacitors,
inductors, influence on switching regulator
performance Lecture No 10 - Power losses in
magnetic components, skin and proximity
effects Lecture No 11 - Pulse transformer
designing basis flyback, for- ward and push
pull converter, power losses in switching
regulator, power losses reduction Lecture No
12 - Regulated switching converters, closed
feedback loop analysis
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Recommended books and articles

• 1. Abraham I. Pressman - Switching Power
  Supply Design, Second Edition,
• 
  McGraw-Hill, New York, 1998
•  
• 2. Billings K. - Switchmode Power Supply
  Handbook,
• McGraw-Hill, New
  York, 1989
•  
• 3. Texas Instrument - Power Supply Design
  Seminars (1996 to 2007),
• to view
  or download go to
• 
  power.ti.com (Support/Training/Seminar Materials)
•  
• 4. Ferenczi O. - Zasilanie ukladów
  elektronicznych.
• Zasilacze impulsowe, WNT, Warszawa,
  1989
•  
• 5. Palczynski B., Stefanski W. -
  Pólprzewodnikowe uklady i urzadzenia
• 
  techniki impulsowej, WKL, Warszawa, 1973

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Basic requirements for low and medium power DC
Power Supplies
General configuration of the Power Supply
safety low voltage area (ELV or
SELV)
hazardous/lethal voltage area
-15 - 10
regulated voltages

/
U1



U2
primary circuit
secondary circuit(s)
.
.
isolated output
.
Un
input/line voltage AC or DC
isolation barrier
output DC voltages
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Essential functions performed by the typical
Power Supply

• Delivering of one or several output voltages with
  certain load capabilities, mostly DC voltages in
  the range of 3V to 48V
• Protection against electric shock sufficient
  isolation of low voltage outputs from hazardous
  supply/line voltage
• Output voltage/voltages regulation against input
  voltage and load changes

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Output voltage static (steady state) parameters
Equation describing the influence of most
important factors on the output voltage
dUout dT
dUout dIo
dUout dUwe
DUout
DT
DIo
DUwe
x
x
x
(1.1)
Load regulation coefficient
Line regulation coefficient
Temperature coefficient
Uout
Uout
Uout
DIo
DUwe
deg
(Iomin Iomax)
(Uwemin Uwemax)
Presented usually in technical data sheets
Presented usually in technical data sheets
Presented usually in technical data sheets
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Ripple and noise observed within the range of
several hundreds of Hz
Uwy
10ms - 100Hz
t
ms
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Output voltage dynamic parameters

• Output voltage ripple noise

output voltage mean value
DUwyp-p
basic ripple
switching ripple
5
10
15
20
25
30
Magnified output voltage waveforms observed
within the range of several hundreds of kHz
10
Dynamic output voltage swing related to load
current step change
load current
output voltage
load current step change
output voltage dynamic reaction
output voltage static change - load regulation
11
Start-up overshoot)
low load
Uout
Uo
heavy load
t