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.
Program of the course
Lecture No 1
-
Lecture No 2
-
Lecture No 3
-
Lecture No 4
-
Lecture No 5
-
Lecture No 6
-
General overview of power supplies, basic functions, static and dynamic parameters related to
the output
protection circuits (overcurrent, overvoltage etc.),
additional functions and indications, paralleling of
power supplies, redundancy
Input parameters specified for power supplies,
Electomagnetic Noise emission, Power Factor,
Immunity against electromagnetic disturbances,
general overview of power supply systems
Linear regulator in comparison to switching one,
analysis of basic topology – step-down switching
regulator, general equations and waveforms
Analysis of step-up and flyback switching topologies, basic equations and waveforms, problem of
discontinuous current (magnetic flux) flow
Switching converters, pulse power transformer,
analysis of single-ended forward converter, transformer reset circuits, transformer saturation
Lecture No 7
-
Lecture No 8
-
Lecture No 9
-
Lecture No 10 -
Lecture No 11 -
Lecture No 12 -
Push-pull converter analysis, transformer operation explanation on hysteresis curve, core saturation problems, bridge an half bridge converters
Single-ended flyback converter analysis, parasitic
(leakage) inductance problems, multi-output
power supplies
Output filter components - capacitors, inductors,
influence on switching regulator performance
Power losses in magnetic components, skin and
proximity effects
Pulse transformer designing basis – flyback, forward and push pull converter, power losses in
switching regulator, power losses reduction
Regulated switching converters, closed feedback
loop analysis
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 układów elektronicznych.
Zasilacze impulsowe, WNT, Warszawa, 1989
5. Pałczyński B., Stefański W. - Półprzewodnikowe układy i urządzenia
techniki impulsowej, WKL, Warszawa, 1973
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
primary
secondary
circuit
circuit(s)
U2
.
.
isolated output .
Un
input/line voltage
AC or DC
isolation
barrier
output DC
voltages
=
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
Output voltage static (steady state) parameters
Equation describing the influence of most important factors on
the output voltage
DUout = dUout
dIo
Load regulation
coefficient
%Uout
x
DIo +
dUout
dUwe
x
DUwe +
Line regulation
coefficient
dUout
dT
x
DT
Temperature
coefficient
%Uout
DIo
(Iomin – Iomax)
Presented usually in
technical data sheets
DUwe
(Uwemin – Uwemax)
Presented usually in
technical data sheets
%Uout
deg
Presented usually in
technical data sheets
(1.1)
Ripple and noise – observed within the range of several hundreds of Hz
Uwy
10ms - 100Hz
t
ms
Output voltage dynamic parameters
Output voltage ripple & noise
output voltage – mean value
DUwyp-p
basic ripple
5
10
15
switching ripple
20
25
30
Magnified output voltage waveforms observed within the
range of several hundreds of kHz
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
Start-up overshoot)
Uout
low load
Uo
heavy load
t