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4. Computer Simulation of Switching Converters
Power Electronic Systems & Chips Lab., NCTU, Taiwan
Power Electronic Systems & Chips Lab.
~
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Contents
Introduction Challenges in Computer Simulation Simulation Process Open-Loop Large Signal Simulation Small-Signal Modeling Controller Design Closed-Loop Large-Signal System Behavior Switching Details Mechanics of Simulation Widely Used Circuit-Oriented Simulators
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Introduction
power input power processor
power outputload
control signals
controller
measurements
reference
viii iv
vo
Switching nature of power converters Modeling of power converters Modeling of power devices Modeling of power losses Dynamic & steady-state behaviors Computer simulation vs. hardware prototype
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Challenges in Computer Simulation
Modeling of power devices
Simulation may take a long time
Accurate models are not always available
Modeling of the (analog or digital) controller
Simulation of steady-state
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Simulation Process
OPEN-LOOP, LARGE-SIGNAL SIMULATION
SMALL-SIGNAL MODELING AND CONTROLLER DESIGN
CLOSED-LOOP, LARGE-SIGNAL SYSTEM BEHAVIOR
SWITCHING DETAILS
Switch-Mode Power Supplies - SPICE Simulations and Practical Designs,Christophe Basso, McGraw-Hill, Feb. 1, 2008.
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Open-Loop, Large-Signal Simulation
power input Power processor (each switching is represented, simple component models)
power outputload
Prespecified control signals
vi iiiv
vo
(ideal switch model)
(define the operating point)
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Small-Signal (Linear) Model and Controller Design
input load
control signals
controller reference
Power processor (small-signal,
linearized) models
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Closed-Loop, Large-Signal System Behavior
power inputPower processor (each switching
is represented; simple switch models; saturation and pertinent
nonlinearities are included)
power outputload
control signals
controller
measurements
reference
POWER ON
saturation, limit, dead zone
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Switching Details
power input Power processor (some components represented in
detail; a few switching cycles)
power output
prespecified control signals
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Mechanics of Simulation
EQUATION SOLVERS
CIRCUIT-ORIENTED SIMULATORS
COMPARISON
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Solution Techniques for Time-Domain Analysis
LINEAR DIFFERENTIAL EQUATIONS
TRAPEZOIDAL METHOD OF INTREGRATION
NONLINEAR DIFFERENTIAL EQUATIONS
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Linear Differential Equations
oicL
LL vvdtdiLir
0Rv
dtdvCi ccL
(KVL)
(KCL)
)(0
1
11
1
tvLvi
CRC
LLr
dtdvdtdi
oic
L
L
c
L
Lvc
iL
rLvoi(t) RC
voiVd
ton toffTs
t0
Simplified equivalent circuit of a switch-mode, regulated DC power supply.
(a) (b)
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Solution of Linear Dynamic Equations
oic
L vtgvi
t
)(and)(x
)()()( tgtdt
td bAxx
0
1and11
1
L
CRC
LLrL
bA
)()()()()( tgtttdt
td bxAx
dgttt ttt )()()()()()( bxAxx
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Trapezoidal Method of Integration
t00 t
dtdx
)()( tbgtAx
)()( ttbgttAx
tt
tgtttgttttttttttttt bbxAxAxx 2121
dgttt ttt )()()()()()( bxAxx
tgtttgttttttttttt bbxAIxAI 212121
tgtttgttttttttttt bbxAIAIx 2121121
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Solution of the Linear Differential Equation
tgttgttt NMxx
AIAIM tt 21121
bAIN tt 21121
tgtttgttttttttttt bbxAIAIx 2121121
AAA )()( ttt
bbb )()( ttt
If A and B are independent of time:
Selection of the time step t plays a key role in computation accuracy!
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Nonlinear Differential Equations
tt ,xfx
t
ttdttt ,xfxx
tttttttttt ,,2
xfxfxx
Numerical Method:Simpsons-Rule, Newton-Raphson Iteration Procedure, Runge-Kutta Methods,
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Equation Solver: MATLAB Simulation
% Solution of the Circuit using Trapezoidal Method of Integrationclc, clg, clear% Input DataVd=8; L=5e-6; C=100e-6; rL=1e-3; R=1.0; fs=100e3; Vcontrol=0.75;Ts=1/fs; tmax=50Ts; deltat=Ts/50;%time=0: deltat : tmaxvst=time/Ts - fix (Time/Ts);%A=[-rL/L -1/L; 1/C -1/(C R)];b=[1/L 0];MN=inv(eye(2)-deltat/2 A);MN=MN (eye(2)+deltat/2 A);N=MN deltat/2 b%IL(1)=4.0; vC(1)=5.5;timelength=length(time);%For k=2 : timelengthx=M [iL(k-1) vC(k-1)]+N (voi(k)+voi(k-1));iL(k)=x(1); vC(k)=x(2);end%plot (time, iL, time, vC)meta Example
vst
)1(s
s fT
vcontrol
0
0
voi
Tst
t
)(0
1
11
1
tvLvi
CRC
LLr
dtdvdtdi
oic
L
L
c
L
Lvc
iL
rLvoi(t) RC
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MATLAB Simulation Result of Low Frequency Behavior
iL
vc
0t
0.5 1 1.5 2 2.5 3 3.5 4.54 53
4
5
6
7
8
9
10
Real Signal
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Simulation Example of a Buck Converter
Rload
Ton=7.5 st0
(a)
(b)
Switch-control signal on off on off
)101( sf
Ts
s
(a) Circuit for simulation. (b) Switch control waveform.
Lvc
iL
rL
vd(t)C
(5H) (5m)(100F)
(8.0V)
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Circuit Simulation: SPICE Approach
vD
0
0
6 2
5
3 4
Diode
Model name= Power_diode
vCNTL
Rsnub=100
Csnub=0.1FSnubber
iL
L rL
C vc
RloadSW
Model name= Switch
Initial conditions: iL(O)=4AvC(O)=5.5V
PSpice Example*DIODE 2 1 POWER_DIODERsnub 1 5 100.0Csnub 5 2 0.1uF*SW 2 0 6 0 SWITCHVCNTL 6 0 PULSE (0V, 1V, 0s, 1ns, 7.5us, 10us)*L 1 3 5uH IC=4ArL 3 4 1mC 4 2 100uF IC=5.5VRLOAD 4 2 1.0*VD 1 0 8.0*.MODEL POWER_DIODE D (RS=0.01, CJ0=10pF).MODEL SWITCH VSWITCH (RON=0.01).TRAN 10us 500.0us 0s 0.2us uic.PROBE.END
1
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PSPICE Simulation Results
i(L)9.0
5.0
3.0
0 100s 200 s 300 s 400s 500s
v(4, 2)
time
Results of PSpice simulation: iL and vc.
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Simulation and Experimental Results
Simulation Experiment
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Simulation Options for Power Conversion Systems
Switching-Mode System
Average modeling Cycle by cycle
Analog Simulation(SPICE, SABER, etc.)
Discrete Simulation(MATLAB, ACSI, etc.)
LargeSignal DC
SmallSignal
AnalyticalExpressional
Voltage,CurrentStresses
Voltage,CurrentRipples
LargeSignal
Analog (SPICE,)&Digital (MATLAB,); Control Loop Design
Closed-Loop Response
Symbolic Analysis(MATHMATICA,MACSYMA, etc.)
Real or IdealDevices
Analog Simulation
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Simulation of a Boost Converter
Sam Ben-Yaakov, "Simulation of Power Conversion Systems: From the State of the Art to Future Trends," pp. 13-24, PCIM Proc., Nuremberg, 1999.
The real device is replaced by an ideal switch.
200V
3.3
IN D4 L2 OUT
RL160
1m
C1
MUR860
30nH
SD
VinRg
Vgate
1nH
Lmain
50nH
LSW
IRFP460
0
M3
200V
3.3
IN D1 L1 OUT
RL160
1m
C1
30nH
SD
VinRg
Vgate
1nH
Lmain
50nH
LSW
Sbreak
0
R1
DbreakS1
0.3
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Behavioral Average-Model Representation of a Power Conversion System
Passive and Active Partsof Circuit
Duty-CycleGenerator
(DCG)
SIM-CircuitInteraction
Switching InductionModel (SIM)
V(a,b)
V(a,c)
a b
c
V(a,b)
V(a,c)
Constant
VE Error Signal
Don Doff ILDon
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Switch Inductor Modeling Techniques
(a) The switch inductor (b) Average switch inductor model
a c
b
Ia
L
Ib
IL = Ic
a
bc
GaGb Gc
ILEL L+
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Simulation of a Boost PFC Converter
L1 L2 L3
R2
R3 R4
R5
R6R7 R8
R9
R10
C1 C2
C6
C5
C7
C8
C9
D1
IC1
IC2
+
+
VREF
CURRENT-ERRORAMPLIFIER
VOLTAGE-ERRORAMPLIFIER
MULTIPLIER
PULSE-WIDTHMODULATOR
RAMP
ACINPUT
LOAD
Q
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Simulation of a Soft-Switching Boost PFC Converter
L1 L2 L3 L4 R1
R2
R3 R4
R5
R6R7 R8
R9
R10
C1 C3 C4
C6
C5
C7
C8
C9
D1
D2 D3
IC1
IC2
+
+
VREF
CURRENT-ERRORAMPLIFIER
VOLTAGE-ERRORAMPLIFIER
MULTIPLIER
PULSE-WIDTHMODULATOR
RAMP
ACINPUT
LOAD
Q
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Equation Solver Oriented Simulators
MATLAB http://www.mathworks.com/
MathCAD http://www.mathcad.com/
Mathematica http://www.mathematica.com/
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General-Purpose Circuit-Oriented Simulators
Ansoft http://www.ansoft.de/ EMTP http://www.eeug.de/ SABER (Analogy) http://www.analogy.com/ PSPICE (OrCAD) http://www.orcad.com/ ICAP4 (Intusoft) http://www.intusoft.com/ PSIM http://www.powersimtech.com/ PowerDesigners http://www.powerdesigners.com/ Simplis http://www.transim.com/ SimPlorer http://www.simplorer.com/ CASPOC http://www.caspoc.com/ Electronics Workbench http://www.interactiv.com/
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Co-Simulation of a Motor Drive
Control System(analog, digital, DSP, FPGA etc.)
Powersupply
AC/DCConverter/
rectifier
AC/DCConverter/
inverterDClink
BLDCmotor
Mechanicalload
PSIM
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Ansoft: PExprt for Power Supply Design Simulation
High Frequency Ansoft DesignerHFSS
Signal Integrity SIwaveSpicelinkTPA
Electromechanical Maxwell 2DMaxwell 3DSIMPLORERPExprtRMxprt
Add-Ons AnsoftLinksFull-Wave SpiceOptimetricsParICsWinIQSIM
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NS Webench for LED Design
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TI Power Design Tools
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TI Analog eLAB Design Center
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SPICE-Based Analog Simulation ProgramTINA-TI Version 7.0 (Aug 21, 2008)
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TI SwitcherPro(TM) Online Design Creator and Management Software
http://focus.ti.com/en/download/aap/demos/switcherpro/switcherpro.html
1. Define a Design Based on the PWM IC
2. Select Components from a Database
3. Complete the Design to Make AnalysesFrequency Response Analysis
Calculated Effuiciency Analysis
PCB Layout Guide
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iSim - Intersils Interactive Web Design Simulation Toolhttp://web.transim.com/iSim/
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ISL6721 Flexible Single Ended Current Mode PWM Controller
ISL6721 Simulation Results
Frequency Response (Loop Gain)
Secondary Responses
Primary Responses
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PowerEsim
Its on-line Its for everyone Worldwide access 100% server side simulation
Its FREE !!
http://www.powerEsim.com
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AEi: Power IC Model Library (http://www.aeng.com/)SPICE Models for the Power Electronics Designer
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Wolfram Computable Document Format (CDF) Player
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Operational Amplifier Gain-Bandwidth Characteristics
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Summary
CAD
CAD
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References
[1] H. Jin, Behavior-mode simulation of power electronic circuits, IEEE Trans. on Power Electronics, vol. 12, no. 3, pp, 443-452, May 1997.
[2] D. Maksimovic, A. M. Stankovic, and V. J. Thottuvelil, and G. C. Verghese, Modeling and simulation of power electronic converters,Proceedings of the IEEE, vol. 89, no. 6, pp. 898-912, June 2001.
[3] Sam Ben-Yaakov, Simulation of power conversion systems: from the state of the art to future trends, pp. 13-24, PCIM Proc., Nuremberg,1999.
[4] V. Rajagopalan (Guest Editor), Special Issue on Computers in Power Electronics, Guest Editorial, p. 397, IEEE Trans. on PowerElectronics, vol. 12, no. 3, May 1997.
[5] Christophe Basso, Switch-Mode Power Supplies - SPICE Simulations and Practical Designs, McGraw-Hill, Feb. 1, 2008.
[6] Christophe P. Basso, Switch-Mode Power Supply SPICE Cookbook, McGraw-Hill Professional; 1st Ed., March 19, 2001.
[7] Steven M. Sandler, SMPS Simulation with Spice 3, McGraw-Hill., 2st Ed., 1996.
[8] Steven M. Sandler and Charles E. Hymowitz, SPICE Circuit Handbook, McGraw-Hill Publishing Co., Aug. 2006.
[9] Muhammad H. Rashid, SPICE for Power Electronics and Electric Power, Second Edition, CRC Press, Nov. 2005.
[10] G. Massobrio and P. Antognetti, Semiconductor Device Modeling with SPICE, McGraw-Hill., 1993.
[11] W. Banzhaf, Computer-Aided Circuit Analysis Using PSPICE, Prentice-Hall, Inc., 1992.
[12] M. H. Rashid, SPICE for Circuits and Electronics Using PSPICE, Prentice-Hall, Inc., 1990.
[13] W. Banzhaf, Computer-Aided Circuit Analysis Using PSPICE, Prentice-Hall, Inc., 1989.
[14] P. W. Tuinenga, SPICE: A Guide to Circuit Simulation & Analysis Using PSPICE, Prentice-Hall, Inc., 1988.
[15] Power Specialist's App Note Book, Papers on Simulation, Modeling and More, Edited by Charles Hymowitz,http://www.intusoft.com/lit/psbook.zip
[16] Inline equations offer hysteresis switch in PSpice, Christophe Basso, On Semiconductor, EDN, August 16, 2001