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8/6/2019 SWIE Report
1/23
Forward Converter Project
Department of ElectricalEngineering and Information
Technology
Copenhagen University Collegeof Engineering
Lautrupvang 15, 2750 Ballerup
Forward Converter Project
ESWIE-EC51-E10
This report forms the documentation of the designing and testing of a
20 W Switch Mode Power Supply.
The process has been highly iterative, and thus it is not possible to
describe the entire process in a chronological manner within the
constraint of these 15 pages.
This document serves as a presentation of the finished product, with
emphasis on key design considerations and the most prominent
features.
Student name Student number Signature
Lasse Kastholm Martinussen 80817
Havan Mohamed Mhedeen 80719
Mohammed Errifi 70303
Kasper Krogh Hansen 70286
Marek Piwonski 81089
Supervisor:Lars Maack
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List of content
1. INTRODUCTION .................................................... .......................................................................3
1.1 PREFACE ............................................................................................................................ 3
1.2 REQUIREMENTSSPECIFICATION........................................................................................................... 3
2. PROBLEM SOLUTION .......................................................... ........................................................4
2.1 BLOCKDIAGRAM ............................................................................................................................ 4
2.2 SCHEMATIC ............................................................................................................................ 4
2.2.1 Coil ......................................................... ................................. ...5
2.2.2 Transformer ......................................................... ................................. ...6
2.3 MAINWAVEFORMS ...........................................................................................................................8
2.3.1 Output voltage and coil current ................................................... .....................................8
2.3.2 Primary current and MOSFET DS voltage ................................................... ................ ..9
2.4 SYSTEMTESTRESULTS...................................................................................................................... 102.4.1 Loop Gain ......................................................... ................................ ..10
2.4.2 Step load ......................................................... ................................ ..11
2.4.3 Efficiency ......................................................... ................................ ..12
3. CONCLUSION .................................................... ........................................................... ...............14
4. APPENDICE ..................................................... ........................................................... ...................15
4.1 TRANSFORMERLOSSES..................................................................................................................... 15
4.2 LITTERATURE .......................................................................................................................... 16
4.2.1 Notes ......................................................... ................................ ..16
4.2.2 Books ......................................................... ................................ ..17
4.3 MATLABCODE .......................................................................................................................... 17
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1. Introduction
1.1 Preface
This project has been developed by a 5 persons group under time constraints
equal to an eighth of a semester. The process has been problem oriented, and
the report is a result of a highly iterative process. Along the way we have
gotten a lot of problems solved thanks to our supervisor Lars Maack.
1.2 Requirements specification
Functional requirements:
1. Nominal input DC voltage: 24 V
2. Input DC voltage range: 20 - 30 V
3. Output DC voltage: 4 V
4. Output load current: 0 - 5 A
5. Output ripple: 300 mVpp (Measured with a +50 MHz BW scope)6. Max. transient output voltage during 4 to 2 A step load: 150 mVpp
(Neglecting ripple at switch frequency and above)
7. Switch frequency: 100 kHz
Non-functional requirements:
1. The efficiency as a function of input voltage must be both simulated
and measured at different loads and presented in a graph.
2. If the efficiency is iteratively optimized, this should be done atmaximum load and nominal input voltage.
3. Inductors and transformers must be home made.
4. Potentiometers and variable resistors are unwanted.
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2. Problem solution
2.1 Block diagram
2.2 Schematic
Above, the schematics of the finished product is depicted.
It is a forward converter topology, which produces a controlled DC output
voltage from an unregulated DC input. The forward converter is a simple
converter which provides a low voltage ripple at the output and a good
conversion efficiency.
The maximum duty-cycle must be less than 50% to prevent core saturation.
The SG3524 PWM controller is rated for a maximum duty ratio of 0.45. Some
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Forward Converter Project
headroom is needed to compensate for losses and therefore we have chosen to
design for a Dmax of 0.35.
The SG3524 is connected to a totem pole configuration of BJTs, that drive theMOSFET gate. The resistor mounted at the gate slows the switching speed a
bit and helps reduce spikes on the drain of the MOSFET.
The maximum allowed ripple at the output is 300 mV.
Having designed the filter coil to allow 2 A of ripple current, a maximum
allowed ESR of the output filter capacitor is 150 m.
By impedance measurement we have selected a capacitor with a proven ESR
of only 56 m, which reduces output voltage ripple beyond the requirement.
The IRF630 MOSFET is chosen not only because of its low on resistance of 0.4
ohm and its Drain current of 9 A.
For development purposes it is suitable to have a high Drain Source voltage
tolerance, which in the IRF630's case is 200 V.
Changing to a MOSFET with a lower rating will make it possible to go lower
than 0.4 in on resistance, thereby lowering on state losses in the MOSFET, but
such optimizations are left to future development.
2.2.1 Coil
The chosen core for the coil is an RM8. This core fullfills the demanded
AcoreAwindow factor calculated by the formula:
AwindowAcoreLIpeakIRMS
FBpeakG(Coil design procedure note)
From this we got 1098,5 mm4 (Se appendice 4.3 for Matlab calculations). The
RM8 have a value of 1900 mm4. (see appendice 4.2.1 for datasheet)
To calculate the number of turns we use the formula:
N=LIpeak
BpeakAcore6 (Coil design procedure note)
(Se appendice 4.3 for Matlab calculations)
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By the formula for the area of the wire, Awire=IRMS
G(Coil design procedure
note), we got an diameter of 0.44mm, but because of the excess of space in thecoil, we fitted a 1 mm thickness.
Designing for a ripple current of 2 A calls for a coil inductance of 16 uH,
which has been achieved by adjusting core airgap while performing
impedance measurements.
2.2.2 Transformer
The purpose of the transformer is to scale the input voltage to a lower output
voltage in an efficient and instantaneous way. This transformation leads to
power losses in practice, which we have been taken in to account.
Once again the RM8 core is chosen due to the formula:
AwindowAcoreUpriton2I pri rms
FB peakG(Trafo design note)
From this we got a value of 617.9mm4, which only calls for an RM7 core.
However, the only available core is an RM8 which was chosen for obvious
reasons. (See appendice 4.2.1 for details.)
The turns ratio of 1.489, is calculated by:
n=Npri
Nsec=
Vpri
Vsec=
Isec
Ipri(The essence of power electronics note)
(Se appendice 4.3 for Matlab calculations)
From our calculated figure of total powerloss,
the number of primary turns is chosen to be 13 since this number i placed in
the region of lowest possible combined losses. (Core + Copper)Furthermore, a ratio of 13 to 9 offers the best integer representation of the
turns ratio. Hereby the practical turns ratio is 1.44.
The curve of total copperloss can be seen below.
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Forward Converter Project
The diameter of the wires is found by:
dpri=2AwindowF
NpriGiving 1.1 mm.
dsec=2AwindowF
NsecGiving 0.7 mm.
(For calculations see appendice 4.1)
2.3 Main waveforms
2.3.1 Output voltage and coil current
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As it can be visually asserted above, the coil current is 2App in the output coil
as intended. (30 V supply, 5 A load)
The output ripple is as low as 70 mV, while specification stated no more than
300mVpp ripple voltage.
This is achieved due to the very low ESR of the chosen output capacitor.
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2.3.2 Primary current and MOSFET DS voltage
The figure above depicts the MOSFET's drain-source voltage and current.
By multiplying the current and voltage, and integrating over one full period,
the average MOSFET power dissipation was found to be 70 mW.
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2.4 System test results
2.4.1 Loop Gain
By meams of simulation, the feedback control was copensated and depicted
above. The system is compensated to give a proper phase margin of 36
degrees at the unity gain point. The following figure shows the practically
measured loop gain:
The graphs are very similar, and the difference in gain is quite expected. The
gain measurement is to high extent misshaped by noise present during
measurement.
Analysing the measured results, we can read that our phase margin is 36
degree as intended.
10
Frequency
300Hz 1. 0KHz 3. 0KHz 10KHz 30KHz 100KHzP(V(R4:1)) DB(V(R4:1))
0
50
100
150
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2.4.2 Step load
The figure above depicts the practically measured step load response.
As specified the system does not exceed 150 mVpp while stepping down from
4 to 2 A load, - in fact the ripple is as small as 127 mV due to the high loop
gain of the system.
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2.4.3 Efficiency
The efficiency has both been simulated and measured.
For the simulation, the measured parameters of both coil and transformer was
put in to provide relistic losses.
As seen, theres quite a good correlation between the two figures.
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Thermal view:
The thermal view displays what elements dissipate most energy through heat
radiation. From the picture it is seen that the diodes contribute most
significantly to the total loss since they are the hottest.
Taking the diode drop of 0.75 for the model used, and current output we can
calculate power dissipation:
P=UI=0.75V5 A=3.75W
As each of the output diodes is active only half the period it is the total powerdissipation in both diodes.
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3. Conclusion
We have managed to construct a power supply that matches, and even
exceeds some of the specified requirements. The converter has a very high
loop gain in a wide frequency range. The supply can even operate at only 18 V
supply at full load. Efficiency varies on current drawn from the supply, but it
maintains a good percentage, as high as 84 % under optimal conditions.
The switches generate very little noise, due to proper board layout and
optimal snubbing, and the output voltage ripple is only 70 mV, which by far
exceeds the reqirement.
This leads to the conclusion that we have constructed a very good switch
mode converter, which we are very proud of and look forward to present in
detail at the exam.
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4. Appendice
4.1 Transformer losses
There can occur some power losses in the transformer. We will look at the
losses in the core and the wires, which can be described by the following
formula:
(Taken from trafo design note)
Here the only unknown is z and K, which can be found in the data book
Magnetic Components Catalogue form the graph showing power loss as
function of frequency under the RM8 core(F44, page 12).
If we take two point on the graph at 100 kHz frequency and put it in the
formula, we will have 2 equations with 2 unknown which can be solved.
(Taken from trafo design note)
z = 1.737
K = 3930000
Now we have all the parameters and we can describe the Pcore
, Pcopper
and
Ptotal
as function of Npri
.
Her we see the graphs showing the relationship and we see that there is
minimum total loss around 13-14 turns. We have chose 13 as Npri.
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4.2 Litterature
4.2.1 Notes
Coil Design procedure.pdf
https://www.campusnet.ihk.dk/cnnet/filesharing/SADownload.aspx?
ElementId=22197&FolderId=151619&FileId=598120(Demands a login)
Trafo Design.pdf
https://www.campusnet.ihk.dk/cnnet/filesharing/SADownload.aspx?
ElementId=22197&FolderId=151619&FileId=598119(Demands a login)
MC Catalogue.pdf
https://www.campusnet.ihk.dk/cnnet/filesharing/SADownload.aspx?
ElementId=22197&FolderId=151621&FileId=598101(Demands a login)
Key solid RM Core Parameters.pdf
https://www.campusnet.ihk.dk/cnnet/filesharing/SADownload.aspx?
ElementId=22197&FolderId=151621&FileId=598102(Demands a login)
4.2.2 Books
The essence of power electronics (J. N. Ross)
4.3 Matlab code
close all;clear all;
clc;
format shorteng;
set(0,'DefaultFigureWindowStyle','docked');
% SEE SCHEMATIC DRAWING FOR DETAILS
% DEFINITIONS
f_switch=100e3;
Vin=20; %range: 20-30 V, worst case scenario = 20 V
Vmax=30;
Vout=4; % 4 V nominally
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Dmax=0.35; % SG3524 is rated for a max D of .45. We subtr. 5 %
for headroom
Dnom=Dmax*(20/24);
Dmin=Dmax*(20/30);
% FINDING TRANSFORMER TURNS RATIO n = N1/N2
% Vout=Vin*Dmax/(N1/N2) (N1/N2) = n = (Vin*Dmax)/Vout hence:
n=(Vin*(Dmax))/(Vout+0.7); % 0.7 V added to compensate for Diode
voltage drop
% No. OF PRIMARY TURNS
% Before calculating the number of primary turns that will give
the lowest
% possible loss, we need to know i_pri_RMS which is dependant on
i_L_RMS
% i_L is specified to max 5 A.
i_L=5; % Assuming that the ripple is 0
i_pri=(i_L/n);i_pri_RMS=i_pri*sqrt(Dmax);
% CHOISE OF TRANSFORMER CORE
% The core must satisfy: A_window*A_core >=
(U_pri*t_on*2*i_pri_RMS)/(F*B_peak*G)
% Constants:
U_pri=20; % the nominal supply voltage
t_on=Dmax*(1/f_switch); % on time pr. period, Dmax=0.4
F=0.5; % fill factor
B_peak=0.3; % Max allowable peak B-field
G=3; % Current density [A/(mm)^2]
A_windowA_core=((U_pri*t_on*2*i_pri_RMS)/
(F*B_peak*G*10^6))*10^12;
% RM8 transformer core is suitable
Awindow=30e-6; % m^2
Acore=64e-6; % m^2
% MIN N0. OF TRANSFORMER PRIMARY TURNS (that will prevent
saturation)
N_pri=(U_pri*t_on)/(B_peak*Acore);
N_sec=N_pri/n;
%N_pri*3
%N_sec*3
% practical turns ratio: 13/9. 13/9
% TRANSFORMER WIRE DIAMETERSd_pri=sqrt((2*Awindow*F)/(pi*N_pri))*1000;
d_sec=sqrt((2*Awindow*F)/(pi*N_sec))*1000;
% FINDING RM8 F44 FERRITE CORE LOSS CONSTANTS K & z
%syms K z;
%A=solve('K*(0.200)^z*2430e-3=250','K*(0.200)^z*2430e-3=160')
%S = [S.x S.y]
%Pcore1=(K*((U_pri*t_on)/(N_pri*A_core))^z)*V_core;
%solution=solve(Pcore,K);
%solution
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K=3.93e6; %[W/m^3
z=1.737;
V_core=2430e-9; %[m^3]
rho_copper=1.68e-8; %[OHM*m]
l_winding=pi*1.e-2; %[m]
% Now using the total power loss formula in the "Transformer
design note"
% to plot total loss (P_Copper + P_Core), as function of N_pri.
% This will show the lowest loss point. RM8 core chosen!
xN_pri=linspace(3,25,1000);
Pcore=K*(((U_pri*t_on)./(xN_pri.*Acore)).^z)*V_core;
Pcopper=(4*(i_pri_RMS)^2)*rho_copper*((l_winding.*xN_pri.^2)./
(Awindow*F));
Ptotal=Pcore+Pcopper;
plot(xN_pri,Pcore);
hold on
plot(xN_pri,Pcopper,'r');
hold on
plot(xN_pri,Ptotal,'m');
%(1/n)*17
% Transformer n=13/9 Measurements
% Lpri: 3.33 Ohm, 31.84 pF, 338.24 uH (Sec open)
% Lpri: 266 mOhm, 37.74 pF, 372.00 nH (Sec closed)
% Demag: 3.34 Ohm, 30.6 pF, 339.85 uH (Sec open)
% Demag: 224 mOhm, 22.3 pF, 775.00 nH (Sec closed) % Lsec: 1.87 Ohm, 54.92 pF, 161.36 uH (Pri open)
% Lsec: 1.4 Ohm, 97.71 pF, 162.233 uH (Pri closed)
% SELECTION OF POWER MOSFET -SEE AND8039/D app note
% MOSFET: IRF630 CHOSEN:
R_DS_on=0.4;
V_DS_on=i_pri_RMS*R_DS_on;
V_D=0.7;
% COIL DESIGN % COILS L VALUE SEE AN-776 (p.113 says otherwise)
i_L_ripple=0.4*i_L;
L=((Vmax-V_DS_on)*(N_sec/N_pri)-V_D-Vout)*(Dmin/
(i_L_ripple*f_switch));
% COILS RMS CURRENT
i_L_RMS=i_L-i_L_ripple+i_L_ripple/sqrt(3);
i_peak=i_L+i_L_ripple/2;
A_windowA_core_L=(L*i_peak*i_L_RMS)/(F*B_peak*G)*10^6;
% RM8 is once again chosen
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% Number of turns
N=(L*i_peak)/(B_peak*Acore); % round up = 6
A_wire_L=i_L_RMS/(G); % result in mm2 = 1.3849
D_wire=A_wire_L/pi;
% SELECTION OF POWER DIODES -SEE AND8039/D app note
% DIODES
V_rev_min=Vmax*(N_sec/N_pri); % > 18 V
i_D_RMS=i_L_RMS*(1-Dmin); % > 3 A
% MBRB1560CT chosen.
% Diode for Demagnetization: BYW29
% OUTPUT FILTER CAP SEE AN-776
C=(i_L_ripple*1/f_switch)/(8*0.3); % however such small cap has significant ESR
% Maximum allowed ESR: deltaVo/i_L_ripple
ESR_max=0.300/i_L_ripple; % 0.150 ohm
% By impedance measurent a good cap was found to be:
% 220 uF/100 V electrolytic w. ESR: 56 mOhm (ESC=221 uF,
ESL=55* nH)
% *is probably lower when properly mounted on PCB
% Calculation of transfer function, ie. poles and zeros of
% uncompensated circuit.
% Compensation of circuit % PCB
% transformer
% coil
% open loop test
% A totem pole conf. of BCX54 and BCX51 in SOT89 housings chosen
for gate drive
% SG3524 timing cap and res to give 200 kHz
R_t=1.3/(200e3*3.48e-9) % 1 nF < cap value < 100nF, 1.8k < R
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%InpCurrVect30=[ 0.0 0.045 0.085 0.12 0.16 0.20
0.24 0.28 0.32 0.365 0.41 0.455 0.5 0.55 0.59 0.64
0.69 0.74 0.79 0.84 0.89]
%InpVoltVect30=[30.000 30.000 30.000 30.000 30.000 30.000
30.000 30.000 30.000 30.000 30.000 30.000 30.000 30.000 30.000
30.000 30.000 30.000 30.000 30.000 30.000]
%LoadCurrVect30=[0 0.25 0.5 0.75 1 1.25
1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75
4 4.25 4.5 4.75 5]
%LoadVoltVect30=[4.05 4.05 4.05 4.05 4.05 4.05
4.05 4.05 4.05 4.05 4.05 4.05 4.05 4.05 4.05 4.05
4.05 4.05 4.05 4.05 4.05]
%InPowerVect=InpCurrVect30.*InpVoltVect30;
%OutPowerVect=LoadCurrVect30.*LoadVoltVect30;
% 30 V supply, new 13/9 transformer
InpCurrVect30=[ 0.045 0.085 0.127 0.16 0.20 0.24
0.29 0.33 0.38 0.42 0.47 0.52 0.57 0.62 0.67 0.720.77 0.83 0.88 0.94]
InpVoltVect30=[30.000 30.000 30.000 30.000 30.000 30.000
30.000 30.000 30.000 30.000 30.000 30.000 30.000 30.000 30.000
30.000 30.000 30.000 30.000 30.000]
LoadCurrVect=[0.25 0.5 0.75 1 1.25 1.5 1.75
2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25
4.5 4.75 5]
LoadVoltVect30=[4.12 4.12 4.12 4.12 4.12 4.12
4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12
4.12 4.12 4.12 4.12]
InPowerVect30=InpCurrVect30.*InpVoltVect30;
OutPowerVect30=LoadCurrVect.*LoadVoltVect30;
% 24 V supply, new 13/9 transformer
InpCurrVect24=[ 0.054 0.1 0.15 0.2 0.25 0.3
0.36 0.42 0.47 0.53 0.59 0.65 0.71 0.78 0.84 0.91
0.98 1.04 1.11 1.19]
InpVoltVect24=[24.000 24.000 24.000 24.000 24.000 24.000
24.000 24.000 24.000 24.000 24.000 24.000 24.000 24.000 24.000
24.000 24.000 24.000 24.000 24.000 ]
LoadVoltVect24=[4.12 4.12 4.12 4.12 4.12 4.12
4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12
4.12 4.12 4.12 4.12]
InPowerVect24=InpCurrVect24.*InpVoltVect24;
OutPowerVect24=LoadCurrVect.*LoadVoltVect24;
% 20 V supply, new 13/9 transformer
InpCurrVect20=[ 0.07 0.12 0.18 0.24 0.3 0.37
0.44 0.5 0.58 0.64 0.72 0.79 0.87 0.95 1.02 1.11
1.19 1.28 1.36 1.45]
InpVoltVect20=[20.000 20.000 20.000 20.000 20.000 20.000
20.000 20.000 20.000 20.000 20.000 20.000 20.000 20.000 20.000
20.000 20.000 20.000 20.000 20.000 ]
LoadCurrVect=[ 0.25 0.5 0.75 1 1.25 1.5
1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4
4.25 4.5 4.75 5]
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LoadVoltVect20=[4.12 4.12 4.12 4.12 4.12 4.12
4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12
4.12 4.12 4.12 4.12]
InPowerVect20=InpCurrVect20.*InpVoltVect20;
OutPowerVect20=LoadCurrVect.*LoadVoltVect20;
figure(2);
plot(LoadCurrVect,OutPowerVect30*100./InPowerVect30);
legend '30 V supply';
hold on;
plot(LoadCurrVect,OutPowerVect24*100./InPowerVect24, 'r');
legend '24 V supply';
hold on;
plot(LoadCurrVect,OutPowerVect20*100./InPowerVect20, 'g');
legend '20 V supply';
hold on;
legend('30 V supply','24 V supply','20 V supply');
title('Forward Converter Efficiency','Fontsize',15)
axis([0, 5, 0, 100]);
grid;
xlabel('Load [A]','Fontsize',15);
ylabel('% Efficiency','Fontsize',15);
% 2 A load, new 13/9 transformer
InpCurrVect2A=[0.56 0.53 0.50 0.47 0.45 0.43 0.41
0.40 0.38 0.37 0.35 0.34 0.33]
InpCurrVect4A=[1.16 1.14 1.08 1.03 0.98 0.94 0.90
0.86 0.83 0.79 0.76 0.74 0.71]
InpCurrVect5A=[1.44 1.45 1.41 1.34 1.27 1.22 1.161.12 1.07 1.03 0.99 0.95 0.92]
InpVoltVect= [18 19 20 21 22 23 24
25 26 27 28 29 30 ]
LoadCurrVect2A=[2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
2.0 2.0 2.0 2.0]
LoadCurrVect4A=[4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0
4.0 4.0 4.0 4.0]
LoadCurrVect5A=[5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0
5.0 5.0 5.0 5.0]
LoadVoltVect=[4.08 4.08 4.08 4.08 4.08 4.08 4.084.08 4.08 4.08 4.08 4.08 4.08 ]
InPowerVect2A=InpCurrVect2A.*InpVoltVect;
InPowerVect4A=InpCurrVect4A.*InpVoltVect;
InPowerVect5A=InpCurrVect5A.*InpVoltVect;
OutPowerVect2A=LoadCurrVect2A.*LoadVoltVect;
OutPowerVect4A=LoadCurrVect4A.*LoadVoltVect;
OutPowerVect5A=LoadCurrVect5A.*LoadVoltVect;
Vs_sim_eff=[18 20 22 24 26 28 30];
Pin_2A=[3.64 4.6 5.6 6.8 8.1 9.5 11];
Pout_2A=[2.84 3.6 4.5 5.57 6.68 7.9 9.2];
Eff_2A=Pout_2A./Pin_2A;
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Pin_4A=[6.93 8.75 10.771 13 15.45 18 20.95];
Pout_4A=[5.15 6.63 8.29 10.15 12.18 14.39 16.81];
Eff_4A=Pout_4A./Pin_4A;
Pin_5A=[8.45 10.65 13.11 15.83 18.8 22 25.5];
Pout_5A=[6.16 7.92 9.92 12.13 14.58 17.24 20.11];
Eff_5A=Pout_5A./Pin_5A;
figure(3);
subplot(2,1,1);
plot(InpVoltVect,OutPowerVect2A*100./InPowerVect2A, 'g'); hold
on
plot(InpVoltVect,OutPowerVect4A*100./InPowerVect4A, 'b');
plot(InpVoltVect,OutPowerVect5A*100./InPowerVect5A, 'm')
legend ('2 A loading current', '4 A loading current','5 A
loading current');
hold on;title('Forward Converter Efficiency, Measured','Fontsize',15)
axis([18, 30, 50, 90]);
grid;
ylabel('% Efficiency','Fontsize',15);
subplot(2,1,2);
plot(Vs_sim_eff,Eff_2A*100,'-*g'); hold on;
plot(Vs_sim_eff,Eff_4A*100,'-*b');
plot(Vs_sim_eff,Eff_5A*100,'-*m');
legend ('2 A loading current','4 A loading current','5 A
loading current');
hold on;
title('Forward Converter Efficiency,Simulated','Fontsize',15)
axis([18, 30, 50, 90]);
grid;
xlabel('Supply voltage [V]','Fontsize',15);
ylabel('% Efficiency','Fontsize',15);
LoopGain = importdata('LoopGainMeas_24V_2R2_300to100k_long.txt' );
%
8/6/2019 SWIE Report
23/23
Forward Converter Project
%--- Phase vs Frequency ---%
subplot(2,1,2);
semilogx(frequency, Phase, 'b', 'LineWidth',2);
grid;
ylabel('Phase [degrees]');
xlabel('Frequency_{log} [Hz]');
axis([300, 100e3,-80,160]);
% [EOF]
23