I'm trying to sove this problem. Most of the code is given. Only the while loops must be done. I tried to do it but the calculations never ends.

% This is the script for completing Task 1e only.

% The input data and modulator parameters are defined here in the same way as

% it was done for tasks 1a - 1d. This part is left unchanged.

% After the part "Initialisation and input data declaration", the specific

% code to implement Task 1e is supposed to be written.

% Step-by-step instructions will be given.

%

% As far as Matlab Grader does not support the Simulink models at the

% moment, Task 1e is supposed to be done partially in local PCs, and partially

% using the Matlab Grader tool in Moodle. Please start completing the task

% here and follow the instruction given further in the code. You will be

% explained all the details there.

%% Initialisation and input data declaratiob (just copied from tasks 1a-1d)

close all; clear all; clc

% Supply network parameters

U_grid_ll = 400; % (V) RMS line-to-line netwotk voltage

U_grid_ph = U_grid_ll/sqrt(3); % (V) RMS phase network voltage

f_grid = 50; % (Hz) network frequency

% Rectified voltage

U_DC = 3*sqrt(2)/pi*sqrt(3)*U_grid_ph; % (V) The average DC voltage of an ideal 6 pulse rectifier

%modulator parameters

m_f = 21; % frequency modulation ratio

m_a = 0.5; % amplitude modulation ratio

f_ref = 50; % (Hz) frequency of reference sine waveform

f_car = m_f * f_ref; % (Hz) carrier frequency (synchronous modulation)

%f_car = m_f * 41; % (Hz) fixed carrier frequency (asynchronous modulation)

% (Uncomment to use instead of synchronous)

T_car = 1/f_car; % (s) carrier wave period

u_tri = 1; % (V) peak triangle voltage

u_ref = m_a * u_tri; % (V) peak reference voltage

SimTime = 1; % (s) simulation length

%% Task 1e

% Step 1. Create the vector of m_a values to be simulated

% The m_a values will be used as x-axis data when building the plot

% We can use 2 options to build the plot. Both will be evaluated as

% acceptable way of task implementation.

% Option 1: Pre-defined m_a-values for a plot accurate enough and fast to run

m_a_vect = [0 0.975 1 1.025 1.05 1.075 1.1 1.13 1.15 1.2 1.3 1.5 2 2.8 4.5]; % m_a values

n_fundplot = length(m_a_vect); % number of the m_a values

% Option 2: Using evenly spaced m_a values (100 values looks good but is very slow 5-10 minutes)

% n_fundplot = 100; % number of m_a-points to run

% m_a_vect = linspace(0,4.5,n_fundplot); % evenly spaced vector with values from 0 to 4.5

% Step 2. Create the values of fundamental output voltage with sinusoidal

% reference waveform

% Note: you are free to do decide on how to switch between sinusoidal reference

% and reference which contains 3rd harmonic. Anyway, this must affect the

% Simulink model. The switching mechanism is suggested to be placed in

% "Sin-Tri PWM", and can be controlled via special variable from this

% script. For example, we can create the variable "Enable_3rd" and write the

% values of 1 or 0 into it.

%set_param('Enable3rd','sw','0')

Enable_3rd = 0 ;

% But, how to implement this switching in the model, you should decide by

% yourself.

% If you did not add any circuit to add 3rd harmonic, the results of THIS

% step will be correct anyway. But, the results of the NEXT step will

% require the 3rd harmonic in reference signal anyway!

% We will use cycle "while" here. If you are good at Matlab, you can use any

% cycle. The objective of this step is to receive the correct values in

% the vector "U_fund_sine".

% Please replace ??? with the suitable lines of the code.

i_sineref = 1; % index for sinusoidal plot points

while(i_sineref <= (n_fundplot)) % create the condition for cycle to work.

% The cycle must run until all the values of m_a

% will be simulated!

m_a = m_a_vect(i_sineref) ; % m_a value for the point to run

u_ref = m_a*u_tri; % [V] peak reference voltage according to m_a

sim('ED_Ex5_T1_Sim',SimTime); % run the model

i_u = length(U_fund.signals.values);% length of the Simulink output signal data, i.e.

% the number of thr last element in the struct "U_fund"

U_fund_sine(i_sineref) = U_fund.signals.values(i_u); % this line picks the last value from signal data

i_sineref = i_sineref ; % increment the "i_sineref" variable to proceed the cycle run

end

% Step 3. Create the values of fundamental output voltage when the

% reference waveform has 3rd harmonic

% This step repeats the previous step but in Simulink model the 3rd

% harmonic must be included in the reference sine signal.

% As was suggested, this can be done if we set:

Enable_3rd = 1;

% REMEMBER: the corresponding circuit/block/function in the model which

% changes its state based on this variable must be done beforehand! If you

% did not modify the model in the way to support the 3rd harmonic in PWM

% reference signal, even correct code from this step will not bring the correct

% result!

% Please replace ??? with the suitable lines of the code.

i_3rd_ext_ref = 1; % index for sinusoidal plot points

while(i_3rd_ext_ref <= (n_fundplot)) % create the condition for cycle to work.

% The cycle must run until all the values of m_a

% will be simulated!

m_a = m_a_vect(i_sineref) ; % m_a value for the point to run

u_ref = m_a*u_tri; % [V] peak reference voltage according to m_a

sim('ED_Ex5_T1_Sim',SimTime); % run the model

i_u = length(U_fund.signals.values); % length of the Simulink output signal data, i.e.

% the number of thr last element in the struct "U_fund"

U_fund_3rd_ext(i_3rd_ext_ref) = U_fund.signals.values(i_u); % this line picks the last value from signal data

i_3rd_ext_ref = i_3rd_ext_ref+1; % increment the "i_3rd_ext_ref" variable to proceed the cycle run

end

save('m_a_vect.txt','m_a_vect','-ASCII'); % This is ready code, don't modify it

save('U_fund_sine.txt','U_fund_sine','-ASCII'); % This is ready code, don't modify it

save('U_fund_3rd_ext.txt','U_fund_3rd_ext','-ASCII'); % This is ready code, don't modify

Answer 1

[Karl]

You need to follow the suggestion given in the comment for the line:

i_sineref = i_sineref ;          % increment the "i_sineref" variable to proceed the cycle run