Intersection of two curves in matlab

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Rajat Powade
Rajat Powade on 15 Jun 2022
Answered: Star Strider on 15 Jun 2022
Hi there i need to calculate intersection point of two curves. Please help i am attaching my code
clc
%crate=0:1:10;
G=-I_BT;
h=4000;%no. of cycles
T=30+273;%temp in kelvin
R=8.314;%universal gas const
capa=200;%battery capacity
%batt_curr batt_HESS=[1,2,3,4]
A=[G];
[n, xout] = hist(A,60);
c_rate=abs((xout.*(n>0))/capa);
B = exp(1.226*exp(-0.2797*c_rate)+9.263);
A_h=abs(xout.*(n>0)).*(n/3600);
Dk=zeros(h,2);
for i=1:h
q_k=B.*exp((-31700+370.3.*c_rate)/(R.*T)).*((i.*A_h).^0.55);
Qk=100-sum(q_k);
Dk(i,:)=Qk;
end
figure(3)
plot(Dk,'LineWidth', 4)
set(gca,'fontsize', 18);
%set(gca,'LineWidth', 4);
ylim([0,100]);
yline(80)
xlabel('No. of Cycles');
ylabel('Capacity Retention %');
%legend('Battery Capacity Retention');

Answers (2)

Torsten
Torsten on 15 Jun 2022
Edited: Torsten on 15 Jun 2022
clc
%crate=0:1:10;
G=-I_BT;
h=4000;%no. of cycles
T=30+273;%temp in kelvin
R=8.314;%universal gas const
capa=200;%battery capacity
%batt_curr batt_HESS=[1,2,3,4]
A=[G];
[n, xout] = hist(A,60);
c_rate=abs((xout.*(n>0))/capa);
B = exp(1.226*exp(-0.2797*c_rate)+9.263);
A_h=abs(xout.*(n>0)).*(n/3600);
fun = @(x) (100 - integral(@(t)B.*exp((-31700+370.3.*c_rate)/(R.*T)).*((t.*A_h).^0.55),0,x)) - 80;
intersection = fzero(fun,3500)

Star Strider
Star Strider on 15 Jun 2022
The ‘I_BT’ variable is missing, so I cannot run the code. However getting the intersection of the exponential and the line is straightforward —
x = 0:4000;
Dk = 100*exp(-6.5E-5*x);
Cv = 80;
xv = interp1(Dk,x,Cv)
xv = 3.4330e+03
figure
plot(Dk, 'LineWidth',2)
hold on
plot(xv, Cv, 'sr', 'MarkerSize',15, 'LineWidth',2.5)
hold off
xlim([min(x) max(x)])
ylim([0 100])
yline(Cv)
.

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