Particle swarm optimisation problem

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RAN
RAN on 18 Aug 2019
Commented: Walter Roberson on 22 Jan 2021
Hello all,
I am trying to use PSO for solving a system of nonlinear transcendental equations used in SHE PWM.
Following is the code i am using to solve
fun = @(alpha) pwm_equations_multilevel_pso(alpha0,1,2,harmonics)
nvars = 3;
lb=[0, 0, 0];ub=[deg2rad(90),deg2rad(90),deg2rad(90)];
options = optimoptions('particleswarm','SwarmSize',200,'MaxStallIterations',200)
options = optimoptions(options,'PlotFcn',@pswplotbestf);
[x,fval,exitflag,output] = particleswarm(fun,nvars,lb,ub,options)
where 'pwm_equations_multilevel_pso' is simply as follows
function F_dot = pwm_equations_multilevel_pso(alpha,M,harmonic_cancellation,harmonics)
F(1) = cos(harmonics(1)*alpha(1)) + cos(harmonics(1)*alpha(2)) - cos(harmonics(1)*alpha(3));
F(2) = cos(harmonics(2)*alpha(1)) + cos(harmonics(2)*alpha(2)) - cos(harmonics(2)*alpha(3));
F(3) = (cos(alpha(1)) + cos(alpha(2)) - cos(alpha(3))) - M;
F_dot=dot(F,F)
end
So the scalar value returned is a dot product of F with itself. I want to minimize F_dot to zero, but when i use PSO i get the following result
Unfortunately PSO does not converge to zero, it does not do anything in my case.
Obviously I am doing something wrong, but I am not sure what
Any help will be appreciated!
  6 Comments
Walter Roberson
Walter Roberson on 18 Aug 2019
particleswarm() does not offer any constraints other than lb / ub .
You could add a penalty to the output for inputs that are out of order.
RAN
RAN on 18 Aug 2019
Ok, I already found some constrained based PSO.
Thank you for your help, now i got the hang of PSO.

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Answers (1)

Nishma Sai
Nishma Sai on 22 Jan 2021
can u just provide the entire code as i got some errors with my code
  1 Comment
Walter Roberson
Walter Roberson on 22 Jan 2021
You could post your attempt, along with the error message, and we could help you debug the problems.

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