How can I create a simulation that supplies power to the motor by connecting fuel cells, dc-dc converters, and supercapacitors?

Hello. I would like to implement an automobile powertrain through a simulink fuel cell block, super capacitor block, and DC-DC converter.

The output of the fuel cell go into the dc-dc converter, and the output from the dc-dc converter is transferred to the motor and supercapacitor. The supercapacitor acts as a battery to compensate for the slow dynamic characteristics of the fuel cell.

A fuel cell block was created through the fuel cell data sheet, and the supercapacitor was implemented according to the specifications to be used.

The problem is the dc-dc converter.

The first problem is that if I design the dc-dc converter as shown in the attached picture and run the simulation, it takes a very long time. This is judged to take a long time because the frequency of the pulse generator is set to 77 kHz.

The second problem is that the dc-dc converter output voltage changes as the fuel cell output voltage fluctuates. It was designed with the goal of 48V output, but it is a problem because it does not actually follow it. In order to solve this problem, Ix` think that the duty ratio of the switching element should be adjusted based on the converter output voltage, but I am not sure.

Are there other alternatives, such as how to solve these problems or how to use simscape?

Lastly, I fixed the load in the simulation I currently implemented, but can it be set to change the load over time?

I would really appreciate your help.

[Faheem Ijaz]

hi, did you manage to find the solution to very slow charging? i am having same problem atm.

Answer 1

[Joel Van Sickel]

This really depends on how much detail you need for the converter. In general, when doing powertrain analysis, you don't need to worry about the control loops on the converers as they are simply so much faster than any of the vehicle dynamics they have no effect on system level performance (assuming you trust your controls engineers to have closed the loop well). In that case, using a behavioral dc/dc converter will work better because you can skip simulating the switching frequency of the converter. You can do this using either PTBS or Simscape blocks. However, if you use simscape, you will want to use the blue components instead of the black components. The blue components use a newer solver technology that is better for implementing behavioral models and has more access to high quality battery and fuel cell models compared to the black components (specialized power systems).

https://www.mathworks.com/help/sps/ref/dcdcconverter.html

There are free onramps on simspcae for simulating circuits and power electronics as well.

https://matlabacademy.mathworks.com/details/power-electronics-simulation-onramp/powerelectronics

[WonHo Shin]

I wanted to use a simscape model too, but I had to use a black model to enter the information on the fuel cell data sheet I have. Thank you for your response. I'll try it and get back to the comments.