Bi-Directional DC-DC converter

[nuflia]

Hi
I'm trying to get a Simulink model for Bidirectional DC-DC converter to be used for battery charge and dis-charge through a dc bus, the control strategy used is a two-controller control; one is for generating the reference current and the other one is for control the voltage, so the battery is controlled to charge when there is sufficient dc bus voltage and discharge to keep the dc-bus constant
It would be great help if someone gave help

 

[chuckey]

Some parameters would be helpful, Vbatt, Vbus, Icharge, Idis etc.
Frank

 

[nuflia]

Many thanks for the reply Frank, the DC bus is intended to be kept in the range 380-420vdc, the battery parameters can be seen form the attached file
Your help is highly appreciated

 

[strkar]

Hi nuflia,

I am also struggling with a bidirectional DC-DC Converter (in order to charge and discharge the storage battery) in my project.
(you could take a look in the following link if you wish)
https://www.edaboard.com/threads/279800/

I am also using Matlab/Simulink for my simulations and after a lot of searching i have found a simulink model of a HEV, which is attached below (the first one). This model is fully functional and the DC-DC converter used for charging the battery in this model might be what you need for your project. The attached .rar file contains two .mdl files which are simulink models (for charging and discharging) of a bidirectional DC-DC converter i developed myself. It is functional but incomplete. The real problem is that i am not able to develop a proper circuit in order to control the power flow (i.e., when the converter will be in charging and when in discharging mode).

I would be happy to help you just a little bit by sending these simulink models.

Best regards,
strkar

 

[nuflia]

Many Thanks for your help, I’ve not seen your files yet but i really wanted to say big thanks to you for your reply. my problem, i guess, it looks like yours, I developed the Simulink model, it is working but it is not functioning well( can not keep the output voltage stable), I know the reason, I have spent great deal of time reading about DC-DC converter buck-boost modelling and trying to get the transfer function using averaged state space approach in order to linearize my circuit and then the PWM should be linearized too and its transfer function must be found before we can design a good compensator ( controllers )
The subject is huge and I am still reading,
Can I email you?

- - - Updated - - -

I will get back to you when i've finished seeing and simulating the files

 

[strkar]

You are very welcome nuflia! It's my pleasure to know that i was able to help someone.

I can understand exactly what you are talking about, as i'm also struggling with the same thing for a long time now. But, are you sure that it is really necessary to linearize the model? I wish it is not, because it seems very difficult to me...
I think that we can make it work well by configuring the PI gains (Kp and Ki). We should try different values until we get good results ('trial and error' method).

 

[nuflia]

configuring the PI gains (Kp and Ki) using ('trial and error' method) is a very boring job, I’ve been doing it but it is not successful, every time i change the settings of the controllers I get different response, the correct way if we work in a design is to find out the transfer function (modelling) and then apply the linear control theory to find the controllers gains otherwise we will always move in the same place.

 

[strkar]

You are absolutely right about the 'trial and error' method. It demands a lot of time and there is always the possibility of not getting the best results...

 

[lsteng]

Hi, I also having difficulties in the control part. Any updates?