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simulink connecting capacitor problem

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David Winthrop
David Winthrop on 9 Oct 2014
Commented: Sanket Chourasia on 23 Jan 2020
I am trying to connect a capacitor in my system and it will not connect to anything. Here is a picture. The wires stay red always.
How do I put a capacitor into my model. It seems like we should be able to use capacitors!!

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David Winthrop
David Winthrop on 9 Oct 2014
I found an old answer that said there are different kinds of capacitors for some insane reason. But my search turned up exactly one kind, the kind I used. I don't want a variable capacitor. Just a plain old simple capacitor. So how do I get the right kind? I want the kind that has a capacitance, like in the link.
Walter Roberson
Walter Roberson on 17 Aug 2018
Sikho Ndzeku asks,
Any solution yet to the problem?

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Answers (2)

Sebastian Castro
Sebastian Castro on 17 Aug 2018
That Capacitor block belongs to a different library (Simscape, and not Simscape Power Systems).
If you want a capacitor that connects to that circuit, use a Series/Parallel RLC Branch block and set its R and L values to zero.
( yeah I know... it's confusing. The later versions of MATLAB have color-coding and tooltips to help prevent these issues )
- Sebastian

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Sanket Chourasia
Sanket Chourasia on 23 Jan 2020
This actually helped. Thankyou
I used 'Parallel RLC Branch' to connect to existing RLC load.
'Parallel RLC Branch' has an option to choose the branch type from R, L, C, RL, RC, LC, & RLC.

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Walter Roberson
Walter Roberson on 17 Aug 2018
Edited: Walter Roberson on 17 Aug 2018
That particular diagram for DC Voltage Source is a PMComponent from the Simscape -> Electrical -> Specialized Power Systems -> Fundamental Blocks -> Electrical Sources library. You can tell because all of the other DC Voltage Source that I could find incorporate a circle as part of the design element, whereas the design for that particular element is similar to those of batteries. The port type is 'p1'.
The DC Voltage Source itself is compatible with the '1' input of Ideal Switch, which is from Simscape -> Electrical -> Specialized Power Systems -> Fundamental Blocks -> Power Electronics and is also a 'p1' port.
However, no-where in Specialized Power Systems is there a resistor as such -- or a capacitor as such.
There is Simscape -> Electrical -> Electriconics and Mechatronics -> Passive Devices -> Resistor, and Capacitor, but those are both Simscape Block, which is not a matching type.
To get anywhere you have a small number of choices:
1) Create custom blocks within powersysdomain; or
2) Move out of Specialized Power Systems into a different domain. This would probably block you from using Ideal Switch
3) Use Sebastian's idea of using an RLC related block (he posted while I was in the middle of investigating and composing)
I do not know if there is a fourth option of somehow creating an adaptor between domains.

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