tikz-pgf,circuitikz,circuits – How to Label Voltages on Flyback Converter in LaTeX

Question

I have the following flyback converter circuit made with latex

\begin{tikzpicture}
 
% Circuit style
\ctikzset{
    resistor = american,
    voltage = american ,
    voltage dir = RP,
    quadpoles/transformer core/inner = 1, %Eliminates the horizontal bars on the transformer
    quadpoles/transformer core/width = 0.6, %Adjusts the width so that the transformers are closer
    diodes/scale = 0.7,
    capacitors/scale = 0.8,
    resistors/scale = 0.8
}
%draw tri and quadpoles
\node[transformer core, anchor = A1, scale = 0.8](transformer) at (2,2){};
\node[circ](c1) at (transformer.inner dot A1){};
\node[circ](c2) at (transformer.inner dot B2){};
\node[npn, anchor = collector, scale = 0.8](npn) at (2,0.25){};

%Primary
\draw (0,0) to [vsource,v=V] ++ (0,2)
 to (0,2) |- (transformer.A1)
 (transformer.A2) -- (npn.collector)
 (npn.emitter) -| (0,0);
 
%Secondary
 \draw (transformer.B1) to[Do] ++ (2,0) coordinate(A)
 (A) to[C] (A |- transformer.B2)
 (transformer.B2) to[short,i = $i_s$] (A |- transformer.B2);
 
 \draw (A) ++(1,0) coordinate(B)
 (A)--(B)
 (B) to [R,v=U] (B|- transformer.B2)
 (B|- transformer.B2) -- (A |- transformer.B2);

\end{tikzpicture}

Now. I need to be able to draw some voltage labels. In particular I need the voltage in the primary and secondary transformer windings and between collector emmiter and base emmiter of the transistor. Since nodes do not allow for the current labels I tried to use the \draw [open]

I simply added at the end of the tikzpicture the following lines

\draw (transformer.A1) to [open, v = $v_p$ , f = $i_p$] (transformer.A2);
\draw (transformer.B1) to [open, v = $v_s$] (transformer.B2);
\draw (npn.collector) to [open, v = $v_Q$] (npn.emitter);
\draw (npn.base) to [open, v = $v_{be}$] (npn.emitter);

As you can see the labels overlap with the components, which is not very good for legibility

I have more or less managed to solve the issue with the following modifications to the code that draws the labels

\draw ([xshift = -20]transformer.A1) to [open, v = $v_p$ , f = $i_p$] ([xshift = -20]transformer.A2);
\draw ([xshift = 10]transformer.B1) to [open, v = $v_s$] ([xshift = 10]transformer.B2);
\draw ([xshift = 10]npn.collector) to [open, v = $v_Q$] ([xshift = 10]npn.emitter);
\draw ([xshift = -5,yshift = -5]npn.base) to [open, v = $v_{be}$] (npn.emitter);

My question:

As you can see this fixes the issue rather nicely. However, I was wondering if there would be a better way to do this.

Feel free to also point out any other mistakes/issues with the whole circuit. I am very new to this package and I am just learning

Thanks in advance

Answer 1

The solution proposed by the OP is correct; I propose an alternative one here. The voltage on open is normally thought to label a centered voltage, but you can use the legacy option to open voltage position to have it behave like you seem to desire. You can define a style to simplify the positioning. Notice that the voltage shift amount is a bit of trial and miss, that part of the code is really rarely used, and I will look into it; it seems to be jerky outside the -1,1 range.

Moreover, it seems that you like the raised option for voltages more than the american one, so let's use them consistently across the diagram. For the same consistency, style options are better suited to the preamble of the document.

The current is better added to short element or to path element in general, it's better semantically clear where it is...

In general, I find the drawing too tight for the quantity of information you want to add, so I have given it a bit of spacing --- although I'd probably prefer it even more spacey.

\documentclass[border=10pt]{standalone}
% Circuit style
\usepackage{circuitikz}
\ctikzset{
    resistor = american,
    voltage = raised ,
    voltage dir = RP,
    quadpoles/transformer core/inner = 1, %Eliminates the horizontal bars on the transformer
    quadpoles/transformer core/width = 0.6, %Adjusts the width so that the transformers are closer
    diodes/scale = 0.7,
    capacitors/scale = 0.8,
    resistors/scale = 0.8
}

%% shifted open voltage 
\tikzset{open shifted/.style={
    open ,open voltage position=legacy, voltage shift=-0.9}
}

\begin{document}
\begin{tikzpicture}[]
%draw tri and quadpoles
\node[transformer core, anchor = A1, scale = 0.8](transformer) at (2,2){};
\node[circ](c1) at (transformer.inner dot A1){};
\node[circ](c2) at (transformer.inner dot B2){};
\node[npn, anchor = collector, scale = 0.8](npn) at (2,0){};

%Primary
\draw (0,0) to [vsource,v=V] ++(0,2)
 to [short, f=$i_p$] (transformer.A1) % current here
 (transformer.A2) -- (npn.collector)
 (npn.emitter) --++(0,-0.5) -| (0,0);

%Secondary
 \draw (transformer.B1) to[Do] ++ (2,0) coordinate(A)
 (A) to[C] (A |- transformer.B2)
 (transformer.B2) to[short,i = $i_s$] (A |- transformer.B2);

 \draw (A) ++(1,0) coordinate(B)
 (A)--(B)
 (B) to [R,v^=U] (B|- transformer.B2)
 (B|- transformer.B2) -- (A |- transformer.B2);

\draw (npn.C) to[open shifted, v^=$v_Q$](npn.E);
\draw (npn.B) to[open shifted, v=$v_{be}$, voltage shift=-1](npn.E);
\draw (transformer.A1) to[open shifted, v=$v_p$](transformer.A2);
\draw (transformer.B1) to[open shifted, v^=$v_s$](transformer.B2);

\end{tikzpicture}
\end{document}