Ich danke Ihnen für Ihre Hilfe und Ihre Zeit.
Seit gestern versuche ich weiter an Ihr Beispiel weiterzuarbeiten und komme leider nicht ganz klar. Dieser Stand habe ich bisher erreicht (s. Anhang). Könnten Sie bitte gucken, was falsch ist?
Ich danke Ihnen.
\documentclass[tikz,border=5mm]{standalone}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{circuitikz}%für mixer
\begin{document}
\begin{tikzpicture}
\draw(0,0) node[draw,circle](m1) {};
\draw[thick,latex-] (m1.north) --++ (0,2) node[pos=.1,right] {$-$} node[right] {i$\alpha$};
\draw[thick,latex-] (m1.west) -- (-3,0) node[midway,above] {i$\alpha$ref} node[pos=0.1,above] {$+$};
%\draw[thick,latex-] (m1.west) -- (6,0) node[midway,above] {i$\alpha$regout} node[pos=0.1,above] {};
\node[draw,minimum width=3em,minimum height=2em] (pr) at (3,0) {PR-Regler $\alpha$};
\draw(0,-3) node[draw,circle](m2) {};
\draw[thick,latex-] (m2.south) --++ (0,-2) node[pos=.1,right] {$-$} node[right] {i$\beta$};
\draw[thick,latex-] (m2.west) -- (-3,-3) node[midway,above] {i$\beta$ref} node[pos=0.1,above] {$+$};
\node[draw,minimum width=3em,minimum height=2em] (pr) at (3,-3) {PR-Regler $\beta$};
\draw(6,0) node[draw,circle](m3) {};
\draw[thick,latex-] (m3.north) --++ (0,2) node[pos=.1,right] {$+$} node[right] {UV$\alpha$};
\draw(6,-3) node[draw,circle](m4) {};
\draw[thick,latex-] (m4.south) --++ (0,-2) node[pos=.1,right] {$+$} node[right] {UV$\beta$};
\draw[thick] (-6,-5) coordinate(a) rectangle (-3,2) coordinate(b) (a)--(b);
\node[below right] at (-6,2) {dq};
\node[above left] at (-3,-5) {$\alpha\beta$};
\draw[thick,latex-] (-6,0) --++ (-1,0) node[left] {idref};
\draw[thick,latex-] (-6,-3) --++ (-1,0) node[left] {iqref};
\draw[thick,latex-] (-4.5,2) --++ (0,2) node[right] {$\theta$};
\node[below] at (-4.5,-5) {Inv-Park};
\end{tikzpicture}
\end{document}