how can i draw a cross sectional of electrical machine like this:

can you help me please?
This kind of picture doesn't require particularly elevated skills, but having an intermediate knowledge of the \foreach statement will help you draw it with a relatively short code. Basically we can draw the smaller circles with a single foreach.

\documentclass[margin=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows.meta, shapes.misc}
\tikzset{
cross/.style={draw, label={[font=\large]center:$\times$}, circle,
inner sep=1mm, outer sep=0pt},
dot/.style={draw, circle, inner sep=1mm, outer sep=0, label={[fill=black, circle, inner sep=.5mm]center:}},
point/.style={fill=black, circle, inner sep=1pt, node contents={}},
}
\begin{document}
\begin{tikzpicture}
\draw (0,0) circle (2cm);
\draw (0,0) circle (2.5cm);
\draw (0,0) circle (3.5cm);
\foreach \one/\two [count=\xi, evaluate=\xi as \angle using int (60*\xi)] in {rb/sB, ra'/sA', rc/sC, rb'/sB', ra/sA, rc'/sC'}{
\pgfmathsetmacro\switch{int(mod(\xi,2)) ? "cross" : "dot"}
\node[\switch, label={\angle+195:\one}] at (\angle:1.85cm) {};
\node[\switch, label={[label distance=-1mm]\angle-25:\two}] at (\angle-30:2.65cm) {};
}
\draw[-{Latex}] (0,0) -- (0,5) node[above] {sQ};
\draw[-{Latex}, dashed] (0,0) -- (120:5cm) node[above left] {sB};
\draw[-{Latex}] (0,0) -- (5,0) node[below] {sD};
\draw[-{Latex}, dashed] (0,0) -- (25:5cm) node[below right] {$r\alpha$};
\draw[-{Latex}] ++(4,0) node[point] arc (0:25:4) node[point] node[midway, right] {$\theta_{r}$};
\draw[-{Latex}] ++(20:6) arc (15:25:6) node[midway, right] {$\omega_{r}$};
\end{tikzpicture}
\end{document}
\documentclass[margin=10pt]{standalone}
\usepackage{tikz}
\begin{document}
\def\inwinding#1#2#3#4#5{
\begin{scope}[shift={#1}, rotate=#2]
\draw [fill=white](0,0) circle (2mm) node[yshift=#3,xshift=#4]{#5};
\draw [thick](1.414mm,1.414mm) -- (0,0) -- (-1.414mm,-1.414mm);
\draw [thick](-1.414mm,1.414mm) -- (0,0) -- (1.414mm,-1.414mm);
\end{scope}
}
\def\outwinding#1#2#3#4#5{
\begin{scope}[shift={#1}, rotate=#2]
\draw [fill=white](0,0) circle (2mm) node[yshift=#3,xshift=#4]{#5};
\draw [fill=black](0,0) circle (0.5mm);
\end{scope}
}
\begin{tikzpicture}[scale=1]
\coordinate (A) at (0,0);
\coordinate (B) at (5,0);
\coordinate (C) at (25:5cm);
\coordinate (F) at (90:5cm);
\coordinate (G) at (120:5cm);
\draw[fill=white] (0:3cm) arc (0:360:3cm);
\draw[fill=white] (0:2cm) arc (0:360:2cm);
\draw[fill=gray!30] (0:1.75cm) arc (0:360:1.75cm);
% % % for rotor:
\outwinding{(0:1.45cm)}{0}{-5mm}{0mm}{$\mathbf{c^{'}}$}
\outwinding{(120:1.45cm)}{0}{2mm}{5mm}{$\mathbf{a^{'}}$}
\outwinding{(240:1.45cm)}{0}{3mm}{-3mm}{$\mathbf{b^{'}}$}
\inwinding{(60:1.45cm)}{0}{-2mm}{4mm}{$\mathbf{b^{}}$}
\inwinding{(180:1.45cm)}{0}{4mm}{0mm}{$\mathbf{c^{}}$}
\inwinding{(300:1.45cm)}{0}{-1mm}{-4mm}{$\mathbf{a^{}}$}
% % % for stator
\outwinding{(330:2.3cm)}{0}{5mm}{2mm}{$\mathbf{C^{'}}$}
\outwinding{(90:2.3cm)}{0}{0}{-4mm}{$\mathbf{A^{'}}$}
\outwinding{(210:2.3cm)}{0}{-5mm}{3mm}{$\mathbf{B^{'}}$}
\inwinding{(30:2.3cm)}{0}{4mm}{-2mm}{$\mathbf{B^{}}$}
\inwinding{(150:2.3cm)}{0}{-5mm}{-2mm}{$\mathbf{C^{}}$}
\inwinding{(270:2.3cm)}{0}{0}{5mm}{$\mathbf{A^{}}$}
% % % % % % % % % % % % % % % %555
\draw[very thick,->,black] (A) -- (B) node [at end,sloped,right,black]{{\small{sD} }} coordinate (sD axis);
\draw[->,dashed,very thick,black] (A) -> (C) node [at end,sloped,right]{{\small{$r\alpha$} }};
\draw[->,very thick,black] (A) -> (F) node [at end,rotate=-90,sloped,yshift=2mm,black]{{\small{sQ} }}coordinate (sQ axis);
\draw[->,dashed,very thick,black] (A) -> (G) node [at end,rotate=-290,sloped,yshift=2mm]{{\small{$r\beta$} }};
\draw[->] (0:4cm) arc (0:25:4.0cm) node [midway,sloped,above]{{\small $\theta_{r}$ }};
\end{tikzpicture}
\end{document}
\documentclass{}...\begin{document}etc. As it is, most of our users will be very reluctant to touch your question, and you are left to the mercy of our procrastination team who are very few in number and very picky about selecting questions. You can improve your question by adding a minimal working example (MWE) that more users can copy/paste onto their systems to work on. If no hero takes the challenge we might have to close your question. – Seamus Mar 01 '16 at 08:40