Device for determining rotational speed of electric machine, particularly direct current motor, on basis of regenerative residual voltage, has circuit with main switch, which is arranged in current path of electric machine

摘要

The device has a circuit with a main switch (2), which is arranged in a current path of the electric machine for switching-on and switching-off the electric machine. The device has another switch (3) and a capacitor (4) which are arranged in another current path, parallel to the main switch. The capacitor and the latter switch are connected in series.