Robert Boschgmbh

Roland Walter

Dietmar Hahn

Klaus Dengler

Juergen Wiker

Jacek Wiszniewski

Michael Maercker

Bastian Kloer

Mario Pauli

Andreas Heilmann

Bastian KLÖR

The invention relates to a method for operating an electric motor () having a phase angle control with the following steps: Applying an AC voltage to a series connection of the electric motor () and a switching element (), particularly a triac, wherein the switching element () connects through by applying an ignition signal and suppresses the flow of a current if the amount of current falls below a holding current; determining the time of a zero crossing of a virtual motor current that would flow if the switching element () were connected through; and turning on the switching element () at an activation time that is dependant on the time of the zero crossing of the virtual motor current.

Method and device for operating an electric drive with the aid of a phase angle control

The invention relates to a method and a circuit for regulating the speed of a commutator series-wound motor, especially a universal motor (), which is supplied with a current from an a.c. voltage source () by means of a semiconductor switching element () mounted in series with an armature winding () and a field winding () and controlled by a control unit () according to a nominal speed value. The control unit () receives, as input signals, signals corresponding to the total voltage drop (Umot) when the motor () is supplied with a current, and a substitute signal for the intensity of the motor current (I), corresponding to the voltage drop (Ua, Ufa) on the armature () alone or on the armature () and on a part () of the field winding (). The input signals of the control unit () are compared with motor-typical characteristic lines of the voltages on the excitation field () and/or on the armature, stored in the control unit, and control signals for the semiconductor switching element are formed from the deviations.

Method and circuit for regulating the speed of a commutator series-wound motor

In a method for shutting off a drive motor () of a power tool that drives a tool, the drive motor () is shut off as a function of a variable threshold value (E) if the tool jams. The threshold value (E) is determined in at least one predetermined time interval (T) as a function of a current load speed (n) and a no-load speed (n).

Method for switching off a power tool

A braking device for an electric motor of a power tool has a short circuit switch for short circuiting an armature winding of the electric motor during a braking process, the short circuit switch for controlling its switch condition having a control input, a control unit connected with the control input of the short circuit switch for performing a phase control of the short circuit switching during the braking process in order to avoid brush fire; also an electrical device with such a braking device and a braking method are proposed as well.

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Tiefenbronn, Germany

Roland Walter