Patent ID: 7781994

Claim:
A method for regulating the speed of a commutator series-wound motor, in particular a universal motor, that is supplied with current from an alternating voltage source via a semiconductor switch element, which is connected in series with the armature winding and field winding and is controlled by a control unit in accordance with a setpoint speed, wherein the control unit ( 28 ) is supplied with input signals—on the one hand in the form of a signal that corresponds to the total voltage drop (U mot ) at the motor ( 10 ) with a current flow (I) and on the other hand in the form of a replacement signal for the magnitude of the motor current (I) in accordance with the voltage drop (U A , U FA ) at the armature ( 12 ) alone or at the armature ( 12 ) and at a part ( 14 ) of the field winding ( 14 , 16 )—and in the control unit ( 28 ), these input signals are compared to motor-typical characteristic curves (U A , U FA =f(I, U mot )) of the voltages in the excitation field ( 14 ) and/or at the armature ( 12 ) and, based on the deviations (ΔU A ; ΔU FA ), control signals are generated for the semiconductor switch element ( 18 ).