Patent ID: 6967459

Claim:
A method of regulating the current in the stator winding arrangement ( 114 ) of a direct current machine to a value defined by a current target-value signal (PHI 1 , PHI 2 ), said direct current machine having associated therewith: an arrangement ( 24 ) for generating said current target-value signal (PHI 1 , PHI 2 ), and a pulse width modulation (PWM) generator ( 182 ) whose output signal (PWM 2 ) is controllable by means of an input control signal (u_ 156 ), said control signal (u_ 156 ) being a function of the current target-value signal and of current flowing in said stator winding arrangement ( 114 ), and controls the current in the direct current machine, comprising the following steps: a) controlling the pulse duty factor of the PWM generator ( 182 ) using the control signal (u_ 156 ); b) using the output signal (PWM 2 ) of the PWM generator, controlling the current in the stator winding arrangement of the direct current machine in such a way that in operation, a pulsed direct current (i_ 2 ; i_ 2 ′) is obtained in a supply lead of the direct current machine; c) deriving a pulsed current-dependent signal (u_ 2 ) from this pulsed direct current (i_ 2 ; i_ 2 ′), said pulsed current-dependent signal and said pulsed direct current being generated as pulsed signals, d) converting one, of said pulsed direct current signal (i_ 2 ) and said pulsed current-dependent signal (u_ 2 ), into a smoothed analog signal (PHI 1 ) and comparing the amplitude of the other pulsed signal to the amplitude of the smoothed analog signal (PHI 1 ); and e) as a function of the result of that comparison, modifying the control signal (u_ 156 ) for controlling the PWM generator in such a way that the current in the direct current machine is regulated continuously in normal operation, even outside a startup range, to the value defined by the current target-value signal (PHI 1 , PHI 2 ).