Patent ID: 7443129

Claim:
A method for controlling a quenching device for a converter bridge with line regeneration, comprising: providing a converter bridge with at least three inputs electrically connected to a three-phase network and at least two outputs electrically connected to a direct-current motor which feeds, when operated as a generator, current back into the three-phase network via the converter bridge; providing a network-time control circuit to control the converter bridge based upon ignition pulses of the control circuit; controlling the quenching device by a trigger unit which emits trigger pulses based upon a monitoring of electrical and temporary variables of a converter; measuring waveforms of at least two phases of the three-phase network as a function of a phase angle over a predetermined area of the phase angle; determining a characteristic value from the waveform of the two phases as a function of the phase angle; comparing the determined characteristic value to a corresponding theoretical characteristic value; and activating the quenching device if the characteristic value determined from the measured values of the phases deviates by a predetermined value from the theoretical characteristic value.