Patent ID: 6459999
Filing Date: 2002-10-01
Classification: H02H

Abstract:
A method for identifying the failure of a phase of a converter-controlled three-phase asynchronous machine, comprising the steps of:a) providing a monitoring circuit having a first monitoring state, a second monitoring state, a third monitoring state, and a fourth monitoring state; b) comparing the instantaneous value of the phase current with a limit value when said monitoring circuit is in said first monitoring state; c) generating a trigger signal responsive to undershooting of said limit value when said monitoring circuit is in said first monitoring state; d) changing from said first monitoring state to said second monitoring state responsive to presence of said trigger signal when said monitoring circuit is in said first monitoring state; e) comparing said trigger signal with the angle of rotation swept by the voltage vector of the phase which rotates with the rotating field; f) changing from said second monitoring state to said third monitoring state responsive to presence of said trigger signal greater than a predetermined field angle; g) comparing said trigger signal with a predetermined delay time interval; and h) changing from said third monitoring state to said fourth monitoring state and signaling phase failure in the event of presence of said trigger signal greater than said predetermined delay time interval.