Patent ID: 6870333
Filing Date: 2005-03-22
Classification: H02P

Abstract:
1. A method for determining triggering times of multi-phase power controllers for operating an asynchronous motor, the multi-phase power controllers being connected to a multi-phase network without connecting a start point of a stator winding of the asynchronous motor and the feeding network and including at least two pairs of antiparallel-connected thyristors, which are triggered at previously determinable times, comprising the following method steps: defining, for the pairs of antiparallel thyristors, potential triggering pulses which lie at a specific triggering angle before a respective zero crossing of the main voltage; defining a sinusoidal fundamental wave at a frequency which corresponds to the desired rotational speed of the asynchronous motor and whose frequency is lower than that of the main voltage; defining two phase-shifted fundamental waves at the same frequency, the waves in each case being phase-shifted in relation to the defined sinusoidal fundamental wave; rejecting, for each phase, previously marked potential triggering times which would cause a current of opposite polarity to that of the respectively associated fundamental wave; and selecting, of the remaining potential triggering times, those times for triggering each phase at which there is a triggering time in one of the two other phases, wherein the selected triggering times are usable as actual triggering times for the thyristors of the three-phase power controllers.