Apparatus and means for starting of AC motors, algorithm for self-adapting motor start with soft-starter

摘要

The invention relates to a method of starting an electric motor (10) powered by an alternating power supply voltage, said method consisting of supplying current to the motor (10) with a delay t_ret, during each period of the power supply voltage. The starting method comprises a first sequence in which the following steps are carried out during each n^th period of the power supply voltage, where n is an integer number greater than 0: a) determine the value of a variation of a resistance of the electric motor during the previous n periods of the power supply voltage; b) compare said value of the variation of the determined motor resistance with a first threshold resistance value; c) if the value of the variation of the motor resistance is less than the first threshold value, reduce t_ret. The invention also relates to a starter device and a computer program.