STARTING METHOD OF PERMANENT MAGNET SYNCHRONOUS MOTOR

摘要

PURPOSE:To effectively start a synchronous motor without step-out by a slowing increasing the output frequency and the voltage of an inverter in a low frequency range. CONSTITUTION:A soft starter 2 outputs a speed command SP which rises linearly from zero speed to a speed set value NS. The speed command SP from the starter 2 is converted by a function generator 3 to become a frequency/ voltage command. The generator 3 is set to input/output characteristic which slowly rises at the output Vs(fS) for the rise of the command SP in a low frequency range starting from zero frequency, and linearly rises together with time at the output VS(fS) coincident to the rise of the command SP after exceeding the low frequency range. This range is set to the operating frequency that the relationship between the load angle of a motor 7 and the generated torque peak from zero frequency becomes constant.