Abstract: A method and a system for controlling parallel-connected frequency converters or inverter units feeding an alternating-current motor (MOTOR1) provided with parallel windings or separate parallel motors having their shafts mechanically coupled together via a load, in which method the current supplied to the motor is measured. The frequency converters/inverter units are connected to each other via a data bus, e.g. a fast serial bus, and one of the frequency converters/inverter units (FCON1 or INU1) functions as a master device in such manner that it sends to the other device/devices (FCON2 or INU2) information over the data bus regarding the instantaneous value of the current (IW1) fed by it to the motor, said other devices functioning as follower devices so that they adjust their own current (IW2) on the basis of the current of the master device.