Patent ID: 7038405

Claim:
A method for controlling parallel-connected frequency converters or inverter units feeding an alternating-current motor (MOTOR 1 ) 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, connecting the frequency converters/inverter units to each other by a fast serial bus, and wherein one of the frequency converters/inverter units (FCON 1 or INU 1 ) functions as a master device in such manner that it sends to the other device/devices (FCON 2 or INU 2 ) information over the data bus regarding the instantaneous value of the current (I W1 ) fed by it to the motor, said other devices functioning as follower devices so that they adjust their own current (I W2 ) on the basis of the current of the master device.