Induction motors with improved starting characteristic - has inductances with large laminated cores to provide attenuation of higher harmonics during start-up

摘要

The starting characteristic of an induction motor is improved by using inductive coils located in the supply lines. The inductances have the effect of alternating higher order harmonics that reduce the starting torque. The inductances have a laminated core of a 'U' shape with a single coil and a solid iron pole piece. Each inductance (5) is located in the supply lines from an inverter (6) to the motor (4). Each line has a relay contact (7) controlled by a unit (8) responsive to a specific voltage level. During start up the contacts are open and the inductances provide the required alternation. Towards the end of the start-up cycle the relay is activated to short circuit the inductances.