The Influence of DC link Components on Induction Motors

The paper at hand describes the influences of DC link and motor components on the operation of variable-speed induction motors. During laboratory tests, two induction motors show insufficient behavior while fed by a certain frequency con-verter in open loop control. Two motors of frame size M112 with a different design suffer from heavy vibrations at different speed. In addition to it, both motors show no abnormal operation while fed by an ideal sinusoidal voltage source with variable frequency. It becomes apparent that the vibration is a result of speed oscillation conditioned by an exchange of rotational energy to the DC link capacitor of the frequency converter. The problem is solved by using a suitable parametrization of the frequency converter to ensure damping of the oscillation. In order to understand this phenomenon in detail, a simulation model of the whole variable-speed drive shows the influences of certain parameters. Thus, it is possible to vary parameters of the DC link components, such as the value of the DC link capacitor, and motor parameters. The results can be used to prevent such oscillations and to make induction motors more resilient against weak control systems and weak damped mechanical setups.