Impact of Switching frequency on Electromagnetic Vibrations in Stator of Doubly fed Induction Machine

Electromagnetic vibration is a crucial aspect which may cause stability problems and disturb the stable operation of the system. DFIM variable frequency operation mainly depends upon rotor excitation through Voltage Source Converter (VSC). The converter's switching frequency is selected depending upon the magnitude of current, i.e., the thermal limit allowed. Using PWM in converter gives rise to Electromagnetic force harmonic content. when frequency and order of exciting Electromagnetic (EM) force conflicts with the natural frequency of the machine structure, a high level of vibration may result, additionally may be mechanical resonance. This paper compares stator magnetic vibration for a doubly fed induction machine with its rotor winding excited through a two-level voltage source converter at two different switching frequencies. Parameters selected for comparison are vibration acceleration and the associated defor-mation. For structural analysis, modal analysis is a prerequisite and has been performed on Doubly fed Induction Machine (DFIM) stator to calculate stator EM Vibration.