Vibration Analysis and Mitigation in Switched Reluctance Machine Drives
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High power density and high speed electric drive systems are required for many applications like hybrid electric vehicles, compressors and electric aircrafts. Permanent magnet synchronous machines (PMSMs), Induction machines (IMs) and switched reluctance machines (SRMs) are usually used for these types of applications. The PMSM has highest power density due to presence of permanent magnets but its speed range is limited by the flux weakening ability and mechanical stress on the magnets and rotor. The magnets can also be demagnetized under certain conditions. IM usually can operate at higher speed but the power density is less than PMSM. Structure of the rotor of IM is simpler and more easily manufactured when compared with PMSM. SRM has the most robust rotor structure to run at high speed and simplest rotor structure to be manufactured. However the vibration and acoustic noise is a major issue for SRMs for noise sensitive application. In this dissertation, a mechanical impulse response technique is developed to predict vibration in SRM drives in tangential and radial directions. Geometrical and mechanical parameters’ effects on impulse response are also analyzed. Acoustic noise modeling based on impulse response is demonstrated by comparing traditional finite element analysis method and the proposed mechanical impulse response method. Secondly vibration is analyzed comprehensively for SRM assembly which includes mechanical coupling in SRM, i.e., end plates and bearing using finite element analysis. Rotor position and excitation effect on the corresponding transfer functions are also analyzed. Finally a new method for mitigation of vibration in SRM drives is proposed. The proposed method includes structural design and current band optimization. The proposed techniques are verified in simulations and experiments.