Conducted electromagnetic emissions in induction motor drivesystems. I. Time domain analysis and identification of dominant modes

摘要

Stray components distributed in a pulsewidth modulation (PWM)ndrive system form parts of resonant circuits which can be excited tonproduce radio frequency (RF) noise driven by the pulsed switching actionnof the power devices. The dynamic response of such circuits is complex.nIt is essential to identify the dominant oscillation modes in the systemnso that electromagnetic interference (EMI) reduction techniques can beneffectively implemented. This paper (Part I) investigates the mechanismsnof conducted EMI emissions associated with a typical PWM inverterninduction motor drive system. A numerical model, which includes thenhigh-frequency effects within the machine, is established to evaluatenthe emissions in the time domain. The dominant high-frequency currentnpaths are identified, and this allows the oscillation frequencies to benpredicted from knowledge of the component values. The analysis isnconfirmed using laboratory measurements. Simplified frequency domainnmethods for direct calculation of the emission spectra based on thendominant high-frequency current paths are discussed in Part II