Nonlinear Effects of Three-phase Diode Rectifier on Noise Emission in the Frequency Range of 2-9 kHz

This paper presents a study on differential mode noise emission affected by a three-phase diode rectifier when there is an input Electromagnetic Interference (EMI) filter. The EMI filter is generally designed for noise attenuation beyond 150 kHz. Therefore, systematic analysis of its behaviour in the new frequency range of 2-9 kHz is essential to identify its unacceptable noise emissions. This is important to comply with upcoming emission standards in the frequency range of 2-9 kHz. This paper presents the impact of a three-phase diode rectifier and an EMI filter in different system damping conditions, different grid types and switching frequencies regarding the harmonic emission in the frequency range of 2-9 kHz. The accuracy of a proposed equivalent circuit model of EMI filter to predict grid current emissions is also evaluated for above system conditions, leading to recommendations to noise reduction at 2-9 kHz.