Active EMI Filters Based on the Fractional Order Compensation

In order to prevent the propagation of EMI noise, the conventional approach involves incorporating passive devices at the input stage, which often results in a significant increase in volume and weight of the power converter. Active EMI filters (AEF) or hybrid EMI (HEF) filters are considered superior alternatives to traditional passive EMI filters as they offer higher power density and enhanced noise attenuation capabilities. However, AEFs suffer from limited effectiveness in suppressing EMI within relatively high frequency bands (typically 5~30MHz), primarily due to constraints imposed by operational amplifier gain bandwidth product. To address this issue, we propose a non-inductive AEF that combines feedforward and feedback techniques while being compensated by fractional order network. The efficacy of this AEF topology is validated through experimentation. This compact and lightweight design effectively attenuates high-frequency noise signals with considerable insertion loss.