A Review of Passive Power Filters for Three-Phase Grid-Connected Voltage-Source Converters

In order to reduce size and cost, high-order passive filters are generally preferred in power converters to cancel out high-frequency harmonics caused by pulsewidth modulation. However, the filter resonance peaks may require the use of passive dampers to stabilize the interactions between the load and source impedances. Furthermore, the stabilizing effect is more difficult to be guaranteed for cost-optimized filters, which are characterized by low-inductance and high-capacitance passive components. In this paper, several passive filter topologies used to interface voltage-source converters with the utility grid are reviewed and evaluated in terms of damping capability, stored energy in the passive components, and power loss in the damping circuit. In addition, the influences of different switching frequencies of power converters on the passive filter design are discussed in the range 1-15 kHz. Illustrative design examples of the passive filters and experimental data are also provided.