An active damping arrangement for a power conditioning circuit comprising a converter or an inverter and an electronically driven output line having an output terminal for connecting to an external load, the active damping arrangement comprising an inductor-capacitor low-pass output filter (OPF) for connecting between an output of the inverter/converter (PWMVC or BBHCC) and the output terminal; means for sensing current in or voltage across the capacitor or voltage between one end of the capacitor (C) and an effective neutral point; means for multiplying the sensed voltage or current by a coefficient G to provide a damping signal, and means for feeding back the damping signal to an input of the inverter/converter (PWMVC or BBHCC), thereby to damp the output of the inverter/converter.