A torsional mode damping controller in which the controller modifies electrical power to an electrical motor to provide active damping control of torsional vibration in rotating masses. The controller receives a measurement of a rotational speed of the rotating masses ωm and an estimate or a measurement of a torque transmitted between the rotating masses Tsh; based on the received transmitted torque Tsh, generate a compensating torque to suppress vibration Tcom; based on the received rotational speed ωm and the compensating torque Tcom, generate an electromagnetic torque modification signal Tmodi; and modify the electrical power provided to the electrical motor on the basis of the electromagnetic torque modification signal Tmodi. The controller is further configured to generate compensating torque Tcom by applying a filter to the received transmitted torque Tsh, based on plural tunable parameters including a tuning gain K, a cut-off frequency ωn and a resonant damping ratio ζ.