Abstract
Most of the icebreaking vessels employ electric propulsion systems which utilize diesel engine prime-movers, ac generators, rectifiers, do motors and fixed pitch propellers. The nature of the icebreaking process imposes certain unique loads on the propulsion systems of ships applied to such service. These systems are subject to inefficient operation in addition to possible failure of propellers, shafting or other system components.
To estimate the static and dynamic performances of the proposed AC-R-DC electric propulsion system applied to the icebreaking ship, a brief description of the icebreaking process is presented and a method for calculating load torques in function of the advance coefficiency is developed. An introduction is given to methods which utilize steady state and dynamic technique for synthesizing the AC-R-DC electric transmission system which meets given performance requirements. Transient characteristics of the system are calculated in cases of step and impulse ice loading. Effects of torsional vibration of shafting are also evaluated.
