Research on the control strategy for the ice-breaking conditions of high polar class pod propulsor

To ensure the high torque overload capacity during icebreaking operations on thick ice layers at high polar levels, and to avoid the risk of damage to the variable frequency drive (VFD) caused by back electromotive force (EMF) of the motor when the weak magnetic control program of the VFD fails at maximum speed, the pod propulsor using permanent magnet propulsion motor typically requires a propulsion VFD with a high power several times bigger. This article proposes a design scheme for a permanent magnet motor pod propulsor that allows for series and parallel switching of winding connections to change the connection with the frequency converter, enabling control mode switching between ice-breaking conditions and open water conditions. This new scheme effectively reduces the capacity of the propulsion frequency converter and saves system costs.