Calculation of electrical machine magnetic stray fields

Most new ships are electrically driven, because of the development of electrical machines and their controls. Some military or oceanographic ships require low magnetic stray fields. Among the equipment on board, the electrical machine for propulsion provides a magnetic anomaly that has to be investigated in order to be controlled. This is the aim of our work. Nevertheless, the values of magnetic stray fields are very low. That causes problems of calculation. This paper presents a model for the calculation of low magnetic fields. Firstly, the model is a static one that represents the magnetic signature of the machine at a given time. This static model has been validated by measurements on a synchronous permanent magnet machine. Secondly, the static model is extended to the motor while rotating.