Basic considerations on the linear motor drive by permanent magnet poles mounted on vehicles

Various kinds of flip-flop linear motors (FFLM) are discussed in comparison with linear synchronous motors (LSM), from the view point of propulsive efficiency. The essential difference between them exists in the waveforms of the current flowing in the ground coils. They are rectangular with various conduction angles for FFLMs and sinusoidal for LSM. The typical circuit configurations of the FFLMs for 180°, 120°, 90° and 60° conduction modes are described. The magnetic fields caused by the periodical arrangement of permanent magnet pairs which are assumed to be mounted on vehicles are then analysed for the respective conduction modes. Considerations on the economical aspects of both the actuators and the driving circuits are also described. The optimum arrangement of the magnet pairs is concluded to depend on the current conduction modes. It is also concluded that if the total length of the actuator is given and higher power is required, 120° FFLM is preferable and if least vehicle weight or most efficient magnet use are required, 60° FFLM is preferable particularly for high frequency traffic