The half-speed linear machine: A new form of linear synchronous motor

The behavior of an unorthodox form of linear synchronous induction machine is investigated in asynchronous and synchronous modes. The machine is inherently brushless, its single stator winding being fed with alternating and direct current for synchronous operation. The machine was studied because of the prospect it offered of controllable power factor. A mathematical model based on the two axis theory which is appropriate to the segmental form of construction of its secondary winding is developed. The model enables a critical assessment to be made of its performance particularly with regard to important machine circuit parameters. Experiments on an experimental machine confirm model validity. Notwithstanding the relatively high resistance and leakage parameters of the trial machine, the possibility of good performance, including high power factor, obtainable in larger sizes is demonstrated.