Linear-motor topology

In rotating electric motors, the working magnetic flux is usually assumed to cross the airgap substantially in radial planes, and, in this respect, the working flux could be said to be ‘1-dimensional’. In transverse-flux machines, 2- or 3-dimensional flux loops are possible, and the number of different shapes of transverse-flux machine which can be built is far greater than when only one dimension is used. Transverse-flux machines find their most attractive forms in linear motors, and several ‘families’ of both transverse- and longitudinal-flux machines are described. These include motors designed to have a low leakage reactance, for high-speed machines fed from 50 Hz supply (and therefore of large polepitch), and machines designed to give lateral stabilisation as well as thrust without the use of an additional primary-coil system.