Topologies for a permanent magnet generator/speed sensor for the ABS on railway freight vehicles

Antilock braking systems (ABS) are being considered for high-speed railway eight vehicles, which since they have no on-board electrical supply, require axle-mounted permanent magnet generators to provide a speed sensing control signal as well as the power for the solenoid valves which control the pneumatic brakes. The authors describe a design study on alternative topologies for such 3-phase generators, and present test results from prototype machines. They then go on to consider the implications of the choice of magnet material and pole number on the design of `interior magnet´ and `surface-mounted magnet´ machine topologies