Abstract: A permanent magnet brushless 3-phase motor comprises windings R, Y, B, each divided into a plurality of sections 1-5 and switch means S1-S12 for selectively connecting the section of the respective winding e.g. R in series and/or parallel with all other sections of that winding R. Control means are provided for actuating the switch means S1-S12 to connect the winding sections 1-5 in different configurations whilst the motor is running to alter the speed/torque characteristics of the motor.

Abstract: A suspension system for magnetically suspending an object O comprises an electromagnetic coil L having an axially extending core 13 of magnetically permeable material and a permanent magnet 14 disposed on its axis. A permanent magnet 10 is also provided in the object O and is arranged such that it is in attraction with the permanent magnet 14 on the coil L, and with the magnetically permeable core 13 so that the object O is suspended at a position below the coil L by the attractive force. Sensors 15,16 on the coil L detect the magnetic field of the permanent magnet 10 in the object O, and provide signals to a control circuit, which applies current to the coil L to attract the object O when the detected field is below a predetermined limit and to repel the object when the detector field is above a predetermined limit.