Torque and EMF ripple reduction in brushless machines

This contribution describes torque and EMF ripple minimisation in electrical machines with slotted iron stators. This is a problem in electronically commutated DC machines which require trapezoidal shaped output waveforms with extended plateau regions. The approaches considered here include winding distribution, slot number selection, stator and rotor skewing, pole shaping, and special lamination designs. Two design examples illustrate the application of some of the above techniques in a two phase brushless tachogenerator and a three phase brushless motor