Prediction and measurement of detent torque of a single-phase machine

A determination method and a measurement technique of detent torque based on an energy approach in permanent magnet systems is presented. The different terms of the expression of the energy are derived and then represented on the B-H (flux density-magnetic field) diagram. As a result of this, the single-phase starting conditions for permanent magnet motors can be analysed. This approach is used to optimise an example of a rotating single-phase motor without magnetic or mechanical dissymmetry. The single-phase starting conditions are particularly studied as a function of the rotor angular width by means of a finite element code.