Numerical field calculation of additional nonlinear effects and additional nonlinear components in permanent excited machines

The continuous nonlinear diagram of the irreversible permeability and of the maximal allowed internal field strength of ferrite magnets depending on their angle against the preferred axis is measured and explained. In addition, the authors describe a novel method for obtaining field-weakening effects in permanent-magnet-excited (PME) machines by nonlinear soft iron bypass at the opposite side of the edge of the shell-type magnets, where demagnetizing will occur. With this method, the usual shunt characteristic of PME motors will be changed to a series-like torque-speed characteristic with up to 50% more speed at no load and 20 to 25% more torque at standstill