Maximisation of back EMF in a high performance PMSM machine with concentrated windings

PMSM machines with concentrated windings have become more and more popular over the last years. The biggest drawbacks of these machines are high cogging torque and the form of the back EMF. Standard approaches try to shape the back EMF sinusoidal to use standard field orientated control. In the following paper an approach is shown to shape the EMF by using derivative free minimization. Using this simple algorithm the back EMF can be maximised by modifying the machine geometry. Thus allowing to combine the benefits of easy construction and maximal back EMF. The maximised EMF is non sinusoidal but there are several approaches to compensate non sinusoidal EMF by control. For this case it is shown that by changing the stator geometry for a given copper loss the output torque can be increased by 9%.