Efficiency invariance laws and development of multiphase AC inverter drives
The main advantage of multiphase frequency controlled AC drives is that they have more control resources than the 3-phase ones. The increase of the inverter system phase number (i.e. the number of the phases) more than five together with the joint application of the over-phase control method and the classical principle of AC motor frequency control in these systems allow to improve considerably a number of the drive technical-and-economic characteristics (speed of response, reliability, manufacturing cost, etc.).