| Abstract |
Winding arrangement and wave form of the phase currents are determining factors for the effectivity of the power conversion in electric machinery. Frequency inverters employing new Semiconductor (SC) components such as GTO's and power transistors enable the realization of higher number of phases with independently controlled currents and limited amount of circuit elements. New permanent magnets and new achievements in the architecture of magnetic circuits in general lead to concepts of electrical machines with high magnetic flux densities, reduced armature reaction and high efficiency. Rectangular current shape, (spatial and depending on time) and rectangular field distribution within the pole area yield a higher rate of interaction between field and current, /1,2/. Synchronous motors with permanent magnet excitation as well as reluctance motors are particularly suitable for using multiphase windings. Frequency inverters in multiphase configuration and individually controlled phase currents together with the improved excitation scheme of machines contribute considerably to implement high performance conversion systems /2,3/. |
