Harmonic losses in LCI-fed synchronous motors

Load-commutated inverters produce considerable current harmonies, which can cause losses and heating inside the machine. As drive outputs increase, it is important to be able to accurately predict not only the magnitude of these losses, but also the precise location of the losses within the motor. Recent experience and modern calculation techniques have shown that the effects of these losses in large motors can be quite dramatic. If not considered at the design stage, they can lead to high-temperature hot spots. These potential hot spots need eliminating to prevent surface temperatures in excess of gas ignition temperatures and also possible early machine failure. New detailed calculations have been performed which allowed a novel technique to be determined to reduce these losses and allow larger ratings of drives to be safely engineered.