Problems associated with electrical variable speed drives

Inverter drives have been available in an acceptable commercial form for about 25 years. Over that period a number of problems have appeared, but due to natural technological progress the type of problems have changed. These problems are very common to most inverter manufacturers as basic designs (power electronics) differ slightly. This presentation covers typical problems with possible solutions, but due to the nature of supplies and installation, only general rules can be suggested. This paper considers two types of inverter: a current fed inverter, and a voltage fed PWM (pulsewidth modulated) inverter. Harmonics, EMC, nuisance tripping, thermal derating, retrofitting to existing machines, hazardous area machines, noise and torque pulsations are discussed