Performance of adjustable speed drives subject to regular voltage fluctuations

The impact of power quality disturbances on customer equipment has been a topic of interest to equipment manufacturers, electricity utilities, customers and to those involved in the development of electromagnetic compatibility standards. Recently, a new interest has developed in the possible impact of voltage fluctuations on customer equipment because of suggestions to relax voltage fluctuation limits and hence the flicker limits in power systems. With a view to contribute to this understanding, this paper investigates the performance of an adjustable speed drive (ASD) when subjected to sinusoidal regular voltage fluctuations. When the ASD is operating in open loop mode, the outcomes of experimental work illustrate that a fluctuating supply voltage will lead to an increase in the rectifier capacitor RMS current. Furthermore, the AC supply side fluctuations can pass through the rectifier and inverter unit and lead to a fluctuation in the induction motor stator current.