EMI studies in motor drives

This thesis reviews in general the topic of electromagnetic compatibility, and electromagnetic interference and their origin and effects in modern electronically controlled motor drives. The measurement techniques for EMI noise are reviewed. The sources of noise of a switching power circuit are described. This thesis investigates the establishment of a procedure for measuring conducted emission produced by motor drives, using a virtual instrument. This procedure is based on the traditional methodology of EMI measurement and the use of simulation techniques. A test bench is designed. The thesis covers the detailed design of a virtual instrument for measuring conducted current produced by motor drives. A line impedance stabilisation network LISN is designed and built. A series of measurements were carried out using the developed instrument. The results show very little difference between the conducted emission produced by induction, permanent magnet and reluctance motor drives. Comparing one of the experimental results with published results from a major test laboratory assesses the validity of the designed instrument. The experimental results refer to drive systems under no load conditions. Useful conclusions are drawn and future research studies recommended.