Energy efficiency of variable speed drive systems

A series of IEEE 112A performance tests were conducted in 1999 and 2000 by MSRF (Motor Systems Resource Facility), Oregon State University, Corvallis, Oregon. The results of those tests were reported in a paper presented in June 2001 at the IEEE/IAS PPIC Technical Conference in Portland Oregon. This paper suggests a similar series of performance tests for VSD (Variable Speed Drives) Systems. Most applications for VSD Systems involve variable torque loads, such as fans and centrifugal pumps, where the load varies as the cube of the speed. Performance tests of VSD systems are planned to measure efficiency of the VSD unit and the efficiency of the involved motor. While efficiency is a magic word, the real benefit of VSD systems is the reduction of energy used to provide the quantity of end product (fluid or air) of the pump or fan.