Indirect Efficiency Measurement of PM Machines of Different Power Classes

Abstract:
In many cases, a direct torque measurement is not suitable or not possible when it comes to efficiency determination of electric machines. Examples are the rising requirements for lower measurement uncertainty due the increasing number of super premium efficiency motors (>IE4) or the rising number of high-speed machines, impeding a direct torque measurement. The efficiency determination from the summation of losses (indirect determination) is a well-known alternative for large-power grid-operated machines. We expand the known loss determination methods to 1- and 3-phase outer rotor PM machines of 13 … 16 600 W rated output power and conclude a good accordance to directly measured efficiency values.