Correction of Finite-Element Calculated Efficiency Map using Experimental Measurements

This paper examines correction of the finite element (FE) calculated efficiency maps based on simple experimental tests. The error between calculated and measured efficiency maps significantly affects the energy consumption in variable-speed applications like electric vehicles. The flux linkage correction requires the measured saturation flux-linkage obtained from stationary testing and the iron loss correction requires open-circuit or no-load test results. These tests need minimum effort and equipment and in the case of open-circuit tests, no inverter is required. This paper also provides a detailed loss analysis by using fitting functions in the form of Tmωn for the losses in the constant torque region and in the form of Pmωn for the losses in the constant power region for both FE and measured results. The results indicated that superposition of the speed dependent coefficients obtained from the no-load test and coefficients obtained from the FE calculation provides a good estimation of the measured loss. Comparing the original FE and modified losses provides loss scaling factors for the iron losses.