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 T^mωⁿ for the losses in the constant torque region and in the form of P^mωⁿ 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.