The research of innovative solutions to improve the efficiency of electric drives is of considerable interest to challenges related to energy savings and sustainable development. In order to successfully validate the adoption of new and innovative software or hardware solutions in the field of electric drives, accurate measurement procedures for either efficiency or power losses are needed. Moreover, high accuracy and expensive measurement equipment are required to satisfy international standard prescriptions. In this scenario, this paper describes an accurate measurement procedure, which is independent of the accuracy of the adopted instrumentation, for the power losses variations involved in electrical drives, namely ΔΔP, useful to detect the efficiency enhancement (or power losses reduction) due to the real-time modification of the related control algorithm. The goal is to define a valuable measurement procedure capable of comparing the impact of different control algorithms on electric drive performance. This procedure is carried out by experimentally verifying the action of different control algorithms by the use of a Field Oriented Control (FOC) with different values of the direct-axis current component (i.e., Id = 0 A and Id = −1 A) applied for fixed working conditions in terms of speed and load torque. Two different measurement systems of power losses, each one characterized by different accuracy and cost, are taken into account for the validation of the proposed method. An investigation is, then, carried out, based on the comparison between the measurements acquired by both instrumentations, for different working conditions in terms of load and speed, highlighting that the uncertainty generated by systematic errors does not affect the ΔΔP measurements. The results reported in this work demonstrate how the ΔΔP parameter can be used as a valuable index for the characterization of the power drive system, which can also be evaluated even with low-accuracy instrumentation.