Behavioral comprehensive efficiency modeling of motor drive systems based on physical measurements

In this paper, a comprehensive behavioral efficiency model of an electric motor drive system is proposed. The proposed model includes all possible motor drive losses without ignoring, approximating or assuming any of the inverter or machine losses, which are usually done for other efficiency models, hence the model is comprehensive. The input (DC electrical) and the output (mechanical) power of the motor drive system were measured and recorded for different drive operating points. These data were used to build the behavioral model through surface fitting using MATLAB. Different kinds of surface fits were used and discussed, and their effectiveness was evaluated. Moreover, a mathematical expression extracted from polynomial surface fit was used to derive the maximum efficiency point. The accuracy of this approach was verified with an additional experimental dataset not used for surface fitting. The proposed model can be easily integrated when designing, manufacturing and commissioning electric drives using rapid prototyping tools, and when designing maximum efficiency or minimum power loss control algorithms.