Characterization of DC permanent magnet motors using a motor-generator system

In this work the characterization of a DC motor is performed by analyzing the input current, the input voltage and the angular velocity. For this purpose, two motors of similar characteristics coupled by means of a motor-generator system were used, where the generator acts as an electromechanical brake applied to the motor. Characteristics such as torque, input power, output power and efficiency were calculated. It was also possible to estimate the values of the counter-electromotive force (back EMF) and the mechanical power. The characteristic constants $k_e=1.62\frac{mV}{rpm}$ and $k_{\tau }=1.69\frac{mV}{rpm}$ were determined and the mechanical power was calculated in two ways, with a maximum discrepancy of 10%. This shows that the motor-generator system is a viable method to study the main characteristics of a DC Motor, without the need to use expensive elements such as torque meters. This experiment can be implemented in electromagnetics teaching laboratories for both science and engineering students at a very low cost.

Keywords:
DC Motor; EMF; Torque; Power; Efficiency