On the accuracy of indirect torque measurement using frequency converter

The article presents evaluation of indirect torque measurement accuracy of converter-fed induction motors. The low-power (5.5 kW) motor supplied by Siemens SINAMICS S120 frequency converters was used to perform the measurement. The converter was set up to vector control method, also the effects of speed sensor presence or absence were compared. The dynamometer test bench with gauge strain measurement of force (torque) to produce the load torque was used. It allows us to evaluate the whole working area of tested drive. The results show that the relative accuracy of torque value is acceptable for specific industrial applications and therefore it allows to cut down expenses for direct torque measurement device. The results presented in the article enlarges our measurement database focused on industrial frequency converter performance.