Measurement of dynamic torque

Modern machine control strategies such as vector control are claiming torque bandwidths of several kHz. The authors discuss the measurement of such performance; this is needed in order to validate the theoretical results and to allow the design of improved closed loop control schemes. Torque performance can be defined in terms of either its time or its frequency response. Theoretically transformation between the two by means of time-frequency domain relationships such as the Laplace Transform is possible. In attempting to monitor dynamic torque responses the authors consider three possible techniques: direct measurement of mechanical torque; infer torque from measurement of angular acceleration; and calculation of electromagnetic torque from flux and current. As a guide the Surrey University 7.5 kW test rig was chosen for calculations