The measurement of transient electromagnetic torque in high-performance electrical drives

A method of measuring transient electromagnetic torque for electrical motor drives is described that uses a commercially-available force-measurement platform. The platform contains crystals which develop charges as a result of the piezoelectric effect. The crystals are sensitive to forces in the three orthogonal directions in space. Measurements of the charges produced by these crystals facilitate the transient stator-reaction forces to be measured directly. The motor torque may then be derived by using a simple linear combination of the measured forces. The technique has the advantage that the motor can be used without modification. It has been successfully employed in a comparative study of the transient responses of high performance, vector controlled induction motor drives.