Emulating dynamic load characteristics using a dynamic dynamometer

Standard test facilities for electric machines have incorporated dynamometers capable of simulating the static torque characteristics of typical industrial loads. Although useful for evaluating basic machine parameters, such dynamometers are not satisfactory for examining transient behaviour. A device that can present the dynamic response of a load superimposed on the steady state characteristics of that load is required for transient experimentation. This paper presents the key aspects of a design for such a device-a “dynamic dynamometer”. Using a control strategy based on local vector (LV) control, a DC machine can be controlled to simulate both the static and dynamic characteristics of a representative industrial load. One particularly interesting aspect of this is that nonlinear effects in real loads, such as backlash and stiction, can be accurately simulated. The paper presents some implementation aspects of dynamometer design, along with simulation results. The structure of the hardware being developed for the system is also discussed