Dynamometer control for emulation of mechanical loads

In this paper, a test facility which is capable of the electronic emulation of dynamic mechanical loads is presented. The primary objective of such a facility is to provide an aid to the testing and commissioning of modern commercial three-phase AC variable speed inverter drives. The experimental test facility comprises a 'DC dynamometer' capable of emulating both linear and nonlinear dynamic mechanical load systems. A detailed description of the control structure employed to create the load emulation is developed. The limitation of practical microprocessor implementation of the control scheme and the restriction that, in order to maintain a flexible test facility, the scheme should operate with no direct measure of torque are explored. The paper also outlines the hardware structure of the experimental rig and experimental results showing good emulation for both linear and nonlinear loads are presented. Operation of the test facility is illustrated with a commissioning example, in which a passenger lift system is emulated, and a test example in which an inverter is tested under a high starting load.