Dynamometer control for emulation of mechanical loads

In this paper a test facility 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 3-phase ac variable speed inverters. The experimental test facility comprises a 'dc dynamometer' capable of emulating both linear and non-linear 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 non-linear 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.