Implementation of a virtual induction machine test bed utilizing the power hardware-in-the-loop concept

In this paper, a method for removing the risk associated with the testing and development of novel drive system topologies, prototype electric machines, advanced control system strategies, or a combination of the aforementioned without using any real motors/generators is presented. For low power machines, the test platforms are relatively inexpensive and accessible, however, as power levels increase into the upper kilowatt and megawatt range, validation of prototype machines and drives becomes costly. The proposed virtual machine (VM) test platform utilizes the power hardware-in-the-loop concept in conjunction with high-fidelity machine model and load dynamics. The electric machine and load dynamics are simulated with a real-time digital simulator, which generates appropriate control commands to a power electronics-based voltage amplifier that interfaces to a variable speed drive (VSD). Specifically, the current draw is recreated via altering the phase and magnitude of a voltage amplifier parallel connected to a VSD under test via a unique transformer-based LCL-type coupling network. Based on the proposed concept, use of a multi-winding, tap-changing transformer establishes a truly versatile and universal test bed in a wide range of power levels. In addition, this paper presents a novel control strategy in the synchronously rotating reference frame in dq-coordinates for parallel connected power electronic converters in VM operation. Experimental results at the kVA-power level validate the feasibility and highly dynamic performance of the proposed test platform.