Electric Machine Emulator in Voltage-Response Mode with Differentiator Compensation

Electric Machine Emulation (EME) is becoming a popular solution in the advanced testing and validation of power-electronics-based machine drive systems. In terms of the emulation of some high-power machines driven by current, the stator voltage references are firstly calculated in response to the sampled current, and then are electrically generated by power electronics converters. Thus, digital differentiators are inevitably introduced, resulting in distortion in frequency-domain behaviors of the EME. Consequently, the steady-state and dynamic performance under high fundamental frequency may deviate from those of the target machine system. In this paper, the limitations of typical EMEs in voltage response utilizing digital differentiators are analyzed, and a novel structure to realizing more accurate mission profile emulation is proposed. With this new method, the direct use of digital differentiators is avoided, and the frequency-domain characteristics of the proposed structure would be theoretically identical to that of actual machine systems. Simulation and experiment results are provided to validate the effectiveness of the proposed method.