Evaluation of Operating Range of a Machine Emulator for a Back-to-Back Power-Hardware-in-the-Loop Test Bench

Inverter testing using laboratory test benches with rotating machines can be bulky, complex, and maintenance intensive. One solution is to use machine emulator for laboratory testing of inverters. The emulator is controlled in such a way that currents and voltages at the terminals resemble a machine connected to a mechanical load. A machine emulator for a back-to-back power-hardware-in-the-loop (PHIL) test bench is proposed in this article. The PHIL test bench consists of two identical voltage source converters (VSCs) with three single-phase inductors as coupling network. The two VSCs are connected to the same direct current supply. One VSC acts as inverter under test (IUT), while the other is part of machine emulator. Aim of this article is to analyze the influence of coupling inductance on operating range of the emulator. An analytical method to dimension the coupling inductance is introduced and verified in experiments. The operating range of the emulator is also evaluated. The performance of the IUT when tested with an equivalent permanent magnet synchronous motor in simulations and that of a prototyped 60-kW rated machine emulator are compared. Sensitivity of emulator control on parameter estimation is discussed. The experimental results show good agreement with simulations in both steady-state and dynamic conditions.