Design of a High-Current Electronic Load Emulator for Frequency-Dependent Impedances

This paper proposes a high-current emulator of resistive-inductive frequency-dependent loads. The case study is the emulation of the electrical behavior of vertical stabilization (VS) coils located in a Tokamak, whose resistance and inductance change depending on the operating frequency. Two different topologies are proposed to achieve an accurate emulation of the VS coils: one based on a single H-bridge and a second based on an n-H-bridges system. Both configurations replicated an arbitrary reference current truncated to the n harmonic. Each topology is regulated by a multi-resonant controller to manage multiple current harmonics contemporarily. Both strategies successfully tracked the reference current and mimicked the equivalent load with different degrees of error. Both the single H -Bridge and the n-H-Bridge configurations are able to effectively track the error with different benefits and drawbacks. Future perspectives include a refinement of the controller tuning to improve the simulation results and further testing of the emulator by means of Hardware-In-the-Loop.