Design of a High-Voltage High-Current Power Stack

Abstract

This research-based thesis presents the 1.2 kV/ 1.4 kA IGBT power module-based power stack with a DC-link voltage of 1.5 kV, featuring the medium voltage power conversion with a simple three-level neutral-point clamped (3L-NPC) converter. The project is intended to design the 750 kVA/ 1.5 MVA high-voltage high-current power stack. The design of the power stack assembly comprises medium-voltage/high-current IGBT power modules, gate driver units with dual-channel IGBT driver cores that are fully equipped with isolated DC/DC converters along with short-circuit pro-tection, DC-link capacitors, and air-cooled heat sink. The 750 kVA single-phase and three-phase 3L-NPC converter is simulated in MATLAB/Simscape software to ana-lyze the power losses and efficiency and the same approach is adopted for the design of 1.5 MVA power stack design. The initial 750 kVA single-leg power stack prototype is designed using a 3L-NPC converter and is tested with an RL load at low power at the laboratory due to the availability of the load and safety precautions. The hardware setup is tested under two experiments with a total average circulated power of 1.045 kW with a modulation index of 0.8 and a power factor of 0.96 in one experiment with an efficiency of 96.7%. In another experiment, the average power of 2.09 kW is injected with a modulation index of 0.9, and a power factor of 0.97 and 97.84%efficiency is obtained and the results are validated with the simulation results.