Ground Current Control Scheme for Back-To-Back Three-Phase T-Type Rectifier and Inverter Systems

This paper presents a method to control the ground current in a back-to-back connection of three-phase T-type rectifier and inverter stages if operated from a three-phase mains with a grounded neutral point and a star-connected three-phase load with grounded star point. The proposed control scheme requires a ground current sensor and a single control loop, achieves a closed-loop control system bandwidth of 1.7 kHz, and does not interact with the existing input phase current control system that is used to achieve sinusoidal mains currents. According to the presented experimental results, an effective reduction of the rms ground current from more than 200 mA (without controller) to less than 3 mA (with the proposed control scheme) is realized. (C) 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.