A Reconfigurable, Modular and Scalable Impedance Measurement Unit with SiC MOSFET-Based Power Electronics Building Blocks

Small-signal stability assessment using measured terminal impedances is getting popular in power-electronic-based power systems. This paper discusses the design of an impedance measurement unit (IMU) with a reconfigurable, modular, and scalable structure for both source and load impedance measurement. The IMU can be configured as a cascaded H-bridge converter and works as a line-to-line current injector when characterizing source impedance. For characterizing load impedance, the IMU can be connected as an interleaved converter with three H-bridges and works as a series voltage injector. The IMU power stage was built with SiC MOSFET-based power electronics building blocks (PEBBs), and a distributed control scheme and communication system was developed for the control implementation. Based on the modular design and distributed control, the unit can be easily scaled to a medium voltage high power IMU. Experimental results are shown to validate the design and control implementation.