A SiC-based power electronics interface for integrating a battery energy storage into the medium (13.8 kV) distribution system

Evaluation of 1.2 kV SiC MOSFETs in multilevel cascaded H-bridge three-phase inverter for medium-voltage grid applications

“…As reported in Ref. [8], four modules per phase are selected to add another degree of freedom for fault resiliency purposes. A three-level three-phase CHB inverter uses the lowest number of modules.…”

“…When SiC devices are used in a three-phase CHB inverter, they present the advantage of either significantly improving the converter efficiency or reducing the number of modules per phase, as reported in Ref. [8]. By taking advantage of the breakdown voltage of SiC MOSFETs (i.e., up to 10 kV), the number of modules per phase can be reduced to two for a 13.8 kV medium-voltage application.…”

“…For each module, a DC-DC stage follows the control algorithm scheme to regulate the battery current during both charging and discharging of the batteries, as reported in Ref. [8]. For different types of batteries, the controller adaptively follows the respective charging profile.…”

“…To achieve a higher efficiency and wide-range of DC bus voltages for the system to be connected to 13.8 kV, a high gain step-up/down DC-DC converter with a wide-range DC bus regulation is recommended in Ref. [8]. For a more compact system that uses fewer switching devices, a current-fed dual active bridge combined with resonant functionality and soft-switching provides a better option to achieve a high step-up/down gain and a considerably reduced ripple in the current flowing into the batteries.…”

“…The central (and fourth) DSP is used to execute a three-phase phase-locked-loop, directquadrature rotating frame control computation as well as active power and ac current control of the overall three-phase inverter. The central DSP with the feed-forward current controller [8] sends three-phase sine references to the Xilinx Artix-7 FPGA or lattice semiconductor complex programmable logic device (CPLD) from the MachXO2 device family to generate all the phase-shifted PWMs to switch on and off the 12 H-bridge cells of the inverter shown in Fig. 1.…”