A standard approach for DCMG

Abstract

Studies on DC microgrid (DCMG) have simply gone too wild and it is time for a standardized approach to design commercial products. The weak nature of microgrid is studied and set as fundamental difference to the studies of bulk grid. It is often seen in some publications that same assumption is taken as in HVDC studies, and is often misleading. A 300 W or inter-leaved 1 kW fly-back converter working at DCM/BCD mode is defined as the generic power electronic converter (GPEC), due to following reasons: the current control can be achieved with an open loop approach, easing the most difficult work of controller design; the output impedance is inherently high and can be set to an arbitrary value in the same open loop approach, making it instantly ready for power extension (paralleling at output) and also for different applications (like battery charger, voltage source, LED driver, PV module simulator, and but not limited to arc welder). High power density of 50 W/cm3 and high conversion efficiency of 97% are achieved with soft-switching of 200-500 kHz. A 17.5 kW power router is defined, which provides safety disconnection with built-in electronic arc elimination circuit, as well as conventional anti-lightning protection and leakage current protection. Apart from electric functions, it also provides information functions not only for monitoring but also for electric pricing-based power flow control.