Comparison of load inverter topologies in a bipolar LVDC-distribution

Abstract

Low voltage direct current (LVDC) distribution is a new low voltage distribution concept. Potential inverter topologies for a bipolar LVDC 1500 V distribution system are compared. Two-or three-level single-phase half or full bridges or three-phase load inverters can be used in LVDC distribution. Inverters can be connected to 750 V DC or 1500 V DC. The bases of comparison are the size of required LC-filters, voltage and current stresses of the components, capability to operate with reduced DC voltage and feed half-wave rectifying load. Two different LC-filter design methods are used. According to the simulation results, the most suitable single-phase load inverter topologies connected to 750 V DC are two-and three-level full bridges. The structure of three-level inverters is more complex, but the size of the required passive filter components is just half of the size of the components with two-level inverters.The difference between LC-filter sizes is not so significant when comparing with two-and three-level inverters connected to 1500 V DC. The maximum voltage stresses of the IGBT-components are udc/2 in three-level inverters but udc in two-level inverters. Smaller voltage stresses are a remarkable advantage especially at higher voltage levels.