A high density 48 V 200 A rectifier with power factor correction-an engineering overview

In telecommunications installations it is desirable for power equipment to draw a balanced three phase current at unity power factor with zero neutral current. A compact 48 V, 200 A rectifier weighing 32 kg has been commercially developed for this need. The rectifier employs the power conversion techniques first reported at INTELEC 1989 by Dennis Chapman of Swichtec Power Systems (formerly Eltec Electronics), New Zealand. Powered from a three wire, three phase 400 V, 50-60 Hz supply the rectifier presents essentially a unity power factor to the line. The thermal layout adopted, combined with fan cooling, keeps the overall dimensions to 400 mm wide×178 mm high×460 mm deep (4U×19 inch rack module). Maximum continuous output power is 11.2 kW (56 V, 200 A) at an efficiency of 90%. The rectifier comprises three modules. Each module operates at 230 V AC and can supply up to 70 A at 56 V DC. The three modules are connected in a star or `Y´ configuration. The junction point of the three modules is maintained at the equivalent neutral point voltage by controlling the power processed by each module