A high efficiency dcââ?¬â??dc converter is studied for light rail transportation applications on\nDC microgrid systems. The adopted structure includes two series-connected resonant circuits with\nsingle isolated transformer from input 750 V to output 48 V. Two half-bridge resonant circuits and\none voltage balance capacitor are used to reduce voltage rating of active devices and to realize split\nvoltages balance. Two series resonant circuits are connected with input-series by single transformer\nto reduce primary root-mean-square currents. Therefore, power devices with low voltage rating are\nselected in studied circuit to reduce power loss on sower devices and transformer winding of the\nisolated transformer. Frequency control approach is adopted to adjust load voltage under different\nvoltage condition and current variations. Since the equivalent resonant tank of the studied circuit\nis activated under inductive load, active devices are easily operated at zero-voltage switching over\nwide voltage and current operation range. The feasibility of the studied circuit has been verified with\na 1 kW prototype.
Loading....