A DC/DC Converter With Buck and Quadratic Buck Characteristic For Loads Connected to Bipolar DC Microgrids With Voltage Balancer Support

The bipolar dc microgrid is attracting interest among several alternatives to power dc networks. Although bipolar dc microgrids present several advantages regarding existing dc network topologies, they may suffer from the voltage unbalance disadvantage. Voltage unbalances can appear between their positive and negative poles as a result of unequal power sourcing or loading. Thus, this paper presents a new multiport dc/dc power converter specially designed for bipolar dc microgrids. The converter is suited to supply unipolar loads requiring lower voltage levels than the grid pole voltage. Additionally, under unbalanced conditions the presented converter will only use the pole with higher absolute voltage to supply the unipolar load, helping to reestablish the microgrid voltage balance. To avoid a wide duty cycle variation between the usage of only one pole and the usage of both poles, the converter can operate in Buck or in quadratic Buck modes. The converter operates in Buck mode when using only used one pole while it operates in the quadratic Buck mode when both poles are used. The multiport dc/dc power converter is also designed to operate as a voltage balancer. Results of the new multiport dc/dc converter obtained through simulation, and by a laboratory prototype are presented and discussed.