Distributed Energy Systems
Technical Lecture Session
Controller and Filter Design for Utility Interface Converters
Distributed system, load converter, input impedance, loop gain
In a distributed power system, stability criterion requires source impedance smaller than load input impedance when their phase differ by 180°. In this paper, the input impedance of four common DC-DC converter types (Buck and Boost, voltage-mode and current-mode) are analyzed, their relationship with voltage loop crossover frequency and phase margin are established. It reveals that lower crossover and higher phase margin will increase impedance, thus a guideline on design of load DC-DC converter loop gain is provided to get preferred input impedance and meet stability criterion. This method generally applies to all DC-DC converters like Boost, Buck, Buck-Boost, and converters derived from them.