Pulse-by-pulse predictive current limiter

This paper presents a predictive based current limiting controller for a boost converter that was developed to charge an electric vehicle battery from the vehicle propulsion bus in an automotive bi-directional conversion system. To meet aggressive power density requirements, it was necessary to operate the three-stage interleaved converter magnetics near the edge of saturation of the boost inductors. Under large load transients the converter control needed to operate the converter as a current source to prevent hard saturation of the magnetics. The predictive limiter was used to achieve maximum slew rate while limiting the current. The implementation used background model calculation and lookup tables to minimize real-time computation and associated delay. The paper presents details of the current limiter design for a boost converter; its implementation into a DSP based controller and experimental results. Further enhancements and other applications are also discussed.