A Hybrid Three-Level Buck Converter with Flying Supercapacitor for High Load Current Surge Capability using Peak Current Mode Control

In aircraft power systems, many non-propulsive loads require large bursts of current, such as electrohydrostatic actuators for positioning control surfaces. Hybridized energy storage systems utilizing batteries and supercapacitors prove an attractive option for supplying power systems with highly variable loads; however, such systems require many more components, increasing mass and volume. In this paper the use of a hybrid three-level buck converter is proposed, featuring an integrated flying supercapacitor for combined energy storage and multilevel operation, capable of providing large pulses of power. In addition to using Peak Current Mode control, a new algorithm is implemented to manage current-limiting and level selection, facilitating high load current surge capability. Advantages include reduced component count, short-circuit protection, and reduced battery stress, inductor current ripple and voltage ripple. This paper explains the operation and functionality of the proposed topology and discusses the proposed control algorithm. A model, developed in MATLAB/Simulink, is used to demonstrate the behavior of the converter and validate the proposals.