Hardware in the loop simulation of direct synthesis based two degree of freedom PID control of DC-DC boost converter using Real Time Digital Simulation in FPGA

Abstract

The second order DC-DC boost converter is a non-minimum phase system as its control-to-output (c2o) transfer function contains a zero in the right half plane. This non-minimum phase behaviour poses several challenges to control design like initial inverse transient response to step changes, smaller bandwidth etc. Conventional One Degree of Freedom (1DOF) controllers, when applied to Pulse Width Modulated (PWM) boost type DC-DC converter suffer from the compromise that has to be made between the set-point response and disturbance rejection. The 2DOF-PID control scheme provides an extra degree of freedom to overcome above mentioned shortcoming. In 2DOF-PID, the feedback controller is designed through Direct Synthesis (DS) approach, where the controller transfer function is derived using Maclaurin series. Further, the rapid prototyping tools such as FPGA based Xilinx System Generator (XSG) facilitate quick realization of real time controllers before they are finally used for field testing. The results obtained by implementing controller in real time FPGA environment, using Hardware in the Loop (HIL) techniques, show the robustness of the presented control scheme to regulate the output voltage of boost DC-DC converter system.