Design and performance analysis of two degree-of-freedom (2 DOF) control of DC-DC boost converter

The application of the two degree-of-freedom (2 DOF) theory to control non-minimum phase DC-DC switching converters is investigated in this paper. The robust control techniques mostly used to attain a regulated output voltage, even under perturbed condition, for DC-DC boost converter are, H_∞ (both linear and nonlinear), μ-synthesis, genetic algorithm, linear quadratic regulator (LQR) control. All of these control techniques are one degree-of-freedom (1 DOF) i.e. conventional error-driven in nature. The 1 DOF control technique suffers from the limitation that there exists a compromise between response and loop goal performances. To overcome this, in the present work, a 2 DOF linear time-invariant (LTI) controller has been designed to achieve the performance goals of DC-DC PWM based boost converter. A 2 DOF controller provides additional degree-of-freedom so as to meet the loop robustness goals as well as to shape the output response according to requirement. The design technique of this controller is simpler than that of the robust control techniques mentioned above. The 2 DOF control scheme has been shown to achieve the output regulation even in the presence of 60% perturbation in load current and obtain fast recovery in output voltage response, through simulation. The veracity of the simulation results has been established through a real-time experimental setup of the boost converter.