Comparative Study of the Normalized-Error-Based Control and Traditional Current-Mode Control for a Sixth-Order Boost Converter

Abstract

Current-mode control is a commonly utilized control strategy for the step-up power converters because these converters’ control-to-output transfer function contains right-half plane zeros. The main concern associated with the recent dual-loop current-mode controller (CMC) is that the integrator operates on the error term itself. Thus, integrand can assume extremely large values when error is large such as during transient response, and the controller output may saturate, especially when sufficiently large controller gains are used. If lower gain values of gains are used, the speed of response in the presence of small parameter variations could be much lower. Thus, there is a compromise between the transient response when error signal is large and speed of the response for small error signals. To address these concerns, an improved normalized-error based current-mode controller (NECC) is employed for voltage regulation in a sixth-order boost configuration. This controller’s main characteristic is that the integrator now operates on a bounded integrand which is a normalized-error. This avoids the integrator saturation and also increase the room for tuning the controller gains. The state-space averaged model of the topology is given and a detailed stability analysis is shown. The main contribution of the paper is that a detailed comparative study of the traditional CMC and an improved NECC based on some simulation and experimental waveforms is provided. Both simulation and experimental outcomes clearly prove the superiority of the proposed NECC in terms of an improved speed and less overshoot of the output voltage response.

Keywords

• High-order boost converter
• current-mode control
• normalized-error