Decoupled Average Current Control of Coupled Inductor Single-Input Dual-Output Buck Converter

Multiple-output dc-dc converters are compact and cost effective as compared to multiple parallel dc-dc converters. This article focuses on a coupled-inductor single-input dual-output (CI-SIDO) buck converter. For the CI-SIDO converter, achieving independent regulation of output voltages and maintaining good dynamic performance are difficult due to cross-regulation and cross-coupling problems. In addition, tuning of controller parameters is challenging. Thus, this article proposes a decoupled average current control (ACC) to suppress cross-coupling and cross-regulation in CI-SIDO buck. It also demonstrates the method of decoupling of inductor currents and the stability issue that exists in ACC of CI-SIDO buck. The analysis shows that decoupling of inductor currents makes the design of controllers independent and simplifies the closed-loop transfer functions. Based on the conditions of decoupling and stability, a systematic design procedure for a Type-II compensator is developed. The proposed control method is compared with the voltage-mode control by using MATLAB/Simulink results. The comparison shows that the proposed ACC exhibits better dynamic performance. Finally, the proposed method is validated using experimental results.