Improved Sliding Mode Active Disturbance Rejection Control for Single-inductance Dual-output Buck Converter
ObjectiveThe single-inductance dual-output (SIDO) converter has gained increasing attention due to its reduced magnetic component count, compact size, low cost, and high efficiency. However, because both output branches share a single inductor, significant cross-coupling arises during input voltage...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Editorial Department of Journal of Sichuan University (Engineering Science Edition)
2025-07-01
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| Series: | 工程科学与技术 |
| Subjects: | |
| Online Access: | http://jsuese.scu.edu.cn/thesisDetails#10.12454/j.jsuese.202300937 |
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| Summary: | ObjectiveThe single-inductance dual-output (SIDO) converter has gained increasing attention due to its reduced magnetic component count, compact size, low cost, and high efficiency. However, because both output branches share a single inductor, significant cross-coupling arises during input voltage transients and load disturbances, degrading output voltage performance. Enhancing the control strategy is crucial to addressing this issue. Given that the SIDO converter is a nonlinear time-varying system, conventional PI control proves inadequate. For such strongly coupled nonlinear systems, advanced nonlinear control techniques can substantially improve both dynamic response and control precision.MethodsActive disturbance rejection control (ADRC) has emerged as a promising strategy owing to its strong disturbance rejection capability and independence from precise system modeling. Nevertheless, conventional ADRC, being a linear approach, suffers from performance limitations. To overcome this, we propose an enhanced ADRC strategy integrating a cascaded reduced-order extended state observer (CRESO) with an improved nonsingular terminal sliding mode control (TSMC). This strategy is successfully applied to the SIDO Buck converter by improving both the disturbance observer and the state error feedback law. First, a state-space averaged model of the SIDO Buck converter in continuous conduction mode is developed, and the mechanism of cross-coupling between output branches is analyzed. The main and auxiliary circuits are then decoupled into two independent second-order ADRC canonical forms for separate controller design. To address the limited estimation accuracy of traditional extended state observers (ESO), a two-stage observer is implemented by cascading a secondary ESO to capture residual disturbances. While this improves estimation, it increases observer complexity. To mitigate this, we leverage reduced-order observer principles—when some system outputs are directly measurable, only the remaining states and disturbances need to be estimated. Based on this insight, the CRESO is formulated to estimate both state variables and total internal/external disturbances. Frequency-domain analysis confirms that the proposed observer enhances estimation accuracy and accelerates disturbance rejection within the same bandwidth. Next, the traditional PD-based ADRC feedback law is replaced with a sliding mode controller to improve system robustness and convergence speed, particularly under large deviations. Among various options, nonsingular terminal sliding mode control (TSMC) is chosen for its ability to drive system trajectories to the origin in finite time, thereby improving both rapidity and robustness. To address the chattering effect commonly associated with sliding mode control, we incorporate a super-twisting algorithm in place of the discontinuous sign function, yielding an improved TSMC with reduced chattering. The stability of both CRESO and the improved nonsingular TSMC is rigorously verified through the characteristic root criterion and Lyapunov stability analysis. Additionally, the steady-state error bounds of CRESO and the convergence time of the enhanced TSMC are derived.Results and DiscussionsA simulation and experimental platform for the SIDO Buck converter is established. Simulations are conducted using MATLAB/Simulink, while hardware implementation is performed using the DSP28335 and an MT 6020 HIL platform. Transient performance under input voltage and load disturbances is evaluated by comparing three control strategies: common-mode voltage/differential-mode voltage (CMV-DMV) control, conventional ADRC, and the proposed improved ADRC. The results show that the proposed control approach significantly reduces output voltage overshoot and shortens recovery time across both output branches.These improvements confirm the effectiveness and superiority of the proposed strategy and demonstrate its practical engineering applicability.ConclusionsThe control strategy in this paper reduces the cross-interference between the output branches of the SIDO Buck converter and improves the transient response performance of the system. |
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| ISSN: | 2096-3246 |