Fast Dynamic Control of Dual-Active-Bridge DC-DC Converter Based on an Adaptive Linear Extended State Observer

Linear extended state observer (LESO) plays a critical role in ADRC's control performance. However, there exists a tradeoff between disturbance rejection and noise immunity for traditional linear ESO (TLESO). Compared to TLESO with similar bandwidth, phase-locking loop observer (PLLO) exhibits a better output tracking performance but weaker noise suppression capability. By combining the advantages of TLESO and PLLO, an adaptive LESO (ALESO) is proposed in this article, which utilizes TLESO in steady state and PLLO during transient state. The dynamic and noise-suppression performances of different observers are analyzed and compared systematically. The proposed ALESO inherits good dynamic response of PLLO and noise-suppression performance of TLESO, without using high bandwidth. It also possesses the advantages of simple structure, requiring few tuning parameters and ease of parameter tuning. To verify the feasibility and effectiveness of the proposed ALESO design, it is employed to a 500 W dual-active-bridge dc-dc converter for pulsed power applications. Experiments results show that, in comparison with TLESO, the proposed ALESO has resulted in 33.3%/37% and 60%/73.3% reductions in output voltage undershoot/overshoot and setting time, respectively, under load step-up/down. For steady-state performance, a noise level reduction of 76.3% is achieved compared to that resulting from PLLO.