A Nonlinear Control Strategy for DC-DC Converter with Unknown Constant Power Load Using Damping and Interconnection Injecting

• Main Authors: Mian Wang, Fen Tang, Xuezhi Wu, Jingkai Niu, Yajing Zhang, Jiuhe Wang
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Energies
• Subjects: DC-DC converter; constant power load; nonlinear control strategy; improved passivity-based controller; damping and interconnection injecting; nonlinear power observer
• Online Access: https://www.mdpi.com/1996-1073/14/11/3031

DC-DC converters with constant power loads are mostly used in DC microgrids. Negative impedance and large disturbances of constant power loads may lead to the instability of DC-DC converters. To address this issue, a nonlinear control strategy consisting of an improved passivity-based controller and nonlinear power observer is proposed in this paper. First, an improved passivity-based controller is designed based on the port-controlled Hamiltonian with dissipation model. By proper damping and interconnection injecting, the fast dynamic response of output voltage and stability of the DC-DC converter is achieved. Second, the constant power load is observed by a nonlinear power observer, which is adopted to estimate the power variation of the constant power load within a small settling time and improve the adaptability of the DC-DC converter under power disturbance. Finally, the simulation and experimental results are presented, which illustrate the proposed control strategy not only ensures the stability of the DC-DC converter under large disturbances, but also can track the desired operating point with low voltage overshoot in no more than 10 milliseconds.