Abstract
The interaction between the source and load converters in cascaded DC-DC converters may cause instability. Thus, improving the stability of cascaded DC-DC converters is important. To solve the above-mentioned problem, a flowchart to improve the control method is established by calculating the eigenvalue sensitivity of a time-domain model of cascaded DC-DC converters. Further, an additional voltage-error mutual feedback control method is firstly proposed based on the flowchart provided in this study to improve the stability of cascaded DC-DC converters. Subsequently, the influence of the proposed mutual feedback control on the stability of cascaded DC-DC converters is analyzed. Finally, the effectiveness of the proposed control method is verified by simulation and experiment.
Highlights
The interaction between the source and load converters in cascaded DC-DC converters may cause instability
The stability can be improved by reconstructing the output impedance of the source converter or input impedance of the load converter to eliminate impedance overlap[3,4]
A passive method reduces the output-impedance amplitude of the source converter by adding passive damping devices into the intermediate bus of a cascaded system and subsequently confirming that the output-impedance amplitude is smaller than the input-impedance amplitude of the load converter in the full frequency range
Summary
The interaction between the impedances of the source and load converters may cause instability in a cascaded system[1,2]. The eigenvalue-sensitivity analysis is combined with a time-domain model of cascaded DC-DC converters to find some stability-improvement methods. According to the flowchart shown, diagonal zero element d22 of matrix D is selected, The list in Tab. 2 indicates that after parameter b2/C1 is added as diagonal d22 in the Jacobian matrix, eigenvalue λ3,4 moves along the positive real axis of the complex plane as b2 increases. A new control method, i.e., additional voltage-error mutual feedback control, is derived
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