An Extended Stability Analysis Method for Paralleled DC-DC Converters System With Considering the Periodic Disturbance Based on Floquet Theory

Abstract

Paralleled DC-DC converters system normally is operated with current-sharing control to achieve equal current distribution among the converters connected in parallel. However, the added currentsharing control might make the paralleled DC-DC converters system suffer from potential degradation of stability and dynamic performances. Hence, the stability analysis of paralleled DC-DC converters system is a hot issue. In order to analyze the stability of paralleled DC-DC converters system accurately and effectively, an extended stability analysis method based on Floquet theory is proposed for paralleled DC-DC converters system in this paper with considering the periodic disturbance. And, a paralleled buck converters system with average current-mode control is taken as an analysis object. The extended stability criterion of paralleled buck converters system based on Floquet theory is derived. Finally, the simulation and experimental results verify the correctness and effectiveness of the proposed stability criterion with considering the periodic disturbance. This paper provides a new choice for the stability analysis of paralleled DC-DC converters system. INDEX TERMS Paralleled DC-DC converter, time domain model, Floquet theory, stability analysis.

Advanced Hierarchical Control and Stability Analysis of DC Microgrids

“…The third group extends the complexity of the DC microgrid to n number of converters [66,67,[217][218][219]. The stability of a reduced-order model has been studied in [66,67], obtaining a stable domain for the droop coefficients.…”

Review of Control Strategies for DC Nano-Grid

“…When the current error can be very small under the large CSEA gain, the expected control effect is achieved. This control strategy is autonomous because each module of the parallel inverter tracks the average current generated by all modules (Li et al, 2020). External noise is injected in the bus because of the distribution of the current sharing bus over the DCNG, and deteriorates the distribution of voltage and current (Wang Z et al, 2020).…”

A Floquet theory‐based fast time‐domain stability analysis forN‐parallel inverters system

“…According to (17) and (19), the transfer function block diagram can be derived as shown in Figure 28. Subsequently, the transfer function block diagram can be simplified, as show in Figure 29.…”

“…However, in practical applications, as the number of inverters in the parallel system increases, or the circuit parameters of each inverter are variant, the derivation of the impedance criterion becomes quite complicated, leading to rare research on modelling and stability analysis of an N-parallel inverters system (especially for N ≥ 3), to our best knowledge. In [17], it has been proved that the complexity of modelling the multi-stage DC-DC converters system in the frequency-domain will increase exponentially versus the number of the DC-DC converters according to the manual derivation process. Hence, the impedance modelling and prediction methods based on the black-box modelling was proposed in [18]; however, since it only uses terminal characteristics and does not pay attention to the inner parameters of the inverters, once deviations occur, it is difficult to correct it, so that the accuracy and the correctness of these methods are difficult to be ensured in practice.…”