Abstract
This paper proposes a method to stabilize and enhance the dynamic performance of a cascaded DC-DC system by adaptively reshaping the source output impedance. The method aims to reduce the ratio of the source output impedance to the load input impedance, referred to as the minor loop gain, to eliminate the interaction between the load and the source systems. This interaction can deteriorate the dynamic performance or might lead to instability. Thus, the bus current is used to improve the dynamic performance by reducing the magnitude of the source’s output impedance adaptively according to the loading condition such that the dynamic performance is consistently improved. Utilizing the bus current facilitates the compatibility between the proposed controller and most widely used DC-DC converters controlled in voltage mode, including non-minimum phase converters. In addition to the flexibility the bus current provides to embed the proposed solution with conventional control schemes. Experimental results have validated the effectiveness of the proposed controller along with time-based simulation and theoretical analysis, for minimum and non-minimum phase converters.
Highlights
Cascaded DC-DC systems have been widely used in aerospace, maritime, and automobile industries due to their attractive features such as modularity, scalability, high power density, and high reliability [1]
A cascaded system consists of a line regulating converter (LRC) [4], which acts as the source, connected in series with a load subsystem, as shown in
To devise a method for ensuring stability and performance of cascaded DC-DC systems with multiple loads and to address the discussed issues, we propose a method that reshapes the output impedance of the LRC to stabilize the system and improve its dynamic performance
Summary
Cascaded DC-DC systems have been widely used in aerospace, maritime, and automobile industries due to their attractive features such as modularity, scalability, high power density, and high reliability [1]. His study resulted in the Middlebrook criterion, which ensures the stability and performance of cascaded systems It is based on relating the ratio of the source output impedance to the load input impedance, which is called the minor loop gain (Tm (s) = Zo (s)/ Zin (s)) in Figure 1), to system stability properties. To devise a method for ensuring stability and performance of cascaded DC-DC systems with multiple loads and to address the discussed issues, we propose a method that reshapes the output impedance of the LRC to stabilize the system and improve its dynamic performance. The proposed method is applicable to minimum and non-minimum phase converters, and it neither incurs additional power losses nor changes the LRC controller parameters.
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