Abstract
DC distributed systems are highly reliable and efficient means of delivering DC power or adopting renewable energy resources. However, DC distributed systems are prone to instability and dynamic performance degradation due to the negative incremental input impedance of DC-DC converts. In this paper, we propose a generic method to eliminate the impact of the negative input impedance on DC systems by shaping the source output impedance such that its bode-plot is restricted in the area that is contained below the product of the source’s duty ratio and its characteristic impedance. The performance deterioration originates whenever the output impedance of the source exceeds, in magnitude, the input impedance of the load converter due to deficiency in stability margins. Hence, confining the impedance in the proposed region helps decouple the interaction between the converters and preserve their own dynamic performances. The proposed method was proven by analytical analysis, time-based simulation, and practical experiments. All of their outcomes were in agreement, proving the effectiveness of the proposed method in preserving the dynamic performance of distributed systems.
Highlights
DC distributed power systems are a remarkable application of power electronics and include a wide range of applications, such as in DC microgrids, motor drive systems, hybrid vehicles, aircrafts, ships, submarines, and satellites [1,2]
A typical distributed DC system consists of a DC-DC load converter connected in series with a DC-DC source converter or an input filter, as illustrated in Figure 1 [4], which is referred to as a cascaded DC system [5]
We proposed an active damping method to stabilize and retain the dynamic performance of cascaded systems by reshaping the impedance of the source converter
Summary
DC distributed power systems are a remarkable application of power electronics and include a wide range of applications, such as in DC microgrids, motor drive systems, hybrid vehicles, aircrafts, ships, submarines, and satellites [1,2]. The Middlebrook, opposing argument, GMPM, and ESAC are design-oriented criteria [8] They assume that the output impedance of the source converter is known; the load system must be designed [22]. This assumption limits the modularity feature of cascaded systems because the dynamic performance would not be guaranteed for any other load converters. Modifying the control loop of the source or the load converters These methods do not typically incur extra power losses; some of them reduce the power-density of cascaded systems, such as the solution proposed in [23].
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