Demystifying Non-Isolated DC–DC Topologies on Partial Power Processing Architectures

Abstract

This paper discusses the possibility of achieving partial power processing with non-isolated DC–DC topologies. To this end, partial power converter architectures are seen as an interesting solution for reducing the power processed by the converter. We observed via simulations that single-inductor non-isolated topologies cannot achieve partial power processing since the obtained current and voltage waveforms were the same as those found in a full-power converter. However, when using double inductor non-isolated topologies, reduced current and improved efficiencies were achieved. In order to confirm the results obtained from the simulations, single- and double-inductor topologies were tested experimentally. Finally, it was concluded that a double-inductor non-isolated topology can improve its performance by using partial power processing.

Review of DC-DC Partial Power Converter Configurations and Topologies

“…Kim and Parkhideh [45] presented a comparison between non-isolated and isolated converters for PVs and battery applications, where they stated higher efficiency for isolated PPC. The work presented in [6], based on the proposed Modified Inductor Boost Converter in [46], states that a K pr of less than 25% is achieved for a power conversion system of 750 W. The proposed topology in this work follows case (c) in Figure 14.…”

“…In addition to the previous equations, the static voltage gain (G V ) is also a key parameter in defining PPC operation, given in Equation (4) [6,[15][16][17].…”

“…Figure 14c,d illustrate inverted boost converter connections. Such topologies are referred to in the literature as the Fractional Power Converter (FPC) [6]. It is to be noted that such configurations might lead to loss of partial power processing, as seen in [28].…”

“…This leads to a reduction in the total cost of the system due to reducing the size of the inverter as well as the filter's passive components. In PPP, as the name indicates, a power converter is used to process only a part of the whole power, thus reducing the losses and permitting a reduction in components size [6].…”

“…The second branch of the PPP family tree is PPC (referred to as Series Voltage Regulator (SVR) by [2]), which can further be distinguished into two groups based on isolation requirements; however, it is to be noted that whether isolation is required for the converter does not imply the fact that the overall system will not have inherited galvanic isolation between its input and its output. The main advantage of PPC operation is its ability to interface a varying voltage on one side (either source or load) to a fixed voltage on the other side, which is a valuable feature for Maximum Power Point Tracking (MPPT) systems and battery charging applications [6]. The sub-group of the isolated topologies further splits into sub-groups: Input-Series-Output-Parallel (ISOP) (also referred to as Series-Input-Parallel-Output (SIPO) in some studies), Input-Parallel-Output-Series (IPOS) (or Parallel-Input-Series-Output (PISO)), Input-Series-Output-Series (ISOS), and Input-Parallel-Output-Parallel (IPOP).…”