Analysis and Control of Input-Parallel Output-Series Based Combined DC/DC Converter With Modified Connection in Output Filter Circuit

Abstract

Input-parallel output-series (IPOS)-based combined converter is usually used in the situation with low input voltage and high output voltage to satisfy the requirements in switch voltage stress reduction and power expansion. In such a system, the voltage balance of filter capacitor in the output side or current sharing in the input side usually used to guarantee the control performance of the conversion system. In this paper, a phase-shifted full bridge (PSFB)-based IPOS converter with modified connection of output filter circuit used for the wide variation of input voltage is proposed, which is beneficial to reduce ripple current of filter inductor significantly. A control scheme using the same phase shifting for the two different modules of this IPOS converter is detailedly investigated with both steady state and small signal model-based analysis, it manifests that special voltage balance and current sharing control scheme are not necessary for IPOS system under the common phase shifting control method. And the small signal transfer functions of this topology used for dual loop control system design are also developed. The simulation and experiment results are presented to validate the analysis and control scheme. INDEX TERMS Input-parallel output-series, combined converter, phase shifted full bridge, voltage balance.

The study of different unidirectional input parallel output series connected DC‐DC converters for wind farm based multi‐connected DC system

“…If categorizing the three different ISIPOS structures by controllability, Figure 4A‐C can be described as a partially input voltage controllable converter, open‐loop controlled converter and fully input voltage controllable converter, respectively. It should be noticed that the structures in Figure 4A,B are modelled based on the ideas in other research studies, 8,10,15 while the structure in Figure 4C is a new topology proposed by the authors. Important information about the converters in Figure 4 can be concluded as follows: In the multi‐terminal HVDC system in Figure 1, the wind turbine (include PMSG) at the very beginning of the sending end can be regarded as the equivalent current source, while the onshore power system at the receiving end should be treated as a voltage source.…”

“…If categorizing the three different ISIPOS structures by controllability, Figure 4A-C can be described as a partially input voltage controllable converter, open-loop controlled converter and fully input voltage controllable converter, respectively. It should be noticed that the structures in Figure 4A,B are modelled based on the ideas in other research studies, 8,10,15 while the structure in Figure 4C is a new topology proposed by the authors. Important information about the converters in Figure 4 can be concluded as follows:…”

“…In this paper, based on the converters study in Reference 14, three different unidirectional converter structures for the 50 to 400 kV DC-DC converter are studied. The identical Three-Phase Bridge and identical single active bridge (SAB) are minor deformations of the converters in other studies, 8,10,15 while the SAB + Three-Phase Bridge is a new F I G U R E 1 Simplified diagram of the multi-connected system topology proposed by the authors. Both the simulation and downscaled hardware testing results of all the converters are presented and analysed in this paper, and the applications of all of them are suggested.…”

Analysis and Extension of the Canonical Model applied to DC-DC converters with Input Filter and Output Post-filter

“…La arquitectura IPOS suele utilizarse en aplicaciones en las que se tiene un nivel bajo de tensión de entrada y un nivel alto en la tensión de salida [72]. Esta arquitectura al igual que la arquitectura IPOP no es adecuada para las aplicaciones ferroviaria porque no permite repartir la tensión de entrada, 𝑣𝑣 𝑖𝑖𝑖𝑖 , en los distintos módulos.…”

Unidirectional thyristor-based DC-DC converter for HVDC connection of offshore wind farms

“…In particular, the unidirectional non-isolated topologies have been considered: chopper-based DC modular converters [9], and the isolated topologies: the phase-shifted full-bridge (PSFB) [10] and the single active bridge (SAB) [11][12]. In order to achieve high voltage stepping ratios [13] while handling important power, converters can be configured in input parallel output series (IPOS) configuration such as presented in [14][15][16]. The power losses reduction in the transmission systems can be achieved thanks to the use of thyristor valves as in Line Commutated Converter (LCC).…”