Power electronic transformer (PET) converter: Design of a 1.2MW demonstrator for traction applications

Zhao, Chuanhong; Weiß, Michael; Mester, Akos; Lewdeni-Schmid, Silvia; Dujić, Dražen; Steinke, J.K.; Chaudhuri, Toufann

doi:10.1109/speedam.2012.6264496

Cited by 43 publications

(13 citation statements)

References 5 publications

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“…The voltage of the DC-link is controlled to 2.2 kV in consideration of the topology and the rating of the semiconductor device. In this case, a minimum of ten modules are needed to take into account the line voltage [14], the second harmonic ripple in the DC-link voltages, and the margin reserved for the control strategy [15].…”

Section: Structure Of the Sst Prototypementioning

confidence: 99%

Implementation of a Single-Phase SST for the Interface between a 13.2 kV MVAC Network and a 750 V Bipolar DC Distribution

Yun

Jeong

Kim³

et al. 2018

Electronics

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This paper presents the implementation of a single-phase solid-state transformer (SST) for the interface between a 13.2 kV medium voltage alternative current (MVAC) network and a 750 V bipolar DC distribution. The SST has ten cascaded subunits in consideration of the device rating and modulation index (MI). Each subunit consists of an AC/DC stage and a DC/DC stage with a high frequency isolated transformer (HFIT). The AC/DC stage consists of cascaded H-bridges (CHBs) to cope with the MVAC. The DC/DC stage employs a triple active bridge (TAB) converter for bipolar DC distribution. Topology analysis and controller design for this specific structure are discussed. In addition, the insulation of HFIT used in DC/DC converters is also discussed. A simple balancing controller at the AC/DC stage and a current sharing controller at the DC/DC stage are used to prevent DC-link voltage unbalance caused by the cascaded structure. The discussions are validated using a 150 kW single-phase 21-level SST prototype at the laboratory level.Electronics 2018, 7, 62 2 of 19 gate bipolar transistor (IGBT) packages for high-voltage and low-current application, and Ref.[12] presented a 3.3 kV 300 kVA back-to-back three-phase SST prototype for universal and flexible power management. In Ref.[13], a 15 kV 1.2 MVA single-phase SST prototype was designed for a railway grid. These prototypes have different structures depending on the purpose of use. In other words, the SST prototypes were designed to be suitable for specific applications.This paper introduces a single-phase 150 kW prototype of an SST for the connection between a 13.2 kV MVAC grid and a bipolar 750 V DC distribution system. This SST prototype consists of an AC/DC stage and a DC/DC stage. The AC/DC stage employs the CHB rectifiers and is responsible for power factor control, voltage regulation, and the voltage balancing of DC-links. The DC/DC stage employs a specially designed TAB converter for connecting to the bipolar DC distribution system. In addition, it is responsible for voltage control, and current sharing in parallel-connected outputs. This paper also discusses the insulation of the HFIT used in the TAB converter.The rest of this paper is organized as follows: the overall structure of the SST system used in this paper is briefly introduced in Section 2. Section 3 provides the details about the controller of AC/DC stage for the voltage balancing of DC-links. In Section 4, the DC/DC stage is analyzed including the characteristics of the topology, modeling, and controller design. In Section 5, the HFIT design for high-voltage insulation is discussed. The simulations and experimental results using a 150 kW SST prototype are presented in Sections 6 and 7, respectively. Finally, the conclusions are provided in Section 8.

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Section: Structure Of the Sst Prototypementioning

confidence: 99%

Implementation of a Single-Phase SST for the Interface between a 13.2 kV MVAC Network and a 750 V Bipolar DC Distribution

Yun

Jeong

Kim³

et al. 2018

Electronics

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“…Secondly, the medium-frequency transformers supply the required voltage value for the load, depending on transformation ratio. Also, the last important task of these topologies in the LLC resonant circuits is assisting to operate soft-switching mode of IGBT modules [6].…”

Section: Medium Frequencymentioning

confidence: 99%

“…Therefore, the leakage inductance value of the medium-frequency transformer is an important parameter in order to achieve resonance [5]. The leakage inductance value (Lr) shown in Fig.1 can be changed with the air gaps placed in the core [6]. Figure 1.DC-DC converter topology with medium-frequency transformer [6].…”

Section: Introductionmentioning

confidence: 99%

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Core material investigation of medium-frequency power transformers

Balci

Sefa

Bayram

2014

2014 16th International Power Electronics and Motion Control Conference and Exposition

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Medium-frequency power transformers are used in DC-DC converters topologies such as photovoltaic, wind turbines, fuel cells, electric vehicles and uninterruptible power supply systems. In the design of magnetic circuit components such as transformer and inductor, the choice of the core material is of great importance in terms of losses and magnetic induction. For determining the size of the medium-frequency transformer, frequency and magnetic flux density are also two key parameters. In this study, the core volume change with the frequency is mathematically analyzed and modeled by using finite element analysis method. Parametric analysis provides very useful information in order to determine the excitation voltage level, which does not cause the saturation in the core, for the switching frequency. Thus, parameters of the designed transformer equivalent circuit can be optimized. Then, medium-frequency transformer is operated in power electronic circuits and saturation effect and core losses according to the preferred magnetic materials are investigated by performing co-simulation.

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“…These converters have poor modularity and reliability. The most promising solution may be converters known as power electronics transformers (PETs) [11], [12], [19], [20]. PETs are designed for high power applications.…”

mentioning

confidence: 99%

A New Resonant Modular Multilevel Step-Down DC–DC Converter with Inherent-Balancing

Zhang

Green

Junyent-Ferré

2015

IEEE Trans. Power Electron.

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Modular multilevel converters (MMCs) have become increasingly interesting in dc-dc applications, as there is a growing demand for dc-dc converters in high voltage applications. Power electronics transformers (PETs) are commonly used for high step-down ratio dc-dc power conversion, with high power rating and efficiency achieved.However, this arrangement requires a large number of high isolation voltage transformers and a complicated balancing control scheme. To provide a simple solution with inherent voltage balancing, this paper presents a new resonant MMC topology for dc-dc conversion. The proposed converter achieves high voltage step-down ratio depending on the number of sub-modules. The converter also exhibits simplicity and scalability with no necessary requirement of high voltage isolation transformers. By using phase-shift control, a much higher converter operating frequency is achieved compared to the switching frequency. Resonant conversion is achieved between the series inductor and sub-module capacitors. The operation principle and theoretical analysis are presented in this paper, which have been verified by experimental results based on a bench scale prototype.

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Power electronic transformer (PET) converter: Design of a 1.2MW demonstrator for traction applications

Cited by 43 publications

References 5 publications

Implementation of a Single-Phase SST for the Interface between a 13.2 kV MVAC Network and a 750 V Bipolar DC Distribution

Implementation of a Single-Phase SST for the Interface between a 13.2 kV MVAC Network and a 750 V Bipolar DC Distribution

Core material investigation of medium-frequency power transformers

A New Resonant Modular Multilevel Step-Down DC–DC Converter with Inherent-Balancing

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