Auxiliary power supply for solid state transformers

Kehler, Leandro B.; Kaminski, Antônio M.; Pinheiro, J.R.; Rech, Cassiano; Marchesan, Tiago Bandeira; Emmel, Rene R.

doi:10.1109/icecs.2016.7841165

Cited by 10 publications

(7 citation statements)

References 8 publications

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“…Recent studies such as [17] and [18] tackle the start-up procedure by focusing on the energization issue based on the use of auxiliary power units (APUs). In all these studies, parameter and/or voltage imbalance conditions during the startup procedure are not considered and, in conclusion, it is recognized that the fundamental task in the start-up procedure is operated by the AC/DC power stage more than the DC/DC power stage.…”

Section: Introductionmentioning

confidence: 99%

Soft-Start Procedure for a Three-Stage Smart Transformer Based on Dual-Active Bridge and Cascaded H-Bridge Converters

Pugliese

Buticchi

Mastromauro

et al. 2020

IEEE Trans. Power Electron.

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Power electronics-based three-stage smart transformers (ST) can be seriously damaged by inrush currents and overvoltages during the start-up phase if the control of the stages is not correctly coordinated. Hence, it is crucial to design properly the start-up procedure, especially in case of modular architectures with distributed DC-links. The design of the start-up procedure depends on the ST power stages topologies, their control systems and the operation modes. This work proposes a soft-shift start modulation technique that allows to limit the inrush current in the DC/DC isolation stage during the DC-link capacitors pre-charging. A fast voltage balancing control, performed by the DC/DC isolation stage, is introduced to avoid overvoltages and unbalanced voltage conditions among the different power cells. Under the proposed method, fast control dynamics is guaranteed thanks to the high frequency bandwidth of the DC/DC isolation stage converters. Theoretical analysis, based on a detailed small signal model of the ST, and simulations are used to demonstrate the principle of the operation. Experimental results, carried out in a ST prototype, confirm the performances of proposed solution in realizing a smooth start-up without voltage/current overshoots.

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Section: Introductionmentioning

confidence: 99%

Soft-Start Procedure for a Three-Stage Smart Transformer Based on Dual-Active Bridge and Cascaded H-Bridge Converters

Pugliese

Buticchi

Mastromauro

et al. 2020

IEEE Trans. Power Electron.

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“…This further increase cost and isolation concerns.  Redundancy intrinsic to the modular design will be compromised if a central APS with multiple outputs is used [17].…”

Section: A Apss Fed From Ac Portsmentioning

confidence: 99%

“…The use of a single APS to feed both HV and LV sides cell circuitry is possible. However, this solution is much more problematic, as it requires a bulky isolation stage, and energization from both sides is not possible without additional start-up circuitry [17].…”

Section: B Apss Fed From Dc-linksmentioning

confidence: 99%

“…It is based on synchronizing their pre-charging process, resulting in effective reduction of the transformer inrush current. Strategies for the APSs design and start-up procedure in a modular three-stage SST is discussed in [17]. However, the work is focused on the validation of the APS but no simulation or experimental results of the SST start-up are provided.…”

Section: Introductionmentioning

confidence: 99%

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Energization and Start-Up of CHB-Based Modular Three-Stage Solid-State Transformers

Saeed

Cuartas

Rodríguez

et al. 2018

IEEE Trans. on Ind. Applicat.

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This paper discusses the energization and start-up process of modular three-stage Solid State Transformers (SSTs) based on a cascaded H-bridge (CHB) topology. A key element of the SST is the Auxiliary Power Supply (APS) feeding the auxiliary circuitry. Redundancy and simpler implementation can be achieved by powering the APSs from the cells DC-link capacitors, but at the expense of a more challenging start-up process of the SST. The first steps of this process must be performed before APSs are operative. This can result in undesired transient events (inrush currents, voltage sags in the capacitors voltages, etc.) which could prevent proper start-up of the SST or even jeopardize the power devices or other elements. A simple strategy for the energization and start-up of SSTs using this APSs structure is proposed. The method is valid both for grid-forming and grid-feeding operation of the SST, regardless of the energization port and without the addition of any extra circuitry. Simulation and experimental results are provided.

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“…In order to reduce the transients at the instant of the SST connection to the MV grid, charging of the MV DC link (22 kV) from the LV port is proposed. Regarding supplying the auxiliary electronics, in [20], strategies for implementing an Auxiliary Power Supply (APS) for a modular three-stage SST and a process to start it up are discussed. The work focuses on the design and the validation of the proposed APS but no simulation or experimental results of the start-up procedure are provided.…”

Section: Introductionmentioning

confidence: 99%

Energization and Start-up of Modular Three-stage Solid State Transformers

Saeed

Rodríguez

Arias

et al. 2018

2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL)

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Grid-connection and startup of solid state transformers (SST) based on modular topologies are studied in this work. A simple solution is implemented to feed the auxiliary electronics (i.e. sensors, control boards, drivers, etc.) of each SST module. It is based on feeding this circuitry from the DC links of the module using Auxiliary Power Supplies (APS). However, this structure leads to a problematic energization of the SST due to the threshold input voltage of the APS. Before the DC link capacitors are charged to this voltage threshold, the APSs are not functional and consequently SST energization and connection to the grid are performed without monitoring. Although startup in this situation is problematic, adequate procedure can prevent unwanted transients. In this paper, a step-by-step simple procedure is proposed for energizing a three-stage SST based on a Cascaded H-Bridge (CHB) modular topology. Simulation results as well as experimental tests are presented.

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Auxiliary power supply for solid state transformers

Cited by 10 publications

References 8 publications

Soft-Start Procedure for a Three-Stage Smart Transformer Based on Dual-Active Bridge and Cascaded H-Bridge Converters

Soft-Start Procedure for a Three-Stage Smart Transformer Based on Dual-Active Bridge and Cascaded H-Bridge Converters

Energization and Start-Up of CHB-Based Modular Three-Stage Solid-State Transformers

Energization and Start-up of Modular Three-stage Solid State Transformers

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