Medium voltage high ratio bidirectional DC-DC converter featuring multilevel bridge operating in quasi 2-level modulation

Posted 3 months ago

SuperGrid Institute brings together 180 employees, of 28 different nationalities who work together within a dynamic environment in the city of Lyon. As an independent research and innovation centre, we are dedicated to developing technologies for the future power transmission system, the “supergrid”, including HVDC & MVDC technologies.

As a multi-disciplinary research centre with advanced simulation capabilities & multiple test platforms, including numerous associated laboratories, SuperGrid Institute uses its comprehensive expertise to provide a wide range of services and solutions to support our customers in developing power systems, equipment and components. We specialise in system architecture and work on ensuring network security and stability while allowing for the integration of intermittent renewable energy sources. Find out more by visiting our website: www.supergrid-institute.com

General Context

The medium voltage direct current (MVDC) technology is emerging in power distribution and collection after the high voltage direct current (HVDC) has been demonstrated and exploited as the economically viable solution for long-distance transmission of bulk power. The MVDC technology has been implemented in some pilot projects in China and Europe. The researchers evaluate the interest of MVDC in solar and wind applications. The benefits of MVDC technology can be analysed in terms of energy efficiency, power dispatch, power capacity, power supply range, raw material consumption, CO2 emissions, resilience of distribution network or ancillary services to the AC grid [1].

It becomes increasingly clear that DC-DC converters could have a key role to play as enabling technology for future DC systems. The main role of the DC-DC converter is to adapt the voltage between two DC systems. However, the DC-DC converter can also provide power flow controllability and fault current blocking/limiting, and can be classified according to power flow directionality, galvanic isolation and modularity. The power flow directionality is the one of the major functional differences between a DC-DC converter in DC systems and a transformer in AC systems. The transformer is inherently bidirectional but the DC-DC converter can be designed to be either unidirectional or bidirectional. This internship will focus on bidirectional DC-DC converters suitable to interface between LVDC and MVDC systems. Isolated DC-DC converters will be considered and focusing on modular bridge topologies [2].

Fig. 1. General diagram of bidirectional isolated DC-DC converter

Objectives / Missions

  • State of the art review (dual active bridge [3], flying capacitor [4], quasi 2 level modulation [5]).
  • DC-DC converter topology and control – design and modelling.
  • Simulations in steady state, transient and under external faults.
  • Techno-economic assessment and comparison with 2-level bridge using direct series connection of SiC MOSFET [6].

[1]             SuperGrid Institute, “MVDC electricity network consulting,” 2021. [Online]. Available: https://www.supergrid-institute.com/wp-content/uploads/2021/10/A4_MVDC-electricity-network-consulting_october-2021.pdf. [Accessed: 13-May-2022].

[2]             SuperGrid Institute, “DC Solid State Transformer for MVDC networks,” 2022. [Online]. Available: https://www.supergrid-institute.com/wp-content/uploads/2022/05/dc-solid-state-transformer-mvdc-networks-supergrid-institute.pdf. [Accessed: 13-May-2022].

[3]             R. W. DeDoncker, M. H. Kheraluwala, and D. M. Divan, “Power conversion apparatus for DC/DC conversion using dual active bridges,” US5027264A, 25-Jun-1991.

[4]             T. A. Meynard and H. Foch, “Multi-level conversion: high voltage choppers and voltage-source inverters,” in PESC ’92 Record. 23rd Annual IEEE Power Electronics Specialists Conference, 1992, pp. 397–403 vol.1.

[5]             A. Tcai, T. Wijekoon, and M. Liserre, “Evaluation of Flying Capacitor Quasi 2-level Modulation for MV Applications,” in PCIM Europe digital days 2021; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2021, pp. 1–7.

[6]             C. M. de Vienne, P. Lefranc, B. Asllani, P.-O. Jeannin, and B. Lefebvre, “Experimental investigation of a 10 kV-70A switch with six SiC-MOSFETs in a series-connection configuration,” presented at the European Conference on Silicon Carbide and Related Materials, 2021.

 

Candidate Profile

Master or engineering school student in the last year of his/her studies. The student must have a good knowledge in electrical engineering (power electronics and power systems). An experience with the Matlab/Simulink software is appreciated. Good proficiency in English is required.

What we have to offer:

–             You will be joining an institute for energy transition, a promising and stimulating field of activity,

–             A young, dynamic working environment,

–             Diverse, international teams (+25 nationalities),

–             Contribution to meal expenses (company restaurant)

–             Sports club within the company (on-site yoga, football, running, etc.)

–             Use of self-service company bicycles

Other information

Applications should be sent to the following address: job-v9nppq@mail.flatchr.io

Start date: September 2022 Ref. Budget: 3.12
Place of work: Villeurbanne Duration: 6 months
Qualifications required for the position (e.g. electrical qualification H0B0): No  

SuperGrid Institute is an equal opportunities employer. We respect and value the diversity of our employees, their backgrounds and their professional experience. We believe in equality and take affirmative action to ensure that discrimination has no place in our recruitment process nor our company.

Job Features

Job CategoryPower electronics & converters
Contract TypeInternship
Duration6 months
Start DateSeptember 2022

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