Advanced modulation and control techniques for cascaded full-bridge inverters and for impedance-source inverters for multiphase motor drives (CFB-ZSI)

Project information

This work was supported by MCIN/AEI/10.13039/501100011033/FEDER, UE under Project PID2021-124136OB-I00.

Principal Investigator Óscar López Sánchez
Funding Agency State Research Agency (AEI), Ministry of Science and Innovation (MICINN), Spain
Period 1st Sep 2022 - 31st Aug 2025
Budget 122,210 €

Abstract

This project will generate knowledge to achieve the objectives of sustainable mobility and a greater use of alternative energy sources included in the strategic action AE5: Climate, Energy and Mobility of the State Plan for Scientific, Technical and Innovation Research, by improving medium- and low-voltage electric drives. In the case of medium-voltage drives, cascaded full-bridge (CFB) multilevel converters will be investigated, whereas in the low-voltage case, impedance-source inverters (ZSIs) will be examined. In both cases, they will feed multiphase electrical machines (with more than three phases), which have significant advantages over three-phase counterparts (e.g. lower torque ripple, higher power density, fault tolerance), leading to their recent commercial application in electric vehicles and high-speed elevators.

CFB converters are a modular topology that permits bypassing the faulty modules (full bridges) without operation interruption. This idea, which is already used in commercial three-phase converters to achieve high-power and high-availability systems (e.g. Siemens GH180), can be directly translated to multiphase drives to achieve high-power variable speed drives with very high fault tolerance and assured industrial application, as they come from combining two commercial technologies. Despite the clear potential of multiphase CFBs, so far their research has focused on the healthy case (for which the research team has proposed various modulation techniques that have had a great scientific impact). Research on fault tolerance of multiphase drives is almost exclusively limited to the case of two-level converters. The novelty of this project lies in the development of new modulation and control techniques that adequately take advantage of the particularities of multilevel multiphase converters to operate without interruptions and with a minimum reduction of the maximum speed (without field weakening) when several modules fail. The expected impact is to achieve effective high-power electrical drives, very modular and extremely fault-tolerant; and that permit, for example, ship or train propulsion using several modules based on low-power fuel cells.

On the other hand, for low-voltage applications, multiphase drives based on ZSIs will be investigated. The ZSI has very attractive characteristics compared to conventional voltage-source counterparts. The most notable is that it is a single-stage boost-buck inverter topology, suitable for applications with reduced or variable supply DC voltages. Recently, many variants of ZSIs have been proposed, some of them suitable for electric vehicles based on hydrogen fuel cells. Studies on ZSIs feeding multiphase machines are few and limited. The novelty of this project is the development and experimental validation of new modulation and control techniques specific for multiphase ZSIs that take advantage of all their advantages to obtain efficient electric drives. The expected impact is the demonstration of the greater efficiency of ZSIs for propulsion of electric vehicles powered by fuel cells, compared to conventional solutions.

Objectives

  1. Development of new post-fault techniques for multilevel multiphase VSIs (OB1).
    1. Characterisation of the drive operation regions in the event of fault in the VSI (OB1a).
    2. Development of effective post-fault techniques with extended motor speed range without field weakening (OB1b).
  2. Development of an electric drive based on ZSIs and multiphase machines (OB2).
    1. Optimal design of a prototype six-phase ZSI of 5 kW and 150 Vdc (OB2a).
    2. Development of new modulation and control techniques specific to multiphase ZSIs that minimise overall drive losses (OB2b).

Research team

PhD Students

Students

Publications

  1. Óscar López, Tomáš Komrska, Jacobo Álvarez, Lukáš Adam, Alejandro G. Yepes, Martín Medina-Sánchez & Jesús Doval-Gandoy, "Post-fault operation strategy for cascaded H-bridge inverters driving a multiphase motor", IEEE Transactions on Industrial Electronics, vol. PP, 2023. doi:10.1109/TIE.2023.3281688 Open access
  2. Óscar López, Jacobo Álvarez, Alejandro G. Yepes, Martín Medina-Sánchez & Jesús Doval-Gandoy, "Postfault operation strategy with minimum harmonic injection for cascaded H-bridge inverters driving a multiphase motor", IEEE Transactions on Power Electronics, vol. 40, no. 1, pp. 8-22, January 2025. doi:10.1109/tpel.2024.3456390 Open access
  3. Fernando Flores, Óscar López, Jacobo Álvarez, María Dolores Valdés Peña & José Manuel Villapún Sánchez, "Acceleration of a compute-intensive algorithm for power electronic converter control using Versal AI engines", in Conference on Design of Circuits and Integrated Systems (DCIS), Catania, Italy, 13-15 November 2024. doi:10.1109/DCIS62603.2024.10769154 Open access Slides

Results

  1. Óscar López, "MATLAB source code demonstrating the postfault operation strategy for n-phase CHB VSIs that minimizes the injection of low-order xy harmonics in the stator voltage", olopezuvigo/CHB_MXY: Final release, Zenodo, Feb. 19, 2025. doi:10.5281/zenodo.14894866
  2. Óscar López, "KiCad projects for a multiphase qZSI for multiphase motor drive applications", olopezuvigo/multiphase-qzsi: v1.2, Zenodo, Oct. 04, 2025. doi:10.5281/zenodo.17264291
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