After finishing high school, I started studying electrical engineering at the university and ended up majoring in power electronics. I designed and implemented my first proper power converter prototype during my Master’s Thesis project in 2003 and have continued doing similar work ever since. This includes both my doctoral studies as well as my professional career in the industrial sector at ABB Corporate Research Center in Switzerland after graduation.

Motivation

Technology is what drives me forward and keeps me motivated every day. I’m interested in trying out new ideas and pushing the boundaries of technologies. Because there is usually no large development team in research projects, one must possess a wide set of skills to be able to design complete power converter prototype systems from scratch. This includes hardware and software design, as well as experimental testing in the lab. Especially in power conversion, experimental verification is extremely important. Simulations are a good starting point, but the true work begins when one enters the lab and starts testing hardware prototypes with full voltages and currents. This I can truly confirm based on my 20+ years of experience in experimental testing of power converters.

I have also briefly worked in product development during my years at ABB, but I found that research is more appealing to me because I’m able to work on multiple topics and applications, and spend more time on running experiments in the lab. Productizing a completely new concept would definitely be interesting, but most product development work is unfortunately only redesign of existing products which has got nothing to do with the technology itself any more.

Experience

I have most experience in low-voltage hard- and soft-switching power electronic converter design optimization, implementation, control, and testing. Such systems are rated for alternating rms voltages up to 1000 V and direct voltages up 1500 V, and their powers range from hundreds of watts to hundreds of kilowatts. However, in the recent years, I have been more and more involved in design and testing of high-power medium-voltage converter systems rated for voltages of 10 kV and higher. A typical work flow comprises circuit simulations, and design of passive components and filters, auxiliary and sensing electronics, cooling system, and control hardware. On top this comes control software and logic development and implementation on embedded system platforms.

All in all, when it comes to developing power conversion systems for typical power electronic applications from scratch, my skill set contains all the necessary skills to reach Technology Readiness Level 7 (System prototype demonstration in operational environment).

More information on my specific skills and the applications I have worked on can be found below. There will be a separate article covering my experience and skills related to software and logic development for embedded systems.

Applications

  • STATCOMs and active power filters
  • Photovoltaic inverters
  • Electric motor drive systems
  • Traction
  • EV charging
  • Battery energy storage systems (BESS)
  • Electrified turbochargers
  • Datacenters
  • UPS systems
  • Marine
  • Hydrogen production
  • Wind power conversion

Hardware Design

  • Power converter topologies

    • Single-phase and three-phase three/four-wire converter topologies

      • Two-level voltage-source converter
      • Multilevel voltage-source converters (DNPC, ANPC, T type, flying capacitor, etc.)
      • Three-phase current-source converter

    • Non-isolated dc-dc converters

      • Standard buck and boost topologies
      • Multiphase converters
      • Multilevel dc-dc converters

    • Isolated dc-dc converters

      • Resonant converters
      • Dual active bridge
      • Flyback and other similar topologies for auxiliary power generation

  • Filter design and implementation

    • Supply filters for grid-connected converters
    • Filters for dc-dc converters
    • EMI filters to meet EMC requirements of grid-connected converters

  • Power semiconductor devices

    • Silicon IGBT devices and modules
    • Silicon carbide (SiC) MOSFETs and diodes (discrete devices and modules)
    • Gallium nitride (GaN) based devices

  • PCB design and assembly

    • 100+ designs of different types of PCBs, incl. power stages of power converters, gate driving, pre-charging, measurement sensing/digitalization, communication, control, filtering, signal interfacing, etc.
    • Designs according to specific standards for various low-voltage and medium-voltage applications
    • Board assembly by hand or reflow soldering

  • Magnetic component design for low-voltage and medium-voltage applications

    • Inductor design for single-phase, three-phase and direct current applications
    • Transformer design
    • Use of, e.g., silicon steel, amorphous metal, metal powder, nanocrystalline and ferrite core materials in different shapes
    • Solid/Litz wire or foil type windings based on copper or aluminum
    • Analytical design algorithm development
    • 2D/3D FEM simulations for design verification
    • Experimental characterization

  • Cooling system design

    • Design of natural/forced convection and liquid cooling based cooling systems for power converters

  • Mechanical design

    • Design of enclosures and other mechanical parts for power converters using CAD software

Power Converter Control

  • Grid synchronization
  • Current control in stationary and rotating reference frames
  • Full-state feedback control (e.g., LQR)
  • State observers
  • Grid forming control
  • Direct voltage control and capacitor voltage balancing
  • Modulation schemes for two- and multi-level converters
  • Control of rotating machines (e.g., field-oriented control)
  • Control of paralleled converters
  • Low/zero-voltage ride-through management
  • Active resonance damping
  • Digital (FIR & IIR) filter design (e.g., for suppression or extraction of harmonics)

Experimental Testing

  • Preparation of experimental test setups and infrastructure for low- and medium-voltage power converter testing with passive and active loads

    • Cabling, protection, and voltage level adaptation and galvanic isolation with transformers

  • Experimental testing of low- and medium-voltage power conversion systems of up to megawatt power levels

  • Power converter efficiency measurements

  • Low/zero-voltage ride-through testing of grid-connected converters

  • Conducted EMI measurements

  • Heat runs

  • Loss characterization of power semiconductor devices

  • Insulation resistance tests