The following tutorials are planned for Friday 9 September 2022:


The tutorials will take place at the Leibniz University of Hannover, Welfengarten 1, 30167 Hannover

(09:30 – 13:00)

Machine Learning Techniques for Reliable Battery State of Health Estimation

  • Daniel-Ioan STROE (Aalborg University, Denmark)
  • Søren B. VILSEN (Aalborg University, Denmark)
  • Xin SUI (Aalborg University, Denmark)

Focus Topic:
Batteries in Power Electronics

Lithium-ion batteries have become a commodity in our daily routine, powering portable electronic devices and electric vehicles, and facilitating renewables’ grid-integration. Nevertheless, the performance of lithium-ion batteries is degradaing during long-term usage. Thus, accurately obtaining the batteries’ state of health (SOH) is critical to prolong the service life of the battery and ensure the safe and reliable operation of the system. Machine learning (ML) techniques are gaining widespread use in the field of electrical engineering as a whole, and for SOH estimation of Lithium-ion batteries in particular. The introduction of ML and statistics in electrical engineering is a consequence of the field slowly subsidising some of the more expensive laboratory testing by using data collected during real-life operating conditions. The main purpose of this tutorial is to provide the audience with a basic understanding of how ML can be applied to ensure reliable and efficient battery SOH estimation.

Full Day
(09:30 – 13:00 & 14:00 – 17:30)

Control of Modular Multilevel Converters for Variable-Voltage Variable-Frequency Applications

  • Jakub KUCKA (Siemens AG Large Drives Applications, Germany)
  • Rebecca DIERKS (Leibniz University Hannover, Germany)

This tutorial focuses on modular multilevel converters (MMCs) and modular multilevel matrix converters (MMMCs) for applications that require a wide range of variable converter output voltages and frequencies. Typical applications with such requirements are medium-voltage drive systems. While the superior voltage quality, the simple voltage scalability, and optional redundancy of both MMCs and MMMCs are attractive, the high complexity of the system is a challenge. It requires special control approaches to enable a stable operation. In this tutorial, the operation principle of these topologies will be explained and control strategies will be presented in detail. An emphasis will be placed on a generalized control approach, proposed by our research group from Hannover, which can be applied to both MMCs and MMMCs, as well as to other similar topologies. Furthermore, specific operation modes will be explained that also cover singular points of the conventional control and thus, allow for a wide range of output frequencies. Besides regular multilevel operation, the quasi-two-level and quasi-three-level operations will be presented, which are capable of reducing the module capacitance by more than one order of magnitude.

After successfully attending this tutorial, the participants will understand:

  • the difference between MMCs with or without branch current control,
  • the need to stabilize and balance the energies in the branches and modules,
  • a generic modelling and control approach for a large class of modular multilevel converters,
  • how specific input or output frequencies affect the sizing of the converters,
  • how dedicated operating modes can deal with these obstacles and what their limitations are,
  • and the benefits and limitations of novel, quasi-two-level PWM modes of operation for widely reduced module energy storage.

Full Day
(09:30 – 13:00 & 14:00 – 17:30)

Design and safety considerations in Low Voltage DC Grids

  • Johan DRIESEN (KU Leuven / Energyville, Belgium)
  • Simon RAVYTS (KU Leuven / Energyville, Belgium)

The focus of courses on electrical safety typically only covers traditional AC systems. For DC systems, the protection methodologies that are used for AC cannot always be used. This is because Low Voltage DC (LVDC) grids are typically dominated by power electronics converters. As such, the protection methodology needs to be tuned to the lay-out of the grid and the used converters. For example, both the type of converter output capacitance and its size will strongly affect the short-circuit behavior of the LVDC grid. Multiple objectives are pursued: First, an overview of the state-of-the-art in LVDC systems and the advantages over AC for typical application areas is presented. Second, the typical faults and the fault behavior is discussed with an emphasis on the influence of the power electronics converters and the shortcomings in today’s standards (e.g. IEC61660-1). Third, short-circuits are discussed; including fault detection, identification, localization and interruption. For the interruption, the typical problems related to arc extinction are treated and an overview of commercially available fuses and circuit breakers is given, including a short-circuit protection methodology. Fourth, earthing strategies, earth faults and the associated touch voltages will be discussed. Finally, practical considerations and emulating fault behavior is treated. The tutorial theoretical material will be supported by experimental results.

Full Day
(09:30 – 13:00 & 14:00 – 17:30)

Testing, Design, and Monitoring of Power Electronic Components for Reliability

  • Francesco IANNUZZO (Center of Reliable Power Electronics (CORPE), Aalborg University, Denmark)
  • Amir Sajjad BAHMAN (Center of Reliable Power Electronics (CORPE), Aalborg University, Denmark)

Focus Topic:
New Power Electronic Devices

In this tutorial, after a review of the basic theory of reliability engineering, several approaches for reliability testing of power electronics components will be presented in the first part. Typical pros and cons of power cycling test setups of Silicon and Silicon Carbide devices will be discussed.

In the second part of the tutorial, loss calculation in a power electronic component as well as the well-established methods for the extraction of an equivalent thermal network of a real power stack will be presented.

Condition monitoring is an emerging topic in reliability engineering, therefore, the third part is devoted to illustrating the state of the art techniques both for junction temperature- and damage estimation.

The tutorial is concluded with an overview of the novel and promising methods for mission-profile-based prediction of Remaining Useful Life (RUL) and a summary and prospects for research on the reliability of power electronics.

Full Day
(09:30 – 13:00 & 14:00 – 17:30)

High-Performance Model Predictive Control of Power Electronic Systems

  • Tobias GEYER (ABB System Drives, Switzerland)
  • Petros KARAMANAKOS (University of Tampere, Finland)

Power electronic systems are often underutilized with conventional control solutions and are being operated in a suboptimal manner. An attractive control alternative is model predictive control (MPC) due to its numerous advantages, such as explicit inclusion of design criteria and restrictions, design versatility, and inherent robustness. Thanks to these features, MPC can bring significant benefits by improving performance metrics (e.g., current distortion, power losses, settling time), and/or reducing the hardware requirements (or, equivalently, by fully utilizing the existing hardware).

Motivated by the above, the objective of this tutorial is to show the performance improvement that can be achieved with control algorithms designed in the framework of MPC. To this aim, different MPC methods (control problem formulations) will be discussed and analyzed. Moreover, it will be shown how these MPC strategies can bring tangible improvements, such as lower harmonic distortions, hardware reduction, increased efficiency, or increased output power.  Furthermore, implementation-related issues will be analyzed, while methods to tackle them will be presented. In doing so, insight into the MPC-based algorithms and the associated challenges will be provided.

Overall, the tutorial aims at providing a balanced mix of theory and application-related material. Special care is taken to ensure that the presented material is intuitively accessible to the power electronics practitioner. This is achieved by augmenting the mathematical formulations by illustrations and simple examples.

By the end of the tutorial, the attendees will:

  • understand the standard and emerging MPC methodologies, their design and real-time implementation as well as suitable embedded system architectures to implement them and to solve the underlying optimization problems,

  • be able to understand what design options exist that maximize the system performance and how MPC-based controllers are to be designed to outperform conventional control techniques and to push the system performance to its physical limits, and

  • appreciate the industrial relevance and benefits of MPC-based controllers.

(09:30 – 13:00)

Soft Magnetic Materials for Electrical Machines

  • Nora LEUNING (Institute of Electrical Machines (IEM), RWTH Aachen University, Germany)
  • Benedikt SCHAUERTE (Institute of Electrical Machines (IEM), RWTH Aachen University, Germany)

Electrical machines are used in the fields of energy generation and distribution, industrial applications, household appliances or in the transportation sector. Electromobility is a broad application field for speed variable traction drives. In order to increase the power density and efficiency, rotational motor speeds are generally increasing with which new challenges arise. The measures to improve the efficiency of electrical machines by constructive measures and design choices are generally exhausted. A bare potential still lies in the magnetic circuit materials which enable the fundamental energy conversion. The correct way of modeling and implementation in FE machine simulations is as important as the consideration of structural material characteristics in order to utilize this material potential. This tutorial will illustrate the most important aspects of soft magnetic materials for electrical machines with a focus on the application of electrical steel in traction drives.

(14:00 – 17:30)

High-voltage conversion-ratio step-up isolated DC-DC converters have been widely used in industrial application such as electrostatic precipitation, medical X-ray, MVDC or HVDC grid, as well as pulsed power supply. This tutorial focuses the recent advances of high-voltage conversion-ratio step-up isolated DC-DC converters. The tutorial starts with the introduction of high frequency high-voltage conversion-ratio step-up isolated DC-DC converters including the basics, development history, the state-of-the-art technologies and future trends. The opportunities and challenges of SiC devices for the high-voltage conversion-ratio step-up isolated DC-DC converters are presented. Secondly, the HV architectures are classified and evaluated in detailed. Then the characterization and modelling of SiC MOSFET, and comprehensive design methodology are given. The generic steady-state circuit modeling methodologies and output voltage sharing technologies are introduced. Finally, the technology demonstrator and prototype experimental results of SiC MOSFET based 300kHz~500kHz 10kW DC-DC converter with 650V input voltage and 140kV output voltage are provided. The audience will be the entry level and intermediate university students and engineers in industry who are interested in high frequency DC-DC converter, SiC devices, and high-voltage conversion-ratio power supply technologies.

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