[ Introduction to Dynamic Watermarking (DW) ]
Dynamic Watermarking(DW) is a general-purpose statistical methodology for the detection of cyber-attacks on Networked Cyber-Physical Systems(CPS). In this tutorial, we will introduce Dynamic Watermarking(DW) method for securing grid connected solar power distribution systems. We address the problem of secure monitoring and control of Solar Photovoltaic Power Distribution Systems through DW. The goal is to design and test a scalable, robust, and online framework that provides much-needed secure monitoring of Solar Photovoltaic generation in the presence of potential cyber-attacks in the distribution grid.

[ Cybersecurity of grid connected PV systems & Review of IEEE 1547 ]
Recently, in 2018, IEEE 1547 standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces was established. This standard focuses on the interconnection and interoperability between utility electric power systems (EPSs) and distributed energy resources (DERs). This further confirms that importance of ensuring the security of CPS in a continuously evolving grid.

[ Man in the middle attack of grd connected PV system]
As mentioned earlier, the grid is continuously evolving and the and Smart inverters are essential in shaping the future of our grid. Such systems are valnurable to cyber intrusions such as a Man in the Middle (MiTM) attack which is performed by manipulating the response of the ancillary service controller. One possible intrucion point is the smart meters that are communicating data to the inverters. Such attack can lead to unwanted triggering of protection relays.

[ Method to develop an effective System Identification]
In addition, we will introduce proper System Identification method in this tutorial. In general, the model of the system is not known due to the nonlinearity of the system as well as its complexity. Therefore, System Identification is essential not only for the control of the system, but also for the analysis of the impacts of external disturbances and faults. System Identification plays an important role in Dynamic Watermarking (DW) defense mechanism against arbitrary physical or cyber-attacks.

Power electronics is an appealing candidate for physical integration with electric machines, motivated by desires to achieve significant mass, volume, and cost reductions via elimination of special enclosures and connecting cables. Integrated motor drives (IMDs) are drawing increased attention worldwide because of the special advantages they provide for demanding electrified land and air transportation applications, combined with the major advances being made in the commercialization of wide-bandgap (WBG) power semiconductor switches. This tutorial explores the past, present, and future of integrated motor drives (IMDs), providing attendees with broad perspectives on the current state of integrated motor drive technology as well as valuable insights into its future. Brief descriptions of the major sections of this tutorial are provided below.

1. Introduction
The defining features of integrated motor drives will be reviewed, followed by a discussion of the major advantages that they can offer for a wide variety of applications. Major technical hurdles that IMDs must meet to achieve high market penetration will also be discussed.

2. Past History of IMD Technology
A concise review will be provided of major milestones in IMD technology development dating back to the earliest days of solid-state power electronics in the 1960s and spanning over 60 years until today. Current commercial IMD product offerings will be briefly reviewed in order to highlight both the strengths and limitations of silicon-based IMD technology.

3. Impact of Wide-Bandgap Power Switch Technology on IMDs
Attention is next turned to major advances in wide-bandgap power semiconductor technology (SiC and GaN) that offers exciting opportunities for shrinking the size of power converters by significantly raising their operating frequencies. Some of the key technical obstacles that are currently slowing the adoption of WBG switches in new IMD products using conventional approaches are reviewed.

4. Opportunities for WBG-based Current Source Inverters in Future IMDs
Looking ahead, the case will be made for using WBG switches to spark a revival of current-source inverters (CSIs) for future machine drives. Attention will be focused on promising opportunities to combine WBG and CSI technology to deliver significant benefits in several key IMD performance features including EMI, operating temperature, voltage overshoot, and fault-mode operation compared to today’s dominant voltage-source inverters (VSIs). A combination of analytical and experimental results will be used to make these comparisons.

5. State-of-the-Art Examples of WBG-Based Integrated Motor Drives
The latest research progress that has been made towards achieving major performance improvements in WBG-based IMD technology at UW-Madison in collaboration with partner universities will be presented. The power range of these new IMD prototype units extends from 3 kW to 1 MW targeting a variety of applications including air conditioners, electric vehicle traction, and electrified aircraft propulsion.

6. Conclusion
The tutorial will conclude with a review of the opportunities and challenges presented by emerging technologies for realizing the full potential of integrated motor drives during coming years.

The tutorial "Electromagnetic Compatibility of Switched-Mode Power Supplies" is subdivided into several sections. Starting with a brief overview of legal regulations, like CE mark and Declaration of Conformity, a selection of emission and immunity standards are presented. This includes the description of test set-ups, for example for measuring conducted emissions using conventional or STFFT based test receivers and their detector circuits, as well as test parameters, like frequency ranges, based on European and International standards. Than four coupling mechanisms (impedance, capacitive, magnetic and radiated) are discussed, based on components and PCB structures. Subsequently basic countermeasures are proposed and evaluated according meaningful applicability to switched-mode power supplies. The section signals and characteristics explains common-mode and differential-mode interferences as well as the Fourier Transform in detail with a number of waveforms, like rectangular, triangular and trapezoidal waveforms, which are typically for switched-mode power supplies. In particular switching transients are discussed against the background of wide band gap devices like GaN transistors. One large section discusses the origin of electromagnetic interferences referring to the previous sections. This section addresses some widely used circuits, their operating modes, like continuous conduction mode, discontinuous conduction mode and boundary conduction mode, and parasitics of passive components, using high frequency equivalent circuits of capacitors, inductors and transformers, and active components, like junction capacitances and terminal inductances. A large number of examples is presented in form of results of measurements, simulations or calculations.

The second half of the presentation deals with EMC design of switched-mode power supplies, also evaluating efficiency and control issues. This section is subdivided into a number of subsections. Firstly the power factor correction is briefly presented. A large subsection addresses EMC filters, which is subdivided into pre filters and post filters. The filter structure is discussed according common-mode and differential-mode attenuation and source and load impedance. Problem solving approaches of the gap between measurements according standards and filter effectiveness are presented. Additionally an outlook to active EMI filters is given. Also design aspects of magnetic components are discussed. Followed by suitable components, which presents for example the impact of start of winding of a magnetic component, suitable circuits with soft-switching principles are compared to hard-switching circuits. After that shielding basics are presented, in particular the impact of holes for cooling purposes on electromagnetic shielding effectiveness. Finally PCB layout structures are evaluated and recommendations are presented. These investigations also address grounding, one of the most discussed topics in PCB design among engineers, as well as component placing and component selection, e. g. based on integrated circuit pin out and return current paths.

Most aspects are explained by measured, simulated or calculated examples. Many examples are discussed against the background of electromagnetic compatibility as well as their impact on efficiency, lifetime and costs of the power supply. The tutorial contains on the one hand practical examples and uses on the other hand the basic physics of Maxwell for a principle understanding. Many principles can be transferred to other electronic circuits.

In the last two decades, renewable energy resources have provided a way forward for meeting the ever-increasing global energy demand in an environmentally sustainable manner, in which solar and wind energies are expected to play pivotal roles. Distributed photovoltaic (PV) farms have become the preferred technology for supplying power to smart buildings and cities and can provide a viable solution for integrating solar energy into low and medium voltage distribution systems, in which the impact of component failure can be confined within a small area. Thus, reducing the number of potential customers could be affected. Moreover, the use of distributed PV farms minimizes the need for transmission infrastructures and losses. In large-scale PV farm, a typical PV module is rated at 30Vdc and 7Adc. Therefore, a combination of parallel and series modules and multiple power conversion stages using state-of-arts power converters are needed to raise the operating voltage to distribution levels.
Recently developed wind farms consist of a number of type 4 wind-turbine generators with rated power ranging from 1.5MW-9.5MW and 0.69kV-3.3kV, with each wind generator has two power conversion stages, i.e., ac-dc and dc-ac. Such relatively low ac voltage may necessitate the use of multiple ac transformers to enable operation at appropriate distribution and transmission levels, including dc transmission system in case of remote offshore wind farms. In all energy conversion systems, power converter is the weak link in terms of reliability and efficiency, particularly, if compared with line transformers. The problem is severe in renewable energy where the intermittencies cause significant fluctuations, which results in deep thermal cycling of devices and exerts more stress on the system.
This tutorial will be organized into two parts. The first part will present a comprehensive review of state-of-arts dc-dc converter topologies for PV farms (resonant and non-resonant), with particular focus on fundamental theoretical bases that underpin each topology, analysis and tailored design criteria for PV systems. Also, emerging dc-dc converters for potential application in dc collection of wind farms will be covered. This part will be concluded by comparative studies of several competing dc-dc converter in which the attributes and limitations will be clearly articulated. The second part of the tutorial will discuss emerging and existing converter topologies for medium voltage dc systems. To bridge the gap between the traditional power electronic research and power systems, both control and power electronics systems point of views will be emphasized.

The term immittance, combining the concept of impedance and admittance, was created by Hendrik W. Bode. Input and output immittances of a converter are a type of transfer functions that define the converter’s frequency response to external disturbances. Immittance modeling and analysis of converters in ac power systems was initially motivated by the need to study converter-based power system stability for electric ship and more-electric aircraft development. The rapid development of renewable energy and HVDC transmission in recent years created an opportunity as well as a urgent need to apply the methods to utility power systems. As a result, a large body of knowledge and a wealth of practical experiences have been developed. Immittance-based frequency-domain modeling now provides a general framework to study the stability of converter-based power systems. It also enables design engineers to optimize converters and their control for stable operation with/in the grid. New immittance-based converter performance specifications and system study procedures/tools are also being developed.

This tutorial presents an overview of the theory and applications of immittance-based frequency-domain modeling and analysis techniques for converters in power systems, with a focus on renewable power generation and HVDC transmission. The tutorial, intended for engineers and researchers working on or interested in grid applications of power electronics, is individed into three parts:

1. Basic Concepts and Applications: We start by discussing the importance of immittance in power systems and the difficulty to define it for converters. After a brief review of different definitions attempted in the early days of research in this field, small-signal sequence immittance is introduced. Practical methods to determine frequency responses of small-signal sequence immittances by laboratory measurement and numerical simulation are then presented. The lecture concludes with the formulation of an immittance-based converter-grid system model for frequency-domain stability analysis based on the classical Nyquist stability criterion.

2. Immittance Models and Characteristics: Alaytical methods to develop immittance models for PV inverters, type-III and type-IV wind turbines, as well as different HVDC converters are reviewed. The mathematical principle and process are explained in sufficient detail to allow those interested in analytical work to apply the methods. The rest of Part II focuses on practical use of analytical models to understand the effects of converter design on immittance response and system stability. For this purpose, the overall frequency spectrum is divided into low, medium and high frequency ranges. The effects of different control functions in each frequency range are explained to provide insights into their design tradeoffs.

3. System Models and Stability Analysis: Stability of individual wind and PV inverters/farms connected to the grod can be studied by using a system model that resembles a single-input-single-output (SISO) feedback loop. For more complex systems, a multiple-input-multiple-output (MIMO) formulation is introduced. Both grid-following and grid-forming controls are considered. Frequency-domain stability analysis of MIMO systems based on the generalized Nyquist criterion is explained. Practical applications of the MIMO formulation includes power systems with multiple renewable power plants in different locations, multi-terminal HVDC, as well as future hybrid ac-dc grids.

The tutorial will present the Solid State Transformer journey from concept to pilot demonstration in a decade. The MV SST for grid interconnection is enabled by advances in HV SiC power devices at 10-15kV blocking voltages. The design, control, development, and testing of SST with HV SiC 10kV MOSFETs and 15kV SiC IGBTs will be presented. A pilot demonstration for the Navy of an MV 4160V, 100kVA SST with SiC 10kV MOSFETs will be discussed. The HV 10kV SiC MOSFET enabled SST for “Mobile Utility Support Equipment” [MUSE] based Applications was focused on integrating an MV to an LV grid. The most impactful effect of using SST lies in the reduced material usage compared to conventional 60 Hz transformers, especially copper and aluminum, which have CO2 production emissions of up to 25 kgCO2/kg. This is important since, with an increased focus on climate change and greenhouse gas emissions, it is imperative to minimize the carbon footprint of transformers.

This tutorial also addresses a Medium-Voltage Asynchronous Microgrid Power Conditioning System (Microgrid PCS), or MV-MV SST enabled by HV SiC series connected power devices to connect, disconnect, and asynchronously flow power from microgrids to the grid. The Asynchronous Microgrid Power Conditioning System is a 60Hz transformer-less modular MVAC (13.8 kV AC) to MVAC (4,160 V AC and 13.8 kV AC) power conditioning system blocks (PCSB) that can be used for grid interconnection of Megawatt-scale flow control microgrids (asynchronous MVAC microgrids), with bi-directional power flow capability and scalable so that they can be used for a broad range of flow control microgrids of different scale (100 kW to multi-MW) including microgrids that have a net generation or a net load power flow at the point of connection to the larger grid. This modular approach is intended to result in higher-volume, lower-cost power electronics building blocks that service many applications at standard voltages: 4,160 V AC and 13.8 kV AC. This Microgrid PCS solution should enable multi-port integration of renewable energy sources to the main grid. The overall efficiency of the Microgrid PCS will be > 98%, and with low/partial load (<30% loading), efficiency > 95%. The Microgrid PCS solution can be implemented with 3.3 kV to 10 kV SiC MOSFET modules. The modular converters will utilize high-voltage, high frequency (>10 kHz) power electronics to reduce cost, size (< 4 m3/MW), footprint of < 3 m2/MW, the volume of >15-20 kW/L, and weight (> 15 kW/kg) and to provide the bandwidth (voltage control BW > 300 Hz and current control BW > 1 kHz) needed for both the grid-facing and microgrid facing functions required by interconnection standards plus functions required for a wide range of generator, storage, and load applications. The roadmap of HV SiC power devices in terms of cost targets, module packaging, and reliability qualification of HV SiC devices will be addressed. Advances in medium frequency magnetics for WBG devices-based power converters and especially for high power converters, with the latest advances in magnetic material qualification and characterization, will be included.

With the increasing use of power electronic converters for electrical energy generation, conversion, transmission, and utilization, our society is moving forward to a fully electrical-driven chapter. From e-mobility, industrial drive, and energy storage to data analytics, information management, and digital transformation, power electronics technology services as a precise and efficient electrical energy conversion unit. They are all heavily electricity-depedent applications and require the electrical energy with proper type. However, power electric converters are subject to frequent operational and environmental strains, which can induce failures. The prediction of these failures is difficult but important so the operation of a system can be halted before a catastrophic failure occurs. Hence, it demands cost-effective and robust condition and health monitoring solutions for operation optimization and predictive maintenance, facilitating life-cycle-reduction and performance boost of power electronic converters.

This tutorial aims to present the state-of-the-art condition and health monitoring methods for power electronic components and converters. It starts with a brief introduction to the reliability and availability challenges of power electronics in different applications, underlining the importance, function, and benefits of condition monitoring, and their demands on field applications. Then, it discusses the condition monitoring methods for power semiconductor switches, capacitors, and power electronic converters. A few case studies for converters with silicon, SiC, and GaN devices, electrolytic and film capacitors are used to illustrate the principles and associated practical considerations.

Finally, it gives perspectives on the challenges and the gap between academic research and industrial applications in condition and health monitoring in power electronic converters. The target participants are: 1) University researchers who are interested in in condition and health monitoring techniques for power electronics, latest condition monitoring techniques, component-level and converter-level solutions; 2) Power electronic engineers who would like to have a better understanding in how to select and involve a proper condition monitoring technique in the power electronic system they are developing.

The fast-switching speed, higher voltage and higher temperature capabilities of wide-bandgap (WBG) power devices such as SiC and GaN devices have brought in clear opportunities in achieving high-density, higher-efficiency, higher-frequency and highly-integrated motor drives. This tutorial will first provide an overview of the performance of state-of-the-art SiC/GaN devices and converters and their applications in motor drive area. Then, the issues due to high frequency switching and their impact on electric machines will be explained. For example, high dv/dt and high switching frequency can cause increased level of motor over-voltage, insulation and bearing degradation and electro-magnetic interference. Under the high dv/dt of WBG motor drives, motor terminals will see clear over-voltage with much shorter cables than that under Si IGBT motor drives and the voltage stress will mostly drop on the first several turns of the motor windings. Also, it has been found there is overvoltage at the motor stator winding neutral point. How the switching speed and switching frequency will affect the winding insulation (e.g. partial discharge) and motor bearing current will be explained. Experimental test results with SiC motor drives will be given and the theory behind the experimental observations will be provided with the analysis in both the time and frequency domain. Several potential solutions in addressing the above negative side-effects of high-frequency WBG drives will be discussed, including filters, waveform shaping through soft-switching and gate drive, alterative converter topologies, quasi-multilevel modulation, etc. A couple of SiC motor drive examples and research projects in this area will also be presented to further demonstrate the opportunities, challenges and potential solutions mentioned above.

Electrification of mobility plays an important role in the roadmap towards a carbon-neutral climate by 2050 in Europe and North America and 2060 in Asia. Chargers, on the one hand, determine the charging time and thereby the user experience, and on the other hand, have a significant impact on the grid, thus becoming a critical technology that has received immense attention in both industry and academia.

EV charging is categorized into four modes, standardized in IEC 61851-1. As the power level increases, the charger configuration changes from single-phase AC to three-phase AC, and eventually DC. When the power level is low, the charger is light enough to be installed in the EV (on-board charger). Nevertheless, when the power level is high, the charger is bulky and heavy and is not appropriate to be carried by an EV all the time. Thus, it is installed in the charger (off-board charger). Then the output of the charging pile is actually the output of the off-board charger, which is DC. An off-board charger is also called a DC charger.

For charging power around hundreds of kW, the charging cable needs liquid cooling and becomes heavy and expensive. Contactless charging is a promising technology to eliminate the charging cable and plug. Additionally, it also enables charging in motion. Contactless power transfer includes capacitive and inductive ones, where the latter is considered to be more promising for contactless EV charging. An inductive contactless charger has a power conversion structure similar to the on-/off- board charger, but the charger is split into two parts separated by the isolation transformer, and the transformer is replaced by two charging panels with coil and magnetic core. One charging panel is on-board, while the other is off-board.

The installation of chargers - both low and high power, is increasing dramatically, under colossal market demand. Whether the operation of our grid infrastructure is robust enough to handle this large amount of integration is still a question mark. In fact, a few power quality (PQ) issues in terms of voltage imbalance, flicker, harmonics, supraharmonics, etc., have already been reported, which are associated with the high power EV chargers nearby.

The primary layer control of the EV charging is the charging current/voltage control. On top of that, the whole charging process can be controlled (not yet implemented in most chargers, but the current charging infrastructure is capable of doing it) in terms of ramping up/down time, charging power, charging time window, etc. A series of intelligent control for th e above-mentioned objective is called smart charging, which has the potential to increase the utilization rate of grid infrastructure, reduce the charging cost with the flexible price of electricity, increase the efficiency in power transfer, reduce grid impact, increase the system autonomy especially when renewables are integrated to the charging station, etc. A unique application of smart charging is bidirectional charging, referred to as vehicle-to-grid, where the energy from the EV battery can be discharged as well. It opens the opportunity for the EV battery to be used as an energy storage device. A key point of attention is the effect that uncontrolled, smart, and fast charging has on the EV battery and its lifetime.

In this tutorial, more details are elaborated in terms of topologies and control of on-/off-board chargers, contactless charging, power quality of EV charging, renewables integration in charging station, smart charging – V2G, and effect on battery degradation.

The cybersecurity research of the power systems has been extensively studied and investigated after national-level cyber-attacks to power infrastructures such as StuxNet cyber-attack targeting supervisory control and data acquisition (SCADA) systems of Iran’s nuclear-enrichment plants in 2011 and Ukraine’s power grid where hackers switched off 30 substation which left 225,000 people without power in 2015. Main research has placed to address the cyber threats to operational reliability and vulnerability, the transient angle and voltage stability, frequency and electricity market causing the performance degradation of the system rather than power electronics (PE) devices. However, cybersecurity of PE is increasingly essential as more systems from renewable energy systems, energy storage systems, electric vehicle charging stations utilize PE devices to connect them into power grids with complex communication and computation systems (i.e., cyber system such as cloud computing and edge computing) through Internet of Things (IoT) for advanced control and situational awareness improvement in smart grid environments. With an awareness of these security concerns, it is crucial to investigate holistic security strategies to secure communication, firmware, and hardware components of the PE devices, while sustaining critical functions of the PE under the malicious cyber and physical attacks. However, PE community may still view cybersecurity as a confusing and highly technical domain. Current cybersecurity studies in PE community have shown very similar approaches to address hardware fault diagnosis and network failures. However, cyber and physical attacks have designed smartly and persistently by advanced persistent threat (APT) groups attackers or disgruntled employees or cybercriminals (e.g., ransomware). Hence, modeling the cyber-physical attacks is more challenging than fault diagnosis or network failure. Moreover, lack of security modeling and tools such as threat modeling, attack modeling, penetration testing tools, and security testbed might impede PE society’s research interests in cybersecurity in PE device and applications.

This tutorial is motivated for PE researchers to build a culture of security or the knowledge and capability to combat cyber threats in their PE devices and systems. This session will greatly benefit (1) attendees who are new to the research area of cybersecurity, as a useful guidance and (2) researchers currently working on cyber-resilient PE, as an avenue to learn about recent advancements and trends.

Field-oriented control of AC drives requires knowledge of the mechanical rotor position. Generally, this is detected by a position encoder, which has to be mounted on the shaft of the servo motor. In cost sensitive applications, however, when maximum performance is not required (for instance in traction drives), it is desirable to save this expensive sensor. Besides the cost advantage, encoderless control convinces with high mechanical robustness, as no sensitive electronic components are present in the machine.

There are two main methods for encoderless position detection, the first is based on using the basic equations of the electrical machine (model-based), whereas the second is based on additional signal injection.

High frequency injection methods are becoming more and more attractive. These methods generally interact with the saliencies (magnetic anisotropies) of an electrical machine obtaining the desired rotor position by demodulation methods. Saliencies are well-known when using Interior Permanent Magnet Machines or Synchronous Reluctance Machines. The most recent progress in this area is the encoderless control of synchronous machines with surface mounted permanent magnets. The saliency to be detected in this type of electrical machine is very small (< 5 %). In spite of that difficulty it is possible to design a encoderless control without the need of additional voltage sensors and with a behavior independent from any parameters of the electrical machine.

The main advantages of encoderless control are:
- Cost saving with respect to encoder and cabling/connection effort
- Significant improvement in reliability and robustness of the drive.
- Cost effective solution for safety related applications (encoderless redundant channel)
- simple possibility to find the position of north pole and south pole of the rotor without any rotation

The main challenges in encoderless control are:
- magnetic anisotropy depending on mechanical load.
- high frequency magnetic flux uses different paths in the cross section than fundamental magnetic flux
- there is no FEM program exploiting the fundamental flux paths and the high frequency flux paths at the same time (most FEM programs are quasi stationary)
- electrical machines with concentrated windings produce magnetic flux with significant non-sinusoidal distribution in the airgap – a parameter independent detection seems to be extremely difficult.

The participants of this seminar will understand:
- The basic concepts and ideas of encoderless control.
- Different basic types of encoderless control
- Different types of magnetic anisotropies detected by high frequency methods.
- limitations of high frequency injection methods
- Practical difficulties and solutions
- Which performance can be expected from encoderless control ?

This tutorial focuses on studying of electromagnetic interference (EMI) mitigation in power electronics converters. EMI is a serious threat to the reliability and operation of the power electronics converters as motor drives. With the application of wide-bandgap power electronics devices,EMI issue becomes even worse and is the main challenge for the power density of the power electronics converters. This tutorial gives a comprehensive solution for EMI mitigation in power electronics converters together with high power density.

Fast switching in power electronic converters brings strong “side-effects” including electro-magnetic-Interference and reflected wave issue. This “second-order” problem is sometimes even referred to as “black magic” because of their high complexity and nonlinearity, yet EMI filters are a “necessary evil.” It is one of the main causes of system failure, and a power electronics system will not function as expected without appropriate EM noise control. Emerging WBG device provides a potential to improve the efficiency and power density of electric power converters, yet it also introduces higher EM emission due to higher switching dV/dt and di/dt. Traditional passive EMI filters designed by rounds of “error-and-try” usually end up with significant volume and weight. Such a traditional filter defeats the purpose of achieving high power density and efficiency, and thus, becomes a bottleneck for modern WBG power electronics systems.

This tutorial provides a highly integrated educational session for modeling/analysis and mitigation of EM “side-effects.” The first part of the tutorial covers various methods for high-power-density EMI filtering solutions, including integrated filter, busbar filter and EMI mitigation using active filter circuits. It will include filter topology selection, stability analysis, and comparison of analog/digital active EMI filters. The tutorial section will also include a comprehensive analysis of reflected wave (RFW) problems and mitigation solutions in WBG converters. The audiences in this tutorial are expected to leave with comprehensive knowledge covering from the fundamental of EMI problem in power electronics converters to its advanced mitigation solutions

Besides EMI filter, the other approach for EMI mitigation in power electronics is through the EMI noise source, especially the pulse-width-modulation (PWM). This tutorial will give an introduction of EMI mitigation through advance PWM technologies. On the basis of the prediction model for power electronics converters, variable switching frequency PWM (VSFPWM) is proposed. This method can improve the EMI and power losses together with control of current ripple or other related parameters. For the general issues of VSFPWM, including the impact on harmonics and feedback control will also be illustrated. For common-mode (CM) EMI issue, this tutorial is with special care. PWM can help to reduce the CM voltage of regular two-level converter, but cannot eliminate it theoretically. Multi-level converter’s common-mode EMI elimination methods are introduced, together with voltage balance considerations. For two-level converter, a novel zero-CM PWM method for paralleled converters is introduced, together with its further improving methods. This method can be integrated with electric machine and further improve the power density.

Current regulation plays a key role in power electronic conversion systems. The central concept is straightforward – compare a measured current against a defined reference and minimise the error between these two quantities by adjusting the switching of the associated power electronic converter. However, while apparently simple in principle, achieving this goal in practice for AC inverter systems has proved to be very challenging. Over the last two decades, such issues have become especially important for grid connected inverters, where the challenges of low per-unit (p.u.) filter inductances, unbalanced grid voltages with significant harmonics, a preference for direct digital control, and stability concerns with the inverter’s associated phase locked loop subsystem, create unique and particular challenges for current regulation.

This lecture will present the current state-of-the-art for digital current regulation of grid connected AC converter systems. It will begin by showing how PWM transport and sampling delays are the primary constraints for linear regulators. Strategies to overcome these constraints will then be explored, including backEMF compensation, PR resonant control and its equivalent synchronous d-q frame implementation. An analytical approach to calculate the maximum gains for these strategies will be developed, verified by simulation and matching experimental results. Next, these concepts will be extended to the particular difficulties of current regulation for grid connected inverters. Issues considered will include gain determination when a low p.u. inductive-capacitive-inductive (LCL) filter is used, formal strategies to design a current regulator in the sampled z-domain transform space, how to best manage modulation saturation, and the influence of common mode EMI filtering on the current regulator performance. The lecture will then explore how to manage grid harmonics, unbalanced grid voltages and high impedance grid networks, by using cascaded PR regulators for each voltage harmonic, and positive/negative sequence current regulators operating in both the synchronous and stationary reference frames. Finally, the lecture will present some recent advances to maintain stable current regulation for a stand-alone microgrid when stability issues associated with the inverter’s phase locked loop are taken into account. All theoretical material presented will be supported by detailed matching simulations and experimental confirmation

The increasing connection of renewables and new loads is challenging the distribution grids. For overcoming actual and foreseen challenges, a new concept, with the capability to form intelligent grid nodes, is proposed: the “Smart Transformer”. The Smart Transformer is a power electronics-based transformer, that does not only transformt the voltage level from MV to LV grids, but it can also increase the power flexibility in the electrical grid by providing novel ancillary services. In order to exploit its capability, the ST requires combining power system aspects and power electronics constraints, resulting in new requirements and challenges.

This tutorial introduces the Smart Transformer concept and takes into account power system considerations as well as power electronics knowledge. Main topics that will be addressed in this tutorial will regard the ST architectures and topologies, basic controller designs and innovative concepts for increasing the availability, and grid integration. Hardware, control and grid connection requirements are described considering the matured industrial experience.

The Project will summarize the results of ten years work withing the EU ERC Consolidator Grant Project “HEART” of Kiel University and the Helmholtz Young Investigator group project “Hybrid Networks” at the Karlsruhe Institute of Technology.

The transition from a predominantly fossil fuel-based power generation towards renewable power sources, predominantly wind turbines and photovoltaic systems, inevitably leads towards an energy supply system that greatly depends on power electronics to feed the energy in the electrical grid. As all power electronic driven systems are intrinsically DC sources or loads, DC transmission and distribution systems become evident, not only because it is more efficient and cost effective, but also increases the ampacity of cables. The development and commercialization of medium-voltage, multi-megawatt DC-DC converters, also called solid-state DC transformers, is a key enabler to realize flexible and interconnected DC grids. Compared to AC transformers, solid-state DC transformers not only need to transform voltage and control power flow, but also need to offer similar efficiencies (up to 99%) at high switching frequencies, provide the same insulation levels and limit fault currents, that is, offer fault-ride-through capabilities.

In this tutorial, we introduce and describe the latest advances and best practices of galvanically isolated bidirectional DC-DC converters for solid-state DC transformers. It covers a wide selection of key enabling technologies from converter topologies, optimized control, to the design of highly efficient megawatt medium-voltage DC-DC converters based on emerging MV SiC devices.

Following a general introduction and a technology roadmap of DC transmission and distribution grids, the tutorial will elaborate the most promising candidates of bidirectional isolated DC-DC converters for solid-state DC transformers. It will start with a comprehensive comparison between single-phase and three-phase dual-active bridge (DAB) converters for LV and MV DC applications, where the pros. and cons. are clearly underlined. Further, advanced modulation and control of the DAB converter will be presented to overcome two important challenges. First, the trajectory modeling approach and the instantaneous flux and current method are systematically presented to explain and resolve the transformer saturation issue under dynamic conditions. Second, the asymmetrical duty-cycle control method is introduced to enable ultra wide voltage operation of the DAB converter with soft-switching and the fault ride-through capability.

An extended discussion on various high-power isolated dc-dc converters for interconnection of MVDC distribution grids and HVDC transmission grids wibll be addressed. It will start with an introduction of a converter topology which combines parallel-connected two-level converters (TLCs) on the MV side and a modular multilevel converter (MMC) on the HV side (this converter is named the TLC-MMC converter). A dedicated operation method will be presented, whereby soft-switching operation and low total device ratings of power devices can be realized. Afterwards, the topics on topology, control, and fault-tolerant operation will be covered.

The last section of the tutorial will focus on the understanding of MV SiC devices (15 kV IGBTs versus 15 kV MOSFETs; 10 kV, 6.5 kV, 3.3 kV MOSFETs) and their applications for the MVDC grid. MVDC grids will be explored with demonstrated and pilot application examples of SST (Solid State Transformer). The roadmap of MV SiC power devices in terms of cost targets, module packaging, and reliability qualification of MV SiC devices will be addressed. Advances in medium frequency magnetics for wide band-gap (WBG) devices based power converters and especially for high power converters, with latest advances in magnetic material qualification and characterization will be included

This Tutorial deals with resilience and effective operative life concepts in the field of power electronics. Resilience is almost the only method for achieving a desired reliability in a converter that operates with non-zero fault possibility. In this tutorial, advanced methods for resilient power electronic converters are presented. Furthermore, the fault mechanism is explained to determine the reason for failure in power converters. Finally, various methods are presented to improve the resilience of the power converters. The following aspects are covered and discussed in this tutorial:

- Analysis of failure mechanisms in power electronic converters including internal and external faults are described.
- Fault prognosis and diagnosis concepts are described and the certain methods for fault detection in power electronics are presented.
- Advanced techniques for reducing the noise effect on the fault detection and prognosis are explained.
- Classic methods of resilience are reviewed and a comprehensive perspective is provided.
- Advanced methods of resilience are presented regarding the mission of the power electronic converter.
- Reconfiguring of a power electronic converter as a design consideration is presented.

The tutorial is prepared in four parts. This division helps the participants to follow the contents easily. The first part, Resilient Power Electronic Systems, presents a general view of the resilience concept in power electronic systems. part 1 provides an introduction for entering the concept of resilience in power electronics. In this part, the resilience concept is described in its general form and mission critical systems are introduced. In this part, the reader is also introduced to the techniques that are used in industries and nature for reaching a resilient performance. The concept of resilience in power electronic converters is introduced with an introduction to these devices and a recognition of their main functions as well as their importance. The conditions for supporting the load during the fault are presented. Internal and external faults are explained and their effects on the converter resilience are presented. The requirements for resilience of a power electronic system are described. The main part of this part deals with the difference between fault tolerance and resilience. In the second part of the tutorial, Useful Life of the Power Electronic Systems, the failure mechanisms of the power electronic systems are presented in both element level and converter level. The concept of useful life and the methods for useful life modeling are described. The third part of the presentation, Health Estimation of the Power Electronic Systems, presents the methods for system health monitoring. Commonly used methods for condition monitoring the converters are presented. The methods of fault prognosis and diagnosis in power electronic systems are described. In the last part of the presentation, Methods of Resilience in Power Electronic Systems, guidelines for achieving resilience are presented. These methods are used in both design and operation processes of the converter. Methods for reducing the stresses on the power electronic systems are described at both system and component levels. Algorithms for derating a faulty power supply are described. Resilient operation of power electronic converters against external faults such as a load short circuit is studied. Some of the methods and techniques for inherently resilient operation of the power electronic converters are reviewed.

To fully exploit the benefits of SiC technology for designing high-performance power electronic converters, three key aspects

emerge, namely, accurate device characterization, modeling, and advanced gate driver designs. The first two aspects allow for fast validation of converter designs, reducing development and prototyping effort. Advanced gate drivers are integral components for manipulating the switching performance of SiC power devices and thus adjusting the electrical and thermal performance of power converters. The first part of this tutorial will introduce SiC power devices and provide an overview of static and dynamic characterization of SiC metal oxide semiconductor field-effect transistors (MOSFETs) in 1.2-3.3-kV classes. A particular focus will be on the design of low-inductive circuits for capturing the dynamic performance of SiC MOSFETs minimizing the impact of parasitic circuit parameters. A brief evaluation of high-bandwidth current measuring sensor technology will be presented. Besides, the development process of accurate SiC MOSFET models for both traditional SPICE-based and real-time simulations utilizing experimental characterization data will be presented. The importance of developing device models suitable for real-time simulations to minimize convergence issues will be analyzed.

The second part of the tutorial will focus on the design, operation, and system-integration principles of adaptive voltage-source and current-source gate drivers for SiC MOSFETs. Besides, this part will shed some light on the design of low-voltage and low- power supplies with galvanically isolated input and output stages for energizing gate drivers. A design example of such a power supply featuring 24 kV isolation voltage capability and 10 pF coupling capacitance will be shown. Finally, the system-level benefits of employing adaptive gate drivers will be discussed briefly. Through adaptive gate driving operation, both cost-effective design and operation of power converters can be achieved. The main benefit of this tutorial is the dissemination of knowledge concerning the design of high-performance converters by integrating and operating SiC MOSFETs. The tutorial content is based on the research conducted by the power electronics group at the Norwegian University of Science and Technology (NTNU). The intended audience are design engineers, PhD students, senior researchers and professors dealing with design of SiC- based power converters