Three level Neutral -Point-Clamped-Converters- State-of-the-art- and Recent Advances in Control Solutions and Reliability (2025)

Welcome to Three-Level Neutral-Point-Clamped Converters: State-of-the-art and Recent Advances in Control Solutions and Reliability (2025)

Description: The three-level neutral-point-clamped (3L-NPC) converters have been widely applied in several applications including motor drives and grid integration such as wind and solar energy systems. Key performance metrics of the 3L-NPC converters like power quality, efficiency, power density and reliability are strongly affected by the used control methods. Therefore, different control methods have been proposed for the 3L-NPC topology to address certain aspects. 

This course aims to address basic concepts and control design challenges of NPC converter applications. It will start with basic operating principles of the topology and their control challenges such as neutral point voltage balancing and thermal stress distribution. Then, two different control approaches will be presented: 1) carrier-based PWM techniques and 2) model predictive control techniques. For each control technique, basic concept and step-by-step implementation guideline will be provided, followed by more application-oriented examples and implementation challenges.

An approach to analyze the reliability of power electronics converters will also be introduced, which includes thermal stress modeling, lifetime prediction, and reliability evaluation (Monte Carlo simulation). It will be demonstrated that control algorithm selection has a major impact on the reliability of semiconductor devices and DC-link capacitors in NPC converters. In the last part of the course the focus will be set on practical application cases of NPC converters in the industry. 

The course is intended both for academia researchers and industry, who do not have previous knowledge about the NPC topology (basic operating principles will be explained), and for those who are familiar with the topology and would like to learn more about ongoing research directions and novel control solutions. 

Key words: Control algorithm, lifetime, multilevel converters, neutral point clamped, modulation, model predictive control, reliability 

Prerequisites: 

•  Fundamentals of power electronics
• Experience with MATLAB/Simulink is recommended for the exercises

Learning objectives: 

• Understand fundamentals of 3L-NPC and required control objectives (neutral point voltage balance, thermal stress distribution)
• Implement the basic carrier-based control methods for 3L-NPC
• Implement the model predictive control methods for 3L-NPC
• Understand how control selection affects the reliability of components in the 3L-NPC
• Practical design considerations for NPC converters

Teaching methods: Lectures, Excercise, Presentations

Form of evaluation: Students are required to solve exercises using the knowledge acquired in the course and submit a short project report with solutions within three weeks after the course, which will be assessed by the lecturers.

Criteria for assessment: Completed exercises (2) submitted as a short report

Remarks: In total about 46 hours (Preparation: 12 hours, Lecture: 16 hours, Exercise and final report: 18 hours)

Key literature: TBA

Organizer: Frede Blaabjerg, fbl@energy.aau.dk, AAU Energy

Lecturers:  Assistant Prof. Ariya Sangwongwanich and Assistant Prof. Mateja Novak from AAU Energy

External lecturers: Radu Dan Lazar, Reserach Engineer, Danfoss Drives

ECTS: 2.0

Time: 25 and 26 September 2025

Place: Aalborg University, AAU Energy (Room: TBA)

Zip code: 9220

City: Aalborg

Maximal number of participants: 20

Deadline: 4 September 2025

Course fee: PhD Students (outside Denmark): 6000 DKK and other participants (from Industry and Universities): 8000 DKK (excluding VAT). Guests at AAU Energy can also attend the course for free.

Important information concerning PhD courses:

There is a no-show fee of DKK 3,000 for each course where the student does not show up. Cancellations are accepted no later than 2 weeks before the start of the course. Registered illness is of course an acceptable reason for not showing up on those days. Furthermore, all courses open for registration approximately four months before start of the course.

We cannot ensure any seats before the deadline for enrolment, all participants will be informed after the deadline, approximately 3 weeks before the start of the course.

For inquiries regarding registration, cancellation or waiting list, please contact the PhD administration at phdcourses@adm.aau.dk When contacting us please state the course title and course period. Thank you.