Replacement of a Permanent Magnet Generator by an Induction (Squirrel Cage) Motor Used as a Generator

This online coached international student research project has come to an end.  We were so lucky to have the opportunity to get involved in this international experience! Thanks to our weekly follow-up with the supervisors, Dr. Olav and Dr. Mervat the work has gone that far in a short three-month period with all the circumstances that we’ve been through.

Our sincere and heartfelt gratitude goes for their continuous guidance and encouragement in the past three months. We can confidently say that we would not have grown professionally as much as we had without their unwavering support and detailed feedback. Their continuous appreciation of our efforts and their support during our struggles helped us transform our mistakes into skills. Working under their supervision has been really enjoyable and uplifting in our career. We are extremely grateful for our friendly chats as we exchanged plenty of cultural information during our weekly meetings which made this journey really exceptional!  

 

To simulate the core losses of our transformer, MATLAB Software was our first choice, as we have tried to configure the transformer equivalent circuit, but since we are designing a new transformer, and changing the type of the core material we found that Ansys Maxwell is a better choice for electromagnetic simulations, it is an EM field solver for electric machines and transformers. It solves static, frequency-domain, and time-varying magnetic and electric fields. Maxwell also offers specialized design interfaces for electric machines and power converters.

After downloading Ansys academic software, we created our first transformer design using Spaceclaim which is an Ansys built-in tool for drawing the geometry of the studied material. The properties of amorphous alloy can be entered into the software and assigned to the core design! After entering the needed parameters, the software can calculate the demanded losses. Unfortunately, Ansys Maxwell is not included in the student free package,  yet we have so far figured out to have access to the license through Ostfold credentials. Thus the simulations will be postponed till after the EXPO presentation.

 

 

For experimental purposes, we want to order a transformer or a core manufactured from the chosen material. In order to do that we have collected the name, website, and location of potential electronic suppliers and core manufacturers in a single list.

After searching through the supplier’s websites, we have found that Metglas supplies the Powerlite C-Cores from the AMCC series which are manufactured with Metglas amorphous alloy 2605SA1, alongside a catalog of different dimensions. Hence all we need to do now is to calculate the required dimensions of our core,  then order it for experimental results.

Metglas® Inc., located in Conway, SC, is a world-leading producer of Amorphous Metal ribbons. This company pioneered the development and production of amorphous metal, the unique alloy that exhibits a structure in which the metal atoms occur in a random pattern. Metglas supplies many types of this alloy:

• • METGLAS® 2605SA1 Alloy
  • METGLAS® 2605HB1M Alloy
  • METGLAS® 2605S3A Alloy

After comparing the different properties of the three mentioned alloys, we have chosen the “METGLAS® 2605SA1  Alloy” as the most suitable material for our generator.

Both, induction machines and transformers work on electromagnetic induction, their core losses follow the same physical processes, and modeling a transformer is simpler than an induction machine, thus the study will be simplified to that of a transformer.  We will design a transformer having its core material made of METGLAS® 2605SA1  Alloy,  a power output of 2 KW, and running at a medium frequency around 500 Hz.

Amorphous metals are made of alloys that have no atomic order. They are made by rapid cooling of molten metals that prevents crystallization and leaves a vitrified structure in the form of thin strips. Due to the lack of systematic structure, this type of metal has also been given the name “The Metallic Glasses”. It is the best material that would be used in our work, due to its great performance at medium frequencies (500 Hz to 5000 Hz), which can offer a high magnetic permeability, high resistivity, high magnetic saturation value, high operating temperature, and low losses which will lead to better efficiency.

Silicon steel, soft ferrites, permalloys, Amorphous and Nanocrystalline alloys are potential core materials for our generator. Now we need to compare the magnetic performance of the materials mentioned at the required frequency and choose the material with the minimal losses and the lowest cost.

 

Our team started using the Microsoft Planner Tool, which allows you to post tasks on a shared whiteboard among team members, set deadlines for these tasks, and assign them to members. Our Supervisors joined this platform in order to edit and add tasks, this helps in organizing our work and keeps all of us on the same page.

Mr. Tore, the librarian of Østfold University College, gave us a great tour in the university library! He showed us how to navigate through the library website and explained how to access its content. Mr. Tore gave us few hints that will help and facilitate our research.

As our first approach to improve this generator, Dr. Olav suggested that we start working on the magnetic characteristics of the core material, finding the best alternative material for iron, in which this material should have a skinny hysteresis loop, and can operate at high frequencies with low power losses.

 

 

We started familiarizing ourselves with the idea of Dr. Olav, and searched more about how an induction motor work as a generator? We compared it to the permanent magnet generator and understood why we are doing this. After few meetings with the supervisors, the idea was clear enough to get started and to focus on how to improve this generator.

 Our team, supervised by Dr. Mervat Madi from the Lebanese University side, had our first meeting with Dr. Hong Wu, Dr. Gunnar Andersson, Dr. Olav Aaker, and Mr. Samer Hamadeh.

 As Dr. Gunnar and Mr. Samer facilitated our first meeting with the supervisors, Dr. Olav Aaker presented his theory to our team. His idea was to use an asynchronous induction motor (squirrel cage) as a generator in a power production system, substituting a synchronous permanent magnet generator. Our role in this project is to work on the dimensions and material type of the induction motor, increase the motor’s efficiency, and reduce its power loss, maintaining an affordable overall cost and simulate the results using MATLAB/SIMULINK software.

 After that, we had a virtual meeting with Dr. Mervat, and we all agreed to proceed with the suggested idea, and the project started! 

 

Thanks to Dr. Gunnar Andersson, Dr. Mervat Madi, and Mr. Samer Hamadeh, our team conducting the final year project at the Lebanese University, faculty technology, got the opportunity to join the “IREXC10018 International student research project” program at Østfold University College.