1. Department of Electrical Machines and Devices, Riga Technical University, Riga, Latvia
2. Department of Electrical Power Engineering and Mechatronics, Tallinn University of Technology, Tallinn, Estonia
3. Electromechatronic Systems Research Centre (CISE), University of Beira Interior, Covilhã, Portugal
4. Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland