1. Riga Technical University, Institute of Power Engineering,Faculty of Electrical and Environmental Engineering,Department of Electrical Machines and Devices,Riga,Latvia
2. Riga Technical University, Institute of Aeronautics,Faculty of Mechanical Engineering, Transport and Aeronautics,Riga,Latvia
3. Riga Technical University, Institute of Industrial Electronics and Electrical Engineering,Faculty of Electrical and Environmental Engineering,Riga,Latvia