1. Electromechanics and Power Electronics Group, Department of Electrical Engineering, Eindhoven University of Technology 1 , 5600 MB Eindhoven, The Netherlands
2. Control Systems Technology Group, Department of Mechanical Engineering, Eindhoven University of Technology 2 , 5600 MB Eindhoven, The Netherlands
3. Department of Energy Science and Engineering, Stanford University 3 , 367 Panama Street, Stanford, California 94305, USA