Modernization of electrical transport systems in EstoniaLaugis, Juhan; Lehtla, Tõnu; Joller, Jüri; Boiko, Vitali; Vinnikov, Dmitri; Lehtla, Madis10th International Power Electronics and Motion Control Conference : EPE-PEMC 2002, Cavtat & Dubrovnik : 9-11 September 2002, Cavtat & Dubrovnik, Croatia2002