Tractive Effort and Wheel Slip Control of Locomotive Type 120

Abstract The locomotive type 120 is an ac electric locomotive equipped with 3-phase traction motors. For the transmission of the high tractive efforts an optimal use of the available adhesion is required. For this purpose, a wheel slip control is integrated into the tractive effort control system. According to the unpredictability and diversity of the friction/creep relationship several wheel slip detecting criteria are implemented. For the operation at low available adhesion a tractive effort maximization is provided. Wheel creep is stabilized by means of parallel connection of traction motors and use of a PLL circuit. The wheel slip control is realized by use of a microprocessor system and a special control language adapted to controlling requirements. Extensive road tests have been carried out to optimize the various wheel slip control features.