Sterowanie prądem wzbudzenia silników trakcyjnych lokomotyw kopalnianych

W polskich kopalniach węgla, soli, rud miedzi, cynku i ołowiu eksploatowane są elektryczne lokomotywy przewodowe, napędzane dwoma silnikami szeregowymi prądu stałego o łącznej mocy od 60 do 100 kW. Silniki tych lokomotyw zasilane są z sieci trakcyjnej prądu stałego o napięciu 250 V, przy czym wahania napięcia sieci trakcyjnej mogą wynosić od –30% do +20%.

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In the majority of electric trolley locomotive operated in Polish mines, a significant (3:1) main poles field weakening in the traction machines is necessary. In the paper special attention was paid to an analysis and result of laboratory tests of a transistor-based system designed for a pulse-mode control of the traction motors' excitation current of the locomotive type Ld31 (90 kW). A capacitor connected in parallel to the excitation winding of the traction motor is discharged through a resistor in the de scribed system. Consequences of the significant difference in the current overload capacity of power transistors an SCR thyristors were presented. The relationships between a field weakening rate and an armature current for different switch duty ratios of the transistor were obtained 0 the basis of an approximate analysis of the system operation. The steady-state characteristic curves of the excitation current versus the armature current and power losses in the resistor were found using Maple computer algebra system. Results of the laboratory tests concerning the relationship between the excitation current and the armature current and selected oscillograms of the voltage and current waveforms were also shown.