Universal control method of auxiliary electric motors

To control the angular velocity of the auxiliary electric motors of electric locomotives, controlled converters are used, making it possible to implement various methods for controlling the electric motors of direct and alternating current. Depending on the technical and technological conditions, different types of controlled converters can be used, and the strictest requirements for controlled converters are imposed at railways. Advantages of converters with resonant inverters, especially a reliable natural turning-off of thyristors and the possibility of obtaining a sine wave form output voltage, make it possible to apply them in DC and AC electric drive systems in railway transport. Analysis of the main methods of controlling the rotational speed of AC and DC electric drives made it possible to reveal the advantages and disadvantages of existing control methods and to concentrate attention on the most promising ones, which include the control method using the pulse-width modulation and the control method using pulse-frequency modulation. The proposed universal method of controlling DC and AC electric drives has the advantages of the known control methods and it is based on the application of resonant inverters circuits. The results of the research give grounds to assert the possibility and feasibility of controlling AC and DC electric drives by means of circuits of resonant series inverters that allow controlling such basic parameters as the average value and voltage frequency of the motor.