Abstract
We have proposed an adjustable structure of the converter of energy of electric drive in the electrotechnical complex of a mine electric locomotive from power sources with different voltage levels ‒ from a contact network and a battery of traction accumulators. A characteristic feature of the converter is the presence of inverter units that can be connected either sequentially or in parallel. When powered by a lowvoltage source, inverter units are connected in parallel over the entire range of change in the output voltage. When powered by a high voltage source, inverter units are connected sequentially in the range of low output voltages and in parallel in the range of high output voltages. Such an approach makes it possible to align the power voltage levels of traction asynchronous motors of a mine electric locomotive at a lower level. The expected alignment of voltage levels is carried out at a lower level compared to a standard circuit of the threephase bridge autonomous inverter and is achieved by controlling the paired bridges in the power circuit of traction induction motors. Given this, the frequency of voltages of widthpulse modulation does not change, which is important for the process of reducing dynamic losses of power in the drive’s elements. It has been confirmed that an increase in the output voltage distortion coefficient in the IGBtransistors of the inverter with the minimal level of energy losses in the electric drive’s elements is achieved by modulating the voltage at a constant switching frequency at different voltage levels. We have proven the fact that the best indicators for the harmonic coefficient were obtained at frequencies about 30 Hz, which are the working ones, so the converter operating mode is most effective at these frequencies. The result of analysis of the classical scheme of the inverter has revealed that increasing the frequency of pulsewidth modulation by three times significantly increases electrical losses in the windings of traction electric motor. In the proposed circuit of the voltage inverter of engine’s power, at leveling the voltage at low level, there is no need to increase the frequency of pulsewidth modulation, which does not lead to a growth in the electrical losses in a traction motor
Highlights
Electrical equipment, including components of traction electric drives for mine electric locomotives, as well as the electric locomotives themselves, are produced in more than 15 countries by 30 firms that are leaders in this industry [1].it should be noted that only a small part of contact and accumulator-based mine electric locomotives is equipped with induction traction electric drives.Other types of electric rolling stock are equipped with ineffective traction electrotechnical complexes (TETC) with contact-resistor control systems and series-woundO
In order to examine and analyze the quality of energy conversion and to estimate losses in traction induction electrical drive (TID) elements by investigating a power voltage pulse-width modulation (PWM), we have developed a model of the structure of a reconfigurable inverter with intermediate thyristors
We have proposed the new structure of the converter, as well as a technique to control the inverter bridges in a traction induction motors (TIM) power supply unit
Summary
Electrical equipment, including components of traction electric drives for mine electric locomotives, as well as the electric locomotives themselves, are produced in more than 15 countries by 30 firms that are leaders in this industry [1]. The result of analysis of electromagnetic processes in the traction induction electrical drive (TID) of the classic structure of a mine traction electrotechnical complex has revealed that when powered by different levels of voltage sources the actual values for energy losses are substantial [3]. In this case, the coefficients that describe the non-sinusoidal curve of induction motor voltage have rather high values that do not agree with acting GOST [4]. That necessitates, based on analysis of known structures [5], the substantiation and development of recommendations for applying the law of control over power voltage of TIM ‒ traction systems of electric drives
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