Research On Non-speed Sensor DTC Variable-Frequency Adjustable-Speed System For Mining Locomotive

Mine electric locomotive is an important conveyance for coal mine, with thepromotion of national energy efficient policy, and the urgent needs of manufacturers toimprove production efficiency and safety, mine electric locomotive has to be developedwith high-performance, low energy consumption, and humane designed. Replace the DCmotors with AC motors, weeding out the speed regulation method of connectingresistance and using converter to regulate speed,will be the inevitable developmenttrend of mine electric locomotive.Paper described the application of mine electric locomotive speed-regulationtechnology and the existing problem present，what’s more，propounded a kind ofvariable-frequency adjustable-speed method which is fit for electric locomotive—DirectTorque Control (DTC). Because of that the current DTC method can cause the motortorque ripple when frequency is low, this paper proposed an improvement method ofasynchronous motor direct torque control in the low frequency area, Namely thecombination of traditional DTC and DTC based on a space vector control. This controlstrategy can either artificially take control of torque and flux ratio of the switchingfrequency, but also to achieve a quasi-constant inverter switching frequency operation.Finally, for the special type of explosion-proof battery locomotive,this paperintroduced the non-speed sensor frequency control system realization process. Thesystem includes hardware circuit design, the choice of the main components, twooperating room interlock design, and implementation of system protection measures.After completing the hardware, the actual field experiments was carried out, and theconclusion based on the results was propounded as well. Experiments show that thelocomotive has a good low-frequency stability, can be output good constant torquecharacteristics and stable voltage and frequency characteristics in the speed range.Motor has no vibration in the entire frequency range and has a smooth speed-regulation、a large starting torque and so on，which meet the requirements of actual production.