Study On AC-DC-AC Reversible Adjustable-Speed System Used In Mine Hoist

After analysed the history of mine hoist's electric power driving project, a question for using double PWM AC-DC-AC direct torque variable-frequency adjustable speed system in 660V-level hoist at the bottom of the mine is put forward in this paper. It is emphasis that three-phase voltage source reversible rectifier is deeply researched both theoretically and practically as this system's power supply.Firstly three-phase VSR's variable calculation, model of AC side at stable static state, normal mathematic model and model under d-q axis are discussed in detail. Secondly combined with specific demands of AC-DC-AC direct torque variable-frequency adjustable speed system in mine hoist, three-phase VSR's control strategy is researched. Vector control scheme without current loop is adopted and its static and dynamic performance is analysed. Some improving measures are taken. Then how to choose main circuit's parameters, including AC side inductance, DC side output voltage, DC side capacity, is also studied. Lastly this system's hardware and software are designed based on DSP (TMS320LF2407) completing digital realization of three-phase VSR. Moreover, the system experiment is made in the laboratory to test the prior research results. Additionally considering three-phase VSR's characteristics and mine hoist's working specialities, the other part of double PWM AC-DC-AC direct torque variable-frequency adjustable speed system—PWM inversion set's control is studied. High precision variable-frequency adjustable speed system should be adopted because mine hoist requires high-precision rotate speed and acceleration or deceleration. There are two kinds of high-precision variable-frequency adjustable speed system. One is vector control system; the other is direct torque control system. Asynchronous motor's direct torque control variable-frequency adjustable speed scheme is used and its theory, mathematic model and controller's design are discussed. Analysis the realization of the direct torque control used in asynchronous motor's four-quadrant operation.