The Study Of Mine Hoist Variable Frequency Speed Regulation System Based On Dual-PWM

Mine hoist plays an important role in the mine; it assumes some responsibility of transporting human beings, mining, equipment, and other things, so the reliability and security of hoist speed performance are essential. With the development of power electronics technology and application of large-scale integrated circuits, AC speed regulation technology has been great developed and applied, so it has greatly improved the speed regulation of mine hoist.First, this paper introduces the development of speed technology of mine hoist. Based on the operating characteristics of mine hoist and some outstanding problems of mine at current stage, a dual PWM frequency control technology applied to mine hoist was put forward. The main circuit of the dual PWM frequency control technology is the AC-DC-AC circuit topology. The rectifier sides adopt PWM rectifier, which has the advantages of reversible net side current unit power factor sine wave, power two-way flow, dynamic response speed and high efficiency of DC side; and can solve the pump problem of the DC side voltage, the braking device do not need to be installed in the DC side, so the structure of the frequency converter is simplified. In the inverter side the direct torque control is used, the method does not require the complex coordinate changes, it directly calculate torque and control motor torque on the stator coordinate, and it has good dynamic performance and good robustness, to further improve the speed regulation system control performance.Second, a simulation model of double PWM frequency was built based on the operating characteristics of mine hoist by MATLAB 7.1, it was carried out and its feasibility and correctness were proved. Finally the dual PWM frequency control device was designed, and its PWM rectifier was detail designed. The device includes the main circuit, sampling circuit, control circuit, auxiliary power supply and so on. DSP2812 was used to finish digital control of PWM rectifier, which can get ideal result.The simulation and experimental research show that this system has good speed performance and high control precision, it can solve the problems existing in small and medium sized mine hoist in our country.