| Scraper conveyor is an important equipment on the coal mine working face, which beared the coal tasks and offered the orbit of Shearer and furnished the goes fulcrum of hydraulic support.As we all know, Scraper conveyor’s frequent and heavy starting is a very difficult process, and it also wasted too much electricity. To solve this problem, research the drive system of scraper conveyor.Comparatived several kinds of coupling drive system and analyzed performance characteristics, the results showed that the degree integrated of variable frequency drive is best. This paper is mainly variable frequency drive control system for the study of the scraper conveyor, which specifically includes the following aspects:First of all, study the load characteristic of the scraper conveyor. Briefly introduced the scraper conveyor drive system and motor characteristics, analysised the cause of starting difficult and overload, while compared four kinds of start curves and the anti-S-shaped curve enabled scraper conveyor smooth starting. To concrete analysis the load characteristics of scraper conveyor, builded Kelvin-Vogit model under scraper chain viscoelastic, analysised the dynamics equation of scraper chain and the kinetics equations of scraper conveyor with the finite element method, thus established dynamics mode with displacement, velocity and acceleration as well as tension. Analysised power imbalance in the nose and tail of the scraper conveyor Dual starte, obtained the impact factor which were the power allocation and startup sequence time difference.Secondly, analysised the feasibility of variable frequency drive model. Direct torque control for its simple structure and liable to direct torque control was adopted in this paper. Briefly introduce the theoretical basis of direct torque control technology, analysised the reason of the low-speed torque ripple in the traditional direct torque control system, while utilized SVPWM technique making up for the defects. In view of this, established the model based on SVPWM direct torque control system and simulated this model. The results showed that the output waveform was relatively smooth and burr less, particularly the differences of the results were not obvious in the two cases. Those indicated that the direct torque control system based on SVPWM has certain feasibility of application in the scraper conveyor inverter drive.For those, set up hardware circuit of variable frequency drive system as the prototype of scraper conveyor DSB75in grid voltage1140V, computing and choosing the devices. The hardware circuit included the main circuit and the control circut as well as protection circuits. Where in the main circuit designed the rectifier circuit, filter circuit, braking circuit, inverter circuit and drive circuit; the control circuit was based on the DSP2407chip; Protection circuits on the DC bus included overvoltage and undervoltage protection as well as short circuit protection, for the IGBT invoved overcurrent and overvoltage protection, and Motor protection incorporated overheating protection and overload protection and phase failure protection too.Based on DSP2407chip, written programs of direct torque control system in the CCS3.3environment. The DSP initialization programs, the main programs and DTC algorithms constituted the programs.While the DTC algorithm programs which achieved by the interrupt service routine were the core of the control system, meanwhile SVPWM program was the key to the interrupt service routine. The design of fault interruption protection can not be ignored, and its main purpose was to protect the power switching devices and motor.In the laboratory, debuged the small power inverter hardware circuit which aim was to verify the feasibility of the program. First, checked errors in the program, generated PWM waveform, achieve interruption protection.Then debuged the hardware circuit, and obtained currentwaves form eight frequencies. Spectrum analysis on the oscilloscope signal showed the largest five times harmonic content within5%of the fundamental wave, proved the feasibility of the control scheme. |
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