The Research Of Control Strategy And Its Application On Mine High-voltage Inverter

High-voltage inverters are widely used in mine hoist and ventilation system. The research of its control strategy and application is important for performance improvements and energy-saving of electric equipment, including mine electrical equipment.With the background of the cooperation project-"The research of low-voltage energy-feedback type inverter" between Henan University of Science and Technology and CITIC Heavy Industries Automation Engineering CO., LTD and postdoctoral project of CITIC Heavy Industries Automation Engineering CO., LTD-"The research of the key techniques of frequency-conversion energy feedback inverter in mine hoist ".The control strategy and PWM techniques of general converter are studied in this paper and corresponding solutions to the existing problems is presented.Firstly, the topology of main circuit and the corresponding control strategy are analyzed, and then cascade H-bridge structure is adopted as main circuit topology. The inverter control strategy and multilevel PWM techniques are focused on from the aspects of efficiency and performance improvement.Secondly, the new multi-level PWM technique based on cascade inverter is studied deeply in this paper. The Carrier phase-shifted SPWM (CPS-SPWM) and Sampling Time Staggered SVPWM (STS-SVPWM) based on U/f control strategy are studied through the simulation. For the problem of the bad real-time property and on huge occupying the system resources existed in both techniques, a new type of multilevel PWM technique-Overlap time staggered PWM technique(OTS-PWM) to the cascade H-bridge inverter. The OTS-SPWM and OTS-SVPWM technology are analyzed in detail in the simulation and the rule of corresponding multilevel PWM techniques are summarized. The result shows that the OTS-PWM technique is effective and it can be used universally.Thirdly, the cascade H-bridge vector control inverter of induction motor is designed in the paper. Through the improvement of two level vector control model and combining with the corresponding modification of OTS-PWM, the scheme of multilevel vector control system which is suitable for cascaded inverter is obtained. The simulation results shows that the scheme of multilevel vector control model based on cascade inverter has excellent instantaneous torque regulation characteristics and good energy-saving effect and possesses some theoretical significance and potential practical value.Finally, two-level low voltage inverter and one unit cascade H-bridge inverter experimental system based on the main control circuit structure of DSP are built up. The system includes main circuit, control circuit and peripheral measure circuit and so on. The novel OTS-SVPWM technology is realized in this system, and some open loop frequency conversion speed regulation experiments are implemented and the experimental results verify the feasibility of OTS-PWM application in this field.