Research On Modular Multilevel Converter For Mine Hoist Control

With the rapid development of electrical drive technology,multilevel converter has been widely applied in mine hoist,which has great significance in improving the equipment performance,energy conservation and emissions reduction.With its unique structural advantages,MMC compensates for many shortcomings of the traditional multilevel converter,which is especially suitable for high-voltage high-power occasions.And its application to mine hoist has great development foreground and practical value.This thesis focuses on the research of MMC used in mine hoist control.Firstly,the advantages and disadvantages of three kinds of multilevel converter structures mainly used in mine hoist are compared,and then the pros and cons of MMC are analyzed in comparison to the above three.Meanwhile,the working principle,mathematical model and modulation method of MMC are introduced,and the structure and control methods of the back-back MMC front-end PWM rectifier for hoist control are also studied in this paper.Secondly,the law of capacitor voltage fluctuation of the sub module of MMC is analyzed.The expression of amplitude of capacitor voltage fluctuation,which is obtained by mathematic derivation,reveals the relationship between amplitude of voltage fluctuation,current amplitude and fundamental frequency.And a control algorithm for suppressing low-frequency fluctuation of capacitor voltage is proposed,which suppresses the voltage fluctuation of the MMC low-frequency operation in a reasonable range,and simulates the control algorithm through building model with the Matlab/Simulink.Finally,a three-phase 10 KW MMC experiment Platform for simulating the operation control of mine hoist is designed and constructed,in which the controller adopts the two-level control architecture of DSP and CPLD.The design of system control circuit,the main circuit and sub module circuit are introduced in detail.Simultaneously,the software flowchart of the experimental device for mine hoist control is designed,and relevant experimental waveforms are given.