Research On Low Harmonic Output Frequency Conversion Technology For High Speed Motor

Research on high-speed motors is currently becoming a research hotspot in the field of international electrical engineering.High-speed motors can directly drive high-speed loads,avoiding losses caused by intermediate mechanical transmissions,and improving the operating efficiency of the entire system.Due to its high speed,the speed per minute can reach tens of thousands of revolutions or even hundreds of thousands of revolutions.High-speed motors have high power density and are much smaller in geometry than medium-speed and low-speed motors of the same output power level,thus saving material and reducing costs.The high-speed motor is generally powered by the inverter.Due to its high-speed and high-frequency characteristics,the high-speed motor current has large harmonics and damage to the motor.Therefore,high-speed motor harmonic suppression has become a hot research topic.This thesis mainly uses five-level inverter as the core,auxiliary filter circuit,builds high-speed motor harmonic suppression control system,and finally realizes high-speed motor harmonic suppression,so that the high-speed motor stator current is closer to sinusoidal.Firstly,the characteristics of high-speed motor are analyzed,and the mathematical model is established.The topology of ANPC five-level converter is studied.The structural characteristics of the topology and the eight switch state relationships corresponding to five levels of output are analyzed.The midpoint potential is analyzed in essence.Fluctuation;build a high-speed motor control system based on filter circuit,analyze the amplitude-frequency characteristics of high-speed motor and calculate the parameters.Secondly,the ANPC five-level inverter SVPWM technology is deeply studied.According to the characteristics of ANPC five-level inverter and its space vector model,an SVPWM control algorithm based on line voltage coordinate system is studied to simplify the solution process of basic vector corresponding action time,optimize the calculation method of basic vector,and analyze the five level.The 10 kinds of capacitor charge and discharge circuits formed by the inverter in 512 switch combination mode,and the space voltage vector table is established according to the characteristics of different loops.By looking up the table,we can see the influence of 125 space voltage vectors on the midpoint potential.On this basis,a midpoint potential balance control strategy based on SVPWM technology is proposed,and the effectiveness of the strategy is verified by simulation under different modulation degrees.Finally,the simulation of harmonic suppression control of high-speed motor inverter is carried out.The comparison between the stator current of high-speed motor and the stator current of high-speed motor when adding filter is proved.The feasibility of the filter circuit is proved,and under different modulation degrees.The midpoint potential control is carried out to prove the effectiveness of the proposed control method.At the end,the stator current of the high speed motor is verified under different modulation degrees,which proves the accuracy of the high speed motor harmonic suppression control system.