The Research Of Multi-level SVPWM Technology In High-Voltage Inverter

Since AC motor was born in a century,the high-voltage and varible frequencytechnology always was a problem that human hasn’t solved.With the rapiddevelopment of large power electronic device and chip,the high-voltage inverterbecame more widely.The cascaded inverter as the earliest multi-level inverter isbecoming a commanding heights technology in the field of power electronic.Thispaper which takes H bridge cascade inverter as the foundation,gives out "samplingtime staggered space vector modulation"(STS-SVPWM) and researchs and putforward the optimization algorithm in the45°coordination.The paper includes thefollowing contents indetail.（1）The paper firstly gives out the development overview and topology of thepower converter，and put out the most widely used structure of H bridge cascadedmulti-level inverter.Secondly,the common modulation strategies of the H bridgecascaded inverter are introduced respectively,and the paper points out superiority ofmulti-level space vector modulation compared to other technolgy.（2）This paper introduces the principle and modulation technology of the twolevel SVPWM,and give out the advantage of high DC utilization rate and easy digitalrealization.It also analies the internal relation between svpwm technology andharmonic injection spwm technology and gives out the svpwm is actually a variantspwm who based on space vector in3-phase wave injected the regulared wave withzero-sequence component.Similar to the carrier phase-shifted spwm,the paper putforward STS-SVPWM technology,which combine SVPWM with mutiplex technologyand muti-level.The paper also researchs the application of STS-SVPWM in thecascaded inverter.Lastly,some simulations are made to prove that STS-SVPWM canachieve high-switch frequency effect in low switching frequency and has a goodharmonic characteristic.（3）This paper makes research on simplified space vector modulation and itsperformance optimization in45°coordinate system.Because it needs to sample theinverter output voltage in every sampling period for HBCMI in simplified spacevector modulation, the single voltage vector modulation method can be changed toimprove the inverter’s output performance in each sampling period.This paper finally makes engineering design for the application of HBCMI in the field of high voltage variable frequency.The paper can promote the very goodindustrial application prospect in high voltage variable frequency areas.