Research On The Reliability Improvement Of M-type Unit Cascade High-voltage Inverter

With the rapid development of modern power electronics and microelectronics technology,high voltage inverter is widely used in large-scale mining production plants,petrochemical industry,electric power and other industries,to provide power for all kinds of fans,pumps,compressors.High voltage frequency conversion device meets the requirements of energy saving and equipment economic operation,and is the inevitable trend of social sustainable development.Among them,the M type unit cascaded high voltage inverter is a most representative high-voltage frequency conversion device which has been developed in recent years.At present the world famous brands include ABB and SIEMENS are two foreign top brands,domestic also presents the development trend and gradually has the ability to meet as equals the contention of a hundred schools of thought with the world's top brands.Although this inverter has been applied to some extent,because of its complex network topology and large number of components,the fault rate is higher,and it can not be popularized in the production line which has high requirement for the reliability of power supply.Especially the domestic high voltage inverter,the reliability is generally low,because MTBF(Mean Time Between Failure,MTBF)is generally short(usually thousands of hours)can not meet the requirements of some industry operation.Although many domestic manufacturers have made different efforts in a variety of parts made of different improvement has achieved good results,but can not effectively reduce the failure rate of the high voltage inverter system,products in different environments continue to appear different problems.This paper through the analysis and Research on M type unit cascaded high voltage inverter reliability problems,determines Reliability model and allocation method,establishs the reliability design criterion and Combined with some practical experience in project practice,set up reliability trget.Do reliability analysis and reallocation for power unit,control system,power control circuit and other components,so as to improve the reliability of the inverter will ultimately benefits the country can also enhance its social value and manufacturers economic benefits.