Design And Reliability Evaluation Of A Single-Phase Inverter With Power Decoupling Module

The output of the AC side contains pulsation power at twice the fundamental frequency in single phase converter.The pulsation power delivered to the DC side will demage the DC source and decrease the reliability of the system.Usually,DC-link electrolytic capacitors are installed at the DC bus to decouple the power between the AC and DC side.However,the cost effective and the reliability of the E-caps can not fufill the need of high quality power electronic equipments.Active power decoupling methods can shrink the DC-link capacitance by improving the voltage flucuation with additional power semiconductors,and use the film capacitors instead of the E-caps with higher reliability.However,it's still an open question whether the additional circuits will improve or dacrease the reliability of the whole system,which is the main purpose of this article.The production mechanism of the double line frequency ripple current and the operation priciple of the power decoupling modules are demonstrated based on circuit analysis and mathematical modeling.Meanwhile the parameters,stresses and power losses of main components are caculated.A closed-loop control strategy is proposed based on Boost type power decoupling module and comparisions are made with Buck type power decoupling module with waveform control strategy.The decoupling proformances of each method are compared through simulation results in PLECS,providing a fundamental materials for later reliability researches.The comparative reliabilities and B₁₀ lifetimes of decoupling capacitors in each method are evaluated by losses calulation,thermal model as well as lifetime model.The fluctuation and mean values of the switch junction temperatures in different power decoupling methods can be obtained from PLECS when the losses and thermal model are bulit.Then,the parameter variations of switches are taken into consideration with Monte Carlo method and the reliability comparative study of power devices in each system is analyzed.Comparisons of the accumulated lifetime consumptions are performed in three cases with a mission profile.At last,the comparative study of systematic reliability in three cases is evaluated using RBD?Reliability Block Diagram?method and Weibull distribution.Circuit simulation and thermal simulation of three power decoupling methods are built in PLECS based on single phase inverter,verifying the validity of power decoupling module analysis.Parameters fluctuation of components considered with Monte Carlo analysis and comparative study results of system reliability and B10lifetime with different decoupling methods are made with a mission profile.