| Uninterruptible power supply(UPS)which provides high reliability and high quality power supply for the load,has been widely used in medical systems,communication systems,data centers,precision manufacturing industry and other applications.The voltage total harmonic distortion(THD)of UPS inverter is a key technical indicator.It is closely related to the inverter's control loop design,and is also among the difficulties in UPS design.This paper focuses on the design of harmonic suppression loop for UPS inverter;In addition,a simulation method of verifying control software for UPS is also investigated.The first chapter introduces the development of inverter control technology and the verification method of power electronics equipment's control program.In the second chapter,the inverter's harmonic suppression loop structure is first introduced.Then the dynamic model in dqO coordinate system is derived.Based on the derived model,control parameters of the harmonic suppression loop are designed.Finally,a 50kVA three-phase four-wire T-type three-level inverter is built for simulation and experimental study.In the third chapter,a circuit simulation method to verify digital control programs for UPS is investigated.This method uses the C block provided by PSIM to integrate digital control program code into the circuit simulation environment.A program module packaging technique is first exploited to guarantee the maximum program code sharing between the circuit simulation and the practical digital controller.Then a software clock is introduced in simulation to emulate the program execution timing sequence in a real digital controller.A code simulation verification platform for UPS inverter is established.Results of programs running on the simulation platform and the experimental platform are compared. |
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