Research On The Improvement Of Output Characteristics For Mid-Frequency Inverter

With a smaller size and weight, mid-frequency inverters are more and more to be usedas marine power supply, air supply, but these applications require the inverter outputvoltage with good dynamic and steady-state characteristics.In this paper, to study toimprove the inverter output characteristics, a single-phase400Hz CVCF inverter isdevelopde, and in-depth study of the inverter control technology is the main works.The establishment of the system mathematical model is the basis of the control system.In this paper, using state-space averaging method and linearization techniques,thesingle-phase PWM inverter continuous、discrete mathematical model were established. Atthe same time, four main reasons of inverter out voltage distortion such as the influence ofdead-time, non-linear load, the dc magnetic bias and over-modulation are analyzed.First, Acomprehensive theoretic analyze is carried out on repetitive control, and combined withtypical embedded repetitive control structure,detailed information on each part of system isdescribed. System stability, error convergence rate, steady-state error are discussed.Finally,the design method of repetitive control uesd in single-phase inverter is given out.Thesimulation and experimental results verify: using repetitive control, the inverter outputvoltage steady state characteristics is good, but its dynamic characteristics is poor.Using active damping solution, the inverter can effectively increase the damping,reduce the high resonant peak of inverter under no-load condition.Then, this paper presentsa thought to improve the repetitive control used active damping.Based on comparativeanalysis of different active damping options, the differential voltage feedback activedamping controller design programs is used, and using low-pass filter suppresses highfrequency noise.This paper details the design parameters of the active damping solution,and low-pass filter parameters on the differential compensation effect is discussed, andgives a simplified controller design that the repetitive control only needs a second-orderfilter compensator.The simulation and experimental results show that: to take activedamping to improve repetitive control, both simplify the repetitive control design processand achieve better steady-state output voltage than the traditional repetitive control.In this paper, to improve dynamic performance of the inverter, a complex control technology is used, and the inner is state feedback regulation, the outer is repetitivecontrol.State feedback controller, based on earlier ideas, uses incomplete derivative of thecapacitor voltage to replace the capacitive current, pole placement method to get feedbackparameters. To improve the steady-state voltage accuracy, a integral part in the inner statefeedback is added.Then, the error caused by the sudden change of the load iseliminated.And this method also can simplify the design of repetitive controller, andsimulation and experimental results show that: using the composite controller, the dynamicperformance of single-phase inverter has been significantly improved, especially forcomplex control scheme with integral, the effect is better.