Research On Repetitive Control And Dual-loop Control Technology For Single-phase Inverters

The output waveform correction technology of single-phase PWM inverter is studiedin this dissertation. High quality waveform has two characteristics. It has not only nicestatic characteristic but also well dynamic response. Aiming at these characteristics,repetitive control technology and dual-loop control technology is analyzed. Both thesecontrol scheme are verified by simulation and experiment. Assuming the load is resistive or taking the current of load as disturbance input,continuous state-space model and discrete state-space model of inverter are established. Aprecise simulation model taking into account dead-time effect is also established withMATLAB software. These models are the bases of farther analysis. It is analyzed thatcausing the waveform distortion including dead-time effect and load disturbing. Essentialityof the waveform correction technology is pointed out. Repetitive control technology is arising from the internal model principle. It's acompensate control technology which base on period. It can entirety eliminate thedistortion of waveform. For the limitation of itself, repetitive control cannot get welldynamic response. The ways of design is given by an example. Stability analyze is carriedout on repetitive control system. Instantaneous feedback control can improve dynamic response of inverter. While,repetitive control can improve static characteristic of inverter. It can get better waveform,incorporating instantaneous feedback control with repetitive control. Two structures arestudied, either state feedback pole-assignment control is in series or PD control is inparallel with repetitive control. Experiments prove that it can get very nice staticcharacteristic and well dynamic response. It's complex on algorithm that incorporating instantaneous feedback control withrepetitive control, and repetitive control occupy many memorizers which increase the costof hardware. For this reason, dual-loop control is presented, and the performance of variousstructures of dual-loop is compared. In order to simplify hardware system and improve theperformance of digital control system, state-observer and disturbance observer is presented.Finally, a dual-loop control scheme, inductor current feedback with decoupling statefeedback and disturbance decoupling, is proved by simulation and experiment.Experimental results accord with theoretic analyze, and it can get nice static characteristicand well dynamic response.