Research On Internal Model Control Of PWM Rectifiers Based On Virtual Flux

PWM rectifier can provide constant dc bus voltage, low harmonic distortion of the sine currents, bidirectional power flow, and controllable power factor. Because of these features, it is widely used in high-power or high-performance converter frequency conversion device, new energy of power electronics, electric system, industrial control fields, etc. Nowadays, the control of PWM rectifiers are based on accurate mathematical model, and it is difficult to adapt to the variational grid frequency and the unbalance grid amplitude. Therefore, it is a great significance that researching a stable operation PWM rectifier under the unknown environments.The mathematical model is established based on the principle of voltage source convert PWM rectifiers (VSR). Combined with the second-order generalized integrator adaptive filter and frequency-locked loop (named as SOGI-FLL) for virtual flux observer to eliminate the dc component and suppress high order harmonics, track the grid frequency fluctuation to adapt to the unbalanced grid conditions, synchronize the grid vector. The a degree of freedom internal model control is used to decouple current loops. The three degree of freedom internal model control replace PI control to keep dc voltage stable and realize the independent control of follow and resistance to disturbance,The system control block diagram is established based on MALAB simulink platform after combining with SOGI-FLL and IMC for PWM rectifiers control. All results of the analysis through the simulation study of100KVA PWM rectifier are indicated that the research on internal model control of PWM Rectifiers based on virtual flux has a high power factor and a well sine input current, meanwhile, it can resist the changes of load and dc link voltage. Also, the current loop and voltage loop have a good follow performance and dynamic performance.35Charts and78references are supplied.