Research On Fractional Order Repetitive Control For Inverter With Experiments

The conventional repetitive control cannot accurately track the input signal when the ratio ofthe system sampling frequency to the desired output frequency is non-integer. The non-integerproblem will also suddenly increase the steady-state error of the output and even disturbe thestability of the system. This thesis introduces the idea of fractional delay, and proposes fractionalorder repetitive control based on Lagrange interpolation together with the optimization of itsparameters.In this thesis, the fractional order repetitive control is applied to the compound control of thesingle-phase full-bridge inverter with bipolar SPWM modulation, where the compound control(both series and parallel structures) is applied to output voltage for the isolated inverter, and thecompound control with series structure is applied to grid current for the grid-connected inverter. Inaddition, this thesis also proposes a design for the adaptive fractional order repetitive control, andapplies the adaptive fractional order repetitive control in the compound control discussed above.In order to verify the effects of the fractional order and adaptive fractional order repetitivecontrol, the simulations with MATLAB and experiments with QuaRC for the isolated andgrid-connected inverter have been done. In the setup of the experimental plateform, the hardwarework mainly includes the optimization of the busbar, IGBT drive and protection circuit, detectioncircuit, and the design of filter parameters. Thanks to the convenience of QuaRC of thehardware–in-the-loop real-time experimental platform, the software work for inverter control israpidly designed and implemented in Simulink.At last, the simulation and experimental results show that the proposed (adaptive)fractional-order RC, where fractional order and adaptive fractional order repetitive controller isput in the compound control of the inverter, significantly improve the performance of theconventional repetitive control, such as the waveform quality of the inverter output and both thestatic and dynamic responses of the inverter system. Besides, the results also show that the seriesstructure is better than the parallel structure, with the fractional order repetitive controller in thecompound control for the isolated inverter.