On Repetitive Control Strategies For SPWM Inverters

Constant voltage constant frequency sine pulse width modulation (CVCF SPWM) inverter is widely used in Power Electronic Systems. There are a large number of periodic harmonics in the output waveform of inverter because of the sinusoidal reference signal. In order to improve the quality of the inverter control, it's necessary to reduce the output waveform distortion. This made the higher requirements for the control. Repetitive control system performance can get continous improvement with the process of repetition, and is suitable for duplicate operating characteristics (such as the inverter) of the controlled object.These major results achieved here as follows:1. Proposed quarter-period repetitive control methods. By analyzing the symmetry properties of the signal disturbance and introducting the ideal error dynamics equation, quarter-period repetitive controller for 2-order AR system is given in detail when the disturbance signal is sinusoidal, and extended to the N-order AR system. Numerical simulation results demonstrate the effectiveness of the algorithm.2. Unipolar modulation of single-phase full-bridge voltage inverter model is established; the continuous time transfer function, continuous time state space model, discrete time state space model are established respectively for single-phase inverter. Four-parameter model for single-phase inverter is given; quarter-period repetitive controller is designed for the model. Numerical simulation shows its effectiveness.3. Establish the mathematical model of three-phase inverter using the Clarke transform for decoupling, and turn it into two mutually independent single-phase inverter models. Bipolar modulation of single-phase mathematical model of the inverter is established, the model of the inverter in discrete time state space is derived, and the five parameter model of single-phase inverter is given. Improve various controllers mentioned above paragraphs proposed for four-parameter model to make it also applies to five-parameter model. Numerical simulation results are given to verify. 4. Design a single-phase inverter hardware, select a DSP TMS320F2812 as the controller. The various control strategies mentioned above are written to the software program. Convntional feedback control, deadbeat control, deadbeat repetitive control, quarter-period repetitive control strategies are simulated and experimental for verification. The results show that the quarter-period repetitive control is effective in suppressing periodic disturbance.