Application of repetitive control for removal of harmonic distortions from inverter output

Abstract: Partial table of contents: Overview of Power Semiconductor Switches Computer Simulation of Power Electronic Converters and Systems GENERIC POWER ELECTRONIC CIRCUITS dc--dc Switch-Mode Converters Resonant Converters: Zero-Voltage and/or Zero-Current Switchings POWER SUPPLY APPLICATIONS Power Conditioners and Uninterruptible Power Supplies MOTOR DRIVE APPLICATIONS dc Motor Drives Induction Motor Drives Synchronous Motor Drives OTHER APPLICATIONS Residential and Industrial Applications Optimizing the Utility Interface with Power Electronic Systems SEMICONDUCTOR DEVICES Basic Semiconductor Physics Power Diodes Power MOSFETs Thyristors Emerging Devices and Circuits PRACTICAL CONVERTER DESIGN CONSIDERATIONS Snubber Circuits Gate and Base Drive Circuits Design of Magnetic Components Index

Abstract: A novel repetitive controller directly combined with an open loop SPWM inverter is presented in this paper. To cope with the high-resonant peak of the open loop inverter that may cause instability, a zero-phase-shift notch filter other than the inverse transfer function of the inverter or a conventional second-order filter is incorporated in the controller. The proposed method has good harmonic rejection and large tolerance to parameter variations. To further reduce the steady-state error, a low-pass-filter Q(z) algorithm is applied. The DC bias problem is also taken into consideration and solved with the repetitive controller itself. The method is implemented with a digital signal processor and achieves low THD% (1.4%-1.7%) with nonlinear loads and fast error convergence (3-5 fundamental periods). It proves to be a cost-effective solution for common UPS products where high-quality output voltage is more stressed than fast dynamic response.

Abstract: This paper presents an enhanced control strategy which consists of a proportional-integral controller and a repetitive controller (RC) for improving the voltage performance of distributed generation (DG) under nonlinear load conditions. The proposed voltage controller is able to maintain a sinusoidal voltage at the point of common coupling (PCC) of the DG regardless of the harmonic voltage drop in the system impedance due to nonlinear load currents. In addition, by employing the delay time of the RC at one-sixth of the fundamental period, the proposed RC can overcome the slow response drawback of the traditional PI-RC. The proposed control strategy is analyzed and the design of the RC is presented in detail. The feasibility of the proposed control strategy is verified through simulation and experimental results.