General High-Order Selective Harmonic Repetitive Control for PWM Converters

In this article, a general high-order selective harmonic repetitive control (HO-SHRC) scheme is proposed, which is composed of a standard high-order repetitive controller structure and a new order-expandable SHRC. Different from conventional SHRC, the proposed new SHRC is capable of being applied into the standard high-order repetitive control (HORC) structure for generating any high-order SHRC. The proposed HO-SHRC can be used to improve the steady-state tracking accuracy of the pulsewidth modulation (PWM) converter systems and is robust to system frequency variations without changing the controller parameters online. The order expansion of the controller will lead to the increase of the implementation complexity, but it will bring the overall improvement of the controller performance, such as the improvement of frequency adaptability, steady-state tracking accuracy, and dynamic performance. Therefore, HO-SHRC can achieve a good compromise between the controller performance and the implementation complexity. Moreover, the proposed HO-SHRC provides a general structure for various repetitive controls (RCs), such as conventional RC (CRC), odd-harmonic RC (OHRC), high-order CRC (HO-CRC), and HO-odd-harmonic RC (HO-OHRC). Application examples of second-order (SO)-6k +/- RC-controlled three-phase PWM inverter show the effectiveness and advantages of the proposed control scheme.