A novel analysis and design method of phase lead filters in repetitive controllers for pulse-width modulated inverters

Repetitive control strategies have been commonly applied in pulse-width modulated (PWM) inverters for many industrial applications. The phase delay in the overall control system, e.g. the delay caused by the digital duty cycle calculation, PWM generation and the repetitive controller, has to be compensated by elaborately designed phase lead filters in order to prevent control performance deterioration and system instability. Nevertheless, quantificational analysis and practical design of the time advance unit in such filters is hardly to be found in existing literatures. To provide explicit analysis of the phase lead filters, this paper presents a novel design method of the time advance unit in repetitive controllers, which can predict the overall system stability margin and improve the control performance. In order to verify its correctness and effectiveness, the proposed method is simulated with PLECS and implemented experimentally to show the accurate stability margin calculation, as well as excellent steady state performance and dynamic response of the control scheme.