Hybrid iterative learning control strategy for single‐phase UPS inverter using inductor current active damping

Abstract

This study proposes a hybrid iterative learning (HIL) control scheme for single-phase uninterruptible power supply (UPS) inverters using inductor current active damping technique. A UPS inverter maintains a tightly regulated output voltage independent of loading conditions and disturbances. To achieve such performance, a fast transient recovery time with a minimum steady-state error is desired. Fast control techniques, such as proportional integral (PI), are not always known for good steady-state performance in single-phase applications. As the load voltage and current are periodic, therefore a hybrid control strategy has been proposed in which a PI controller is combined with an iterative learning controller to produce better transient and steady-state dynamics. Adoption of such a strategy enables the UPS inverter control to be realised with one voltage and one current sensor, respectively. System modelling, filter magnitude-frequency characteristics shaping and control design with stability analysis have been presented in this study. The designed HIL control strategy is examined through simulations in a MATLAB environment in the discrete time frame and experimentally verified for a single-phase UPS inverter system prototype using a Texas TMS320F2812 digital signal processor.